Polycystic kidney disease

Polycystic kidney disease, or PKD, is an inherited disorder in which cysts, small fluid-filled sacs, form in the kidneys. Cysts are present from kitten age and slowly grow, crowding out normal kidney tissue. It is most often found in Persians, Exotic Shorthairs and cats with Persian ancestry, and has also been seen in other breeds.

The disease is passed on by a dominant gene, so a cat with one copy of the faulty gene can develop it and pass it to about half of its kittens. A DNA test on a cheek swab can show whether a cat carries the gene. Breeders use it to avoid producing affected kittens, and a buyer can ask for the parents' results. Vets can also see cysts on an ultrasound scan, even in young cats.

Many affected cats do not show illness for years. Signs usually appear in middle age and look like chronic kidney disease: drinking and urinating more, weight loss, a poor appetite and vomiting. How quickly the disease progresses varies a great deal between cats. Vets monitor kidney values, blood pressure and urine and manage kidney failure as it arises. Ask your vet about screening if you have a Persian-type cat, and about the right time for follow-up tests.