Polycystic Kidney Disease in Cats: Welfare and Breeding
Disease Overview
Feline polycystic kidney disease (PKD) is caused by an autosomal dominant mutation (PKD1 gene) causing progressive development of fluid-filled cysts in the kidneys and sometimes liver. It affects Persian, Exotic Shorthair, British Shorthair, and related breeds. Cysts present from birth but cause progressive kidney enlargement and renal failure typically in middle to older age (7-10+ years). Prevalence in Persians has historically been 40-50% in some countries, though breeding programmes have reduced this significantly.
Welfare Consequences
PKD causes progressive chronic kidney disease with all associated welfare consequences: weight loss, muscle wasting, vomiting, reduced appetite, polydipsia, and ultimately uraemic crisis. The progressive nature means affected cats experience years of gradually declining welfare before end-stage disease. Large cysts can cause abdominal discomfort. The high prevalence in affected breeds meant PKD was causing widespread, often unrecognised welfare compromise in pedigree cat populations.
Genetic Testing and Breeding
The causative PKD1 mutation was characterised by Dr. David Biller in the late 1990s. A simple cheek swab DNA test identifies affected (heterozygous positive) and clear (homozygous negative) cats. The Feline Advisory Bureau (now iCatCare) and cat fancy organisations have promoted PKD testing since the early 2000s. Breeding only PKD-negative cats (two PKD-negative parents cannot produce PKD-positive offspring) eliminates the disease from affected lines within 1-2 generations. This represents one of the most successful welfare genetics programmes in companion animals.
Diagnosis and Monitoring
Ultrasound examination is the standard diagnostic method for identifying cysts in living cats. It can detect cysts from approximately 6 months of age (earlier with experienced operators). In genetically affected cats, ultrasound monitoring every 1-2 years tracks cyst development and renal function. Blood tests (creatinine, SDMA, BUN) and urinalysis monitor renal function as disease progresses. IRIS staging guides management of secondary CKD using the same approach as non-PKD CKD.
Welfare Advocacy and Breed Health
PKD testing requirements are now embedded in GCCF, TICA, and many FIFe breed standards for affected breeds in most countries. Responsible breeders test all breeding cats before mating. Buyers of Persian, Exotic Shorthair, or British Shorthair kittens should ask for both parents' PKD test certificates. The success of PKD eradication programmes demonstrates that genetic testing can achieve major welfare improvements in pedigree populations within a relatively short period — a model for addressing other inherited diseases in pedigree breeds.