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Home / Equine Research Bank / J Vet Emerg Crit Care (San Antonio) / A Novel Equine F[ab’]2 Veterinary Antivenom for North ...
Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001)2026; 36(1); 45-55; doi: 10.1111/vec.70082

A Novel Equine F[ab’]2 Veterinary Antivenom for North American Viperid Snake Envenomation Demonstrates Efficacy by Rapid Serum Venom Removal and Improvement in Snakebite Severity Score.

Abstract: To assess the efficacy of a new equine F[ab'] antivenom (US Department of Agriculture code 6101.05) in removing serum venom and lowering the snakebite severity score (SSS) in animals suffering from naturally occurring viperid envenomation. Methods: Retrospective study, April 2020 to October 2021. Methods: Veterinary hospitals across four North American regions. Methods: Twenty-two dogs, one cat, and one horse. Methods: All patients received the new antivenom intravenously and were assessed for clinical response. Most dogs required one vial for clinical control of signs. Results: Among the dogs and cats with detectable initial serum venom, 94.4% showed a strong response to antivenom administration, with a reduction in serum venom ranging from 94% to >99% at 2 h. Animals that experienced a 90% reduction of serum venom within 2 h greatly exceeded the 0% expected of an ineffective antivenom. The canine and feline SSS improved relative to the initial SSS at 2, 6, and 12 h in 57.9%, 77.8%, and 90.9% of cases, respectively. A favorable reduction in SSS was also appreciated in the single horse in the study. Conclusions: In the canine, feline, and equine cases of North American viperid envenomation studied, antivenom 6101.05 adequately removed serum venom and lowered the SSS.
© 2026 Veterinary Emergency and Critical Care Society.
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Publication Date: 2026-01-26 PubMed ID: 41582890DOI: 10.1111/vec.70082Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study evaluates a new equine-derived F[ab’]2 antivenom designed for treating North American viperid snakebites in animals.
  • The research assesses the antivenom’s ability to quickly remove venom from the blood and improve the clinical severity of snakebite symptoms in dogs, cats, and a horse.

Study Objective and Design

  • The primary goal was to assess the efficacy of an equine F[ab’]2 antivenom (USDA code 6101.05) in reducing circulating venom levels and improving clinical outcomes in veterinary patients naturally envenomated by North American viperid snakes.
  • Study type: Retrospective analysis conducted from April 2020 to October 2021.
  • Setting: Multiple veterinary hospitals across four geographic regions in North America.
  • Subjects: A total of 24 animals—22 dogs, 1 cat, and 1 horse—were treated with the antivenom and monitored.

Treatment Protocol and Venom Removal

  • All animals received intravenous administration of the antivenom.
  • Most dogs required only a single vial of antivenom to control clinical signs of envenomation.
  • Among animals with measurable venom in their serum at baseline:
    • 94.4% (majority) showed a strong positive response to antivenom, as evidenced by a substantial reduction in serum venom levels within 2 hours after treatment.
    • The decrease in venom ranged from 94% to over 99%, showing rapid and effective venom clearance.
    • Achieving a ≥90% reduction in serum venom by 2 hours markedly surpassed the expected 0% reduction that would be typical if the antivenom were ineffective, demonstrating clear efficacy.

Clinical Outcomes and Snakebite Severity Score (SSS)

  • The study utilized the Snakebite Severity Score (SSS) to quantify clinical injury from envenomation over time.
  • Improvement in SSS was observed at:
    • 2 hours post-treatment in 57.9% of canine and feline cases
    • 6 hours post-treatment in 77.8% of cases
    • 12 hours post-treatment in 90.9% of cases

    indicating progressive clinical recovery after antivenom administration.

  • The single horse treated also demonstrated favorable reduction in severity score, suggesting the antivenom’s broader applicability across species.

Conclusions and Significance

  • The equine F[ab’]2 antivenom 6101.05 effectively removes venom from the bloodstream of envenomated dogs, cats, and horses, with rapid reduction in serum venom levels.
  • The treatment is associated with meaningful clinical improvement as measured by the SSS, supporting its clinical utility in veterinary cases of North American viperid snakebite.
  • This antivenom represents a promising option for veterinary practitioners treating snakebite envenomation, helping to mitigate venom effects and improve animal recovery.

Cite This Article

APA
Carotenuto SE, Broussard G, Fox GA, Hayes WK. (2026). A Novel Equine F[ab’]2 Veterinary Antivenom for North American Viperid Snake Envenomation Demonstrates Efficacy by Rapid Serum Venom Removal and Improvement in Snakebite Severity Score. J Vet Emerg Crit Care (San Antonio), 36(1), 45-55. https://doi.org/10.1111/vec.70082

Publication

Journal of veterinary emergency and critical care (San Antonio, Tex. : 2001)
ISSN: 1476-4431
NlmUniqueID: 101152804
Country: United States
Language: English
Volume: 36
Issue: 1
Pages: 45-55

Researcher Affiliations

Carotenuto, Sarah E
  • Emergency Veterinarian, Tucson, Arizona, USA.
Broussard, Gena
  • MT Venom, Canoga Park, California, USA.
Fox, Gerad A
  • Department of Earth and Biological Sciences, School of Medicine, Loma Linda University, Loma Linda, California, USA.
Hayes, William K
  • Department of Earth and Biological Sciences, School of Medicine, Loma Linda University, Loma Linda, California, USA.

MeSH Terms

  • Animals
  • Antivenins / therapeutic use
  • Snake Bites / veterinary
  • Snake Bites / drug therapy
  • Snake Bites / therapy
  • Retrospective Studies
  • Dogs
  • Horses
  • Cats
  • Viperidae
  • Dog Diseases / drug therapy
  • Male
  • Horse Diseases / drug therapy
  • Female
  • Immunoglobulin Fab Fragments / therapeutic use
  • Cat Diseases / drug therapy

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