Dog: Cryptorchidism

General information

Other common/scientific names: retained testicle(s)

Canine cryptorchidism is a fairly common condition in males where one or both testicles fail to descend or drop into the scrotum. Cryptorchidism can be unilateral (occurring on one side) or bilateral (occurring on both sides). During the development of the canine embryo, the testes will migrate from just behind the kidneys to their normal position in the scrotum. This migration of the testes is usually complete at 2 months of age but can take place as late as 6 months of age in some breeds. The right testicle is more commonly retained than the left.


While the exact cause of cryptorchidism is unknown, it has been shown to be heritable as a sex-linked autosomal recessive gene. The incidence of cryptorchidism seems to be higher in certain small-breed dogs, such as Chihuahuas, poodles, Pomeranians, Yorkshire terriers and miniature schnauzers.


Most young dogs show no clinical signs of illness with cryptorchidism unless the retained testicle is torsed (twisted) or neoplastic (cancerous). Studies have shown the risk of developing cancer in the cryptorchid testicle to be over 13 times higher than the normal testicle. Because older dogs are more prone to developing neoplasia (cancer) of the retained testicle, these dogs may show signs of an enlarged testicle depending on the location of the affected testicle.

The undescended testicle can be found near the scrotum, in the inguinal (groin) area or in the abdominal cavity. Because of the higher body temperature inside the abdomen, the retained testicle is unable to produce sperm. Therefore, bilateral cryptorchid dogs are usually sterile. However, unilateral cryptorchid dogs can be fertile and therefore impregnate a female.

Although not common, another complication of cryptorchidism is torsion of the undescended testicle. This condition results when the testicle twists on its cord causing acute abdominal pain, lethargy and other complications.


All puppies should be carefully examined for the presence of both testicles in the scrotum at their first visit to the veterinarian. The examining veterinarian will palpate (feel) for the testicles in the scrotum. If one or both testes are not present in the scrotum by six months of age, the dog is diagnosed as a cryptorchid.

Other diagnostic tests may be needed if the dog is older or his neutering history is unknown. Ultrasonography can be helpful in identifying the location of the undescended testicle. Radiographs may be useful if testicular neoplasia or torsion is suspected. A male dog’s testosterone level can be measured to determine if he has testicular tissue present. A dog with a retained testicle or testicles will have similar levels of testosterone as an uncastrated male.


Castration or surgical removal of both testicles is the treatment for choice for cryptorchidism. The cryptorchid testicle should be removed to prevent testicular cancer and testicular torsion. The normal testicle should be removed to prevent propagation of this undesirable trait.

Cryptorchid surgery can be more complicated than a routine castration depending on the location of the retained testicle. Undescended testicles located near the scrotum can be removed in a similar manner as a normal castration. Retained testicles located in the inguinal area or abdominal cavity will require a separate incision to allow removal. Intra-abdominal testicles can be difficult to locate resulting in a longer than normal surgical time.


Cryptorchid dogs which have undergone castration at a young age can expect to live a normal lifespan.


Prevention of canine cryptorchidism is best accomplished by not breeding cryptorchid dogs or their sires and dams.

Abb. GFTE1E3Z: Canine Bilateral Cryptorchidism.
This is a picture of a dog with bilateral cryptorchidism. Note the undescended testicles (arrows) in the inguinal area. The large swelling might indicate a cancerous retained testicle.

Update version: 4/24/2014, © Copyright by
Join the discussion!
- This article has no comments yet -

The information offered by enpevet Ltd. is intended solely for information purposes and and does under no circumstances replace a personal consultation, examination or diagnosis through a veterinarian. Thus, the information serves as an addition to the dialogue between pet owner and veterinarian, but can never replace the visit to the veterinarian. enpevet® would like to ask all users, whose animals have health concerns, to see a veterinarian as required. If you have any questions regarding the health of your animal, we recommend that you turn to your trusted veterinarian , instead of starting, changing or breaking off treatments on your own. The content of enpevet® cannot and should not be used for making your own diagnoses or for the selection and application of treatment methods.