Health

Fanconi Syndrome

Understanding Fanconi Inheritance Through Breeding

As a breeder, we are here to create healthy, happy puppies. This was created so that when Breeding, we can avoid Fanconi Affliction.

It is not complicated rocket science, it’s simple genetics and here it is explained in simplex form.

Fanconi is a disease known as a “simple recessive” gene. With these, every dog receives one gene from each parent. The following “Punnett Squares” show what could be produced with every possible breeding due to the genetic makeup of its parents.

You can learn more about the Fanconi Linkage test and FAQs on the basenjihealth.org site.

For all basic purposes, we will use the following notations/abbreviations: N=Normal, or “unaffected” with the gene. N=abnormal or “affected” with the gene

N – CLEAR( Normal Parent not affected with the mutant Fanconi gene)

Nn-CARRIER ( A Parent which carries the Gene)

nn- AFFECTED (a parent which is affected with the abnormal/mutant gene.

The percentages seen below indicate the likelihood or chance that EACH puppy in that litter will have at being Clear, Carrier, or Affected with Fanconi Syndrome.

Some people will tell you that those percentages mean that is how many from each litter will be clear, carrier, or affected.

THAT IS WRONG!! Genetics of a simple recessive is based on probability or chance.

How Punnett Squares work:

Each dog has 2 letters in which explain which gene they carry [as described above by example, NN is our example for normal] but technically speaking, a capital letter is used for a good or dominant trait. A lowercase letter is used for a bad or a recessive trait (recessive is not always bad. Tri colored is recessive in Basenjis) and then 1 upper letter and 1 lowercase letter is usually used to explain carriers of a trait but are not affected themselves by the trait they carry. So a blind carrying dog is not blind itself although it can pass it down to its children if bred to the wrong mate)

One of each “letter” (these are the genes) from each parent goes into each “square.” Shown above.

The four squares represent the probability, or chance, that the offspring has of getting the desired (or non-desired) trait.

For each square, the chance or probability is equal to 25%. So you add each one by how many times it appears.

So the AA appears one time. Meaning there is only 25% chance that the offpring will be That gene. The Aa appears twice, which means the offspring have 50% chance of having that gene. And the aa appears once so the offspring have a 25% chance of having that gene as well.

How Punnett Squares Work

	A \| V	A \| V
A —>	AA	AA
a —->	Aa	Aa

1. Each dog has 2 letters in which make up a particular gene which they carry [as described above by example, NN is our example for normal]

2. One of each of these“letters” (these are the genes) from each parent goes into each “square.” Shown above. (arrows show how to read it)

The four squares represent the probability, or chance, that the offspring has of getting the desired (or non-desired) trait.

For each square, the chance or probability is equal to 25%. So you add each one by how many times it appears.

So the “AA” appears one time. Meaning there is only 25% chance of that offpring having that gene. The “Aa” appears twice, which means the offspring have 50% chance of having that gene. And the “aa” appears once so the offspring have a 25% chance of having that gene as well.

Technically speaking:

A capital letter is used for a good or dominant trait (Tho dominant is not always good.)

A lowercase letter is used for a bad or a recessive trait (**tho recessive is not always bad)

and An upper and lowercase letter is usually used to explain carriers of a trait they are not affected by. (*** A carrier example)

* Ex: Dominant bad chests because of to many strong bad chested breedings and is undesirable.

** Ex: Tri colored is recessive in Basenjis but this is not a bad trait

*** Ex: A dog carries the blind gene but never becomes blind itself, (Carrier)

So now that you understand punnet squares,

Lets get into our chances/probabilities using our original Letters.

NN = CLEAR, Normal
Nn = CARRIER, Carries 1 Mutant Gene

nn = AFFECTED, Has both mutant genes and the disease

SAFE BREEDING PAIRS and Acceptable breedings

The following breeding combinations are the ONLY breedings that are recommended by the BCOA Health Committee.

If a breeder tells you otherwise, go somewhere else for a puppy.

There is absolutely NO BREEDING– that gives you even the smallest chance of producing Fanconi affected puppies– that would be worth doing the breeding and taking the risk.

FANCONI CLEAR to a FANCONI CLEAR

	N	N
N	NN	NN
N	NN	NN

EACH PUPPY from this litter

has a 100% Chance of being Fanconi CLEAR, or normal.

because all puppies show NN (which is normal) for the gene.

THIS IS AN ACCEPTABLE BREEDING

FANCONI CLEAR to a FANCONI CARRIER

	N	n
N	NN	Nn
N	NN	Nn

EACH PUPPY from this litter

has a 50% Chance of being Fanconi CLEAR, or normal.
has a 50% chance of being Fanconi CARRIER,(able to pass to children)

THIS IS AN ACCEPTABLE BREEDING

FANCONI CLEAR to a FANCONI AFFECTED

	n	n
N	Nn	Nn
n	Nn	Nn

EACH PUPPY from this litter has a 100% chance of being Fanconi CARRIER, (Able to pass to kids)

THIS IS TECHNICALLY AN ACCEPTABLE BREEDING

WHY CHANCE THE LIFE OF A SWEET PUPPY??

UNSAFE BREEDING PAIRS – DO NOT BREED THESE

FANCONI CARRIER to FANCONI CARRIER

	N	n
N	NN	Nn
n	Nn	nn

EACH PUPPY from this litter

has a 25% Chance of being Fanconi CLEAR, or normal.
has a 50% chance of being Fanconi CARRIER, (Able to pass to kids)
has a 25% chance of being Fanconi AFFECTED, (Has the disease)

THIS IS NOT A GOOD BREEDING

FANCONI CARRIER to FANCONI AFFECTED

	n	n
N	Nn	Nn
n	nn	nn

EACH PUPPY from this litter

has a 50% chance of being Fanconi CARRIER, (Able to pass to kids)
has a 25% chance of being Fanconi AFFECTED, (Has the disease)

THIS IS NOT A GOOD BREEDING

FANCONI CARRIER to NON TESTED

	?	?
N	N?	N?
n	n?	n?

EACH PUPPY from this litter

has a 25% Chance of being Fanconi CLEAR or CARRIER.

has a 25% chance of being Fanconi AFFECTED, (has the disease). The rest of the probability is unknown.

THIS IS NOT A GOOD BREEDING

UNTESTED FANCONI to UNTESTED FANCONI

	?	?
?	??	??
?	??	??

Each puppy from this litter has the chance of receiving anything…

The genetic makeup is completely unknown. Fanconi syndrome could affect All, any, or none of the puppies.

THIS IS NOT A GOOD BREEDING…

Better to play Roulette in Las Vegas!!

Fanconi Carriers

A Fanconi Carrier Basenji makes just as good of a companion as a Clear Basenji does, so do not be misled that you cannot have them as a pet. They are not themselves suffering from the disease and are not affected by the gene that causes the mutation, they simply carry/possess the gene.

Knowing the results of a Fanconi Carrier Basenji is mostly important when they are being used in breeding programs and being purchased as show potential. This is because they carry the gene that causes the affliction, which means it can be passed down to offspring. Proper health testing is important for a Fanconi Carrier breeder because if bred to the wrong partner, some or all of the PUPPIES can become affected with Fanconi syndrome. A FANCONI CARRIER BASENJI SHOULD NEVER BE BRED TO ANYTHING OTHER THAN A FANCONI CLEAR DOG.

But having a carrier as a pet does not harm anyone or anything because pets are spayed or neutered and there is no chance/fear of passing the mutation down to their puppies.

What matters is that the puppy is FREE from Fanconi Syndrome and that they are not Afflicted/Affected with Fanconi during their lifetime.

There is absolutely no reason to buy a puppy from a breeder that is not following the recommended breeding practices set forth by the BCOA (Basenji Club of America) Health Committee.

Breeding against these practices is not only irresponsible but it is NOT fair to the resulting puppies and their new owners!

PLEASE ask about other diseases that can affect your Basenji. PRA and HIP DISPLAsIA are not simple recessive diseases therefore they do not follow the above probabilities. BUT there is absolutely no reason to breed a Basenji that is AFFECTED with PRA or HIP DISPLASIA.

Anyone telling you otherwise is irresponsible in their breeding practices.

For info on Fanconi and how Amore Basenji’s Strives to produce only puppies that will NEVER become afflicted with this disease, please contact Whitney at mspodhradsky@gmail.com

BCOA Explains Fanconi:

Fanconi Synrdome:

Fanconi syndrome is a late-onset kidney problem that, at the time of discovery of the DNA test, was determined to occur in approximately 7% of all Basenjis. The incidence since then appears to be dropping rapidly. Untreated, the problem is fatal; with treatment, which consists of bicarbonate and other supplements, dogs with the disorder have a nearly normal lifespan.

A DNA marker test, which looks at multiple markers, was used from 2007 to August 2011. Dogs tested using this test have OFA results which are listed as “probable” results. The current direct DNA test, introduced in August of 2011 and available through OFA, gives definitive results.

For more information about this test click Direct Fanconi Syndrome DNA Test FAQ.

Fanconi is a disorder in which the kidney does not properly reabsorb electrolytes and nutrients back into the body, but instead “spills” them into the urine.

Symptoms include excessive drinking (polydipsia), excessive urination (polyuria), and glucose in the urine (glucosuria.) If Fanconi is left u

ntreated, muscle wasting, acidosis, and poor condition will also occur.

The onset of inherited Fanconi is typically between four and eight years of age, although onsets as early as three years and as late as ten years have occurred.

Untreated, a Basenji with Fanconi syndrome will generally die from the disorder. If caught early and put on the treatment protocol, affected Basenjis can do well. Studies indicate that dogs on the treatment protocol have a lifespan statistically similar to unaffected dogs.

For the Owner

Owners should insist that at least one parent of any puppy they purchase be tested “Probable clear” for Fanconi, unless the pup itself has been individually tested and was not tested “Probable Affected.” While not a guarantee of health, studies to date indicate that dogs with one or both parents tested probable clear are very unlikely to develop the disorder.

Owners should periodically “strip test” their dogs for glucose in the urine, starting at age 3. Presence of glucose in the urine suggests the need for further testing to determine if the dog has Fanconi. This is especially important if the dog does not have a tested probable clear parent. In that case, monthly testing is generally suggested.

Urine glucose test strips (not blood test strips), such as those used by diabetics, are inexpensive and can be purchased at most pharmacies. The strip should be placed in the Basenji’s urine stream and then read as specified in the strip instructions. If it is not possible to place the strip in the urine stream, then the owner may need to catch the urine. Some owners use a pie pan, ladle, or serving spoon.

A positive result (glucose present) suggests the possibility of Fanconi, but is not sufficient for definitive diagnosis. Owners should then go to their vet for further testing, which would normally include a blood glucose level. Strip testing indicates only the current presence or absence of glucose in the urine. It does not diagnose Fanconi and it is valid only on that day. A dog that test strips normal now may later develop Fanconi. Because elevated urine glucose is also found in diabetes, Basenjis with Fanconi are often misdiagnosed with diabetes. Diabetes will show high blood glucose along with urine glucose. In Basenjis, a combination of urine glucose and normal or low blood glucose strongly suggests Fanconi syndrome. Venous blood gas studies can verify an electrolyte imbalance consistent with Fanconi syndrome. A veterinarian should evaluate dogs that have Fanconi symptoms but are not spilling sugar.

Pets can be DNA tested to verify a Fanconi diagnosis or to help assess their likelihood of coming down with Fanconi. However, even if your dog is DNA tested clear or carrier, you should still strip-test, as there is a small risk of error with the linkage DNA test and a small number of false positives and false negatives have occurred.

Work is continuing on a direct DNA test for Fanconi syndrome, which will test for the actual mutation. This will increase test accuracy.

More detail is given on the page for Fanconi Test FAQ.

For Breeders

Breeding stock should be DNA tested for Fanconi. The linkage marker DNA test for Fanconi is available through the Orthopedic Foundation for Animals at and all test results are in the searchable open database on that site.

The test can determine if a dog is a carrier, clear, or affected with a high degree of accuracy, and can predict that a dog will become affected prior to the development of symptoms.

Any planned Basenji litter should have at least one parent that tests probable clear, to minimize the chance of producing affected puppies.

More detail is given on the page for Fanconi Test FAQ.

Additional Information

Current OFA statistics are available online at OFA website — just highlight Basenji and click Search. Percent normal are dogs that are neither carriers nor affected. Percent abnormal is the same as percent affected.

For DNA tests, if you take 100, subtract the % percent normal, and subtract the percent affected, you will get the percent that are carriers, equivocal, or indeterminate.

Note that all percentages are cumulative. For Fanconi, the percentage affected of newly tested dogs is lower than the cumulative average, because the higher original incidence is averaged with the lower new incidence.

Treatment

In 1990 Dr. Steve Gonto developed a treatment protocol for dogs with Fanconi, based on the treatment human Fanconi patients receive. The protocol uses dietary supplements for acid neutralization and replacement of lost electrolytes and nutrients. This is accomplished with bicarbonate and other supplements in specified doses to re-establish the body’s acid-base balance and keep electrolytes at appropriate levels. Dr. Gonto was given lifetime membership in the Basenji Club of America in recognition of the importance of his work.

