In developing fetal dogs and cats, the testicles are located near the kidneys. A structure called the gubernaculum connects each testicle to the scrotum and is responsible for guiding the testicle to its final position in the scrotum. When the gubernaculum fails to develop properly, the testicle cannot descend into the scrotum, leading to cryptorchidism (or retained testicles).
Cryptorchidism is fairly common in dogs, but rare in cats. It can occur bilaterally (both testicles retained), or can happen unilaterally with one testicle affected. When one testicle is retained, it is usually the right one. Puppies should have both testicles in the scrotum by three weeks of age, and kittens should have descended testicles by six months of age.
Cryptorchidism has in increased incidence in purebred dogs, especially toy breeds and brachycephalic breeds. Though the condition is rare in cats, Persian cats are affected more often than others.
Your veterinarian will check for scrotal testicles at each of your pet’s well puppy and kitten visits. Unless you are planning to breed your dog, most veterinarians advocate neutering to control the pet population and avoid unwanted male behaviors.
Neutering is especially important in cryptorchid pets, for several reasons. First, cryptorchidism is inherited. So cryptorchid pets are likely to pass this trait on to their offspring. Secondly, retained testicles are prone to torsion, a condition in which the spermatic cord twists on itself, cutting off the blood supply to the testicle. This leads to testicular swelling, abdominal pain, and can end in shock and death. Finally, retained testicles are about ten times more likely to develop cancer.
Neutering a cryptorchid pet is not as straight forward as neutering one whose testicles have descended for obvious reasons--one or more testicles is missing from the scrotum! Most of the time, the retained testicle is located in the inguinal ring, which is near the groin area. Occasionally, however, the testicle is retained in the abdomen. Prior to surgery, it’s likely that your veterinarian will not know exactly where the retained testicle is. This means that your pet will have more than one incision as your vet searches for and removes the missing testicle.
A very common questions surrounding the neutering of a cryptorchid pet is, “If the retained testicle is so hard to find, why not just leave it and only removed the testicle that has descended?” In theory, this might work, as the retained testicle doesn’t make sperm. It does, however, produce some testosterone, so it will contribute to unwanted male behaviors. But most importantly, the retained testicle should always be removed due to its increased chance of torsion and cancer.
Similarly, removing the retained testicle while leaving the scrotal testicle is also not a good idea. In this case, the animal would still be able to reproduce, thereby passing his condition on to his offspring. To remove this possibility, cryptorchid pets should be neutered.
For most people and their pets, cryptorchidism is not a big deal. Most of us don’t plan on breeding our pets, anyway, so you probably already planned to have your dog or cat neutered. If your puppy or kitten has been diagnosed with cryptorchidism, try not to worry. Once he’s neutered, you won’t even know the difference!