Ketamine-paraldehyde anesthesia for rabbits.

Combination of ketamine hydrochloride (50 mg/kg) and paraldehyde (0.5 ml/kg), both administered intramuscularly, was found to be safe and effective for induction and maintenance of anesthesia for prolonged major surgical procedures in rabbits. Time of induction of deep surgical anesthesia was 20 to 30 minutes. Surgical procedures (creation of intestinal loops for perfusion studies) lasting 3 to 4 hours were performed, with an additional dose of ketamine (25 mg/kg) occasionally being given after 2 hours. At the end of the experiments, rabbits were killed. Another group of rabbits was maintained in a deep surgical plane of anesthesia for 5 hours without any surgical operation being done. Rabbits were then allowed to recover and, on the next day, were again anesthetized and allowed to recover without the performance of surgical operation. Finally, after a day's hiatus, the same rabbits were used in intestinal perfusion experiments. The use of 2 complementary anesthetics, each with a wide margin of safety for respiratory centers, provided safe anesthesia. The ability to administer a relatively fixed dose obviated the need for inordinate expertise to anesthetize rabbits for long periods.