What is ... ?:

During development before birth, the testicles migrate from the abdomen into the scrotum. Normally this is complete by 10 days of age. Cryptorchidism means that one or both of a dog's testicles have not descended into the scrotum. If this does not happen by 8 weeks, the dog is generally diagnosed as cryptorchid, although the testicles may still descend up to 4 months or so.

How is ... inherited?:

Although the condition is of course seen only in male dogs, both males and females can carry the gene for cryptorchidism. Heterozygous males and females, and homozygous females, will be physically normal, but can pass the gene on to their offspring. Homozygous males are cryptorchid. Thus cryptorchidism is thought to be a sex-limited autosomal recessive trait

What breeds are affected by ... ?:

What does ... mean to your dog & you?:

Dogs that are cryptorchid have a much increased risk of testicular cancer (approximately 10 times). Castration will of course eliminate this risk. Dogs with cryptorchidism can not be shown.

How is ... diagnosed?:

Your veterinarian will diagnose this condition when s/he examines your dog at the time of vaccination. Most affected dogs have 1 testicle that is not descended.

How is ... treated?:

The only treatment for this condition is removal of both testicles (neutering or castration). Dogs with cryptorchidism should be castrated for 2 reasons: if the testicles are not removed, there is an increased risk of testicular cancer, and if your dog is bred, the trait will be passed on to future generations.

Breeding advice:

Affected dogs and their parents (who carry the gene) should be not be bred.

Resources:

Wheeler R. Cryptorchidism. In: Côté E, ed. Clinical Veterinary Advisor Dogs and Cats. Missouri: Mosby Elsevier, 2007:261.

Sargan DR. Cryptorchidism. In IDID - Inherited diseases in dogs:web-based information for canine inherited disease genetics.

retained testicle

Cryptorchidism, retained testicle