Undescended testicle(s), or cryptorchidism, is a failure of one (unilateral) or both (bilateral) of a cat’s testicles to properly settle into the scrotum during development. In cats, the testes typically settle by four months of age. If one or both testicles cannot be detected in the scrotum by this time, a diagnosis of cryptorchidism is made. Feline cryptorchidism is usually an inherited disorder and is rare.
Cryptorchidism often produces no symptoms, but abdominal pain sometimes occurs. Bilateral cryptorchidism typically leads to infertility. Testicles remaining in the abdomen also have a higher risk of developing cancer or torsion. Abdominal testicles usually do not produce sperm, but still produce testosterone. Both testicles must be removed when neutering cryptorchid cats in order to eliminate the concern for torsion or cancer as well as undesirable behavior like urine marking.
Cryptorchidism itself is not an emergency. In some cases, when one or both of a cat’s testicles remain in the abdomen, the cat’s spermatic cord twists on itself (spermatic cord torsion). This torsion causes severe abdominal pain, and is an immediate medical concern. Bilateral cryptorchidism is likely to lead to infertility, as the heat of the abdomen slows and stops sperm production. Neutering a cryptorchid cat is a more invasive and complex surgery than the standard procedure on an anatomically normal cat, and is often significantly more expensive.
A cat typically inherits cryptorchidism from its parents, and it is more common when both parents carry the gene. It results when the gubernaculum, the fetal ligament which guides the descent of the testes into the scrotum, does not develop properly.
Cryptorchidism varies in presentation. One or both testicles may be undescended.
Cryptorchidism results in increased risk of testicular torsion and cancer.
A potential explanation for the persistence of male behaviors, like spraying, in a cat with unknown medical history who appears to be neutered is bilateral cryptorchidism. Another possibility is unilateral cryptorchidism, but only the visible testicle was removed during a neutering procedure earlier in the cat’s life.
The absence of visible or palpable testicles in the cat’s scrotum is sufficient for diagnosis. Discovery of the missing testicle(s) is often challenging. Locating the missing testicle is important because surgical removal is indicated. Possible locations include:
• In the fold where the rear leg meets the abdomen on the same side as the missing testicle. Testicles in this location can typically be felt.
• In the inguinal canal • Somewhere inside the abdomen
Abdominal testicles often do not show up on x-rays, but ultrasound is often helpful for locating testicles. Examining the cat’s penis is helpful for determining if an abdominal testicle is present. Male cats with at least one testicle develop spines on the shaft of the penis, even if the testicle is out of sight in the abdomen. Neutering (castration) is recommended for all pet cats and is even more critical for cryptorchid cats to eliminate:
• Passing along the gene for this abnormality • Risk of testicular torsion • Risk of testicular cancer
The surgical procedure is more complicated for cryptorchid cats because the location of the testicle is sometimes difficult to determine, and the surgery itself is more invasive.
Cryptorchidism can be mistaken for:
• Monorchidism (one testicle doesn’t exist) • Anorchidism (neither testicle exists)
Cryptorchidism itself is typically asymptomatic as long as complications like testicular torsion or cancer are not present. Even though only one - or no - testicles are apparent, abdominal testicles are still capable of producing testosterone, so normal masculine behaviors, such as spraying and aggression, persist until the cat is neutered.
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