Field immobilisation of southern elephant seals with intravenous tiletamine and zolazepam

Southern elephant seals (Miroungo leonina) were immobilised with a mixture of tiletamine and zolazepam administered intravenously at a mean (sd) dose rate of 0.46 (0.08) mg/kg. This dose provided a satisfactory degree of anaesthesia with no side effects, and the induction, duration and recovery times were short. The mean (sd) induction time was 26 (9) seconds and the mean level of anaesthesia was 4.4 units on an eight-point scale. Male seals were given less drug than female seals, remained immobilised for shorter periods and recovered sooner. The mean (sd) dose of drug administered to males was 0.44 (0.06) mg/kg and to females 0.48 (0.08) mg/kg, and the mean (sd) duration times were 14.9 (4.5) minutes and 16.1 (5.3) minutes. The mean (sd) time taken to recover from immobilisation was 14.5 (4.6) minutes for males and 15.7 (5.3) minutes for females. Physiological condition and size significantly affected the duration of anaesthesia. Thin seals remained immobilised for 18 (7) minutes whereas fatter seals remained immobilised for 15 (4) minutes (P<0.0001).