Introduction
Normal male puppies are born with both testicles in their abdomen. Cryptorchisism, also called retained testicles, is the failure of one or both testicles to descend completely into the scrotum, which usually happens by the time a puppy is 6 to 8 weeks of age but can occur later in some breeds. Certainly by 6 months of age, both of a puppy’s testicles should be fully descended into the scrotal sac. Cryptorchidism is often asymptomatic, and many owners are unaware that their dog has the disorder. It is important to diagnose and treat this condition, because retained testicles have an approximately 10-fold increased chance of becoming cancerous than testicles that descend normally.
Symptoms of Retained Testicles in Dogs
Retained testicles can occur in any male dog of any breed. Purebred toy and miniature breeds (Yorkshire terriers, toy poodles, Pomeranians) seem to be at significantly higher risk. Some family lines of German shepherds, Staffordshire bull terriers and Boxers also are predisposed. There is thought to be a strong genetic component to this condition. It is much more common for affected dogs to only have one retained testicle (unilateral cryptorchidism) instead of two (bilateral cryptorchidism). Interestingly, the right testis in dogs is retained almost twice as frequently as the left.
Cryptorchidism is rarely accompanied by pain, unless the spermatic cord of the retained testes torsions (flips on itself), which can be very painful. In those cases, the dog will show acute onset of extreme abdominal pain. The main clinical sign of this condition is the definition of the disorder itself: the physical absence of one or both testicles in the scrotum of a dog by 6 months of age. Owners may notice that one or both sides of their dog’s scrotum look empty and loose.
Another sign associated with this disorder is male breeding behavior, including mounting and possible dog-aggression, in a supposedly neutered dog. Some cryptorchid dogs can impregnate female dogs, depending upon the location of their retained testicle(s). Obviously, this can be rather surprising to owners who have had their dog “neutered” but unknown to them only one testicle was surgically removed. Other dogs may try but be unable to reproduce successfully due to impaired sperm development in the retained testicle(s).
While signs of cryptorchidism are normally mild or nonexistent, the condition does carry some risks. Retained testicles develop disease at a much higher rate than do normal testicles – including infection and cancer. Retained testicles are also at risk for becoming twisted, or “torsed”, which can cause severe pain.
Cryptorchidism is usually an inherited disorder. Affected dogs should be neutered and should not be bred. Dogs sired by affected animals should be removed from the breeding population as well. Both testicles should be removed to prevent propagation of the condition and reduce the chances of future infection, torsion and cancer in affected animals.