Comparison of subcutaneous and intramuscular ketamine-medetomidine with and without reversal by atipamezole in Dutch belted rabbits (Oryctolagus cuniculus).

Forty male Dutch belted rabbits (Oryctolagus cuniculus) enrolled in a minimally invasive pharmacokinetics study were used to compare the efficacy of an anesthetic combination delivered through 2 injection routes. Rabbits were randomly assigned to 4 groups (n = 10/group) to determine the sedative and physiologic effects of ketamine (25 mg/kg)-medetomidine (0.5 mg/kg) given either intramuscularly (IM) or subcutaneously (SC). Palpebral, pedal, ear pinch, and righting reflexes, as well as cardiopulmonary parameters (heart rate, respiratory rate, and arterial blood oxyhemoglobin saturation), were recorded every 5 min. In addition, the reversal effects of an intravenous dose of atipamezole (1 mg/kg), an alpha 2 adrenoreceptor antagonist, were assessed by comparing the return of the righting reflex in rabbits given the reversal agent with those that recovered spontaneously. Compared with the IM route, SC ketamine-medetomidine effectively induced chemical restraint with less than a 2-min difference in onset of anesthesia and markedly less resistance (for example, fl inching, kicking, and so forth) during the injection. In all groups, the anesthetic regimen, regardless of the route of administration, provided an adequate level of anesthesia. Reversal with atipamezole improved arterial hemoglobin oxygen saturation for both the SC and IM groups; however, an enhanced rate of recovery from anesthesia was clinically apparent only for animals given the combination by the IM route.