Response of Antarctic fur seals to immobilization with ketamine, a ketamine-diazepam or ketamine-xylazine mixture, and zoletil

Adult Antarctic fur seals (Arctocephalus gazella) were immobilized with Zoletil® (n= 172), ketamine (n= 30), ketamine mixed with diazepam (n= 23) and with ketamine mixed with xylazine (n= 45). Response to all drugs was highly variable. There was a relationship between dose rate and level of immobilization in females given Zoletil®. Males were slightly more sensitive to Zoletil® than females but this could have been due to the greater body mass and lower mass‐specific metabolic rate of males. The dose required to achieve a level of immobilization declined with greater body mass for Zoletil® and ketamine but not for ketamine‐diatepam. Ketamine and ketamine‐sedative mixtures commonly caused mild tremoring and occasionally caused convulsions. Neither reaction was seen with Zoletil®. Mean doses were, Zoletil® 1.5 mg/ kg, ketamine 6.9 mg/kg, ketamine‐diazepam 6.3 mg/kg ketamine and 6.3 μg/kg diazepam, and ketamine‐xylazine 7.3 mg/kg ketamine and 0.62 mg/ kg xylazine. Zoletil® performs at least as well on Antarctic fur seals as ketamine but it may cause respiratory depression. The dose of ketamine required for Antarctic fur seals was greater than for most other species of seals.