Causes of Canine Cryptorchidism
The testes are in the abdomen during fetal development. They normally descend through the inguinal canal into the scrotum by the time a male puppy is 6 to 8 weeks old, although this can take longer. Certainly by 6 months of age, both of a puppy’s testicles should be fully dropped. Sometimes, one or both testicles are retained in the abdomen and do not descend properly as a puppy matures. Most breeders check male puppies for this condition before placing them in their forever homes. Retained testicles can occur in any male dog of any breed. There is a strong genetic component to this condition; it is thought to be inherited as an autosomal recessive trait. Other causes of cryptorchidism remain a mystery.
Most authorities agree that dogs with one or both testicles undescended should be neutered early in life and never bred, because of the hereditary component of this condition. Any dogs sired by affected animals probably 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.
Testicles can descend but later temporarily retract back into the inquinal canal, especially when a young dog is excited, very active or cold. This is not cryptorchidism. If you acquire a male puppy, be sure to ask the breeder whether both testicles have descended. And, when having your dog neutered, ask your veterinarian whether both testicles were successfully removed.