From Dog

Fomepizole inhibits alcohol dehydragenase in dogs[1], the enzyme that catalyzes the initial steps in the metabolism of ethylene glycol and methanol to their toxic metabolites.

Fomepizole is used for treatment of ethylene glycol toxicity and appears to neutralize the acute renal injury effects of this drug if given within 8 hours following ethylene glycol ingestion[2].

The drug appears to be well tolerated by dogs and few side effects have been reported. The drug is rapidly metabolized via the cytochrome P450 mixed-function oxidase system and is excreted unchanged in the urine.

Recommended dose rate in dogs is initial dose of 20 mg/kg given intravenously, followed by 15 mg/kg 12 hours and 24 hours later. A final dose of 5 mg/kg is given intravenously 36 hours after the initial dose[3].


  1. Connally HE et al (2000) Inhibition of canine and feline alcohol dehydrogenase activity by fomepizole. Am J Vet Res 61(4):450-455
  2. Dial SM et al (1994) Efficacy of 4-methylpyrazole for treatment of ethylene glycol intoxication in dogs. Am J Vet Res 55(12):1762-1770
  3. Connally HE et al (1996) Safety and efficacy of 4-methylpyrazole for treatment of suspected or confirmed ethylene glycol intoxication in dogs: 107 cases (1983-1995). J Am Vet Med Assoc 209(11):1880-1883