Cryptorchidism in Donkeys

Cryptorchidism is a developmental condition in which one or both testicles fail to move down into the scrotum. In donkeys, as in other equids, the retained testicle may stay inside the abdomen or get stuck in the inguinal canal. A donkey with one retained testicle may still have one normal testicle in the scrotum, while a bilateral cryptorchid has neither testicle fully descended.

This matters for both health and management. A retained testicle is usually too warm to make normal sperm, but it can still produce hormones. That means some donkeys continue to show jack-like behavior such as mounting, vocalizing, aggression, or interest in jennies even when pet parents think the animal was already castrated or is "half gelded."

Unilateral cryptorchids may remain fertile because the descended testicle can still produce sperm. Bilateral cryptorchids are more likely to be sterile, but they can still behave like intact males. Because cryptorchidism is considered inherited in domestic animals, affected donkeys should not be bred.

See your vet promptly if your donkey has only one visible testicle, an empty scrotum, or persistent male behavior after castration. Early planning can make diagnosis and surgery more straightforward.

Cryptorchidism happens when the normal process of testicular descent does not finish. In equids, the testicles form in the abdomen before birth and then move toward the scrotum through a series of hormonal and mechanical steps. If that pathway is interrupted, one or both testicles may remain retained.

Veterinary references describe cryptorchidism as a condition influenced by genetic, epigenetic, and environmental factors. In practical terms, that means inheritance likely plays an important role, even though the exact pattern is not fully mapped in donkeys. Because of that concern, breeding an affected donkey is not recommended.

A retained testicle can be located anywhere along the normal descent pathway, from near the abdomen to the inguinal canal. Some donkeys are identified when young, while others are not recognized until they show persistent male behavior or are examined before sale, breeding, or castration.

This is not something a pet parent causes through routine care. It is a developmental problem present from early life, even if it is only discovered later.

Diagnosis starts with a careful physical exam. Your vet will palpate the scrotum and inguinal area and review any history of prior castration. In some equids, especially younger animals, normal structures near the scrotum can be mistaken for a descended testicle, so a calm exam under sedation may be needed.

If the retained testicle cannot be felt externally, imaging is often the next step. Transabdominal or transrectal ultrasound may help locate retained tissue in the inguinal canal or abdomen. This can guide surgical planning and help determine whether a field procedure is realistic or whether referral is safer.

Hormone testing may also be used when history is unclear or when a donkey is thought to be gelded but still acts intact. Testosterone-based testing may be considered by your vet. However, Cornell's equine diagnostic laboratory states that its anti-Müllerian hormone cryptorchid panel is not available for donkeys, so testing options can be more limited than they are for horses.

If exam, imaging, and bloodwork still do not give a clear answer, definitive diagnosis may happen during surgery. The goal is to confirm whether retained testicular tissue is present and remove all of it during the same procedure whenever possible.

There is no guaranteed way to prevent cryptorchidism in an individual foal because it develops during early growth and is influenced in part by heredity. The most practical prevention step is breeding management. Donkeys known to be cryptorchid should not be used for breeding, even if only one testicle is retained.

Early exams also help. Young male donkeys should have both testicles checked during routine veterinary visits, pre-purchase exams, and before any planned castration. Finding a retained testicle early can reduce confusion later and help your vet choose the safest surgical plan.

Good records matter too. If a donkey has had prior reproductive surgery, keep the operative report and share it with future veterinarians. In equids, incomplete or poorly documented unilateral castration can create major confusion and may lead to repeat procedures.

If you are buying or adopting a male donkey with an uncertain history, ask for a reproductive exam before assuming he is a true gelding. That step can protect safety, breeding plans, and your future care budget.