Abstract

Propofol (Diprivan®, Zeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, DE 19850 USA) is used extensively in reptilian anesthesia.¹ It has been shown to be a safe and rapid agent in iguanas and tree snakes,^2,3 but requires vascular access. The only published investigation in turtles used the intraosseous route,⁴ but the high dose requirement combined with cumbersome catheterization protocols has reduced its practicality. The supravertebral sinus has been described as a safe alternative for IV injections in chelonians.⁵ This study investigated the anesthetic effects of propofol administered at 10 and 20 mg/kg via the supravertebral sinus in 10 adult red-eared sliders (Trachemys scripta) in a blinded, randomized cross-over design.

Patterns of reflex and muscle tone loss and recovery were characterized. Parameters recorded were spontaneous movement, extremity relaxation (head, forelimb, hind limb, tail tone), jaw tone, response to deep pain, and corneal, palpebral, and spinal reflexes. Observations were made every 60 sec until no changes in parameters were observed for 5 minutes. Data was compared between dosages using paired t-tests and Wilcoxson-Rank Sum tests.

Significant differences between the two doses were found for anesthetic depth, anesthetic duration, and in times to recovery of muscle tone. Additionally, a greater proportion of subjects in 20 mg/kg trials experienced loss of palpebral reflexes and sensation of deep pain, while corneal and spinal reflexes remained highly conserved at both doses. No significant differences were seen in the time to maximal relaxation or reflex loss. Total anesthetic time was 63 and 91 min, for 10 and 20 mg/kg respectively.

Results suggest that propofol administration via the supravertebral sinus can be a reliable means of achieving anesthesia in healthy chelonian patients.

Acknowledgments

The authors thank J. Hounsgaard, G.S. Jacobsen, and W. Sears for their valuable assistance.

Literature Cited

1.  Read, M.R. 2004. Evaluation of the use of anesthesia and analgesia in reptiles. J. Am. Vet. Med. Assoc. 224:547–552.

2.  Bennett, R.A., J. Schumacher, K. Hedjazi-Haring, and S.M. Newell. 1998. Cardiopulmonary and anesthetic effects of propofol administered intraosseously to green iguanas. J. Am. Vet. Med. Assoc. 212:93–98.

3.  Anderson, N., R.F. Wack, L. Calloway, T. Hetherington, and J.B. Williams. 1999. Cardiopulmonary effects and efficacy of propofol as an anesthetic agent in brown tree snakes, Boiga irregularis. Bull. Assoc. Reptil. Amphib. Vet. 9:9–15.

4.  Fonda, D. Intraosseous anaesthesia with propofol in red-eared sliders (Trachemys scripta elegans). 1999. J. Vet. Anaesth. 26:46–47.

5.  Divers, S.J., and S.M Divers. 2001. Clinical applications of a supravertebral (subcarapacial) vein in chelonia. Proc. Am. Assoc. Zoo Vet. Pp: 4–5.