Health Issues in the Persian Cat: Polycystic Kidney Disease

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CH Donegal’s Irish Mist (Misty)

Polycystic Kidney Disease (PKD) is similar to Hypertrophic Cardiomyopathy (HCM) in that it only takes one parent to pass the disease. PKD is an inherited kidney disease that passes from a genetically affected parent at a statistical rate of about 50%. It can be a relatively silent disease for many years until it manifests later in life as renal failure. Or it can strike early and unexpectedly with renal demise characterized by multiple cysts in both kidneys. This disease, like HCM, can have variable expression from cat to cat. For decades, the two most common diseases that cats died from were kidney disease and cancer. Cardiomyopathy is now competing for a similar rank.

Evolution of Testing
When sonograms became available to the veterinarian world, specialty veterinarians began offering kidney ultrasounds to cat owner clients. Accuracy of the ultrasounds was considered to be approximately 95% in cats that were 10 months of age or older. Like HCM at a minimum of two years of age, early signs of PKD could be detected in most cats at a minimum of 10 months of age. One such cat was found to be positive for PKD at Donegal Cattery and quelled from breeding. (You can read about Misty on the HandiCats Donegal web site.)

Donegal Cattery
Health is a major concern at Donegal Cattery. All Donegal Cattery breeding cats are DNA PKD (Polycystic Kidney Disease) Negative, tested at UC Davis Genetics Laboratory and/or Texas A& M Research Facility (CatDNATest).

Breeders have been aware of PKD and FIP for decades now and most are making efforts to eliminate PKD genetically and minimize FIP incidence with appropriate breeding practices. If they are not doing this, then it is wise to question their ethics in breeding Persian cats.

Having ultrasounds allowed conscientious breeders to “breed away from” the disease and eliminate it in their breeding cats. Unfortunately, some breeders continue to use positive cats either because they haven’t had them genetically tested or because they simply don’t care. There was a period of time where chocolate and lilac breeders were using positive PKD cats and selectively keeping negative offspring because that color gene pool in the Persian breed was very small. That is no longer necessary with having had scores of years of outcrossing chocolates and lilacs to negative Persian cats who did not carry the chocolate gene.

Unlike the genetic marker for HCM which appears to be breed specific, PKD is genetically similar in several breeds of cats. Persians have been used in those breeds and may or may not account for the origin of this disease. According to UC Davis: “The heritable form of PKD1 may not have initially occurred in Persians as a new mutation, but perhaps in random bred cats.” So in the cat world those breeds, which include but are not limited to British Shorthair, Persians (including Himalayans), Exotics, and Scottish Folds, share a common genetic marker for the disease referred to as PKD1 and they can be tested genetically for this disease.

PKD1 Gene Testing
The following facilities test for the PKD1 gene in Persian cats for a nominal fee:

Texas A & M University Animal Genetics Laboratory
http://www.catdnatest.org

The University of California Davis Veterinary Genetics Laboratory
http://www.vgl.ucdavis.edu

All Persian breeders should have their breeding cats DNA tested for this disease. If both parents are DNA negative then neither parent can pass the disease to its progeny. At this point in the breeding world of Persian cats there is no longer any excuse for using a PKD DNA positive cat for breeding.

CFA's DNA Testing Coalition
Jeanne O'Donnell discovered that a lot of breeders, like her, lost hundreds of dollars testing for PKD and other parameters when the CFA set up their DNA testing coalition with Catgenes, run by Melba Ketchum, DVM. Many erroneous test results were sent, some never redone as promised, and some never sent at all. The researcher eventually refused to return breeders' phone calls and the CFA disbanded that coalition and retrieved the data.

The CFA then set up a new coalition with the researcher who is doing the HCM research in Persians: Texas A&M Animal University Laboratory led by Gus Cothran, DVM. It is called Catdnatest. However, Jeanne also discovered at a recent cat show from a well-known Persian breeder that many breeders don't know that it has changed. They believe that the link on the CFA web site is still the one where they received erroneous results and/or lost money. So they are using UC Davis for DNA testing, which is also a reputable facility, but at a greater expense when ordering more than just PKD testing (i.e. colorpoint, chocolate, and agouti genes).

Prior to providing this service as Catdnatest, Texas A&M had lots of experience testing the new DNA test chip having practiced with all the DNA that Jeanne O'Donnell sent them for the HCM research. She wants other breeders to know that Dr. Cothran can be trusted to provide them with accurate DNA testing results for the parameters that were supposed to be tested by the previous organization. PKD testing is part of their Panel B and cannot be ordered separately. They just need to request the Panel B which includes PKD and all available genetic tests for Persians listed in Panel A for a total of $65.00. Panel A for $55.00 includes MPS, PRA, B blood type, chocolate, colorpoint, agouti, and dilute in Persians. If they want only PKD testing, they will need to continue using UC Davis or other facilities around the world offering that test as the sole parameter. The web address for the tests that are done at Texas A&M for the two panels is http://www.catdnatest.org/.

Article Author: 

Jeanne O'Donnell