Retained Testicle (Cryptorchidism) in Cats

What is cryptorchidism?

Cryptorchidism refers to the failure of one or both testicles (testes) to descend into the scrotum. Cryptorchidism is much less common in cats than in dogs. The testes develop near the kidneys, in the abdomen, and normally descend into the scrotum by two months of age. This may occur later in some cats, but rarely after six months of age. Cryptorchidism may be presumed if the testicles cannot be felt in the scrotum after two to four months of age.

If the testicles aren't in the scrotum, where are they?

In most cases of cryptorchidism, the testicle is retained in the abdomen or in the inguinal canal (the passage through the abdominal wall into the genital region through which a testicle normally descends). Sometimes, the testicle may be located in the subcutaneous tissues (just under the skin) in the groin region, between the inguinal canal and the scrotum.

How is cryptorchidism diagnosed?

In cases of abdominal cryptorchidism, the testicle cannot be felt from the outside. An abdominal ultrasound or radiographs (X-rays) may be performed to determine the exact location of the retained testicle, but these are not often done before surgery, as they are not required to proceed with surgery.

Typically, only one testicle is retained; this condition is called unilateral cryptorchidism.  A dog that does not appear to have testicles, but is exhibiting male behaviors, can have hormonal tests done to see if he is already neutered (e.g., hCG stimulation test or GnRH stimulation test). Even simpler, your veterinarian can check for penile spines, which are dependent on testosterone and will disappear six weeks after neutering.

What causes cryptorchidism and how common is it?

Cryptorchidism affects less than 2% of cats. The condition appears to be inherited, since it is commonly seen in families of cats, although the exact cause is not fully understood. Cryptorchidism occurs in all breeds, but may occur more often in purebred or pedigreed cats, such as Persian, Himalayan, and ragdoll breeds.

What are the signs of cryptorchidism?

This condition is rarely associated with pain or other signs unless a complication develops. In the early stages, a single retained testicle is significantly smaller than the other, normal testicle. If both testicles are retained, the cat may be infertile. This is because retained testicles continue to produce testosterone but do not produce sperm.

The most common signs of cryptorchidism are male marking behavior (spraying), aggression, and a particularly strong odor associated with unneutered male cats. There is also a risk that a retained testicle will become cancerous, although cats appear to have fewer incidences of testicular cancer and complications associated with cryptorchidism than dogs. The clinical signs associated with testicular cancer depend on the specific type of cancer.

What is the treatment for cryptorchidism?

The recommended treatment for cryptorchidism is to remove both testicles (neutering). If only one testicle is retained, the cat will have two incisions: one for extraction of each testicle. If both testicles are in the inguinal canal, there will also be two incisions. If both testicles are in the abdomen, a single abdominal incision will allow access to both.

What if I don't want to neuter my cat?

There are several good reasons for neutering a cat with cryptorchidism. First, neutering removes the genetic defect from the breed line. Cryptorchid cats should never be bred. Second, cats with a retained testicle will continue to exhibit male behaviors such as marking and spraying, odors, and aggression toward other cats. Third, as described, the testicle can twist, causing pain and requiring emergency surgery to correct. Finally, the retained testicle may develop a cancerous tumor.

What is the prognosis for a cat with cryptorchidism?

The prognosis is excellent for cats that undergo surgery early, before problems develop in the retained testicle. The surgery is relatively routine and the outcomes are overwhelmingly positive.