The Gonto protocol was studied and validated for the veterinary literature by Jennifer Yearley, DVM, while she was completing her professional studies. This was an important step in expanding the awareness of the treatment. The protocol has been very successful in improving both quality and length of life for Fanconi-affected Basenjis. The disorder can be controlled by the protocol, but it cannot be cured.

The Fanconi Protocol can be downloaded HERE.

http://www.basenji.org/joomla/index.php?option=com_content&view=category&layout=blog&id=155&Itemid=292#FS

As described by Khani’s Basenjis. http://khanisbasenjis.com/fanconi.html Slightly revised to help me better understand and hopefully you too

Progressive Retinal Atrophy (PRA)

Progressive Retinal Atrophy (known as PRA)

Canine Genetics and Epidemiology Explains:

http://www.cgejournal.org/content/1/1/3

Progressive retinal disorders

Progressive retinal atrophy (PRA) and cone-rod dystrophy (CRD) are collective terms for two broad forms of progressive, bilateral degenerative diseases that affect the retinal photoreceptor cells.

Progressive retinal atrophy

In general, PRAs are characterized by initial loss of rod photoreceptor function followed by that of the cones and for this reason night blindness is the first significant clinical sign for most dogs affected with PRA. Visual impairment in bright light invariably follows, accompanied by characteristic changes to the fundus that are visible upon ophthalmoscopic investigation. Typical changes include attenuation of the blood vessels of the retina, increased reflectivity of the tapetal layer as a result of retinal thinning and atrophy of the optic disc. In many dogs secondary cataracts develop, which might become extensive enough to obscure the retina and require the use of electroretinography (ERG) for diagnosis. Whereas most dogs show the same ophthalmoscopic abnormalities the age at which these abnormalities develop varies considerably between breeds and genetically different forms of PRA can be broadly divided into early- and late-onset forms.

Early-onset forms of PRA

Early onset forms of the disease are typically expressed between 2 and 6 weeks of age, the period of postnatal retinal differentiation in dogs, and are characterized by the abnormal development of the rod and cone photoreceptors. Four well-characterized, genetically distinct forms of autosomal recessive, early-onset retinal degeneration are rod-cone dysplasia type 1 (RCD1), rod-cone dysplasia type 2 (RCD2), rod-cone dysplasia type 3 (RCD3) and early retinal degeneration (ERD) [1]. RCD1, which affects Irish Setters from approximately 25 days after birth and culminates at about 1 year when the population of rods and cones is depleted, is caused by a nonsense mutation at codon 807 of the gene encoding the beta subunit of cGMP phosphodiesterase (PDE6B), an essential member of the phototransduction pathway [2]. This mutation was the first responsible for any form of PRA to be identified in the dog. An 8 base pair (bp) insertion after codon 816 in the same gene causes a genetically distinct form of PRA in the Sloughi which has a later age of onset than the Irish Setter form, with the first signs of visual impairment not being noticed until dogs are between 2 and 3 years of age [3]. PRA in the Cardigan Welsh corgi, termed rod-cone dysplasia 3 (RCD3), is also caused by a mutation in a subunit of cGMP phosphodiesterase, this time the alpha subunit, which results in a disease with a comparable age of onset to RCD1 [4]. In RCD3 affected dogs normal rod-mediated ERG responses fail to develop, photoreceptor outer segments do not reach maturity and rod cells are lost by apoptosis [5]. The genetically distinct RCD2 segregates in rough and smooth collies [6] and is caused by an insertion in RD3 that results in a stretch of altered amino acids and an extended reading frame [7]. Mutations in RD3 have been associated with retinal degeneration in both humans and mice[8].

Whereas the early onset forms of PRA, RCD1 and RCD3, described above, were among the first canine inherited diseases to be characterized at the molecular level, the mutation responsible for the similarly early onset condition ERD (early-onset degeneration) has only recently been identified. This condition, which was originally described in Norwegian Elkhounds [9], and was first mapped more than 10 years ago [10] is caused by an exonic SINE insertion in the gene STK38L[11]. Although known to have neuronal cell functions STK38L has not previously been associated with abnormal photoreceptor function; being associated with such a disease in dogs establishes this gene as a potential candidate for similar diseases in other species, including man.

A different form of early-onset PRA affects Miniature Schnauzers. Histologically this disease is evident from a very early age, when the normal retina is nearing the end of postnatal differentiation, and as it affects both rods and cones it is termed photoreceptor dysplasia (PD) [12]. This disease was originally associated with a missense mutation in phosducin (PDC) [13]. However additional research has since led to the complete exclusion of phosducin and to the identification of the gene and mutation that do in fact cause this disease, that is also known as Type A PRA [14]. Evidence suggests that Type A PRA is in fact a rare form of PRA in the Miniature Schnauzer and that other, genetically distinct forms of PRA segregate within the breed, for which the mutations have yet to be identified [14].

Recently a complex mutation, consisting of the combination of a one basepair deletion and a 6 basepair insertion was identified in exon 26 of CNGB1 in Papillons with an early onset PRA. The mutation leads to a frameshift and a premature stop codon. Affected dogs demonstrated an early lack of rod function followed by a slow retinal degeneration, a phenotype comparable to mice and humans with CNGB1 mutations [15]. CNGB1 combines with CNGA1 to form the rod cyclic nucleotide gated channel. Previous studies have shown the requirement of CNGB1 for normal targeting of CNGA1 to the rod outer segment [16] and indeed the authors were able to demonstrate a lack of detectableCNGA1 protein in the rod outer segments of the affected Papillons homozygous for the mutation [15]. The same mutation was also described in Phalene dogs by Ahonen and collegues [17].

The early onset forms of PRA described above are all caused by mutations in autosomal genes. In contrast, a mutation in the X-linked retinitis pigmentosa GTPase regulator gene (RPGR) causes a very severe form of PRA, known as XLPRA2, that has been described in mixed breed dogs [18]. The XLPRA2 mutation is a 2 nucleotide deletion that results in a frameshift that significantly changes the predicted peptide sequence by leading to the replacement of many acidic glutamic acid residues with basic arginine residues and results in the premature termination of the protein 71 amino acids downstream. Unlike the genetically distinct, relatively late onset XLPRA1 that is described below, the phenotype associated with the frameshift mutation in XLPRA2 is very severe and manifests during retinal development. ERG abnormalities are evident by 5–6 weeks of age and cell degeneration is present by 4 months, suggesting the mutant protein has a toxic gain of function that severely compromises the early stage of development of the photoreceptors.

Late-onset forms of PRA

The late-onset forms of PRA are degenerations of photoreceptors that have completed normal development. Whereas the genes implicated in early-onset diseases are those necessary for the correct development of photoreceptors the genes associated with later-onset forms of disease are those necessary for the long-term maintenance and function of these cells.

Progressive rod cone degeneration (PRCD) is a late-onset form of PRA that affects multiple breeds. Prior to characterization of this disease at the molecular level, elegant interbreed crosses were undertaken to determine that the phenotypically similar diseases that were segregating in multiple breeds, including the miniature poodle, the English and American cocker spaniels, the Labrador retriever, the Australian cattle dog, the Nova Scotia duck tolling retriever and the Portugese water dog, were in fact allelic [19,20]. However, when PRCD-affected dogs were mated to PRA-affected dogs of the Border Collie, Basenji and Italian greyhound breeds the progeny were normal, indicating these breeds are affected by genetically distinct forms of disease. The PRCD locus was mapped to a large region on CFA9 in 1998 [21] before the canine genome sequence was available and while tools with which to investigate the canine genome were relatively unsophisticated. However, the fact that a genetically identical disease segregated in so many breeds proved to be invaluable as it allowed the use of linkage disequilibrium mapping across affected breeds to considerably narrow the PRCD-associated region [22]. This led to the eventual identification of a single nucleotide substitution in the second codon of a previously unknown gene that is now known to be the cause of PRCD in at least 18 different breeds [23]. Intriguingly, an identical homozygous mutation was identified in a human patient with recessive retinitis pigmentosa, the human equivalent of PRA, and established the novel retinal gene, PRCD, as an important gene for the maintenance of rod photoreceptor structure and function across species.

A genetically distinct, late onset PRA has been described in the English Mastiff. This disease is unique, to date, among canine inherited retinopathies in that it is inherited as an autosomal dominant disease, and is caused by a single non-synonymous C → G transversion at nucleotide 11 of rhodopsin (RHO) that changes Thr-4 to Arg (T4R). Dogs carrying the RHO mutation have normal photoreceptor-specific ERG function at 3 to 6 months of age but by 13 months these responses are abnormal. In young affected dogs retinal structure, rhodopsin expression and photoreceptor activation is normal; disease progression is characterized by regions of initial focal photoreceptor degeneration surrounded by areas of structurally normal retina, which interestingly is very similar to the phenotypes of humans with RHO mutations [24]. A characteristic component of the phenotype associated with T4R mutation is the dose–response relationship that has been demonstrated between light exposure and the early alterations in retinal tissue that occur in affected animals. Highest doses of light cause rapid loss of neurons, reaching complete degeneration of photoreceptors in < 4 weeks whereas the lowest doses of light exposure enable mechanisms acting over a time scale of weeks to months to repair the abnormal alterations resulting from neuronal stress [25]. This mutation, originally identified in the English mastiff, has also been identified in PRA-affected bull mastiffs but has not been identified in any other breeds to date [26].

A different late onset form of autosomal recessive generalised PRA has been described in Schapendoes where the age of onset is typically between 2–5 years. During the early stages of the disease affected dogs become night-blind, lacking the ability to adjust their vision to dim light; later their daytime vision also fails. This process of complete photoreceptor degeneration takes up to 2 years [27]. The causal mutation for the disease has been shown to be a single bp insertion in exon 6 of the recently discovered gene coiled-coil domain containing 66 (CCDC66) that leads to a stop codon. CCDC66 is evolutionarily conserved in different vertebrate species and exhibits a complex pattern of differential RNA splicing resulting in various isoforms in the retina. Immunohistochemically, CCDC66 protein is detected mainly in the inner segments of photoreceptors in mouse, dog, and man although the retinas of affected Schapendoes have been shown to lack CCDC66 protein [28].

A different mutation in RPGR from that associated with XLPRA2 (described above) is responsible for a sex-linked form of late-onset form PRA that was originally described in the Siberian Husky [29] known as XLPRA1. The mutation, which has also been identified in the Samoyed, is a five nucleotide deletion that causes a frameshift and an immediate premature stop; the truncated protein lacks 230C-terminal amino acids which causes a slight decrease in the isoelectric point [18]. The photoreceptors of dogs that carry this mutation develop normally, in contrast to those of dogs with XLPRA2, and remain morphologically and functionally normal until young adulthood, indicating the C-terminal of the RPGRprotein is not essential for functional and structural differentiation of rods and cones.

Recently a frameshift mutation was identified in C2orf71 that causes an autosomal recessive form of late onset PRA in the Gordon and Irish Setters [30]. The average age of onset in the dogs studied was approximately 10 years of age. This variant was homozygous in 19 of 21 PRA cases and was at a frequency of approximately 0.37 in the Gordon Setter population. Approximately 10% of cases in this study (2 of 21) were not associated with the C2orf71 mutation, indicating that PRA in this breed is genetically heterogeneous and caused by at least two mutations. This variant is also present in a number of Irish Setter dogs with PRA and has an estimated allele frequency of 0.26 in the breed. The function of C2orf71 remains unknown, but it is important for retinal development and function and has previously been associated with autosomal recessive retinitis pigmentosa in humans [31–34]. The form of PRA associated with the mutation in C2orf71 has been termed RCD4, for rod-cone degeneration 4, to distinguish it from other forms of rod-cone degeneration [30]. The mutation has also been found in Tibetan Terriers affected with PRA (Mellersh and Downs, unpublished).

All the progressive, late-onset retinal disorders described behave, more or less, as single-gene conditions, caused by highly penetrant mutations. There is, however, some evidence that environmental modifiers may play a role in some of these diseases, causing phenotypic variation between and within breeds [20].

Cone-rod degenerations

Cone-rod dystrophies are disorders predominantly of cones, with rods becoming affected later. CRDs have ophthalmoscopic changes that are very similar to those of PRA and detailed ERG studies that measure both cone and rod-specific responses are required to distinguish between the two types of condition. For this reason several disorders have been initially described as PRAs to be later re-classified when extensive ERG investigations have been undertaken.

