Unilaterally castrating horses (removing only one testicle), often as a result of failure to identify cryptorchidism prior to commencing a surgical castration, is an expensive and unethical procedure that continues to occur too frequently, according to researchers.

David Moll, DVM, MS, Dipl. ACVS and colleagues at the Oklahoma State University College of Veterinary Medicine, determined the incidence of cryptorchidism and unilaterally castrated horses and recently discussed their findings in a study published in Journal of the American Veterinary Medical Association. In addition, the researchers also compared the cost of diagnosing and treating these horses.

Between January 2002 and December 2006, 160 horses were admitted to Oklahoma State for castration. Of these, 16 (10%) of horses had previously been unilaterally castrated and 44 (27.5%) were diagnosed with cryptorchidism and referred for complete castration.

Horses referred for cryptorchidism averaged 2.36 years old, while unilaterally castrated horses were typically older (4.09 years) before they received treatment. Further, no significant differences in the distribution of retained testicles were noted except unilaterally castrated horses had more right inguinal testicles compared to cryptorchid horses.

Unilaterally castrated horses were significantly more expensive to diagnose and treat. The average cost of a standard cryptorchid surgery was approximately 22% less expensive than surgery performed on unilaterally castrated horses. This is in addition to money previously spent by the owner on the original unilateral castration or additional diagnostic procedures performed prior to referral.

“Horses that are unilaterally castrated may continue to exhibit stallion-like behavior, and can be a diagnostic and surgical challenge,” reported Moll.

In addition, Moll advised that unilateral castration is unethical, results in a significant fina