Cryptorchidism in horses

• Cryptorchidism is a congenital condition in which one (unilateral) or both (bilateral) of the testes fail to descend into the scrotum.Generally, unilateral cryptorchids are usually fertile, while bilateral cryptorchids are generally sterile
• Cryptorchidism in the horse can occur with either the left or right testis or with both testes.
• Failure of one or both testes to descend into the scrotum may be due to genetic predisposition, insufficient androgen (i.e. testosterone) stimulation, and other factors.
• Cryptorchid testes are incapable of producing sperm due to the elevated temperature of the retained testes. If one or both testis remains in abdomen,the horse is called Rig.
• Consequently, a stallion would be sterile if both testes are cryptorchid. Libido and aggressive male behavior is present in cryptorchid stallions since testosterone is still produced by the retained testes

Causes
Hereditary


Symptoms and Types
Bilateral
Both testicles remain in abdomen
Infertility
Stallion like behaviour


Unilateral
One testicles remains in abdomen
still fertile from one testicles


Treatment
Surgical removal of both the testis is the only treatment.