What PKD Is
Polycystic kidney disease, or PKD, is a hereditary condition in which fluid-filled cysts form in the kidneys and sometimes in other organs. The cysts slowly grow and crowd out healthy kidney tissue, which can lead to chronic kidney failure later in life. Typical signs include increased thirst, weight loss, vomiting, and a reduced appetite, and they often appear only in middle age. Historically the disease has been common in Persians and closely related breeds such as Exotics and British Shorthairs.
How It Is Inherited
PKD follows an autosomal dominant pattern, caused in most cases by a mutation in the PKD1 gene. Because the trait is dominant, a kitten only needs to inherit it from one parent to be affected, so roughly half the offspring of an affected cat will carry it too. This is why the disease can spread quickly through a line if it goes untested. The upside of a dominant single-gene disease is that it is also straightforward to identify and remove.
What the DNA Test Tells You
A DNA test for the PKD1 mutation sorts cats into clear categories that guide your decisions. A cat with an N/N result is free of the mutation and cannot pass it on to kittens. A cat with an N/P result carries the mutation, is genetically affected, and should not be bred. The test uses a simple cheek swab or blood sample and gives a definitive answer that does not change over the cat's life.
Breeding It Away for Good
Because the test is so reliable, PKD is one of the few serious diseases a breeder can eliminate from a line with confidence. Test breeding cats before you pair them and use only N/N cats in your program, and the mutation simply cannot be passed to the next generation. Kittens from two N/N parents do not need to be tested for this mutation themselves. Work with your veterinarian and a reputable laboratory, and keep records so buyers and fellow breeders can see the status of the parents.