Abstract

Two adult male Florida manatees (Trichechus manatus latirostris) housed at The Seas with Nemo and Friends® were experiencing social challenges characterized by chasing, pectoral grasping, and feeding displacement of one manatee toward the other. The displaced male was on long-term diazepam therapy (10–25 mg BID, 0.014–0.03 mg/kg BID) for appetite stimulation and anxiolysis. Undesired changes in swimming, resting, and feeding behavior were noted in the displaced male.

Since alternative housing was unavailable at the time, megestrol acetate therapy was proposed to curb the behavior of the more assertive manatee. Baseline data was collected, including physical exam, behavioral observations, and hormone assessment of blood, urine, and fecal samples. Oral megestrol therapy was started at a dose of 40 mg (0.05 mg/kg) once daily in the assertive manatee. Weekly urine and fecal samples, monthly blood samples, daily food consumption, and twice-daily behavior observations were collected on both manatees during the treatment period. Hormonal analyses were performed using in-house enzyme immunoassays at Disney’s Animal Kingdom®.

Results showed a reduction in chasing and grasping behavior concurrent with reduced androgen measurements in the assertive manatee. Relaxed swimming and feeding behaviors increased in the previously-displaced male. The assertive male was weaned off megestrol over an 8-week period in October 2022 and undesired behaviors remained low. Hormone analyses showed no change in androgens in the assertive male during this weaning time. Hormones and behavior will continue to be monitored for several weeks after discontinuation of megestrol.

Acknowledgements

This study was supported by the United States Fish and Wildlife Service and the Manatee Rescue and Rehabilitation Partnership. The authors would like to thank the Animal Care, Animal Health, Nutrition, and Science Operations teams at The Seas with Nemo and Friends®, Walt Disney’s Parks and Resort®, and the Science Operations Endocrine Team at Disney’s Animal Kingdom® for their assistance with the hormone sample processing and assays.

*Presenting author