Feline Ethylene Glycol Toxicity Study Guide

Overview and Clinical Importance

Ethylene glycol (EG) toxicity is a life-threatening emergency that is particularly devastating in cats due to their extreme sensitivity to this compound. Ethylene glycol is a colorless, odorless, sweet-tasting liquid found in antifreeze (up to 95% concentration), engine coolants, hydraulic brake fluids, and various household products. Cats are the most susceptible domestic species, with a minimum lethal dose of only 1.4 mL/kg of undiluted ethylene glycol–less than a teaspoon can be fatal to an average cat. This is compared to 4.4-6.6 mL/kg in dogs. The sweet taste makes it palatable to animals, and cats may also be exposed through cutaneous absorption during grooming after walking through spilled antifreeze.

The toxicity of ethylene glycol lies not in the parent compound itself, but in its toxic metabolites formed through hepatic metabolism via alcohol dehydrogenase (ADH). These metabolites cause severe metabolic acidosis and irreversible acute kidney injury through calcium oxalate crystal deposition in the renal tubules. Feline mortality rates may reach 97% without early intervention, making rapid diagnosis and treatment critical for survival.

Pathophysiology and Metabolism

Ethylene Glycol Metabolism

Ethylene glycol itself has relatively low toxicity. The severe clinical effects result from its hepatic metabolism through a series of oxidation reactions. Understanding this metabolic pathway is essential for both diagnosis and treatment.