Intoduction Anaesthesia in lambs undergoing experimental surgery may develop problems associated with age-related immune incompetency: a postoperative complication in a 3 week old Scottish blackface lamb after spinal surgery is presented.
Case history and management Both lamb and ewe were in good condition. The ewe was vaccinated against Clostridium perfringens and Clostridium tetani 5 weeks pre-partum. There were no apparent problems with the lamb’s intake of colostrum. Pre-anaesthetic medication was intramuscular medetomidine (10 μg kg−1). Anaesthesia was induced and maintained with sevoflurane in oxygen. Morphine (0.5 mg kg−1), meloxicam (0.6 mg kg−1) and ketamine (1 mg kg−1 followed by 10 μg kg−1 minute−1) were administered intravenously (IV) for perioperative analgesia. Atracurium (0.5 mg kg−1 IV, followed by 0.17 mg kg−1 injected when the first twitch of the four, train-of four count was palpated) was used to improve muscle relaxation. The lamb’s trachea was intubated and the lungs mechanically ventilated to maintain normocapnia. Intrathecal morphine (0.2 mg kg−1), IV meloxicam (0.3 mg kg−1) and edrophonium (0.5 mg kg−1) were administered before recovery. Operative and initial recovery periods were unremarkable. Three hours after surgery the lamb became depressed. Tachycardia (180–250 beats minute−1), tachypnoea (30 breaths minute−1), poor peripheral perfusion and cold pelvic limb extremities were present mimicking severe pain, and/or hypovolaemic shock. Analgesics – morphine (total dose 1.3 mg kg−1) - and IV fluid therapy boluses – crystalloids (300 mL), colloids (120 mL) and fresh whole blood (60 mL) – failed to ameliorate clinical signs and so the lamb was euthanized 10 hours after surgery. Post-mortem findings supported a possible diagnosis of peracute Clostridium perfringens enterotoxaemia.
Conclusion Clostridium perfringens enterotoxaemia should be considered when clinical signs of severe pain and/or hypovolaemic shock fail to respond to analgesics and fluid resuscitation in lambs after major surgery.