Safety and efficacy of high-dose fomepizole compared with ethanol as therapy for ethylene glycol intoxication in cats.
OBJECTIVE
To determine the safety and efficacy of high-dose fomepizole compared with ethanol (EtOH) in cats with ethylene glycol (EG) toxicosis.


METHODS
Prospective study.


METHODS
University veterinary research laboratory.


METHODS
Thirteen cats.


METHODS
Two cats received injections of high-dose fomepizole (Study 1). Three cats received lethal doses of EG and fomepizole treatment was initiated 1, 2, or 3 hours later (Study 2). Eight cats received a lethal dose of EG and were treated with fomepizole or EtOH (Study 3). Cats treated with fomepizole received 125 mg/kg IV initially, then 31.25 mg/kg at 12, 24, and 36 hours. Cats treated with EtOH received 5 mL of 20% EtOH/kg IV initially, then every 6 hours for 5 treatments, then every 8 hours for 4 treatments. Cats also received fluids and supportive therapy as needed.


RESULTS
Clinical signs were monitored and serial blood analyses performed. Cats receiving fomepizole experienced mild sedation but no biochemical evidence of toxicity. Cats receiving fomepizole for EG intoxication survived if therapy was initiated within 3 hours of EG ingestion. One of the 6 developed acute renal failure (ARF) but survived. Only 1 of the 3 cats treated with EtOH 3 hours following EG ingestion survived; 2 developed ARF and were euthanized. Cats treated 4 hours following EG ingestion developed ARF, whether treated with EtOH or fomepizole.


CONCLUSIONS
Fomepizole is safe when administered to cats in high doses, prevents EG-induced fatal ARF when therapy is instituted within 3 hours of EG ingestion, and is more effective than treatment with EtOH.
Connally
Heather E
HE
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1671, USA. hconnall@hotmail.com
Thrall
Mary Anna
MA
Hamar
Dwayne W
DW
D000704:Analysis of Variance; D000818:Animals; D000931:Antidotes / Q000592:standards / Q000627:therapeutic use*; D002371:Cat Diseases / Q000139:chemically induced* / Q000188:drug therapy; D002415:Cats; D002492:Central Nervous System Depressants / Q000592:standards / Q000627:therapeutic use*; D000431:Ethanol / Q000592:standards / Q000627:therapeutic use*; D019855:Ethylene Glycol / Q000506:poisoning*; D005260:Female; D000077604:Fomepizole; D008297:Male; D011446:Prospective Studies; D011720:Pyrazoles / Q000592:standards / Q000627:therapeutic use*; D016896:Treatment Outcome
D000931:Antidotes; D002492:Central Nervous System Depressants; D011720:Pyrazoles; D000431:Ethanol; D000077604:Fomepizole; D019855:Ethylene Glycol