One such disorder is a form of retinal degeneration that has been described in the Miniature longhaired dachshund (MLHD). The disease was originally described as an early-onset, autosomal recessive PRA with all affected dogs within an inbred research colony displaying ophthalmologic abnormalities that were detectable by ERG by six weeks of age and 25 weeks by fundoscopy and becoming blind by the time they were 2 years of age [35]. A subsequent electroretinography study identified an initial reduction of the cone photoreceptor function which led to the condition being re-classified as a cone-rod dystrophy (CRD), rather than a rod-led PRA, and the disease was termed CORD1 for cone-rod degeneration 1 [36]. The same condition has also been referred to as CRD4 by others, for cone-rod degeneration 4 [20]. Later findings by Lheriteau and co-workers were also consistent with the condition being a CRD [37]. Using the same colony of dogs CORD1 was mapped to a large region on CFA15 and a mutation in RPGRIP1 was identified that co-segregated completely with CORD1 in the research colony [38]. The mutation is a 44 bp insertion of a A29 tract flanked by a 15 bp duplication in exon 2 of the gene, that creates a frameshift and introduces a premature stop codon early in exon 3. Mutations in RPGRIP1 have been associated with Leber congenital amaurosis (LCA) [39], retinitis pigmentosa (RP) [40] and CRD [41] in humans, as well as inherited retinal abnormalities in mice [42] which suggests it plays an important role in visual function. The gene product’s precise role is not currently understood but it is thought to anchor regulatory complexes at the photoreceptor connecting cilium, which acts as a bridge between the inner and outer segments of photoreceptor cells [43] as well as having functions in disk morphogenesis [42] and in the structure of the ciliary axoneme [44]. RPGRIP1 also interacts with NPHP4, a gene that has been associated with a genetically distinct form of early-onset CRD segregating in the standard wire-haired variety of Dachshund [45–49]. Within the research colony of MLHDs there was complete correlation between theRPGRIP1 genotype and phenotype of the dogs with respect to their CORD1 phenotype whereas in the pet MLHD population this was not the case [50]. Outside of the colony there was considerable variation in the age of onset of retinal degeneration in dogs that were homozygous for the RPGRIP1insertion (termed RPGRIP1-mutant), which has also been identified in other breeds, including the English springer spaniel (ESS) and the Beagle. In a study of a small number of RPGRIP1-mutant Beagles ERG cone responses were undetectable whereas rod responses were variable between dogs, and between eyes of the same dog [50]. In the same study all RPGRIP1-mutant MLHDs showed reduced cone responses, even in the absence of ophthalmoscopic abnormalities, a finding that has also been corroborated by Busse and co-workers [51]. Together these findings suggest that additional mutations are involved which modify the age of onset of ophthalmoscopic abnormalities associated with the RPGRIP1 mutation. Because the original research colony used was developed from a very small number of dogs it is a real possibility that the colony was fixed for these additional loci which, therefore, went undetected until the more outbred pet population was investigated. The mutation inNPHP4 described above, that causes an early onset cone-rod dystrophy in standard wire-haired dachshunds [49] was not present in the dachshunds studies by Miyadera, enabling that mutation to be excluded. A recent association study using RPGRIP1-mutant MLHDs that had either early or late onset cord1 has indeed revealed a second locus that segregates with early-onset disease [52], indicating early onset CRD in MLHDs is more likely to be a digenic condition, and that the RPGRIP1 insertion alone causes a late onset CRD, although ERG abnormalities may be detected early in life.

Another form of canine cone-rod dystrophy to be characterized at the molecular level is crd3, for cone-rod dystrophy 3, that segregates in the Glen of Imaal terrier. This disease becomes evident ophthalmoscopically in affected dogs as young as 3 years of age, and progresses to end-stage retinal degeneration over several years. Very recently the causal mutation has been identified by two research groups almost simultaneously, as a large genomic deletion of ADAM9 (A Disintegrin And Metalloprotease domain, family member 9) that removes exons 15 and 16 of the ADAM9 transcript[53,54] and generates a premature stop codon that is predicted to result in a truncated protein that lacks critical domains. This finding established CRD3 as a true orthologue, and a potentially useful model, of the similar human condition CORD9 in which four distinct ADAM9 mutations have been found [55].

Stationary retinal disorders

The forms of both PRA and CRD described above are all inherited retinopathies that are characterized by increasing severity and decreasing visual function over time. Progressive retinal changes during the dog’s lifetime invariably lead to complete blindness.

The first non-progressive retinopathy to be well-characterized was described in the Swedish Briard by Narfstrom and colleagues [56] as stationary and congenital, resulting in it being termed congenital stationary night blindness (CSNB). Since the initial report the disease has also been described as having a progressive component leading to it also being called a hereditary retinal dystrophy [57]. However CSNB and hereditary retinal dystrophy have since both been shown to be caused by a four nucleotide deletion in exon 5 of the RPE65 gene, indicating they are genetically identical conditions[58,59]. RPE65 is involved in the conversion of all-trans-retinoids to 11-cis-retinoids and in its absence the visual cycle is interrupted, resulting in a lack of visual pigment [60]. This canine disease has a very characteristic clinical phenotype; affected dogs have profound visual impairment present from at least 5–6 weeks of age, but remain ophthalmoscopically normal, at least for the first 3–4 years of life. Older dogs may show subtle retinal abnormalities indicative of a slowly progressive retinal degenerative process. Both cone and rod mediated ERG responses are highly abnormal, probably due to a combination of responses from rods and possibly cones with very reduced sensitivity [58]. It was the unique absence of visual function in dogs with healthy rod photoreceptors that was observed in CSNB-affected dogs that led to landmark studies in the field of retinal gene therapy. Subretinal injections of adeno-associated virus vectors expressing RPE65 resulted in restoration of rod photoreceptor function and improved visual function, first in dogs [61,62] and subsequently in humans [63–65].

Cone degeneration (CD) is also different from other progressive disorders in that early-onset cone degeneration occurs in the absence of the subsequent rod degeneration that characterizes cone-rod dystrophies. In cd, which was originally described in Alaskan Malamutes [66], affected puppies develop day-blindness and photophobia between 8 and 12 weeks of age, when retinal development is normally completed in dogs, although these clinical signs only occur in bright light and the dogs remain ophthalmoscopically normal throughout their entire lives. Cone function starts to deteriorate by the age of 6 – 12 weeks and is unrecordable in adult dogs [67]. Rod photoreceptors, however, remain functionally and structurally normal throughout the animal’s life. A large genomic deletion that removes all exons of CNGB3, the gene that encodes the β subunit of the cone cyclic nucleotide-gated cation channel, has been identified in CD-affected Alaskan Malamute-derived dogs, although there is evidence that the condition might be genetically heterogeneous in this breed as some dogs have been identified with clinical signs of day blindness that lack the CNGB3 deletion [68]. A missense mutation in the same gene has been detected in German Shorthaired Pointers affected with a clinically identical allelic disorder [69]. These findings established CD as an orthologue of human achromatopsia, a condition also known as rod monochromacy or total congenital colour blindness, that shares many of its clinical features with CD and has also been associated with mutations in CNGB3[70,71]. The potential of these orthologues has recently been demonstrated by the successful restoration of cone function and associated photopic vision in both of the canine achromatopsia models by gene replacement therapy [72].

Another inherited retinal disorder that is generally non-progressive is canine multifocal retinopathy (CMR), a disease that has been recognized in several breeds, particularly Great Pyrenees, Coton de Tulear, English Mastiff and Bullmastiff [73,74]. Ophthalmoscopic changes are usually evident in affected dogs before the age of around 4 months and are characterized by multifocal areas of retinal elevation that contain subretinal accumulation of serous fluid. Retinal elevations can remain static for several years, whereas multifocal outer retinal atrophy is often seen in older animals. Several different variants in the Bestrophin gene (BEST1 (alias VMD2)) have been identified as likely causal mutations for CMR in the dog. In Great Pyrenees, English Mastiff, and bullmastiff dogs, a C73T mutation in exon 2 causes a premature translation termination that limits the open-reading frame to 25 codons, compared with 580 codons in the wild-type mRNA (cmr1) and in Coton de Tulears a G482A transition changes an evolutionarily conserved glycine residue to aspartic acid (cmr2). In Lapponian Herders two coding changes have been described in CMR affected dogs; a deletion at nucleotide position 1,388 (c1388del) and a substitution at nucleotide position 1,466. The c1388del results in a frame shift (Pro463fs) introducing a new stop codon at amino acid 490 and the G1466T substitution by itself leads to a conservative change in the amino acid sequence (Gly489Val), which is predicted to change the protein function with only marginal significance. In combination with the C1388del, however, the G1466T substitutions results in an additional stop codon at amino acid position 489 within the shifted reading frame (Gly489X). Since the mutations have only been found in complete linkage disequilibrium, the authors conclude that the combination of changes results in the disease they refer to as cmr3[75].

These mutations establish CMR as a novel animal model for Best macular dystrophy (BMD) in humans, an autosomal dominant, childhood retinal disease also caused by mutations in the Bestrophin gene[76,77].

Developmental diseases

Retinal dysplasia is the term used to denote disorderly proliferation and imperfect differentiation of the developing retina and can be subdivided into focal, multifocal, geographic and total types. Focal and multifocal types manifest as linear folds and ‘rosettes’ of tissue in the inner (sensory) retinal layer whereas in geographic forms there are larger areas of defective retinal development that appear as large irregular or horseshoe-shaped areas of mixed hyper- or hyporeflectivity in the central retina. Total or generalized forms of retinal dysplasia have been described as an inherited trait in several breeds, including the Bedlington terrier [78], Sealyham terrier [79], Labrador retriever [80] and the Yorkshire terrier [81] and are associated with complete detachment of the abnormal neuroretina from the retinal pigment epithelium that results in blindness of affected eyes. All forms of retinal dysplasia are congenital and non-progressive. Retinal dysplasia appears to be inherited as an autosomal trait, at least in those breeds where sufficient numbers of individuals have been studied to reliably estimate the mode of inheritance [82–84]. The genetics of isolated or non-syndromic forms of retinal dysplasia have not been characterized at the molecular level in any breeds to date and no mutations have been associated with this condition.

Forms of syndromic retinal dysplasia have been reported in the Labrador retriever [85–87] and the Samoyed [88]. Homozygous affected dogs had short-limbed dwarfism and a range of ocular changes characterized by complete retinal detachment and cataract whereas heterozygous dogs had only focal or multifocal retinal lesions [85,86]. Breeding studies determined that these two disorders are non-allelic [89] and they were termed DRD1 (dwarfism with retinal dysplasia type 1, Labrador retriever) and DRD2 (Samoyed), respectively (these conditions have also previously been referred to as OSD1and OSD2 for oculoskeletal dysplasia). Mutations have recently been associated with both disorders; a 1-base pair insertional mutation in exon 1 of COL9A3 is associated with DRD1 and a 1,267-bp deletion in the 5’ end of COL9A2 co segregates with DRD2. Both mutations affect the COL3 domain of their respective genes, the expression of which are both reduced in affected retinas [90].

Another complex congenital defect of the retina is collie eye anomaly (CEA), although retinal involvement is secondary to the primary ocular defects associated with this disorder. The primary phenotypic element of the disorder is regional hypoplasia of the choroid, the highly vascular layer underlying the retina. Associated retinal lesions, known as colobomas are often detectable ophthalmoscopically, as are tortuous retinal vessels and multiple retinal folds in a minority of cases[91]. CEA, which segregates in several herding breeds with Collie ancestry, was mapped to a large region of CFA37 that included over 40 genes [92]; subsequently the fact that the disorder segregates in multiple, closely related breeds was used to reduce the size of the critical disease-associated region and pinpoint the causal mutation to a 7.8 kb intronic deletion in the NHEJ1 gene, which spans a highly conserved binding domain to which several developmentally important genes bind [91]. The precise mechanism by which the deletion causes CEA has not however been established to date.

Hereditary cataract

The lens is the transparent, biconvex, avascular structure in the anterior segment of the eye that is partly responsible for the refraction of light to be focused on the retina. The lens consists of a nucleus, cortex and capsule and is suspended by many dense zonular ligaments which are attached to the capsule and connect between the ciliary body and the lens equator. Transparency is a crucial property of the lens which is achieved, in part, by the absence of light-scattering organelles within the lens fibres. New lens fibres are generated from the equatorial cells of the lens epithelium, which elongate, synthesize crystallin and finally lose their nuclei as they become mature lens fibres. The crystallins, which make up over 90% of the proteins in the lens, are specially adapted to contribute to the maintenance of transparency by forming soluble, high-molecular weight aggregates that need to stay in solution for the duration of an individual’s life.

Cataracts are simply defined as opacities of the lens and can develop for a variety of reasons, including advanced age and the secondary effects of other diseases such as diabetes or progressive retinal atrophy, and trauma. Primary or hereditary cataracts (HC) are common among dogs and are a leading cause of blindness. HC has been reported in as many as 97 different breeds [93,94], with around 60 breeds being reported to be at increased risk compared to mixed-breed dogs [95]. Hereditary cataracts reported in different breeds vary with respect to their anatomic position within the lens, their age of onset and their progressive or stationary nature, although within a breed cataracts usually display marked breed specificity. Despite the large number of breeds affected by HC only a single gene, the transcription factor HSF4, has been implicated in the development of cataracts in dogs to date. HSF4 belongs to a family of heat shock transcription factors that regulate the expression of heat shock proteins in response to different stresses, such as oxidants, heavy metals, elevated temperatures and bacterial and viral infections [96]. Different mutations in HSF4 have been reported to cause both human autosomal dominant and recessive cataracts [97–99] and studies in mice have shown HSF4 is required for normal fibre cell differentiation during lens development [100,101]. Disruption of the gene leads to the development of cataracts via multiple pathways, including the down-regulation or loss of post-translational modification of different crystallin proteins [102]. A single recessive nucleotide insertion in exon 10 of the gene (CFA5 g.85286582_85286583insC), that causes a frameshift and introduces a premature stop codon, is responsible for an early onset, bilaterally symmetrical and progressive form of HC in the Staffordshire bull terrier [103]. This cataract starts to develop from a few months of age and invariably progresses to total cataract within 2–3 years if left untreated [104]. The mutation is shared by the Boston terrier, in which it causes the clinically identical early-onset hereditary cataract (EHC), one of two genetically distinct forms of cataract known to affect this breed [104,105]. The mutation associated with the clinically more variable, late-onset hereditary cataract (LHC) in this breed has yet to be identified [106]. The same mutation has also been identified in a small number of French bulldogs with a clinically identical cataract (Mellersh, unpublished).

