Evaluation of the clinical and analgesic effects of subarachnoid ketamine-lidocaine administration in goats undergoing mastectomy

Twenty adult female goats affected with chronic mastitis were subjected to mastectomy or hemimastectomy under subarachnoid regional analgesia using a ketamine-lidocaine combination. Ketamine at 1.5 mg/kg and lidocaine hydrochloride at 1.25 mg/kg were administered intrathecally at the lumbosacral intervertebral space. Goats were then subjected to a 120-minute observation period for systemic or neurotoxic symptoms such as agitation, restlessness, hind limb paralysis, or seizures. In addition, analgesia of the caudal abdominal region and signs of systemic sedation were scored on a scale of 0-3. Heart rate, respiratory rate, and rectal temperature were also recorded prior to (baseline values) and at 5, 15, 30, 60, 90, and 120 minutes after administration. Mastectomy or hemimastectomy operation was carried out after full assurance of the analgesic effect on the udder and caudal abdominal region. Time of onset of surgical analgesia (score 3) was achieved at 15 minutes and lasted for 60 minutes. Maximal sedation score was recorded at 15 minutes and lasted for 60 minutes, then decreased thereafter, with the lowest sedation score recorded at 120 minutes. There was a significant (P<0.05) rise in heart rate at some point between 5-90 minutes, while the respiratory rate and rectal temperature did not change significantly from baseline values. Postoperatively, animals did not show any signs of pain or discomfort. Follow-up on the operated goats showed that all wounds were fully healed without any significant complications. In goats, intrathecal administration of ketamine-lidocaine combination resulted in a safe and effective analgesia of the caudal abdominal and udder region sufficient to perform mastectomy or hemimastectomy.

Keywords: analgesia; mastectomy; ruminants; sedation.