At birth, the testicles of a puppy are still within his abdomen. As the animal develops, the testicles slowly 'descend' into the scrotum. In mammals, sperm development does not occur correctly at the high temperatures found within the body. The testicles are therefore held outside of the abdomen and within the scrotum to provide a cooler environment. The production of testosterone is usually not influenced by temperature.
Frequently, owners notice that the puppy they just purchased only has one or possibly no testicles within the scrotum. Although different dates are listed in some of the veterinary literature, both testicles are usually within the scrotum by the time the animal is six weeks of age and they should definitely be there by the time the puppy is eight to ten weeks of age. If one or both testicles are not present at that location by twelve weeks of age, they probably never will be and the animal is said to be suffering from cryptorchidism or 'retained testicles.' This is a disorder that may be passed from generation to generation.
What are the symptoms?
These animals rarely show any abnormalities because of this condition. They have normal activity levels, growth, and behavior. Although fertility may be affected, they will usually show normal breeding behavior and frequently impregnate females, especially when one of the testicles has descended into the scrotum.
What are the risks?
Some researchers believe that dogs with cryptorchidism may have a higher incidence of other testicular diseases. Specifically, these would be cancer and torsion.
What is the management?
Cryptorchid dogs should never be allowed to breed. This is a well-documented genetic trait, passed on to future generations. In addition, because of the potential for an increased incidence of torsion or cancer within the retained testicle, it is strongly recommended that all of these individuals be neutered. The surgery to remove a retained testicle is more involved than a routine neuter. The veterinarian must literally hunt for the testicle, which may be located anywhere from the area around the kidney in the abdomen to the muscle near the groin.