Acute toxicosis in two dogs associated with etomidate-propylene glycol infusion

Etomidate, formulated in propylene glycol, was used as the primary anesthetic agent in two dogs (No. 1 and 2) and etomidate, formulated in saline, was used as the primary anesthetic agent in an additional 20 dogs, while developing a canine model for baroreceptor sensitivity testing. Dogs 1 and 2 had signs of acute toxicosis after infusion of etomidate in propylene glycol. Dog 1 received less total etomidate than did dog 2, 5.9 mg/kg vs 15.8 mg/kg, respectively. Average infusion rates were 4.7 and 9 mg/kg/h, respectively. Dog 1 developed clinical signs of mild hemoglobinuria, whereas dog 2 recovered from anesthesia slowly, was obtunded, bradycardic, and hypothermic, with marked hemoglobinuria and intravascular hemolysis. After supportive treatment, dog 2 regained consciousness and hemodynamic variables improved within 12 h. None of the additional 20 dogs that received infusion of etomidate in saline had any clinical adverse effects, suggesting a causal relationship between the etomidate-propylene glycol formulation and the adverse effects in dogs 1 and 2. Although etomidate may be useful in designing cardiovascular models under general anesthesia, such complications may warrant use of a different etomidate formulation in the dog when the agent is administered at these infusion rates.