Practical experiences and clinical parameters in a xylazine-ketamine-anaesthesia of horses

The paper describes the clinical experience in 101 horses undergoing anaesthesias (TIVA) of more than one hour duration under clinical conditions. The horses were routinely given a sedative premedication of xylazine and diazepam, and anaesthesia was induced with ketamine. Anaesthesia was maintained by re-injection of xylazine in a dose of 0.2 mg/kg body weight and ketamin at a dose of 1 mg/kg body weight, given as mixed injection every 10 minutes. Occurring movements have been suppressed by intermediate injections of xylazine, diazepam or a guaifenesin solution. The behaviour during recovery has been evaluated in regard to time and quality with and without additional sedation with xylazine, romifidine or detomidine. In 66 horses a surgical state of anaesthesia could be reached by regular administration of the xylazine-ketamine-combination. 35 horses needed additional doses of diazepam (for light movements 6 horses), additional xylazine injection (14 horses) or guaifenesin infusion (5 horses) when anaesthesia became too superficial. The recovery (first lifting of head) lasted 40+/-17 minutes, the time to wake up (until movement into sternal position 8+/-8 minutes, the average coordination time from sternal position to first attempt to rise to safe standing) 37+/-12 minutes. An average of 1.68 attempts to stand up were recorded. A comparison of the quality with the pre-sedative recorded behaviour (calm, cooperative, frightened, uncooperative) did not show statistical significant differences. Although of no statistical relevance, the additional post-operative sedation with romifidine resulted in a slightly longer, but calmer recovery with less attempts to stand up when compared to xylazine. The fact that the presented anaesthetic protocol with an anaesthetic duration of up to 3 hours and 50 minutes showed no life-threatening complications supports the thesis that the TIVA has to be considered as a safe and economical possibility.