A single nucleotide deletion at the same position in HSF4 (CFA5 g.85286582delC) has also been associated with HC in the Australian Shepherd. The form of cataract caused by the insertion identified in the Staffordshire bull terrier and related breeds has a recessive and highly penetrant mode of inheritance, is early onset, highly progressive and uniform. In contrast, the form of cataract observed in the Australian Shepherd, caused by the deletion described above, has a dominant, or co-dominant mode of inheritance, is not completely penetrant and is typically associated with a posterior polar subcapsular cataract that also has a variable age of onset. It is highly likely that other mutations associated with the development of cataracts are co-segregating in the Australian Shepherd population because not all the dogs with bilateral posterior polar subcapsular cataract carried a copy of the HSF4deletion [107].

HSF4 has been excluded from involvement in the development of HC in a long list of breeds, including the Alaskan Malamute, American Cocker spaniel, Bichon Havanais, Belgian Shepherd Tervueren and Groenendael, Dachshunds, English Cocker spaniels, English Miniature Terrier, Finnish Lapphund, Golden retriever, Griffon Bruxellois, Kromfohrlander, Jack Russell terrier, Lapponian Herder, Miniature Schnauzer, Miniature Pinscher, Nova Scotia Duck Tolling Retriever, Rottweiler, Samoyed, Schnauzer, and Tibetan Mastiff [103,107–111]. The paucity of canine cataract mutations that have been reported in the literature, compared to those associated with, for example, inherited retinal degenerations in the dog, is testament to the fact that HC is probably a genetically complex disorder in most breeds of dog and studies to date have not included the analysis of sufficient numbers of cases and controls to identify DNA variants associated with the disease. A recessive mode of inheritance has been suggested for congenital cataracts and microphthalmia in the Miniature Schnauzer [112] as well as cataracts in the Entlebucher mountain dog [113], the Bichon Frise [114] and the American Cocker spaniel [115]. In contrast, an autosomal dominant mode of inheritance with a high degree of penetrance has been suggested for the pulverulent (dust-like) form of cataract observed in the Norwegian Buhund [116] and autosomal dominant with variable penetrance has been suggested for inherited posterior polar subcapsular cataracts in the Labrador and Golden retriever [117], although current anecdotal evidence indicates that in the Labrador cataracts could also be inherited as an autosomal recessive trait. Evidence of inheritance has been reported for a handful of other breeds, including the Leonberger, Jack Russell terrier and Chow chow, although the precise mode of inheritance has rarely been identified [111,118,119].

Primary lens luxation

Primary lens luxation (PLL) is not a disease of the lens itself, but rather an inherited deterioration of the lens suspensory apparatus, the zonule, which is a system of fibres that suspend the lens from the ciliary body, maintaining it within the visual axis and in contact with the anterior surface of the vitreous body. In dogs affected with PLL ultrastructural abnormalities of the zonular fibers are already evident at 20 months of age [120] long before the lens luxation that typically occurs when the dogs are 3 to 8 years old, as a result of degeneration and breakdown of the zonules which cause the lens to be displaced from its normal position within the eye [121–124]. In the majority of cases the dislocated lens will pass into the anterior chamber where its presence is likely to cause acute glaucoma. The condition has been recognized as a canine familial disorder for more than 100 years [125,126] and is encountered at high frequency in several terrier breeds and in some other breeds with probable terrier co-ancestry [121–124,127]. PLL is recessively inherited in the Tibetan terrier [127] and inheritance has been suggested to be recessive in the Shar Pei and other Western terrier breeds in which it has been studied [128]. A mutation in ADAMTS17 has been described as the cause of PLL in three breeds, the Miniature Bull terrier, the Lancashire Heeler and the Jack Russell terrier. The mutation is a G→A substitution at c.1473 + 1, which destroys a splice donor recognition site in intron 10 and causes exon skipping that results in a frameshift and the introduction of a premature termination codon [129]. The great majority of PLL-affected dogs are homozygous for the mutation, but a small minority are heterozygous, leading to speculation that carriers, of some breeds at least, might be at increased risk of developing the condition compared to dogs that are homozygous for the wildtype allele [129].ADAMTS17 is one of 29 known mammalian members of the ADAMTS family of genes that encode secreted metalloproteases that proteolytically modify extracellular structural proteins. Mutations in a variety of ADAMTS genes have been associated with a diverse set of human diseases including Ehlers-Danlos syndrome [130] and Weill-Marchesani syndrome [131]. The canine ADAMTS17 splice site mutation is shared by at least 17 different breeds, many of which are terriers or terrier-type breeds, but some of which have more diverse origins [132]. Some breeds that are known to be at increased risk of PLL, such as the Border Collie, do not carry the same ADAMTS17 mutation as the terrier breeds, indicating their form of the disease must be genetically distinct although clinically similar[132].

Other conditions

The diseases of the lens and retina described above represent the overwhelming majority of inherited eye conditions in the dog for which causal mutations have been identified. Many other ocular conditions have been reported to be more common in certain breeds than others, which is indicative that they have a genetic component. However, a rigorous estimate of the mode of inheritance has been undertaken for relatively few of these conditions. To list comprehensively all the eye conditions that have been reported in dogs is outside the scope of this review, so the remainder of conditions described is restricted to those conditions for which an estimate of the mode of inheritance or the heritability has been reported.

Glaucoma

Glaucoma is the term used to describe a group of conditions that result in increased intraocular pressure, with damage to the retinal ganglion cells and their axons, leading to vision loss and blindness. Glaucoma is commonly divided into congenital, primary and secondary types, depending on the aetiology of the condition. Congenital glaucoma is rare in the dog [133] and secondary glaucoma, which is the most common form of the condition observed in the dog, arises as result of antecedent or concurrent ocular disease, so is not itself inherited, although the primary, causal condition might be. Primary glaucoma occurs in the absence of any other ocular disease, and, therefore, is presumed to have a genetic component in most breeds. Primary glaucoma can occur in the presence (angle closure glaucoma) or absence (open angle glaucoma) of an abnormal, narrowed or closed opening into the ciliary cleft, which prevents the efficient drainage of aqueous humour from the anterior chamber of the eye, via the iridocorneal angle through openings between the pectinate fibres. Goniodysgenesis is the most common cause of primary glaucoma in dogs, and refers to the presence of abnormal, irregularly-shaped or imperforate sheets of pectinate fibres. Glaucoma has been reported to be more prevalent than average in several breeds, including the Flat Coated Retriever, American Cocker spaniel, the Bassett Hound, the Shar Pei, the Norwegian Elkhound and the Boston terrier[134–137]. A strong and significant correlation between goniodysgenesis and glaucoma was reported in the Great Dane, and the same study reported a high heritability for goniodysgenesis, suggesting glaucoma may be heritable in this breed [138]. A similarly significant association has been reported between pectinate ligament dysplasia and adult-onset primary glaucoma in the Flatcoated retriever, for which the heritability was estimated to be approximately 0.7 [139,140]. To date no mutations have been identified that are associated with angle closure glaucoma in any breed of dog although the first glaucoma-associated locus has recently been identified in Dandie Dinmont Terriers [141].

Autosomal recessive, primary open-angle glaucoma (POAG) has been very well characterized in the Beagle [142–146] and a Gly661Arg variant in ADAMTS10 has been associated with the condition in Beagles that developed elevated intraocular pressure from 8 to 16 months of age, due to increased resistance to outflow of aqueous humour despite normal appearing open iridocorneal angles [147].

Persistent hyperplastic primary vitreous

Persistent hyperplastic primary vitreous (PHPV) is a congenital, non-progressive condition which results from the abnormal regression of the foetal hyaloid vasculature. The condition is rare but is seen more commonly in Staffordshire bull terriers in which pedigree analysis supports a hereditary etiology for the condition but is insufficient to determine the exact mode of inheritance, [148,149]. PHPV and persistent hyperplastic tunica vasculosa lentis (PHTVL) has also been described in detail in the Doberman [150].

Conclusion

At the time of writing 29 different mutations have been associated with inherited eye disease in the domestic dog, and more are likely to have been identified by the time this review goes to press. This number far exceeds those associated with any other category of disease, meaning that inherited eye diseases are arguably better understood, at both the clinical and genetic level, than any other category of canine disease. The dog has already played an important role in emerging therapies for inherited blindness in humans and similarities in disease phenotype and eye structure and function between dog and man, together with the increasingly sophisticated genetic tools that are available for the dog, mean that the dog is likely to play an ever increasing role in both our understanding of the normal functioning of the eye and in our ability to treat inherited eye disorders.

BCOA Also Explains:

Basenji retinopathy, or progressive retinal atrophy (PRA) is an eye condition in which the retina begins to deteriorate later in life, causing night blindness and, if the dog lives long enough, causing deterioration of day vision that can lead to blindness. Onset as diagnosed by specialist eye exam varies, typically between ages 4 and 10, although some cases have been reported between as early as age 3 and as late as 13. Based on Canine Eye Registration Foundation Statistics through 2006, approximately 25% of Basenjis age 8 and older showed signs of retinal changes, although most changes were characterized as PRA suspicious rather than PRA affected. Not all of those dogs have hereditary eye disease, as retinal changes may be acquired or may be due to other disorders.

It is not currently known if Basenji PRA is one disease or more than one. Mode of inheritance is presently unknown.

Basenjis can also have some unusual, but benign, forms of retinal pigmentation that can easily be confused with PRA or retinal degeneration. Both false positives and false negatives are common with Basenji PRA.

For the Owner

Most Basenjis diagnosed with retinopathy show little change in behavior until very late in life. Reduced vision in low light tends to occur first, typically in mid to late life for affected dogs. Daytime visual deficits do not tend to occur until late in life for most affected dogs. There are rare exceptions that go blind in mid-life. Blindness before mid-life is extremely rare. This is primarily a disease of older dogs, and one in most cases with very subtle symptoms until very late in life.

For Breeders

Although retinopathy has limited effect on the quality of life for most affected dogs, it is a serious disorder that must be considered in breeding. Because dogs rarely show any sign of the disease until mid-life, an affected dog may be bred prior to diagnosis. Without specialist exam, affected dogs often go undiagnosed throughout their lives.

Canine Eye Registration Foundation (CERF) exams by an American College of Veterinary Ophthalmologists (ACVO) certified veterinary ophthalmologist include examinations for retinal abnormalities and PRA, as well as the other eye anomalies noted below. CERF exams are recommended annually for breeding stock. Dogs that test normal can receive a certificate.

A CERF exam indicates only the present state of a dog’s eyes. Since retinopathy/PRA onsets later in life, a CERF exam cannot predict whether or not a dog will develop the problem in the future. Further, a CERF exam cannot evaluate whether or not the dog will produce it.

Basenjis used for breeding should be tested throughout their life, including after they are retired for breeding, so their retinopathy status is known. Dogs diagnosed with retinopathy should not be bred. Dogs with a parent or offspring with retinopathy should not be bred to each other.

If your dog is diagnosed with PRA, blood samples of your dog, his or her parents, any offspring, and any full siblings should be sent to Dr. Gary Johnson at the University of Missouri. Please contact BCOA for instructions to send samples. There are plans to do research on Basenji retinopathy, with a goal of identifying the mode of inheritance and the causative gene.

Addtional Information

The CERF statistical reports are available through the Canine Eye Registration Foundation athttp://www.vmdb.org/member_order.html — ask for the statistical report. The cost is $15 per report.

CERF (eye) results are also shown at the OFA website.

http://www.bregorreyglens.co.uk/pra.html a link–though not regarding Basenjis, does give some more insight to PRA

Persistent Pupillary Membrane (Also known as PPM)

BCOA Explains:

Persistent Pupillary Membrane is a condition where the fetal membrane of the eye does not completely reabsorb. It is a minor and normally benign disorder that is extremely common in Basenjis. Based on CERF statistics through 2006, about 77% of all Basenjis have some PPM as puppies, with about 70.5% having the mildest form – a form that is permitted in dogs certified by the Canine Eye Registration Foundation and is generally agreed to have no affect on quality of life or vision. Of the remaining 6.5%, about 1.8% have sheets as puppies, the more severe form that can cause visual blurring.

PPM does not progress, and in fact often puppies with mild PPM have it reabsorb and disappear completely as they age. For this reason PPM can get better, and it does not get worse.

For the Owner

Most PPM has no effect on a dog’s life. PPM severe enough to cause visual problems is normally visible to a non-specialist vet, but PPM that severe is extremely uncommon.

For Breeders

While most PPM does not have a negative effect on a dog’s life, severe PPM can. Severe PPM is now quite rare in Basenjis, but it was more common early in the breed’s history. Breeders were able to successfully breed away from it.

To prevent severe PPM from becoming common again, it is a good idea for breeders to have an ACVO certified veterinary ophthalmologist check their puppies at 7-9 weeks of age, to determine the presence or absence of PPM. All breeders should be aware of the PPM status of their dogs.

