Abstract

An eleven-year-old, 75 kg, 1.7 meter, female California sea lion (Zalophus californianus) is one of the most popular performers in the Hualien Farglory Ocean Park. The sea lion lost weight due to abnormal regurgitation of food. Time of regurgitation was variable and could happen minutes to hours after eating. The character of the regurgitated food ranged from undigested to partially digested. Since 2005, we have tried various treatments without improvement. All examinations and tests were within normal parameters for physiology, hematology, serum biochemistries, radiology, contrast radiology, cytology, and microbial cultures. The sea lion showed no neuro-muscular clinical signs, and she still performed perfectly in the routine show. Based on our findings, we ruled out all causes except esophagitis and psychogenic behavior. According to the timing and type of regurgitation, we focused on pharmacological modification of behavior first. We used the antidepressant drug, fluoxetine (Prozac), which is a selective serotonin reuptake inhibitor. Response to therapy was initially favorable, but three months later the frequency of regurgitation had increased. We changed to the antipsychotic drug, haloperidol (Haldol), which is the original butyrophenone. Mechanisms of action include blocking D₂-dopamine receptors and reduction of dopaminergic neurotransmission in the forebrain. Side effects seen in the sea lion were lethargy and sleep during show time. Presently we combine medical treatment with environmental and behavioral enrichment to improve the behavior.