Hyperoxaluria is a rare hereditary renal disorder. Clinical signs of the disorder are due to nephrocalcinosis and renoliths caused by excessive oxalate accumulation in the kidneys. This causes a reduction in renal function. Affected kittens may show muscular atrophy, dehydration, anorexia, and weakness which may present prior to or after the onset of renal dysfunction. Affected kittens develop acute end-stage renal disease typically between five and nine months of age.

Treatment is supportive care; however, due to the progressive nature of the condition, clinical signs typically lead to euthanasia for welfare reasons.

There are many responsibilities to consider when breeding cats. Regardless of test results it is important that your cat is in good general health and that you are in a position to care for the kittens if new responsible owners are not found. For first time or novice breeders, advice can be found at most cat registry websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to be shown. A carrier cat with one copy of the Hyperoxaluria type II mutation can be safely bred with a clear cat with no copies of the Hyperoxaluria type II mutation. About half of the kittens will have one copy (carriers) and half will have no copies of the Hyperoxaluria type II mutation. Kittens in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected kittens. Please note: It is possible that disease signs similar to the ones caused by the Hyperoxaluria type II mutation could develop due to a different genetic or clinical cause.