Cardiopulmonary effects of a medetomidine-ketamine combination administered intravenously in gopher tortoises

Abstract

The combination of medetomidine and ketamine administered IV resulted in effective short-term immobilization adequate for minor diagnostic procedures in gopher tortoises. This combination also caused moderate hypoventilation, and it is recommended that a supplemental source of oxygen or assisted ventilation be provided. Atipamezole administration hastens recovery from chemical immobilization but induces severe hypotension. It is recommended that atipamezole not be administered IV for reversal of medetomidine in tortoises and turtles.

Chelonia (Tortoises, Turtles, and Terrapins)

“…Similar effects were seen in Aldabra tortoises (Aldabrachelys gigantea) at the dose of 0.025-0.08 mg/kg (Lock et al 1998). In gopher tortoises, the combination of medetomidine (0.1 mg/kg) and ketamine (5 mg/kg) produced moderate hypertension, hypercapnia, and hypoxemia (Dennis & Heard 2002). For these reasons, the use of supplemental oxygen is highly recommended when α 2 -adrenergic agonists are used.…”

“…Pronounced cardiopulmonary side effects, however, are common after administration of α 2 -adrenergic agonists in chelonians and appear to be similar to those seen in mammals (Dennis & Heard 2002). The effect of alpha 2 -adrenergic agonists on the cardiovascular system appears to be dose-unrelated.…”

“…The antagonist atipamezole (0.5 mg/kg) given IV was demonstrated to produce severe hypotension and even undetectable carotid pulse in gopher tortoises (Gopherus polyphemus) (Dennis & Heard 2002). Based on these Patient temperature can be continuously monitored using cloacal or esophageal probes.…”

Clinical Applications of Cystoscopy in Chelonians

“…5 Because 2 of the tortoises vomited during cystoscopy and 2 following administration of reversal agents, no clear cause of emesis was able to be determined. Emesis in chelonians was not reported in studies in which medetomidine, 30 medetomidine-ketamine, [31][32][33][34][35] or morphine were administered. 36 Seven percent of the hatchling turtles undergoing celioscopy given a combination of medetomidine-ketamine-morphine vomited after naloxone and atipamezole administration.…”

Crocodilians (Crocodiles, Alligators, Caimans, Gharial)

“…Its major disadvantage is that it must be injected IV, limiting its use in large crocodilians unless they are restrained. Although dosages in reptiles of 10 to 15 mg/kg IV have been reported, it is the author's opinion that dosages as low as 5 mg/kg IV may be enough to allow for intubation in many crocodilian species (Dennis and Heard, 2002). A butterfly catheter or extension set may be used to allow the needle to be left in the vein for additional propofol to be titrated to effect.…”