The Modern Equine Vet
April 2026
Vol 16 Issue 4 2026
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AAEP guide for infectious abortion
The AAEP published Field Diagnostic Guidelines for Equine Infectious Abortion, which are designed to assist practitioners with their differential and diagnostic approaches to equine abortion cases of unknown etiology.
Several abortion etiologies
Equine abortion etiologies range from viral, fungal and bacterial infections to environmental or developmental factors. Due to the contagious nature of some equine abortion pathogens, obtaining a definitive diagnosis is essential to guiding targeted treatment and bio-security strategies, the AAEP said.
Infectious causes should be considered in any case of equine abortion, prompting implementation of biosecurity practices that limit herd-mate exposure to the fetus, fetal membranes/fluids, and dam.
The guidelines include step-by-step instructions for examining the mare, placenta and fetus/necropsy, along with an abortion field necropsy sample collection worksheet.
The differential and diagnostic flowchart contained within the guidelines will help practitioners navigate their differential list, sample collection and diagnostic test selection to aid in achieving a definitive diagnosis.
“An efficient and accurate diagnosis is essential, as the impact from infectious causes of abortion can spread to the herd and trigger additional outbreaks,” said Toby L. Pinn-Woodcock, DVM, DACVIM, chair of the AAEP Infectious Disease Committee and associate clinical professor, Department of Population Medicine and Diagnostic Sciences, at Cornell University College of Veterinary Medicine. “These field diagnostic guidelines are intended to serve as comprehensive and accessible resources for practitioners to ease diagnostic selection and increase the diagnosis of equine infectious abortion.”
Sarah Eaton, DVM, DACT, DABVP-Equine, chair of the AAEP Disease Guidelines Subcommittee and associate professor of practice at the University of Arizona College of Veterinary Medicine, added, “The flowchart is especially beneficial to practitioners who may not see many abortion cases and want step-by-step directions.”
Authored by the members of the AAEP Field Guidelines Subcommittee, the guidelines were reviewed and approved by the AAEP’s Infectious Disease Committee and board of directors. View the guidelines here or save them to your mobile device.
This is the fourth set of Field Diagnostic Guidelines published by the AAEP and follows previous issuance of similar step-by-step protocols for Infectious Neurologic Disease, Acute Infectious Diarrhea and Infectious Respiratory Disease.
AAEP’s Field Diagnostic Guidelines are accessible here. MeV

“An efficient and accurate diagnosis is essential, as the impact from infectious causes of abortion can spread to the herd and trigger additional outbreaks.”
—Dr. Toby L. Pinn-Woodcock

