Treatment of Stress Hyperthermia in Elk with Ketanserin, a Serotonin Receptor Blocker

Abstract

Ketanserin, a peripheral serotonin (S2) receptor blocker, was evaluated as a therapy for stress induced hyperthermia in 18 wild, recently captured Rocky Mountain Elk (Cervus canadensis). The experiments were carried out in an outdoor experimental laboratory on two hot (>33°C) days separated by a week. Animals were randomly allocated to receive ketanserin (0.1 mg/kg, IV) or saline (4 ml, IV) following induction of hyperthermia via herding into distribution chutes and a squeeze cage during the first day. One week later, the experiments were repeated in the same fashion except that ketanserin and saline were not administered, and temperatures and heart and respiratory rates were not measured. Ketanserin produced dramatic decreases in temperature (43 ± 1 to 40 ± 0°C), and heart (110 ± 12 to 77 ± 5 beats/min) and respiratory rates (56 ± 7 to 26 ± 5 breaths/min), while saline resulted in no change in any of the measured variables. None of the elk died the first day; however, 1 week later, three elk died within 4 hours of completion of the experiment. All three animals had had temperatures of 45° C or above the previous week and had received ketanserin.