Safety and efficacy of 4-methylpyrazole for treatment of suspected or confirmed ethylene glycol intoxication in dogs: 107 cases (1983-1995)

Abstract

Objective - To evaluate safety and efficacy of 4-methylpyrazole (4-MP) treatment in dogs and to determine clinical signs and outcome of, and clinicopathologic abnormalities in, dogs treated in early or late stages of ethylene glycol (EG) intoxication. Design - Retrospective study. Animals - 107 dogs. Procedure - For dogs treated with 4-MP, 1 of 2 dosage regimens was usually used: 20 mg/kg of body weight, IV, initially, 15 mg/kg 17 hours later, and 5 mg/kg 25 and 36 hours after the initial dose, or 20 mg/kg, IV, initially, 15 mg/kg 12 and 24 hours later, and 5 mg/kg 36 hours after the initial dose. Results - Neither adverse clinical signs nor clinicopathologic abnormalities were associated with the administration of 4-MP except in 1 dog, which developed tachypnea, gagging, excess salivation, and trembling after the second dose of 4-MP was given. Ethylene glycol intoxication was confirmed in 37 dogs. Of these, 21 were azotemic or became azotemic within 18 hours after admission, and only 1 of the 21 survived. All 16 dogs that did not become azotemic survived. Median time from EG ingestion to treatment with 4-MP was 5 hours (range, 2 to 8.5 hours) for dogs that were not azotemic at admission and 14.5 hours (range, 8.5 to 38 hours) for dogs that were azotemic at admission. Clinical implications - 4-MP was a safe and effective treatment for EG intoxication when it was given before sufficient quantities of EG had been metabolized to induce renal failure. Dogs treated within 8 hours of EG ingestion had a good prognosis.