A Basenji with iris to iris PPM can receive a Canine Eye Registration Foundation certificate. All other grades of PPM (iris to lens, iris to cornea, and iris sheets) cannot. Most Basenji breeders will not disqualify a dog from breeding solely due to mild PPM. A CERF exam will show current PPM status, but it does not tell you whether or not the dog can produce offspring with PPM.

Additonal Information

The CERF statistical reports are available through the Canine Eye Registration Foundation athttp://www.vmdb.org/member_order.html — ask for the statistical report. The cost is $15 per report.

CERF (eye) results are also shown at the OFA website.

OFA Hip Evaluation

Hip Dysplasia

BCOA Explains:

Hip dysplasia is a hereditary condition in which the hip socket is badly formed, often leading to lameness and arthritis. It is believed to be polygenic, with multiple genes involved in its expression. Approximately 3—3.5% of Basenji x-rays submitted to the Orthopedic Foundation for Animals (OFA) are dysplastic.

For the Owner

When purchasing a puppy, the parents should have been tested for hip dysplasia, and the x-rays should have been read by the Orthopedic Foundation for Animals (OFA.)

For Breeders

Breeding stock should be x-rayed for hip dysplasia. The Orthopedic Foundation for Animals has a web site that permits downloads and searches of dogs that have passed with a grade of Fair, Good, or Excellent. In addition, the OFA has recently added the option of having results placed in an open health registry, so that Borderline and Dysplastic ratings can be made public.

Good and Excellent are the preferred grades for breeding stock, although Fair is not considered dysplastic. OFA status at 2 years of age is generally considered definitive of that dog’s hip status. However, there is a small chance a dog can go dysplastic later in life.

For permanent results, dogs can be X-rayed for hip dysplasia at 2 years of age or older, with the films reviewed by the OFA for the definitive reading. Dogs can be x-rayed earlier for preliminary results if they are being bred prior to 2 years of age. Hips can also be examined by PennHip, and PennHip results can be included in the OFA database.

Breeding from tested normal stock, and using vertical pedigrees to consider the scores of relatives are the recommended methods of controlling hip dysplasia. A discussion of the use of pedigree data to avoid genetic disease is online at http://www.offa.org/hovanart.pdf. While this article features hip dysplasia, the techniques are useful for avoiding any genetic disease.

Thyroid Problems

Thyroid Problem –Hypothyroidism

BCOA Explains:

Hypothyroidism is known to occur in Basenjis. The most common symptoms include weight gain, poor coat, reduced activity level, and irritability. Other symptoms, i.e., weight loss have been described. The Orthopedic Foundation for Animals reports that, of Basenjis tested, at the time of this writing, 82.9% were normal in all respects, 6% had autoimmune thyroiditis, 0.4% had idiopathic hypothyroidism, and 10.8% were equivocal. Autoimmune thyroiditis is known to be inheritable.

For the Owner

Hypothyroidism is easily treated with an inexpensive thyroid supplement; the dose may need periodic adjustment, and this should only be done with veterinary supervision.

Pet owners may want to have their vet periodically check their dogs, especially if they show any symptoms that suggest hypothyroidism.

Thyroid panels test only for current thyroid status. They cannot predict future changes, and they do not indicate if a dog can produce offspring with hypothyroidism.

For Breeders

It is a good idea for breeders to periodically check their breeding stock with a full thyroid panel beginning in early adulthood. The Orthopedic Foundation for Animals has an open registry for dogs that have been tested for autoimmune thyroiditis at 12 months or older, using approved labs. This thyroid test is part of the CHIC panel for Basenjis.

Testing for breeding stock is done primarily to rule out autoimmune thyroiditis, which is known to be inheritable. A full thyroid panel is used, one that includes total thyroxine (T4), thyroid-stimulating hormone (TSH), free T4 by dialysis, and thyroglobulin autoantibody (TgAA or TAA.)

Elevation of both TSH and TgAA levels are used to diagnose autoimmune thyroiditis – however, as the disease progresses, these levels may decrease due to complete destruction of the thyroid gland. Dogs that have had autoimmune thyroiditis for several years but have never been tested might not show the elevated TSH and TgAA needed for definitive diagnosis.

CERF Eye Examination

Hernia Information

Umbilical and Inguinal Hernias

BCOA Explains:

Umbilical hernias are very common in Basenjis, with most being minor hernias that do not normally cause problems for the dog.

For the Owner

Umbilical hernias can be repaired at any time; the surgery is often done when a pet is spayed or neutered or during any other procedure requiring anesthesia. Small closed hernias generally do not cause problems; large or open hernias can cause problems if a loop of intestine gets caught in the hernia. Some breeders routinely repair even small closed hernias. Dogs which have had umbilical hernias repaired are still eligible for participation in AKC conformation events.

Inguinal hernias are uncommon in Basenjis. They generally do require surgical repair. Dogs with repaired inguinal hernias are not eligible for participation in AKC conformation events.

For Breeders

Small closed umbilical hernias generally are not an issue in breeding, although selection away from umbilical hernias is desirable. Large or open hernias should be considered as a strike against breeding stock.

Inguinal hernias are a serious defect, and dogs with inguinal hernias should not be bred.

Other Health Issues

Persistent Pupillary Membrane (PPM)

Pyruvate Kinase Deficiency — Hemolytic Anemia (HA)

Immuno Proliferative Small Intestinal Disease (IPSID) and Exocrine Pancreatic Insufficiency (EPI)

Patellar Luxation

Umbilical and Inguinal Hernias

HERE is the website complete with images, etc. I simply copied and pasted. but to see them as they should be, please click the following link:

http://www.basenji.org/joomla/index.php?option=com_content&view=category&layout=blog&id=166&Itemid=292#Cystinuria

Basenji Club of America Explains

Basenji Health Information Updated August 2014

Basenjis are a natural breed and are relatively healthy when compared to other breeds of dogs. Like all breeds, basenjis have disorders that may occur more frequently than in the general canine population. As responsible dog owners, it is up to us to work together to ensure the best for our breed. The basenji community has a long history of working together to identify and breed away from hereditary diseases. We have learned that regular health testing and open reporting of those results will provide us with the working knowledge necessary to ensure our breeds overall health.

Regular health testing of basenjis is essentialfor the breed’s overall health and well-being.

It is important to understand the different types of disorders that may occur in basenjis and the impact these disorders have on their quality of life and reproductive potential. All basenjis, whether affected with a disorder or not, need regular health testing as described in the sections below. Some dogs may carry a genetic component for a disorder but have no symptoms. These dogs will live a normal life, but are still important to track to have a full understanding of the disorder and to avoid passing the disorder on to offspring. Genetic or hereditary disorders can quickly become an issue if the breeds’ population is not health tested regularly.

Below is a list of some health problems known to occur in basenjis. Click each item to learn more information about these disorders. There are separate sections for breeders and owners who are not interested in breeding. If you have any questions about this information, please contact your breeder, regional basenji club, or the Basenji Club of America (BCOA) Health Committee.

Persistent Pupillary Membrane (PPM)

Progressive Retinal Atrophy (PRA)

Fanconi Syndrome

Pyruvate Kinase Deficiency — Hemolytic Anemia (HA)

Hip Dysplasia (HD)

Immuno Proliferative Small Intestinal Disease (IPSID) and Exocrine Pancreatic Insufficiency (EPI)

Patellar Luxation

Thyroid Problems

Umbilical and Inguinal Hernias

Genetic Testing

What is DNA?

Deoxyribonucleic Acid (DNA) is made up of the genetic building blocks (nucleotides) Adenine (A), Guanine (G), Cytosine (C), and Thymine (T). Simply put, the order of these nucleotides within your DNA make up a code of instructions for building a living organism.

Photo credit http://www.canstockphoto.com

What is a mutation?

DNA is copied every time a cell divides. Sometimes an error occurs in this process. This is called a mutation. If this happens when germ cells (eggs or sperm) are being formed, this mutation is called a germline mutation and can be passed to the offspring of the affected individual. Most mutations do not cause disease, but occasionally these changes can cause problems.

Genetic Disease Research

For the last 30 years Polymerase Chain Reaction (PCR) technology has been available to test for disease mutations. This along with innovations in DNA sequencing caused a revolution in biomedical research. If one could find the mutation responsible for a disease, one could test individuals for the mutation.

Inheritance of Genetic Diseases

Every individual has two copies of every gene, one from their mother and one from their father. In some cases the genetic mutation is dominant, meaning that only one copy of the defective gene is necessary for the disease to occur. Examples of this include: Huntington’s Disease and Marfan Syndrome in humans. Other times the disease is a simple recessive, meaning that two copies of the mutant gene are necessary for the disease to be present. Examples of this are Sickle Cell Anemia and Cystic Fibrosis in humans. In still other cases, inheritance is more complex. It may be polygenetic, meaning that more than one gene is involved in disease expression; X-linked, meaning that the mutant gene is on the X chromosome, which determines sex, and therefore requires two copies for expression in females and only one copy when present in males; or even have variable expression, meaning that sometimes individuals with one copy (carriers) may have the disease or they may not. Some disease causing mutations may only be expressed if the individual is exposed to some specific environmental factor.

Importance of Genetic Testing

Before genetic testing for diseases became more common, breeders were forced to guess at the genetic make-up of individuals based on their own disease history and the disease history of their progeny, siblings, and dogs in their pedigree. In some cases, it was easy to determine the genetic status of an individual in this way, but in other cases it was very difficult. Now, in some cases, we can make more educated choices by testing individual dogs and getting a direct “snapshot” of their DNA.

DNA Testing in Basenjis

We are fortunate to have three DNA tests available for basenjis. Sometimes there are multiple mutations that cause the same disease in different breeds, so most canine genetic tests are breed specific.

Fanconi Syndrome: In August of 2011 Fanconi Syndrome in basenjis was discovered to be caused by an autosomal (not x-linked) recessive trait. At that time a DNA test was developed to detect the mutation responsible for the disease. Dogs tested were and continue to be determined to be Normal, Carrier, or Affected. Fanconi is a potentially fatal disease and everyone is encouraged to use this DNA test to determine the disease status of their dogs.

Prior to the current DNA test (2007-August 2011), while researchers were looking for the mutation responsible for Fanconi Syndrome, a linkage test was available through OFA. Unlike the test available now, a linkage test does not directly test for the mutation responsible for a disease. It tests for DNA markers (DNA sequences thought to be physically near the gene of interest) that are thus likely to travel with the gene of interest through the generations and not be separated by crossover events. Because of the way a linkage test works, it is inherently a less accurate test. For this reason, the results that were given to owners were prefaced with the word “probably” or the letter “p”. Results from this linkage test should NOT be used for making breeding decisions.

In 2011 when the current DNA test for Fanconi Syndrome was introduced, it was often referred to as a “direct” DNA test to differentiate it from the previously available linkage test. Since we no longer have any accepted DNA linkage tests available for basenjis, this distinction will be phased out. All DNA tests can be assumed to be “direct” tests unless they are specified to be a “linkage” test.

Progressive Retinal Atrophy (PRA): PRA-BJ1 A test has been developed for one form of PRA in basenjis. PRA-BJ1 is also autosomal recessive and dogs will be determined to be Normal, Carrier, or Affected.

There are at least two different genetic mutations which cause PRA in basenjis, so even if a dog tests normal for PRA-BJ1, this does not mean that this dog will not develop or pass down another type of PRA to their offspring. Research is ongoing to find other genetic causes for PRA in basenjis. In the meantime everyone is encouraged to test for PRA-BJ1.

Hemolytic Anemia (HA): Pyruvate Kinase Deficiency-Hemolytic Anemia is a fatal genetic disease. The test for HA was the first DNA test available to basenji breeders. It is another autosomal recessive trait. Dogs will be determined to be Normal, Carrier, or Affected. The vast majority of basenjis are descended from tested stock; however, the test is still available.

Genetic testing is simple. Most genetic tests can be made with a swab of cheek cells. Tests can also be performed using frozen sperm or blood samples.

Cystinuria

Production of urine is the normal process by which a dog’s kidneys filter liquid waste from the body. However, if there is a problem with this process, certain amino acids and other substances like minerals can build up, forming crystals. The urine may also lack substances that keep crystals from sticking together. So, as the urine passes through the urinary tract and becomes concentrated, crystals may fix together to become stones in the ureter (the thin tubes that carry urine from the kidneys to the bladder) or the bladder. When the liquid in the dogs urine contains more crystals than can be diluted, the crystals can clump together or become large enough to form stones. In humans, these problems occur more frequently in the kidneys (kidney stones), while in dogs the problems occur more frequently in the bladder (bladder stones).

Urinary stones are usually diagnosed by x-ray and are categorized based on the predominant amino acid(s) and/or mineral(s) found in the stones. Treatment is determined based on the type of stones. Common stones are struvite, calcium oxalate, urate, or cystine.

In most breeds of dogs including basenjis, struvite stones are the most common and usually form in response to an infection, such as a urinary tract infection (UTI). In the absence of a UTI, they may form when dogs pass highly concentrated urine. Your veterinarian may prescribe a specific diet to help dissolve them.

