Effects of Sedation on Rectal Temperature During Equine Dental Procedures Performed in Cold to Warm Ambient Temperatures

Abstract

Sedation is important for safe equine dental procedures, but it is unknown if there is a higher risk of sedation causing hypothermia in procedures performed during cold months. The authors hypothesize that sedation for a dental procedure will significantly decrease rectal body temperature in cold as compared to warm ambient temperatures. Adult equids (N = 246), from a private equine dentistry practice, that underwent dental equilibration, were selected for the study. Each horse's weight was estimated and sedation was administered intravenously (0.01 mg/kg detomidine and 0.01 mg/kg butorphanol) and intramuscularly (0.5 mg/kg xylazine and 0.03 mg/kg acepromazine). Ambient and serial rectal temperatures (presedation [PRE], 15 min after initial intravenous sedation [POST15], and at the end of the procedure [END]) were recorded. Statistics included Shapiro–Wilks test, Spearman's correlation coefficient, and a Friedman test with Dunn's posthoc test (significant at P < .05). Ambient temperatures ranged from −7.8 °C to 30 °C. The median (95% confidence interval) rectal temperature was PRE: 37.4 (37.2 °C-37.7 °C), POST15: 37.5 (37.2 °C-37.8 °C), and END: 37.4 (37.1 °C-37.7 °C). POST15 temperatures were significantly increased from PRE (P = .001) to END (P = .005) temperatures. PRE to END temperatures were not significantly different (P > .9). There was a weak positive correlation between ambient and POST15 temperatures (rho = .26, P < .001) and END temperatures (rho = .25, P < .001). Seven animals became hypothermic (<36 °C), only 2 at ambient temperatures below 4.44 °C. Rectal body temperature in equids after sedation at ambient temperatures between −7 °C and 30 °C remains at a safe level in most instances, suggesting dental procedures can be performed under sedation during cold weather.