Angela M. Lennox, DVM, Diplomate ABVP-Avian, Avian and Exotic Animal Clinic of Indianapolis, Indianapolis, Indiana

Because of their different anatomy, castration techniques for exotic mammals differ from approaches in dogs and cats. Several species are discussed in this paper, including rabbits, guinea pigs, prairie dogs, and sugar gliders.The male rabbit anatomy is similar to that in marsupial species with the penis located caudal to the testes.The testicles lie in 2 hemiscrotal sacs. Another peculiarity is that the inguinal canal remains open and the testicles can move from the hemiscrotal sacs into the abdomen making them "functional cryptorchids."The position of the testicles (elongated, not round) depends on such factors as body position, body temperature, breeding activity, gastrointestinal tract filling, and the amount of abdominal fat. Scrotal and prescrotal approaches are discussed. A peculiarity of the prairie dog is that it does not have a scrotal sac. During the breeding season, the testicles are often palpable beneath the perineal skin and subcutaneous tissue, and access can be challenging. The author prefers a "scrotal" approach during the breeding season, but an abdominal approach is also described.

COMMENTARY: This is a good summary of common exotic species that a practitioner would be asked to neuter.The practitioner should be aware that tissue handling must be as gentle as possible to minimize hematoma formation and possibly infections in rabbits and rodents.
Finally, veterinarians who are neutering their first older rabbit should be warned that exposing the tunic is difficult due to fibrosis of the scrotal tissues.