The condition responsible for cystine stone formation is called cystinuria. Cystinuria, a genetically complex disease, is an inherited error of metabolism that keeps the renal tubules in the kidneys from properly reabsorbing the amino acid cystine. In other words, the kidneys are not able to correctly process cystine (an essential building block of protein). When a dog’s kidneys are functioning normally, cystine will be reabsorbed by the kidneys and will not be excreted into the urine. However, the genetic defect associated with cystinuria does not allow reabsorption to take place and excess cystine is excreted into the urine. Over time, the unprocessed cystine crystallizes in the urine and clumps together to form grit and stones. These grit and stones can irritate the lining of the bladder causing chronic infection and can block the ureter so that the dog cannot urinate. A blocked urinary tract is a veterinary emergency because the affected dog’s bladder may expand to the point of potential rupture. Dogs that block must have their ureters cleared of stones and grit by passing a catheter, or through surgery.

Affected dogs are born with this condition, however it may take years before the situation progresses to physical symptoms. The typical age of symptom onset is 2 to 7 years. The mode of inheritance for cystinuria has been identified in Newfoundlands and Mastiffs, but has not yet been identified in affected Basenjis.

Cystinuria is a life-long defect that cannot be cured, but the condition can be managed to reduce the potential for future stone formation. Cystine stones tend to recur within 1 year of removal if no action is taken to manage the condition. Typically, management consists of attempting to double the affected dog’s urine volume through hydration and adopting dietary restrictions and/or drug therapy to reduce the possibility of stone formation. New stones often recur despite attempts at prevention. Not all dogs with cystinuria will form stones, but there is always a chance that stones will reform in a dog previously diagnosed with cystinuria or cystine stones.

For the Owner

Often the first symptom of cystinuria in male dogs is a urinary tract blockage caused by a bladder stone or grit formed by cystine crystals. Symptoms of a blocked urinary tract include: frequent urination, straining to try to urinate, passing small amounts of urine rather than a steady stream, visible blood in the urine, a weak or “splattery” urine stream, and/or sudden involuntary incontinence in a previously housebroken male. Sometimes these symptoms are mistaken for UTI’s or prostate problems in intact males. If your male basenji exhibits any of these signs, contact your local veterinarian immediately because a blocked urinary tract can be fatal without prompt treatment. In some cases reoccurring urinary tract disorders may be a sign of cystinuria. In most cases dogs with cystinuria will have cystine in their urine which can be seen in a urinalysis. However, there is evidence that some dogs may spill excess cystine only intermittently.

According to the AKC Canine Health Foundation, which has funded research on cystinuria since 1996, there are 3 tests available to help diagnose cystinuria. All the tests are based on urine composition. The first is a basic urinalysis which can be performed at any veterinary clinic and is the cheapest of the three tests. The second is a nitroprusside test, performed at the University of Pennsylvania (for sample submission to screen for Cystinuria using a simple urine sample, see Instructions for Sample Submission.) Urine must be sent to the university which increases the cost of the test. The third is a urine amino acid quantitation test that can only be performed in a human laboratory and is the most expensive method of diagnosis. With respect to all these tests, it is important to note that a negative test result for the presence of cystine does not mean that your dog does not have or will not have cystinuria. Multiple tests may be necessary to “catch’ a dog spilling cystine into its urine and even a series of negative tests cannot predict whether a dog will begin spilling cystine at a later date.

In the absence of a DNA-based test for cystinuria in basenjis, the typical mode of diagnosis is stone analysis. If your dog is diagnosed with cystine bladder stones or if you have questions about the condition, information is available online at http://www.caninecystinuria.com.

For the Breeder

There is no treatment for the genetic defect that causes cystinuria. Affected dogs do not always form stones. Knowing the history of the condition in your dogs vertical and horizontal pedigree is, at present, the only method for evaluating the risk of the disease. Affected dogs should NOT be used for breeding.

Eye Health Overview

Basenji eye examinations are an important part of their routine health care. Regular eye examinations are important because some hereditary eye conditions are diagnosed in basenjis as puppies and some occur later in life. In the United States, it is advisable to have a basenji examined by a veterinary ophthalmologist who is a certified Diplomat of the American College of Veterinary Ophthalmologists (ACVO http://www.acvo.org). These practitioners have advanced training in canine eye conditions and can perform an OFA Eye Certification Registry certificate examination. Dogs that test Normal can receive an Eye Certification (known as Normal). These exams are recommended at 9 weeks of age followed by annual examinations for breeding stock throughout their reproductive lives and every other year thereafter to determine if any genetic eye disorders develop.

Keep in mind there can be abnormal conditions found in dogs eyes that do not affect their quality of life. If you have questions about the results of an OFA Eye Certification Registry certificate examination, ask your breeder and canine ophthalmologist. Remember a Normal result from an eye examination does not guarantee that the dog will not later develop a hereditary eye problem. In the pages that follow, there are brief descriptions of some of the more common eye conditions occurring in basenjis.

The OFA Eye Certification Registry certificate examination is part of the Canine Health Information Center (CHIC) list of health tests for basenjis. CHIC is a centralized canine health database jointly sponsored by the AKC/Canine Health Foundation (AKC/CHF) and the Orthopedic Foundation for Animals (OFA).

Parts of a Normal eye (permission by Google images)

Coloboma

Coloboma is an inherited eye condition in which a part of the eye does not develop properly. The mode of inheritance of coloboma is not understood. Basenjis typically have an optic nerve coloboma and it does not progress or get worse with age.

Basenji’s eyes should be assessed as a puppy (9 week examination) to determine if they have a coloboma. Basenjis’ eyes sometimes have a unique appearance that is normal for our breed but different than other breeds. Basenjis can, in some cases, have normal optic nerves that are more deeply cupped than other breeds making it is possible to have a false positive diagnosis of coloboma. If a basenji is diagnosed with a coloboma, a second opinion, from an ophthalmologist familiar with basenji eyes, is recommended.

For the Owner

The type and location of the coloboma determines if the dog will have vision problems or not. A veterinary ophthalmologist should be consulted in each case to explain how the condition will affect the dog. Basenjis with colobomas generally lead a normal life.

For the Breeder

A basenji with a coloboma will not receive certification from the OFA Eye Certification Registry. Breeding dogs with colobomas is NOT recommended by the American College of Veterinary Ophthalmologists (ACVO).

Corneal Dystrophy

There are many types of corneal dystrophy in canines. The following paragraphs contain a brief description of the predominate types of corneal dystrophy occurring in basenjis. In some cases the corneal dystrophy may have a genetic cause but we do not know how or if these eye conditions are inherited in our basenjis. You should check with your certified veterinary ophthalmologist for additional details regarding causation, treatment and breeding recommendations for any type of corneal dystrophy.

Definition of Corneal Dystrophy

The term “corneal” refers to the cornea or the outer part of the eye which is made up of several layers. In this case, “dystrophy” is used to describe a wasting of the tissues. The location of the corneal dystrophy is described by indicating the name of the layer(s) of the cornea affected; epithelial, stromal or endothelial.

Description of the Cornea

The cornea is a transparent protective cover on the front part of the eye that allows light to enter for vision. The main layers of the cornea are;

a) Epithelial layer: Epithelial cells comprise the outer protective layer that covers the surface of the cornea. This layer prevents foreign objects from entering the eye.

b) Stromal layer: is the middle, thickest layer and is made of mostly collagen and water.

c) Endothelium layer: this is a single layer of cells making up the inner lining of the cornea. The endothelial layer maintains corneal transparency mostly by pumping excess water out of the stromal layer. These cells cannot be repaired by the body.

Epithelial Corneal Dystrophy

Epithelial corneal dystrophy is a small, shallow and painful erosion or ulceration in the outer layer of the cornea. With epithelial erosions/ulcerations, your dog may show signs of discomfort such as increased tearing, squinting and rubbing the eye. Erosions or ulcerations can be caused by mechanical injury. However if this is a chronic reoccurring condition, it may be genetic. Epithelial dystrophy occurs occasionally in basenjis and can happen anytime during the life span. Treatment depends on the severity of the problem.

Stromal Corneal Dystrophy

Stromal dystrophies usually cause no discomfort and do not generally interfere with vision. Stromal dystrophy can be visible to the naked eye and appears as a tiny whitish spot on one or both eyes. These spots are thought to be lipid (fat) deposits in the stromal layers. Treatment is not generally necessary for this type of dystrophy unless vision is impaired or irritation occurs. It occurs occasionally in basenjis at any time in the life span and the cause is unknown.

Endothelial Corneal Dystrophy

Canine cornea endothelial cells do not repair themselves and when too many corneal endothelial cells become damaged the endothelium cannot regulate the water in the stromal layer and the cornea develops edema (swelling) and subsequently vision problems. This edema is initially painless but without treatment will progress and can cause “water blisters” called bullae that will rupture through the cornea surface causing painful corneal ulcers. The extent of visual impairment is dependent upon the severity and response to treatment.

This type of corneal dystrophy is the most serious of the types described and may have a genetic cause. It is important to keep in mind; the endothelial layer can also be damaged by other eye conditions such as glaucoma, severe inflammation or injury. When endothelial cell damage occurs secondary to another eye problem, it is called endothelial degeneration and is not considered genetic. If it occurs spontaneously it is called corneal dystrophy and has a genetic component. Consult your certified veterinary ophthalmologist to discuss treatment and causation of these conditions.

For the Owner

Depending on the type and severity of corneal dystrophy, your dog may or may not exhibit symptoms. Regular eye examinations by a certified veterinary ophthalmologist are essential for early diagnosis and treatment of corneal dystrophy. In addition, when you examine your dog, be observant. If you notice an unusual discharge from their eyes or the dog is rubbing them, have their eyes checked.

For the Breeder

Since we do not know how or if these conditions are hereditary, it is very important to keep track of the occurrences by tracking your puppies and disclosing any incidence. Consult a veterinary ophthalmologist regarding breeding recommendations for a basenji with any type of corneal dystrophy.

The 2009 American College of Veterinary Ophthalmologists (ACVO) recommendations for Basenjis with Corneal Dystrophy Epithelial/Stromal is Breeder Option. And the 2009 ACVO recommendations for Basenjis with Corneal Dystrophy Endothelial is that they should NOT be used for breeding.

Persistent Pupillary Membrane (PPM)

Persistent Pupillary Membrane (PPM) is a common condition known to be inherited in basenjis. In PPM, a normal membrane in the eye of the unborn puppy does not completely reabsorb and disappear after the puppy is born. As the unborn puppy develops, the part of the eye called the iris initially forms as a solid sheet known as the pupillary membrane. This important membrane contains blood vessels to supply nutrients to the developing lens of the eye before birth. During the first two weeks of life, before the eyes open, the membrane normally reabsorbs and disappears. However some of the pupillary membrane may persist in different forms. The location and extent of the persistent membrane or strands of membrane will indicate whether it affects vision. PPM can and should be assessed by a veterinary ophthalmologist at approximately 9 weeks of age. The OFA Eye Certification Registry certificate examination paperwork will describe the absence or presence, and location of these strands, tags, or sheets.

Examples of PPM findings in an eye exam:

Iris to iris strands (are the mildest PPM and the dog WILL pass the OFA Eye Certification Registry certificate examination)
Iris to lens strands (will NOT pass OFA Eye Certification Registry certificate examination)
Iris to cornea strands (will NOT pass OFA Eye Certification Registry certificate examination)
Iris sheets (will NOT pass OFA Eye Certification Registry certificate exam and, although rare in basenjis, are the most severe form of PPM).

Ask the veterinary ophthalmologist conducting the examination to what extent your dog’s vision may or may not be affected by the PPM findings.

For the Owner

Most PPM has no effect on a dog’s life. PPM does not progress, and in fact puppies with mild PPM often have it reabsorb and disappear completely as they age.

PPM severe enough to cause visual problems is normally visible to a non-specialist veterinarian and occasionally to the naked eye. PPM that severe is extremely uncommon. Puppies with more severe PPM (PPM visible to the naked eye) may have loss or blurring of vision but basenjis generally adapt and live normal lives.

For the Breeder

While most PPM does not have a negative effect on a dog’s life, severe PPM can. Severe PPM is quite rare in basenjis, but it was more common early in the breed’s history. The exact way PPM is inherited is not known.

Breeders should be aware of the PPM status in their stock, to prevent severe PPM from becoming common again. It is recommended for breeders to have an ACVO certified veterinary ophthalmologist check their puppies at approximately 9 weeks of age, to determine the presence or absence of PPM.

A basenji with iris to iris PPM (the mild form) will receive a Normal eye exam result. All other grades of PPM (iris to lens, iris to cornea, and iris sheets) will not. Most basenji breeders will not disqualify a dog from breeding solely due to mild PPM. A OFA Eye Certification Registry certificate exam will show current PPM status, but it does not tell you whether or not the dog will produce offspring with PPM.

Progressive Retinal Atrophy (PRA)

Progressive Retinal Atrophy (PRA) is an inherited eye disease that occurs in many breeds of dogs. In basenjis, it causes progressive vision loss leading to blindness. Inherited PRA occurs in both eyes (bilateral) and the part of the eye affected is the retina. With PRA the retina deteriorates (atrophies) over time (progressive) and ultimately causes blindness. The progression of vision loss may take a number of years and there is no treatment.

