Suspected envenomation by the common European adder (Vipera berus berus) in 28 horses in Finland.
Authors: Leppänen V, Mykkänen A
Journal: Journal of equine veterinary science
Summary
# Envenomation by European Adder in Horses: Clinical Outcomes and Treatment Patterns Over a 15-year period, Helsinki University Equine Hospital documented 28 cases of suspected Vipera berus berus envenomation in horses during the warmer months, providing the first substantial dataset on this condition's presentation and management in Nordic equine populations. Clinical examination findings, laboratory results, and treatment protocols varied considerably among cases, with antivenom administered to 11 horses whilst supportive therapies—including NSAIDs (22 horses), antimicrobials (19), intravenous fluids (11), corticosteroids (9), and local wound treatment (11)—formed the backbone of management across all cases. Remarkably, all 28 horses survived to discharge; however, antivenom treatment showed no association with reduced hospitalisation duration, and horses with moderate envenomation required significantly longer stays than mildly envenomated animals regardless of antivenom use. The findings raise important questions about the routine use of antimicrobials and corticosteroids, neither of which demonstrated clear evidence of benefit in this cohort. Whilst this series represents the largest published clinical experience with equine adder bite, larger prospective studies are needed to establish evidence-based treatment protocols and to determine whether antivenom administration influences long-term soundness and recovery outcomes beyond survival to discharge.
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Practical Takeaways
- •European adder envenomation in horses carries a good prognosis with supportive care alone; antivenom use should be risk-stratified rather than routine, as it does not reduce hospital stay in moderate cases
- •NSAIDs and IV fluid therapy appear beneficial for managing envenomation, but antimicrobials and corticosteroids lack strong evidence and should be used judiciously
- •Severity assessment (mild vs moderate envenomation) should guide treatment decisions, with moderate cases warranting closer monitoring and potential antivenom consideration
Key Findings
- •All 28 horses with suspected European adder envenomation survived to discharge regardless of treatment
- •11 of 28 horses received antivenom treatment, with no difference in hospital stay length compared to non-treated horses with moderate envenomation
- •Horses with moderate envenomation required longer hospitalization and were more likely to receive antivenom than horses with mild envenomation
- •Common treatments included NSAIDs (22/28), antimicrobials (19/28), IV fluids (11/28), and corticosteroids (9/28), with limited evidence supporting antimicrobial and corticosteroid use