Abstract
The U.S. Navy Marine Mammal Program (MMP) cares for a population of California sea lions (Zalophus californianus) that provide support to U.S. military operations worldwide. The program has utilized surgical castration for male sterilization since the 1960s to maintain mission-capable animals. Benefits include decreasing breeding-associated behaviors and conspecific aggression, obtaining reliable year-round behavioral control, and having working animals of appropriate size for expeditious transport.
Limited data on surgical castration techniques utilized in California sea lions and associated short- and long-term outcomes are available. A retrospective data review was conducted of medical records from 89 castration procedures performed at the MMP between 1968–2019. Variables reviewed included age at castration, length of anesthesia and surgery, surgical approach and closure techniques, anatomical anomalies encountered, and postoperative complication rates.
Surgical and perioperative techniques directly parallel those used for the domestic dog. The average age at castration was 3.4 years. Only one anatomical anomaly was described (1.1%, unilateral cryptorchidism). Postoperative complications were found to be frequent but mild, with superficial incision dehiscence and scrotal swelling as most common. Closure techniques became more aggressive over time in an effort to reduce dehiscence. The most recent cases had a 3- to 4-layer closure with secondary reinforcement (staples, adhesives).
Surgical castration is a safe and reliable permanent sterilization option in the California sea lion, with the appropriate equipment and expertise. This procedure can be considered in conjunction with alternative contraceptive options1,2 for sea lions in managed care.
Acknowledgements
The authors would like to sincerely thank the MMP for spearheading the advancement of marine mammal medicine. We thank all clinicians, veterinary technicians and training personnel that contributed to the care of the animals referenced in this presentation. Additionally, the authors would like to recognize all Army Veterinary Corps personnel that have dedicated their time in service to support military working animals, to include marine mammals.
*Presenting author
Literature Cited
1. Martinez-Giménez J, Ferrero-Vicente L, Feltrer-Rambaud Y. Effects of a GNRH vaccine (Improvac®) on Patagonian (Otaria byronia) and California sea lions (Zalophus californianus). J Zoo Wildl Med. 2021;52(2):721–725. doi: 10.1638/2019-0098. PMID: 34130417.
2. Asa C, Agnew M. Contraception. In: Fowler’s Zoo and Wild Animal Medicine. 8th ed. St. Louis, MO: Saunders; 2014:735–739.