Sedative and analgesic effects of intravenous detomidine and tramadol on horses

Abstract

This study was performed to evaluate the sedative and analgesic effects of intravenous (IV) administration of detomidine (D) and tramadol (T) to horses. Six warmblood horses each received D (10 ㎍/kg), T (2 mg/kg), and a combination of DT (10 ㎍/kg and 2 mg/kg, respectively). Heart rate (HR), respiratory rate (RR), rectal temperature (RT) and indirect arterial pressure (IAP) were measured by a patient monitor (MEDIANA®). Degree of sedation was scored using two methods. One was a measurement of lip height from the ground, the other thing was a 4 - point criteria system. Ataxia was also calculated by a 4 - point criteria. The analgesic effect was examined by 4 - point scale of electrical stimulator and pinprick. Blood samples were analyzed by i-STAT®. Gastrointestinal (GI) motility was evaluated by 5 - point scale using auscultation. No significant differences were found for HR, RR, RT, IAP and GI motility between D and DT. The sedative effect was shown at 5 min after D and DT administration. However, DT induced slightly longer sedation than D alone. D and DT showed a similar analgesic effect until 50 min after injection, but D recovered sharply from the analgesic condition and DT showed a longer analgesic effect. An increase in blood glucose was seen for D until 30 min after the injection, but not for DT. A horse with T and DT showed excited behavior within 5 min of the injection. This study suggests that the DT combination could be used for diagnostic procedures and simple surgery in standing horses, with caution taken for CNS excitement in the early phase after the administration.