Pharmacologic effects of epidural versus intramuscular administration of detomidine in cattle.

OBJECTIVES: To determine whether epidural administration of detomidine hydrochloride to cattle induced analgesia of the perineum and to compare analgesic and systemic effects of epidural versus i.m. administration of detomidine at a dose of 40 microg/kg in cattle. ANIMALS: 18 healthy adult cows. PROCEDURE: 6 cows were given detomidine by epidural administration, 6 were given detomidine i.m., and 6 (control group) were not given detomidine. Analgesia was assessed by determining responses to needle pinpricks in the perineum and flank and by applying electrical stimuli to the perineum and flank and determining the voltage that induced an avoidance response. Degree of sedation and ataxia were scored, and mean arterial pressure, heart rate, respiratory rate, and frequency of ruminal contractions were measured. RESULTS: Epidural and i.m. administration of detomidine induced comparable degrees of analgesia of the perineum and flank, accompanied by moderate sedation and ataxia, hypertension, cardiorespiratory depression, and rumen hypomotility. CONCLUSIONS AND CLINICAL RELEVANCE: Epidural and i.m. administration of detomidine at a dose of 40 microg/kg induced similar analgesic and systemic effects in cattle. Epidural administration of detomidine did not appear to be advantageous over i.m. administration.