Reptile Anesthesia

 Injectable and inhalant anesthetics are commonly employed both for surgery and sedation for diagnostic or treatment procedures.

Preparation Removal of food and water is recommended for hours prior to surgery Supplemental heat is also used to maintain the patient at approximately 85 degrees F. It is also important to keep this temperature consistent throughout the anesthetic induction, the surgical procedure, and the recovery phase. Water circulating heating pad

Injectables  Renal portal circulation may reduce the efficacy of anesthetic drugs when injected in the leg muscles or veins. However, this is of little clinical significance as one can increase the anesthetic dose until the desired effect is achieved

Injectables  Dissociatives: ketamine and telazol, very useful, safe, reliable.  Ketamine is administered IM or SC at dose of 22 to 44 mg/kg.  Telazol is administered IM or SC at dose of 4 to 5 mg/kg

Propofol:  short acting for induction of quick diagnostics, must go IV or IO (intraosseous catheter)  Dose 3 to 10 mg/kg  It will last about minutes and can be redosed as needed.

Inhalant  Use an induction chamber for nearly all reptiles or face mask.  Isoflurane is the best agent to use here with Halothane being a close second. This is very smooth, very reliable, and has a short recovery. 5% isoflurane for induction and 1.5% for maintenace.

 In squamata the tracheal ring is incomplete but turtles and crocodilians have complete tracheal rings and it is important not to use ET tube cuff in these species.  Except in crocodilians where the pulmonary morphology is similar to that of the mammals, most reptilians have more primitive lung structures and possess air sacs which do not involve in gas exchanges.

 Reptiles have an extensive pulmonary shunting. They also undergo extensive anaerobic metabolism which is particularly well developed in aquatic reptiles such as sea turtles.  Succinylcholine is a drug used to induce muscle relaxation and is the recommended drug use for sea turtles  Their ability to withhold breath and extensive pulmonary shunting can significantly delay inhalation anesthetic induction

Intubating the animals once the anesthesia is induced will provide a secure airway as well as reducing the anesthetic leakage. Note the glottis is positioned at the base of the tongue and is easily visualized. There is no epiglottis.

 Maintain them on 1.5% isoflurane and 1L/min oxygen.  Use a non- rebreathing system for these "bagging" them to a pressure of 10 cm-water every 30 seconds to assist their respirations

Judging anesthetic depth Palpebral Palpebral Withdrawal Withdrawal Righting reflex Righting reflex Spontaneous respiration Spontaneous respiration

Anesthetic monitoring  Observation (rib expansion)  ECG: only shows electrical activity. Reptile hearts can beat after removal from the body!  Esophageal stethoscope  Anesthetic monitoring utilizing combination of an ECG and a Doppler flow detector (typically placed in a site near the heart) will provide useful monitoring of electrical and mechanical activities of the heart.  Due to their thick skin (scales) pulse oximetry and noninvasive blood pressure readings are difficult to obtain.

Recovery  Ensure to maintain optimal temperature of the particular species for faster drug metabolism (and recovery)  Provide a secure and clear airway  Provide adequate analgesia  Reverse any reversible drugs that may prolong the recovery