Equine Infectious Abortion Field Diagnostic Guidelines

The AAEP Field Diagnostic Guidelines provide step-by-step instruction for the diagnostic work-up and management of clinical syndromes commonly encountered in equine practice. They are intended to help practitioners determine appropriate samples and tests necessary to achieve a definitive diagnosis while implementing appropriate biosecurity measures.

Infectious causes of equine abortion can impact both individual horse and herd health and may present as abortion outbreaks with the potential for significant economic loss. Equine abortion etiologies range from viral, fungal and bacterial infections to environmental or developmental factors. While the presence of pathognomonic gross necropsy lesions can narrow the equine abortion differential list, gross lesions are frequently lacking, and ancillary testing is necessary to reach a definitive diagnosis. Due to the contagious nature of some equine abortion pathogens, such as equine herpesvirus-1 (EHV-1), obtaining a definitive diagnosis is imperative to guiding targeted treatment strategies, implementing biosecurity protocols and launching epidemiological investigations. Proper diagnosis is essential, especially when necessary to eliminate the source of disease, as may be the case with equine arteritis virus (EAV) and Taylorella equigenitalis, the causative agent of Contagious Equine Metritis (CEM).

Flowchart reprinted with permission from Cornell University College of Veterinary Medicine.