Cryptorchidism, sometimes called retained or undescended testis, is the absence of one or both testicles in the scrotum of a male puppy by the time it reaches 6 months of age. It is the condition in which one or both testicles of a male dog fail to descend into scrotum.
The testis normally descend into the scrotum in very young age. In case of dogs, this descent is completed by the time puppy is two months old. Descent may occur a bit later in some breeds but rarely after six months.
When cryptorchidism occurs, the testicle is retained in the inguinal canal (the passage through which the testis descend into the scrotum) or in the abdomen. Or, it’s located in the subcutaneous tissues in the groin region, between the inguinal canal and the scrotum.
If the testis is in the inguinal canal, it can be felt (palpated) during a physical examination. If the testis is deeper in the abdomen, it will be difficult to palpate or identify with an x-ray. Ultrasound is the best available option to determine the size and location of the testis if it is in the abdomen. Toy and miniature breeds are more prone to this condition though it can occur in any dog of any breed. Purebreds are more at risk than cross-bred (hybrid dogs). Failure to descend is twice as high for right testis than the left testis.
Cryptorchidism is often asymptomatic and is rarely painful unless a complication develops. Infact, the condition can go unnoticed for long time. However, acute onset of abdominal pain generally indicates that the spermatic cord of the retained testes has become twisted, cutting off the blood supply to the testis. Many times, this testis will develop tumors, which is symptomized by feminine behavior. The risk of testicular cancer is thought to be approximately ten times greater in affected dogs than in normal dogs.