Abstract

Intravenous administration of propofol, followed by inhalant gas, remains the most popular method of anesthetizing aquatic chelonians; however, the consistent success of immobilization depends on adequate intravenous administration of propofol, which in turn depends on the species, the experience of the anesthetist, and the size and disposition of the animal. The objective of this study was to evaluate the safety, utility and efficacy of an intramuscular ketamine (K)/medetomidine (Me)/morphine (Mo) combination for the immobilization of aquatic chelonians. The addition of opioids, such as butorphanol, to intramuscular combinations of anesthetics, has become popular because of its synergistic and analgesic effects. However, little is known about butorphanol in the reptilian patient, and previous reports suggest that morphine is a better choice due to its μ-agonist activity. The goal of this study was to investigate a protocol that: 1) was reversible, for use under field conditions, 2) offered a wider margin of safety, 3) provided analgesia, and 4) provided an adequate plane of anesthesia to perform short surgical procedures, but 5) did not cause significant negative effects.

Nineteen map turtles (Graptemys spp.) were immobilized with ketamine at either 10 mg/kg (n=9), or 20 mg/kg (n=10), and medetomidine (0.15 mg/kg) and morphine (1.5 mg/kg) IM. The average induction time was 42 minutes. The average time for harvest of shell biopsies was 60 minutes. The anesthesia was reversed using atipamezole (0.5 mg/kg IM) and naloxone (0.02 mg/kg IM). The average time to spontaneous movement was 196 minutes. Ten animals needed re-dosing of naloxone (at various doses) the following day due to re-narcotization.

Twenty-two red-eared slider turtles (Trachemys scripta elegans) were anesthetized with either K (10 mg/kg)/Me (0.1 mg/kg)/Mo (0.1 mg/kg) IM (group 1, n=7), or K (15 mg/kg)/Me (0.15 mg/kg)/Mo (0.1 mg/kg) IM (group 2, n=15). The average induction time for the Trachemys spp. groups was 9 and 12 minutes, respectively. The average surgical procedure was 46 minutes. The reversal protocol for Trachemys spp. was as above, except naloxone was increased tenfold to 0.2 mg/kg. The recovery time after reversal administration was 10.4 and 5.9 minutes. All animals behaved normally within 30–60 minutes from reversal administration. All Trachemys spp. were euthanatized the following day. No evidence of pathology associated with anesthetics was found on full necropsies. Subjectively, the best results were obtained following the protocol for group 2. Morphine appears to be a key supplement to previously described ketamine/medetomidine anesthetic protocols, allowing for rapid, consistent, reliable and reversible surgical anesthesia for short procedures.