Research has shown there are at least two different forms of PRA in basenjis. In March 2013 a gene test (seeGenetic Testing section) for one form of PRA (PRA-BJ1) was made available to the basenji community. This gene accounts for approximately 50% of all PRA disease affecting basenjis. Currently there are multiple research teams around the world working to identify the causes of the other type or types of PRA in basenjis.

Basenjis affected by PRA usually do not exhibit changes in their vision until they are well into middle or even old age (5 – 8 years or even older). Due to the late onset of PRA it is important to have the genetic test for PRA-BJ1 completed before breeding. We can decrease the incidence of blindness in our breed with this one simple, inexpensive test.

As breeders and owners it is our responsibility to test our basenjis for PRA-BJ1 and share our test results so the disease can be prevented through informed breeding choices.

The gene test for PRA-BJ1 is offered by multiple labs. The Orthopedic Foundation for Animals offers this DNA test under the name ”Basenji Night Blindness/PRA DNA Test” located at the following link (http://www.offa.org/dnatesting/basenjipra.html). OptiGen offers the same test but it is called Bas_PRA1 and is located at the following link (http://www.optigen.com/opt9_basenjipra.html).

Unlike OFA, Optigen does not require disclosure of results. We encourage all breeders and owners to list their results on the OFA website, because only through disclosure of results are we able to eradicate genetic diseases. Both the OFA and Optigen tests determine whether the tested dog is genetically Normal/Clear, Carrier, or Affected for PRA-BJ1.

Since we know we have at least two forms of PRA in basenjis, a Normal/Clear or Carrier result only means the dog will not be affected by PRA-BJ1. Keep in mind, this dog or its offspring may still develop a different type of PRA. Testing for other type(s) of PRA must be done by regular OFA Eye Certification Registry certificate examinations and is explained in more detail below.

In addition, it is important to keep in mind, not all retinal changes are due to PRA; some changes may occur through injuries, caused by parasites, or due to a different disorder. Normal basenjis may also have an unusual looking retina that can be confused with PRA. When a clinical diagnosis of PRA is made with an ophthalmic examination, it is wise to have a second opinion conducted a year later to verify the findings and determine if retinal degeneration is progressing.

Many basenjis with PRA also develop cataracts (cloudiness on the lens of the eye). Owners may think their basenji’s cataracts are the reason for its vision loss, when in fact the dog could have PRA, as well. Both conditions affect vision and should be evaluated by a veterinary ophthalmologist.

The PRA-BJ1 test is part of the Canine Health Information Center (CHIC) list of health tests for basenjis. CHIC is a centralized canine health database jointly sponsored by the AKC/Canine Health Foundation (AKC/CHF) and the Orthopedic Foundation for Animals (OFA).

For the Owner

Puppy buyers should insist their breeder test for PRA-BJ1. At least one parent needs to be Clear/Normal and both parents should have been examined by an American College of Veterinary Ophthalmologists (ACVO) certified Diplomat within the year prior to the breeding. Ask for a copy of the OFA Eye Certification Registry certificate examination.

Most PRA affected basenjis do not exhibit symptoms of PRA (any type) until they are at least 5-6 years old. The first symptom usually exhibited is difficulty seeing at night. You may also notice dilated pupils (large pupils) even in good lighting. The disease will progress slowly and you will notice over time your dog loses vision during the day and will eventually become completely blind. This progression of vision loss may take a number of years and there is no known treatment or cure. Fortunately basenjis with PRA adapt to their vision loss and with a stable, predictable environment, can continue to have a high quality of life even after they lose much of their vision.

If you suspect your basenji has visual changes, have them examined by a veterinary ophthalmologist. If your basenji is diagnosed with PRA other than PRA-BJ1, please contact the BCOA Health and Research Committee as we are trying to collect information to learn more about this disease.

For the Breeder

All breeding stock should be tested for PRA-BJ1. This is a one-time test consisting of a simple cheek swab preformed at home and sent into one of the sites indicated above. At least one parent used in any litter should test Clear/Normal for this mutation.

Since there is at least one other form of PRA in Basenjis, it is recommended all breeding stock be examined by a veterinary ophthalmologist prior to each breeding to assess for retinal atrophy and other eye conditions. An examination by a veterinary ophthalmologist can detect early retinal deterioration before your dog exhibits symptoms or changes in its behavior due to vision loss. This examination is the best tool breeders can use to identify the other type(s) of PRA for which we have no genetic test. Since PRA can occur later in life, the exam cannot predict whether or not a dog will develop the problem in the future.

We do not know how many other type(s) of PRA are inherited, so dogs that are diagnosed with PRA by veterinary ophthalmologist exam, but have not been identified as affected with the PRA-BJ1 form of the disease, should NOT be used for breeding.

Fanconi Syndrome

Fanconi syndrome is an inherited disease in which the kidneys do not properly reabsorb electrolytes and nutrients back into the body, but instead spill them into the urine. Symptoms include excessive drinking (polydipsia), excessive urination (polyuria), and glucose in the urine (glucosuria). If left untreated, muscle wasting, acidosis (increased acidity in the blood), and poor condition occurs.

The disease, typically progresses slowly, despite treatment and eventually results in death from kidney failure. However, if caught early and put on treatment (Fanconi Treatment Protocol), dogs with the disorder can do well and often have a nearly normal lifespan.

The Orthopedic Foundation for Animals (OFA) offers a genetic test to determine whether your dog is Normal/Clear, a Carrier, or genetically Affected with Fanconi Syndrome. Fanconi Syndrome is genetically inherited as an autosomal recessive disease (see Genetic Testing above). Dogs that inherit only one abnormal gene in the pair are considered Carriers. Although Carriers will not develop the disease, they can pass the abnormal gene to their offspring. Those genetically Affected are at risk for developing the disease.

For more information about this test go to this page (information dated 2011).

The Fanconi Syndrome gene test is part of the Canine Health Information Center (CHIC) list of health tests for basenjis. CHIC is a centralized canine health database jointly sponsored by the AKC/Canine Health Foundation (AKC/CHF) and OFA.

Although Fanconi Syndrome found in basenjis is typically inherited, there have been cases reported in small, non-basenji breeds where the disease is acquired due to idiopathic (unknown) means or from medication side effects. In many cases it is hard to differentiate between genetic and idiopathic causes. Specifically Hooper and Roberts (2011, J. Am Animal Hosp. Assoc. 2011 Nov-Dec 47 No 6:178-18) presented evidence of Fanconi Syndrome in four non-basenji dogs exposed to chicken jerky treats. The symptoms of the acquired forms of Fanconi Syndrome vary, depending on the cause.

Understanding the Orthopedic Foundation for Animals (OFA) test results for Fanconi Syndrome:

In August 2011 OFA began offering the DNA test which reveals whether a dog has the gene responsible for causing Fanconi Syndrome. Between July 2007 – August 2011, OFA offered a linked marker test as part of the research to identify the actual gene responsible for Fanconi.

The OFA database provides a public record of results. When looking up an individual dog, the OFA # tells you:

BJ = breed (Basenji)

FAC = Fanconi test (both gene or linked marker)

sequential number of sample assigned by OFA/

age at time of test in months

M or F for male or female

test related code

The test related codes are:

PI = permanent identification in the form of tattoo or microchip.

NOPI = no permanent identification.

VPI = animals that are permanently identified AND have had the identification verified by the attending veterinarian at the time of the test.

For example, an OFA # BJ-FAC9999/35F-NOPI would be a female Basenji tested Clear/Normal for Fanconi at the age of 35 months but with no permanent identification and was the 9999th dog sampled by OFA. While an OFA # BJ-FAC9989/45M-CAR would be a male Basenji tested Carrier for Fanconi at the age of 45 months with a tatoo and/or microchip identification and was the 9989th dog sampled by OFA.

Effective 1/1/08, only dogs with verified permanent identification (VPI) will have their OFA data transmitted to the AKC for inclusion in their database.

Clear by parentage

For current DNA gene tests only (since August 2011 to date), the OFA will issue clearances to untested offspring: if the sire and dam have both been DNA tested Normal/Clear, if the sire and dam’s DNA disease test results have been OFA registered, and if all three (sire/dam/offspring) have been DNA identity profiled and parentage verified. The resulting OFA certification will contain the suffix “CBP” (Clear by parentage), indicating that the dog itself was not tested but that the clearance was based on the sire and dam’s test results and known science at the time. Because of the possibility for new mutations, or as of yet undiscovered gene mutations, only first generation offspring will be designated CBP.

For the Owner

Owners should insist that at least one parent of any puppy they purchase be tested “Normal/Clear” for Fanconi using the gene test (see above). Pets can be DNA tested to verify a Fanconi diagnosis or to help assess their likelihood of coming down with Fanconi [http://www.offa.org/dnatesting/fanconi.html]. Owners of DNA tested “Affected” dogs and dogs of unknown status should periodically ‘strip test’ (see information on strip testingbelow) their dogs for glucose in the urine starting as early as age 1 year. Strip testing indicates only the current presence or absence of glucose in the urine. It does not diagnose Fanconi or predict future results. A dog that strip tests “normal” now may later develop Fanconi.

Because elevated urine glucose is also found in diabetes, basenjis with Fanconi are often misdiagnosed with diabetes. Diabetic dogs will have high blood glucose levels, as well as urine glucose levels. In basenjis, a combination of urine glucose and normal or low blood glucose strongly suggests Fanconi Syndrome. The venous blood gas test (a simple blood test that estimates systemic carbon dioxide and pH levels) can verify an electrolyte imbalance consistent with Fanconi Syndrome. A veterinarian should evaluate dogs that have Fanconi symptoms but are not spilling sugar.

For the Breeder

All breeding stock (both sire and dam) should be DNA tested for the Fanconi gene using the current DNA test. The current DNA test for Fanconi is available through the OFA at http://www.offa.org/dnatesting/fanconi.html and test results are in the searchable open database on that site. Results from the DNA linked marker test (available between 2007 to August 2011) should NOT be used for making breeding decisions. The current (as of August 2011) gene test, which tests for the actual mutation responsible for this disease, will tell you the genetic state of the dog. The test will determine if the dog is Normal/Clear, a Carrier, or genetically Affected. This is particularly important prior to the development of symptoms if the dog is Affected. Catching the onset of the disease early and starting treatment can, in some cases, lessen the severity of the disease.

Any planned basenji litter should have at least one parent that DNA tests Normal/Clear, to eliminate the chance of producing Affected puppies.

Fanconi Treatment Protocol

In 1990 (updated in 2003 and 2012) Dr. Steve Gonto developed a treatment protocol for dogs with Fanconi based on the therapy human Fanconi patients received. The protocol uses dietary supplements for acid neutralization and replacement of lost electrolytes and nutrients. This is accomplished with bicarbonate and other supplements in specified doses to re-establish the body’s acid-base balance and keep electrolytes at appropriate levels. Dr. Gonto was given lifetime membership in the Basenji Club of America in recognition of the importance of his work.

The Gonto protocol was studied and validated for the veterinary literature by Jennifer Yearley, DVM, while she was completing her professional studies. This was an important step in expanding the awareness of the treatment. The protocol has been very successful in improving both quality and length of life for Fanconi-affected basenjis. The disorder can be controlled by the protocol, but it cannot be cured.

The most current Fanconi Protocol can be downloaded HERE.

Urine Strip Testing

Urine glucose test strips (not blood test strips), such as those used by diabetics, are inexpensive and can be purchased at most pharmacies. The strip should be placed in the basenji’s urine stream and then read as specified in the strip instructions. If it is not possible to place the strip in the urine stream, then the owner may need to catch the urine. Some owners use a pie pan, ladle, or serving spoon.

Pyruvate Kinase Deficiency – Hemolytic Anemia

Pyruvate kinase deficient – hemolytic anemia was first diagnosed in basenjis in the 1960s, although prior to that date basenjis had died of a then-unknown form of anemia. Research on this anemia began in the 1960s and there is a DNA test available.The inherited form of the disease now is extremely rare.

Pyruvate Kinase Deficient – Hemolytic Anemia (PK-deficient HA) is different from idiopathic autoimmune hemolytic anemia (IAHA), a non-inherited hemolytic anemia that occurs in all breeds of dogs. Because of the great reduction in the frequency of the inherited form, the non-inherited form is now the likeliest cause of any hemolytic anemia in basenjis.

Affected dogs may faint, are likely to have low energy levels, typically have very white gums and mucous membranes, and have light, “golden” colored stools. Affected dogs typically die by age 2, with age 4 being the outside limit of survival.

For the Owner

The disorder has been virtually eliminated from the breed and testing has been largely discontinued. Owners can ask for information about whether or not the dogs have been tested or are entirely descended from tested normal stock. Because a DNA test is available, a definitive diagnosis can be made to rule out PK-deficient HA.

For the Breeder

Testing for PK-deficient HA can still be obtained at some DNA testing labs. Most basenjis are now descended from tested normal stock. A few carriers still exist in the gene pool, so it is a good idea to use only dogs descended from tested normal stock or dogs that have themselves been tested. A list of labs that perform the HA test (pyruvate kinase deficiency) is online at http://www.offa.org/dnaother.html. OFA has an open registry for hemolytic anemia DNA status.

All new imports from Africa were DNA tested prior to inclusion in the AKC studbook.

This DNA testing gives a definitive reading of the dog’s status as Clear, Carrier, or Affected, so the testing does not have to be repeated. The gene is inherited as a simple recessive.

