Objectives: To evaluate the analgesic, physiologic, and behavioral effects of the epidural administration of tiletamine/zolazepam in horses. Study design: Prospective, double-blind, randomized experimental study. Animals: Five adult, healthy horses aged 10-16 years and weighing (mean ± SD) 400 ± 98 kg. Methods: The horses were sedated with 1.0 mg kg-1 intravenous (IV) xylazine, and an epidural catheter was placed into the first intercoccygeal intervertebral space. After a 48-hour resting period, epidural tiletamine/zolazepam, 0.5 mg kg-1 (treatment I) or 1.0 mg kg -1 (treatment II), diluted up to 5 mL in sterile water, was administered with a 1-week interval between the treatments. Heart rate, respiratory rate, arterial blood pressure, and sedation were evaluated. In order to evaluate the respiratory effects, blood from the carotid artery was withdrawn at time O (baseline), and then after 60 and 240 minutes. Analgesia was evaluated by applying a noxious stimulus with blunt-tipped forceps on the perineal region, and graded as complete, moderate, or absent. Data were collected before tiletamine/zolazepam administration and at 15-minute intervals for 120 minutes, and 4 hours after tiletamine/zolazepam administration. Data were analyzed with ANOVA and Bonferroni's test with p < 0.05. Results: The results showed no significant difference between treatments in cardiovascular and respiratory measurements. Sedation was observed with both doses, and it was significantly different from baseline at 60, 75, and 90 minutes in treatment II. Moderate analgesia and locomotor ataxia were observed with both the treatments. Conclusions and clinical relevance: The results suggest that caudal epidural 0.5 and 1.0 mg kg-1 stimulation in the perineal region in horses. The use of epidural tiletamine/zolazepam could be indicated for short-term moderate epidural analgesia. There are no studies examining spinal toxicity of Telazol, and further studies are necessary before recommending clinical use of this technique.
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- Epidural analgesia