AAEP releases field diagnostic guidance for equine abortion cases

The AAEP has added equine infectious abortion to its Field Diagnostic Guidelines series, giving practitioners a new, mobile-friendly framework for approaching abortion cases in the field. Announced March 13, 2026, the document is designed to help veterinarians move from initial suspicion to sample collection, diagnostics, and biosecurity decisions more systematically, particularly when the etiology is unclear. (aaep.org)

The release builds on AAEP’s broader push to create practical field guidance for syndromes where early decisions can shape both case outcomes and outbreak control. The association says this is its fourth Field Diagnostic Guideline, following similar resources for infectious neurologic disease, acute infectious diarrhea, and infectious respiratory disease. Across the series, AAEP emphasizes a consistent principle: if an infectious cause is possible, veterinarians should act conservatively on biosecurity until testing narrows the differential. (aaep.org)

In the abortion guideline itself, AAEP frames infectious abortion as both an individual-patient and herd-health issue. The document says infectious causes should be considered in any equine abortion case and recommends limiting herd exposure to the fetus, fetal membranes, fluids, and the dam. It outlines a workup that includes a complete history, examination of the mare, placental assessment, fetal necropsy considerations, and a sampling worksheet. It also notes that state animal health officials should be alerted promptly, according to state rules, when an infectious and reportable cause is suspected, including EHV-1 or Taylorella equigenitalis. (aaep.org)

The differential list is broad, reflecting how often gross lesions alone fail to provide an answer. AAEP includes infectious causes such as ascending bacterial infection, equine arteritis virus, equine herpesvirus-1 and -4, equine infectious anemia, leptospirosis, mycotic placentitis, Potomac horse fever, and nocardioform placentitis, alongside noninfectious causes like twins, umbilical cord torsion, placental insufficiency, congenital abnormalities, and fescue toxicosis. That structure is useful because it reinforces that abortion workups need both reproductive and infectious disease thinking from the start. (aaep.org)

AAEP leaders positioned the new guidance as a practical aid for busy clinicians. Toby L. Pinn-Woodcock, chair of the AAEP Infectious Disease Committee, said efficient diagnosis matters because infectious abortion can spread within a herd and trigger additional outbreaks. Sarah Eaton, chair of the AAEP Disease Guidelines Subcommittee, said the flowchart is especially helpful for practitioners who may only encounter a small number of abortion cases and want step-by-step direction. (aaep.org)

That emphasis fits the wider evidence base around equine abortion pathogens. The updated ACVIM consensus statement on equine herpesvirus-1, published in 2024, describes EHV-1 as ubiquitous and notes that its most serious consequences include abortion and neurologic disease. It also underscores that outbreak prevention and control practices remain central even as evidence on vaccination and treatment continues to evolve. In other words, when abortion could be infectious, getting the field response right still matters as much as ever. (academic.oup.com)

Why it matters: For veterinary professionals, the biggest significance may be operational rather than scientific. Many equine clinicians, especially outside large breeding practices, don’t handle abortion cases often enough to rely on routine alone. A concise field document can reduce missed samples, improve diagnostic yield, support cleaner communication with diagnostic labs, and help practices respond faster on isolation and reporting. It may also help veterinarians guide pet parents and farm managers through a stressful event with clearer expectations about what needs to be examined, packaged, submitted, and monitored. (aaep.org)

What to watch: The next question is whether the guideline changes behavior on the ground, particularly around earlier biosecurity measures, more complete submissions to diagnostic labs, and faster notification when reportable diseases are on the table. It’s also worth watching how often practitioners pair this new abortion resource with AAEP’s disease-specific guidance on EHV and EVA, since those documents add pathogen-level detail beyond the field triage framework. (aaep.org)