A mating of XX and Xx parents would produce all positive kittens with PKD but few XX cats are known to have survived long enough to breed. At present, polycystic kidney disease can only be diagnosed by ultrasound scan as research is still attempting to isolate the PKD gene and produce a reliable DNA test. Scanning should be done by a trained operator with a 7.5mHz or 10mHz transducer. Kittens can have their first scan as young as 4 weeks but minute cysts may not be visible and it is usually recommended to give a first scan at age 10 months. The ultrasound scan should be done on both kidneys, side to side and front to back.
Positive cats show black holes as the cysts are full of fluid.
Cysts can be inside the kidney as well as on the outside. Kittens with one positive parent should be re-scanned at a later date if no cysts show up on the first scan. Only after a series of clear scans can the kitten be declared as a likely negative. Often very small cysts can be missed on a scan and a repeat scan may pick them up when they have grown bigger. Kittens with two negative parents should not need to be scanned but it may help the owner to check if they are not confident with the status of either of the parents.