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Safety and efficacy of high-dose fomepizole compared with ethanol as therapy for ethylene glycol intoxication in cats

Authors

  • Heather E. Connally MS, DVM, DACVECC,

    1. Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1671
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  • Mary Anna Thrall DVM, MS, DACVP,

    1. Department of Microbiology, Immunology, Pathology, Colorado State University, Fort Collins, CO 80523-1671
    2. Department of Pathobiology, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts, West Indies
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  • Dwayne W. Hamar PhD

    1. Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523-1671
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  • A portion of this study was presented as an abstract at the 2002 8th International Veterinary Emergency and Critical Care Symposium, San Antonio, TX.

  • A portion of this study was funded by a grant from the Miki Society, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO. Fomepizole was provided by Orphan Medical, Minnetonka, MN.

  • The authors declare no conflicts of interest.

Address correspondence and reprint requests to
Dr. Heather E. Connally, Veterinary Specialty Center of Tucson, 4909 N. La Cañada Dr, Tucson, AZ 85704, USA. Email: hconnall@hotmail.com
Submitted February 26, 2008; Accepted November 8, 2009.

Abstract

Objective – To determine the safety and efficacy of high-dose fomepizole compared with ethanol (EtOH) in cats with ethylene glycol (EG) toxicosis.

Design – Prospective study.

Setting – University veterinary research laboratory.

Animals – Thirteen cats.

Interventions – 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.

Measurements and Main 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.

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