Immobilization of California sea lions using medetomidine plus ketamine with and without isoflurane and reversal with atipamezole

The use of medetomidine and ketamine, alone and ill combination with isoflu rane, with atipamezole reversal was evaluated for immobilizing 51 Californi a. sea lions (Zalophus californianus) for a variety of medical procedures a t a rehabilitation center in Northern California (USA) between May 1997 and August 1998. Animals were given 140 mu g/kg medetomidine with 2.5 mg/kg ke tamine intramuscularly. Mean (+/-SD) time to maximal effect was 8 +/- 5 min . At the end of the procedure. animals were given 200 mu g/kg atipamezole i ntramuscularly. Immobilization and recovery times were, respectively: 25 +/ - 12 and 9 +/- 7 min for 35 animals maintained with medetomidine and ketami ne alone and 58 +/- 30 and 9 +/- 9 min for 16 animals intubated and maintai ned with isoflurane. No mortalities occurred as a result of the immobilizat ions. Disadvantages of the medetomidine and ketamine combination included a moderate variation in time to combination and plane of sedation, a large i njection volume and high cost. However, this bu the intramuscular route and that produces a plane of anesthesia that is sufficient to carry out most r outine diagnostic procedures.