ABSTRACT
OBJECTIVE: To evaluate the extent and duration of analgesic effects of tramadol hydrochloride administered epidurally in standing healthy adult cattle. Animals-5 mixed-breed adult female cattle. PROCEDURES: 1, 2, or 3 mg of tramadol/kg was injected into the first intercoccygeal space of each cow in random order at 1-week intervals. Analgesia, sedation, and ataxia were scored on scales of 0 (no effect) to 3 (complete analgesia or extreme sedation or ataxia) at 5-minute intervals beginning 5 minutes prior to injection and ending 120 minutes after injection. Analgesia was evaluated on the basis of response to pinprick stimuli over 9 caudal regions. Heart rate, respiratory rate, rectal temperature, and rumen motility were assessed 5 minutes before and at predetermined intervals for 120 minutes after tramadol injection. RESULTS: Analgesia induced via tramadol administration was dose dependent (eg, mean duration of complete analgesia at the perineum was 18 minutes when cows received the 1 mg/kg dose, 60 minutes when cows received the 2 mg/kg dose, and 92 minutes when cows received the 3 mg/kg dose). Slight to mild sedation and ataxia were observed when cows received 2 or 3 mg of tramadol/kg. No significant tramadol-associated changes in heart rate, respiratory rate, rectal temperature, or rumen motility were detected. CONCLUSIONS AND CLINICAL RELEVANCE: Caudal epidural tramadol administration induced analgesia with slight to mild sedation and ataxia in cows. Analgesia in affected regions after administration of 2 or 3 mg of tramadol/kg was considered sufficient to allow common surgical procedures to be performed in standing cattle.