Cryptorchidism

• CRYPTORCHIDISM

The incomplete descent of the testes. The ectopic testes may be at any site from the posterior pole of the kidney to the external inguinal ring. Not uncommon in all species but especially seen in the horse, dog and pig. Usually unilateral but may be bilateral. The cryptorchid testis is sterile because of high environmental temperature. Increased risk of tumours in ectopic testisespecially in the dog.

Aetiology is unknown but several factors may be involved:

1. Genetic factors:dominant inheritance in the horse, recessive in other species. Breed incidence is greater in Poodles.
2. Hormonal factors:MIS and testosterone responsible for migration.

Gross:small, firm.
Histologically:hypoplastic tubules, increased fibrous tissue.

Information by kind permission of Professor R W Else