Hip Dysplasia

Hip dysplasia (HD) is a complex hereditary condition in which the hip socket is badly formed, often leading to lameness and arthritis. It is believed to be polygenic (with multiple genes), as well as having environmental factors involved in its expression. According to the OFA, the basenji ranks 157th of 172 breeds in incidence of Hip Dysplasia. Of 2,651 hip evaluations performed by OFA between January 1974 and December 2013; 23% were rated Excellent and 3.5% were rated Dysplastic.

For the Owner

When purchasing a puppy, the parents should have been tested for hip dysplasia and the x-rays should have been read by the Orthopedic Foundation for Animals (OFA.) Results can be found by looking under the dogs AKC registration number at http://www.offa.org. Your breeder should be able to provide a link to the results for the parents of your pup.

For the Breeder

Breeding stock should be x-rayed for hip dysplasia. The OFA has a web site that permits downloads and searches of dogs that have passed with a grade of Fair, Good, or Excellent. In addition, the OFA has recently added the option of having results placed in an open health registry, so that Borderline and Dysplastic ratings can be made public.

Good and Excellent are the preferred grades for breeding stock, although Fair is not considered dysplastic. Affected or untested animals should never be used for breeding. OFA status at 2 years of age is generally considered definitive of that dog’s hip status. However, there is a small chance a dog can become dysplastic later in life.

For permanent results, dogs can be x-rayed for hip dysplasia at 2 years of age or older, with the films reviewed by the OFA for the definitive reading. Dogs can be x-rayed earlier for preliminary results if they are being bred prior to 2 years of age. Hips can also be examined by PennHip and PennHip results can be included in the OFA database.

Breeding from tested unaffected stock and using vertical pedigrees to consider the scores of relatives are the recommended methods of controlling hip dysplasia. The rate of incidence of HD within a litter has been shown by OFA to be strongly correlated to the hip scores of the parents with litters of parents both rated Excellent having the least chance of having HD.

In the chart below each parent is assigned a numerical score 1=excellent, 2= good, 3=fair, 4=borderline, 5=mildly dysplastic, 6= moderately dysplastic, and 7= severely dysplastic. Parental scores were then added together and the % dysplastic progeny calculated for each score. So, excellent x excellent = 2 and the chart shows a 3.58% incidence of dysplasia in progeny of excellent x excellent breedings from the OFA database.

This chart represents hip phenotype data on 490,966 progeny in the OFA database for which the hip phenotype for both parents are known. It is reprinted here from Dr. Keller’s talk with the permission of OFA.

A hip x-ray evaluated by three board certified radiologists is part of the Canine Health Information Center (CHIC) list of health tests for basenjis. CHIC is a centralized canine health database jointly sponsored by the AKC/Canine Health Foundation (AKC/CHF) and the Orthopedic Foundation for Animals (OFA).

Immuno-Proliferative Small Intestinal Disease and Exocrine Pancreatic Insufficiency (EPI)

Immuno-Proliferative Small Intestinal Disease and Exocrine Pancreatic Insufficiency are presented together because they are both disorders of maldigestion or malabsorption.

IPSID stands for Immuno-Proliferative Small Intestinal Disease but it is a disease of many names. It is also called Basenji Enteropathy, Immunoproliferative Lymphoplasmacytic Enteritis, Basenji Diarrheal Syndrome, and malabsorption. IPSID is a type of inflammatory bowel disease (IBD), which results in the dog not being able to utilize and absorb nutrients correctly from food.

A predisposition to IPSID is inherited, but inheritance appears to be only one of the factors involved. A dog genetically predisposed to IPSID and its resultant immunological impairment might present with usual IBD and eventually progress to IPSID. Physical and/or emotional stresses may be aggravating triggers.

Exocrine pancreatic insufficiency (EPI) can be confused with IPSID but the treatment is very different. A dog with EPI is not able to produce the enzymes needed for digestion. EPI occurs when a dog’s exocrine glands in the pancreas become atrophied and can no longer produce or secrete pancreatic digestive enzymes. Some food particles then remain undigested and unabsorbed causing Small Intestinal Bacterial Overgrowth (SIBO). That results in the dog, although eating copious amounts of food, being constantly undernourished and literally wasting away. Without proper treatment, the EPI dog can suffer greatly and even die a painful death from malnourishment, starvation or organ failure.

EPI should be ruled out before a diagnosis of IPSID is made. The only way to confirm EPI is with a TLI (Trypsin-Like Immunoreactivity) blood test. If your dog is diagnosed with pancreatic insufficiency or if you have questions about the disorder, information is online at http://www.epi4dogs.com.

For the Owner

IPSID symptoms can include diarrhea, vomiting, weight loss, increased or decreased appetite, gas, and depression. EPI symptoms are very similar and include weight loss despite a strong appetite, greasy globs of voluminous yellowish stools, diarrhea, vomiting, and personality changes. The type of symptoms and their severity differ from dog to dog, and from one episode to another. Dogs with IPSID or EPI often will have good periods as well as bad spells. Rarely will a dog present with profound weight loss but no other symptoms. Testing for EPI and IPSID can rule out instances where a dog suffering from either condition is not suffering from other outward symptoms like vomiting and diarrhea.

Diagnosing IPSID involves investigating and eliminating other possible causes of the dog’s symptoms. Blood serum protein levels may be low. Intestinal biopsy is the only reliable way to diagnose IPSID; it is done to rule out irritable bowel syndrome, inflammatory bowel syndrome and other diseases, lymphangiectasia (which most basenjis with IPSID have as a secondary condition), colitis, cancer, and systemic fungal infections. Endoscopic biopsies are preferred to prevent complications with healing.

Traditional methods of treating IPSID include systemic prednisone and antibiotics. Some dogs do well on a holistic regimen; it is important to discuss a long-term treatment plan with your veterinarian. Symptoms may diminish or increase over time. A veterinarian must oversee treatment and changes to treatment. IPSID affected dogs can harbor microorganisms that may cause problems for other dogs in the household; proper household hygiene is important.

A change to the dog’s diet may be required to optimize nutrient utilization. Some veterinarians suggest switching diets on a monthly basis. A homemade diet also can be used and additional vitamin supplementation may be indicated.

EPI should be confirmed with a trypsin-like immunoreactivity blood test. This test detects trypsinogen and trypsin levels in the pancreas. Values below 2.5 µg/L indicate EPI. Values between 3.5 and 5.7 µg/L may be indicative of other pancreatic disease.

Treatment for EPI includes supplementation with enzymes and changes to the dog’s diet. Antibiotics and supplementation with vitamin B-12 (cobalamin) may also be required. The most common enzymes used to treat EPI dogs are porcine-based (from pigs). However, some EPI dogs do not tolerate porcine enzymes. These dogs are often helped by plant-based (soy) enzymes that aid digestion.

There are many web resources for dogs and owners dealing with EPI, including discussion lists for owners of affected dogs. See, for example: http://www.epi4dogs.com/.

For the Breeder

While IPSID and EPI are not common, they are serious diseases. Dogs with IPSID or EPI should NOT be used for breeding. While the mode of inheritance is not known, susceptibility to these diseases, rather than direct inheritance, may be involved.

Patellar Luxation

Patellar luxation occurs when the kneecap pops out of place. As of December 2013, 0.9% of those basenjis checked have been reported Affected by the Orthopedic Foundation for Animals.

For the Owner

Patellar luxation can be diagnosed by a veterinarian.

For the Breeder

The Orthopedic Foundation for Animals has an open registry of dogs whose patellas have been evaluated at 12 months of age or older. The exam is non-invasive and inexpensive. Patellar luxation is suspected to be heritable, though the mode of inheritance is unknown.

Thyroid Problems

The thyroid glands (there is a pair) secrete and regulate the hormones responsible for metabolism and some organ function. Thyroid gland disease in dogs is most often hypothyroid (underactive / low functioning gland). It may be the only symptom of the disease or it may be a part of a broader autoimmune disorder. One form of hypothyroidism is caused by autoimmune thyroiditis and is known to be an inherited disease. But idiopathic (cause unknown) thyroid gland atrophy can also occur. An underactive thyroid generally means that the dog’s metabolism is slower than normal.

Hypothyroidism can be controlled very easily by medication.

Some or several of the following symptoms may be observed: weight gain without an increase in appetite, symmetrical hair loss and poor coat, ear and skin changes (including dryness, chronic bacterial infections, discoloration, or thickening), lethargy and lack of interest in physical activity or play, and/or significant behavioral changes like aggression.

Testing is available to learn the current thyroid status of your dog but the blood test cannot predict future changes.

A comprehensive thyroid panel is used and should include:

total thyroxine (T4 or TT4 which is total thyroxine hormone)
thyroid-stimulating hormone (TSH),
free T4 (or FT4 which is the free or active thyroxine hormone) by equilibrium dialysis, and
cTGAA (Canine Thyroglobulin Autoantibody or TAA) levels show negative or positive for thyroglobulin antibodies.

Elevation of TgAA levels are used to diagnose autoimmune thyroiditis; however, as the disease progresses, these levels may decrease due to complete destruction of the thyroid gland. Dogs that have had autoimmune thyroiditis for several years but have never been tested might not show the elevated TSH and TgAA needed for definitive diagnosis. Your veterinarian may test other thyroid levels when making a diagnosis.

The minimal thyroid level necessary for healthy function varies depending on breed of dog, age, and reproductive phase. Sometimes it can even vary between pedigree lines. Puppies have higher normal thyroid levels, while seniors and sighthounds have lower normal thyroid levels.

Basenjis require a thyroid panel including at least TT4, FT4, TGAA, and TSH, to be accurately diagnosed.

When testing your basenji, TT4 and FT4 must be analyzed in conjunction with TSH. Basenjis typically have a lower reference range for TT4 than other breeds. Research conducted by the University of Sydney found that basenjis and some other sighthounds have lower normal levels of TT4 than other dog breeds (Seavers, A.; Snow, D.H.; Mason, K.V.; Malik, R. 2008. Evaluation of the thyroid status of Basenji dogs in Australia. Australian Veterinary Journal: 11, 429-434). Given the difficulty of accurately measuring TT4 concentrations that low, TSH level measures are essential to properly assess thyroid function. Otherwise, your basenji may be diagnosed as hypothyroid by the standard all-breed normal range and be medicated for no reason.

Autoimmune thyroiditis disease has variable onset but tends to become symptomatic at 2 to 5 years of age. Dogs that are negative at 1 year of age may become positive at 6 years of age. Dogs may be clinically normal for years, only to become hypothyroid at a later date. Therefore, periodic retesting every year or two is recommended. Since the majority of affected dogs will have autoantibodies by 4 years of age, annual testing for the first 4 years is recommended. After that, testing every other year is recommended.

The Orthopedic Foundation for Animals has an open registry for dogs that have been tested for autoimmune thyroiditis at 12 months or older, using approved labs. For the current list of laboratories approved to perform analysis for OFA thyroid certification, see http://www.offa.org/thy_labs.html.

The autoimmune thyroiditis test is part of the Canine Health Information Center (CHIC) list of health tests for basenjis. CHIC is a centralized canine health database jointly sponsored by the AKC/Canine Health Foundation (AKC/CHF) and the Orthopedic Foundation for Animals (OFA).

For the Owner

Hypothyroidism may be treated with a thyroid supplement under veterinary supervision including periodic adjustment of the dosage. Pet owners may want to have their vet periodically check their dogs, especially if they show any symptoms that suggest hypothyroidism.

For the Breeder

It is a good idea for breeders to periodically check their breeding stock with a full thyroid panel beginning in early adulthood. Testing for breeding stock is done primarily to rule out autoimmune thyroiditis, which is known to be inheritable. The thyroid panels test does not indicate if a dog can produce offspring with hypothyroidism.

It is recommended to perform a thyroid wellness test before the bitch begins any signs of her heat cycle. A thyroid imbalance often occurs as a result of whelping. For puppies, the first wellness thyroid panel should be done 3 months after the first heat, for dogs & bitches.

Umbilical and Inguinal Hernias

Umbilical hernias are very common in basenjis, with most being minor hernias that do not normally cause problems for the dog. Inguinal hernias, although uncommon, can be serious. Both types of hernias are hereditary.

For the Owner

Umbilical hernias can be repaired at any time; the surgery is often done when a pet is spayed or neutered or during any other procedure requiring anesthesia. Small closed hernias generally do not cause problems, however large or open hernias can cause problems if a loop of intestine gets caught in the hernia. Some breeders routinely repair even small closed hernias. Dogs which have had umbilical hernias repaired are still eligible for participation in AKC conformation events.

Inguinal hernias are uncommon in basenjis and can be diagnosed by your veterinarian. They generally do require surgical repair. Dogs with repaired inguinal hernias are not eligible for participation in AKC conformation events.

For the Breeder

Small closed umbilical hernias generally are not an issue in breeding, although selection away from umbilical hernias is desirable. The use of individuals with large or open hernias should be carefully considered.

About Basenjis[[PASTING TABLES IS NOT SUPPORTED]]

Health Links[[PASTING TABLES IS NOT SUPPORTED]]

Health Endowment[[PASTING TABLES IS NOT SUPPORTED]]

Joomla Templates

Amore Basenjis

Health