What is cryptorchidism?

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 cryptorchidism 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 cryptorchidism?

This is a fairly common condition, which is seen most often in the toy and miniature poodle, pomeranian, Yorkshire and Cairn terrier, dachshund, Chihuahua, Maltese, boxer, Pekingese, English bulldog, miniature schnauzer, and Shetland sheepdog.

For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.

What does cryptorchidism 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 cryptorchidism 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 cryptorchidism 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 should be not be bred. It is best not to breed their parents as well, who carry the gene.


Copyright 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: December 05, 2001.

This database is a joint initiative of the Sir James Dunn Animal Welfare Centre at the Atlantic Veterinary College, University of Prince Edward Island, and the Canadian Veterinary Medical Association.