Intramuscular and intravenous immobilization of juvenile southern elephant seals

We compared intravenous and intramuscular administrations of ketamine and diazepam to immobilize juvenile (8 to 24-month-old) southern elephant seals (Mirounga leonina), to determine the most appropriate method for immobilizing seals to a level required for stomach flushing or attaching electronic activity recorders. With intravenous injections, time to induction was shorter (P < 0.001) and less variable (P < 0.001), the duration of immobilization was shorter (P < 0.001) and less variable (P < 0.003), and dose of ketamine was lower (P < 0.001) and less variable (P < 0.001). Eight of 32 seals (25%) injected intravenously had apneas ranging from 8 to 20 minutes (mean = 16 +/- 4.5 min), and 6 of 27 seals (22%) injected intramuscularly were apneic for more than 5 minutes. Seals that became apneic after intravenous injection began breathing before theoretical aerobic dive limit was reached.