Polycystic Kidney Disease

Polycystic means multiple cysts. In effect, PKD denotes multiple cysts on each kidney. These cysts grow and multiply over time, also causing the mass of the kidney to increase. Ultimately, the diseased kidney shuts down causing end-stage renal disease for which dialysis and transplantation are the only forms of treatment in humans, but little can be done for our feline friends.

Polycystic kidney disease is an inherited kidney disease that has been found in Persians and other purebred cats as well as humans. Feline Polycystic Kidney Disease has been reported in veterinary medical literature since around 1967, but actual studies into this renal disease did not begin until 1990 when The Ohio State University teaching hospital was presented with an affected six-year-old female Persian with large kidneys and symptoms of renal failure that was then diagnosed as PKD. Offspring of this female were used to start a colony and thus began the research into this condition in cats.

The condition has been proven to be inherited and the resulting cysts are present from birth, but are smaller in younger animals. PKD is a disease that will not manifest until later in life; with enlarged kidneys and kidney dysfunction occurring generally around seven years of age, but can occur anywhere between three and ten years of age. A cyst resulting from PKD can range from less than 1 mm to greater than 1cm in size. Older animals will generally have more and larger cysts than the younger afflicted animals. The kidney's ability to function properly is diminished as the cysts start to grow and progressively enlarges the kidney. As stated above, the ultimate end is total kidney failure.

PKD is now diagnosed by DNA testing, which is 100% accurate. The test was developed by the University of California, Davis. Testing is done at the Veterinary Genetics Laboratory at the University of California's School of Veterinary Medicine. Rights to the DNA test were also given to Gribbles Molecular Science Laboratory in Australia. A simple swab of buccal cheek cells is all that is required to perform the DNA test.

PKD is an inherited disease and cannot be transmitted to other cats. Dr. David Biller of Kansas State University has recently completed studies and published results showing PKD to be an Autosomal Dominant inherited trait. Published results are in the Journal of Heredity. 1996:87:1-5. Clinical signs of PKD that you can look for are depression, reduced or even lack of appetite, overly excessive thirst, overly excessive urination and weight loss. There seems to be a noticeable difference in when or how quickly individual cats begin to exhibit signs of PKD, including the possibility of this developing so late in life that the cat can die of other natural causes before potential kidney failure. However, kidney failure is certain if the cysts grow and cause problems.

Treatment of PKD is similar to the treatments of any other chronic kidney failure. This treatment includes moderate dietary protein restriction using high biological value protein, dietary phosphorus restriction, providing fresh drinking water at all times, use of phosphate binders, and treatment of the anemia if necessary. However, there is no specific treatment for this disease. There is still a lot more work needing to be done on polycystic kidney disease in cats to understand the underlying causes and devise a suitable treatment.

How do we at KaddyShack protect you from PKD?

All cats in the breeding program at Kaddyshack Cattery have been DNA tested for PKD. We are proud to report all of our cats are PKD negative. If cats do not posess the positive gene, they cannot pass it on to their offspring.

It is estimated that PKD is far more common in Persians than is currently diagnosed and we recommend you ask any Persian breeder if their cats have been DNA tested for the disease. With more study and published information about the disease, breeders and veterinarians can work to establish PKD-free breeding programs. In this manner, breeders can eliminate this genetic health problem.