Reserpine toxicosis in a horse.

A single injection of reserpine in an adult horse was believed to induce toxicosis for several days. Clinical signs included erratic, colic-like behavior followed by depression, bradycardia, miosis, ptosis, and paraphimosis. Diarrhea was not observed and may have been due to the effect of xylazine given with the reserpine. The horse was supported with IV fluids and intensive nursing care. Gradual improvement was noted 72 hours after the horse received the drug. Qualitative analysis via high-performance liquid chromatography was positive for reserpine. Methamphetamine is the recommended antidote but was not used in this case.