My Persian cat is nine months old and his testicles still haven’t dropped. He is as flat as can be in the back of his stomach. I have never seen this in a male cat before unless it had been neutered, which my cat is not. Could you tell me what the problem might be or what I can do about it?

Failure of either or both testes to move into the scrotum normally.

During fetal development a kitten’s testes will normally be positioned within the abdomen. Sometime before birth, the testes descend from the abdomen through the inguinal canal to the scrotum. This process is usually complete before birth. However, in some cats testicular descent may take up to eight weeks. If a kitten’s testes are not fully descended by this time, the kitten has cryptorchidism and is said to be a cryptorchid.

Cryptorchidism is the condition in which either or both of the testes fail to descend into the scrotum. This problem occurs infrequently in cats. Most cases of cryptorchidism are caused by heritable genetic factors. Persian and certain other breeds of cat have a greater chance of producing male kittens with undescended testes than other breeds.

Most cryptorchid cats have one undescended testicle rather than both being affected. In these "unilateral" cases, the descended testicle will function normally and the cat will be fertile. In bilateral cryptorchidism, in which both testes remain in the abdomen and fail to descend normally, the affected cats will usually be sterile. The relatively high temperatures of the abdomen destroy the sperm-forming tissue of the undescended testes. Both descended and undescended testes will retain the ability to produce sufficient male hormone (testosterone) to cause urine spraying and other tomcat behaviors. Unlike cryptorchid dogs, affected cats only rarely develop cancer of the undescended testes.

Diagnosis of cryptorchidism is made by physical examination and occasionally a blood test that measures testosterone-level response to injected hormonal stimulants. No treatment to lower the undescended testes in cats has been found to be effective in cats.

If your pet has no testicles down at nine months of age, it is doubtful that they will descend. The retained testicles most likely are still up in the abdomen. Undescended testes could not produce sperm even if medical intervention could relocate them.

Since undesirable tomcat behavior is still prompted by hormonal output of the testes, surgical removal of both descended and undescended testes (neutering) is the recommended treatment.

I encourage you to talk to your veterinarian about what he or she feels is the best treatment for your pet.