American Association of Equine Practitioners Publishes Nocardioform Placentitis Guidelines

Healthy foal lying near grazing mare in pasture.
Healthy foal lying near grazing mare in pasture. Matt Barton, UK agricultural communications

Newsdate: Friday, June 24, 2022 - 19:35 am
Location: LEXINGTON, Kentucky

Equine veterinarians can help protect their clients’ broodmares and unborn foals from nocardioform placentitis (NP) with new disease guidelines published by the American Association of Equine Practitioners.

Mare licking and cleaning newly-born foal.

Mare licking and cleaning newly-born foal

The insidious nature of nocardioform placentitis that can cause abortion, stillbirth, or delivery of a weak premature or term foal makes early diagnosis and onset of treatment challenging in clinical practice.
© 2017 by Melissa E Dockstader New window.

The AAEP’s Nocardioform Placentitis Guidelines present the clinical features, risk factors, treatment, control measures and more for a form of bacterial placentitis that can cause abortion, stillbirth, or delivery of a weak premature or term foal.

NP was first diagnosed in central Kentucky in the mid-1980s, and its occurrence since has varied from sporadic cases to outbreak years in the region. Outside of Kentucky and the United States, NP has been reported primarily as isolated cases and rarely as outbreaks. 

The suggested window from exposure to clinical signs is generally three to five months. In addition, there is a strong association between weather conditions during mid- to late-pregnancy and increased occurrence of NP, specifically exposure to low rainfall and high temperatures during August and September in central Kentucky.

“The insidious nature of NP makes the early diagnosis and onset of treatment rather challenging in clinical practice,” said guidelines co-author Igor Canisso, DVM, MS, Ph.D., DACT, DECAR (Equine Reproduction), Associate Professor of Theriogenology at the University of Illinois College of Veterinary Medicine.

Attempts to create experimental NP infection have been unsuccessful, limiting evidence-based assessment of therapy efficacy. Currently, mares suspected to have NP based on ultrasonographic lesions are usually empirically treated with antibiotics (e.g., sulfa, doxycycline, or gentamicin), anti-inflammatories (flunixin or firocoxib), steroids (altrenogest and/or estrogens) and supporting medications (pentoxifylline and vitamin E).

Dr. Canisso co-authored the Nocardioform Placentitis Guidelines with Maria Schnobrich, VMD, DACT, shareholder and theriogenologist at Rood & Riddle Equine Hospital; Carleigh Fedorka, Ph.D., postdoctoral fellow at the University of Kentucky’s Maxwell H. Gluck Equine Research Center; and Barry Ball, DVM, Ph.D., DACT, who recently retired as the Albert G. Clay Endowed Chair and Professor in Equine Reproduction at the University of Kentucky’s Maxwell H. Gluck Equine Research Center.

View the Nocardioform Placentitis Guidelines or save them to your mobile device as a PDF file at

Besides Nocardioform Placentitis, AAEP guidelines for 23 additional equine infectious diseases can be found at In addition, five foreign animal disease guidelines are available at

About AAEP

The American Association of Equine Practitioners, headquartered in Lexington, Ky., was founded in 1954 as a non-profit organization dedicated to the health and welfare of the horse. Currently, AAEP reaches more than 5 million horse owners through its over 9,000 members worldwide and is actively involved in ethics issues, practice management, research and continuing education in the equine veterinary profession and horse industry.

Press release by Sally Baker

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