What is Cryptorchidism?
Cryptorchidism is a condition where one or both testes do not fully descend into the scrotum. Fetal testes begin formation in the abdomen and descend through the inguinal canal into the scrotum. A cryptorchid testicle can remain in the abdomen, become trapped in the inguinal canal or appear under the skin outside of the inguinal canal.
Is Cryptorchidism An Inherited Trait?
A genetic basis for the cryptorchid trait has been identified in the pedigrees of some stallions, dogs, cattle, humans and other species. A number of factors are involved in the movement of the testes from abdomen to scrotum; androgen hormone levels, size of the inguinal canal, size of the testes and timing of hormone release all play a part. Thus, cryptorchidism is considered a polygenic trait and predicting its heritability is complicated.
Retained testicles are almost always infertile in regards to sperm production because the testicle is maintained at too high body temperature for spermatogenesis. They do, however, produce testosterone, so a male with a retained testicle will exhibit intact male behavior. Medical induction of descent is controversial and not very effective so, given that the condition has a genetic component, surgical castration is recommended in affected animals. This prevents passing any genetic predisposition on to future generations and avoids possible adverse health effects later in life, such as testicular tumors.