Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Assessing Anesthesia in Reptiles

©1999 R. Avery Bennett, DVM, 115th Ohio VMA Conference Proceedings, 1999

As reptiles become anesthetized, relaxation progresses from cranial to caudal and during recovery motor function returns in the opposite direction. A variety of reflexes are used to assess the level of anesthesia in reptiles. The righting reflex is lost at light planes of anesthesia but is a useful indicator of recovery. A toe pinch reflex is lost at a variable period during the anesthetic episode; however, at surgical planes of anesthesia the toe-pinch reflex should be abolished. The tail pinch reflex follows the pattern of the toe pinch reflex and should be abolished at surgical anesthesia. The vent stimulation reflex (movement of the tail or leg in response to squeezing the vent) is lost at deeper planes of anesthesia and is often still present at light anesthesia. If the vent stimulation reflex is abolished the patient may be excessively deep. The palpebral reflex is generally lost at light planes of anesthesia while the corneal reflex should be present at light surgical anesthesia. If the cornea reflex is lost the patient may be excessively deep. In chelonians the head withdrawal reflex is also useful and should be lost at surgical anesthesia. The tongue withdrawal reflex is useful in snakes and is often still present at a surgical plane of anesthesia. Loss of the tongue withdrawal reflex in snakes may be an indication that the patient is excessively deep. Generally, a patient at a surgical plane of anesthesia will maintain the corneal and vent stimulation reflex and all other reflexes are abolished. At a surgical plane of anesthesia many patients will loose all motor function including the ability to ventilate spontaneously. Assisted ventilation will help maintain a proper acid base balance and prevent the patient from converting to anaerobic metabolism.

From Capsule