During the early part of the 2011 foaling season, the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) reported an increased number of abortions and abnormal placentas due to nocardioform placentitis. The UKVDL epidemiology laboratory constantly surveys the occurrence of animal diseases and notes and monitors trends immediately.

Nocardioform placentitis is a unique form of bacterial placentitis affecting late gestation mares, causing abortion, stillbirth, or foals born alive but compromised. The disease was first diagnosed in Central Kentucky in the 1980s and has also been reported in other areas of the United States and abroad. Nocardioform placentitis cases are diagnosed annually, with some years experiencing few cases and other years noting higher numbers. The 2011 foaling season was associated with an unusually large number of cases, and before the foaling season was over, a total of 94 abortions were caused by nocardioform placentitis. Two hundred and twenty nine placentas were submitted with a diagnosis of nocardioform placentitis at the UKVDL. 

In February 2011 the University of Kentucky Gluck Equine Research Center and UKVDL coordinated a meeting with a small group of local veterinarians to discuss the status of nocardioform placentitis abortions in Central Kentucky and devise potential studies. The Gluck Center hosted an informative follow-up meeting for veterinarians and farm managers a few weeks later.

Researchers at the Gluck Center, in collaboration with UKVDL and local practices, submitted a grant proposal to the Kentucky Thoroughbred Association (KTA) at the end of March outlining a comprehensive plan to investigate nocardioform placentitis' route of infection, conduct an epidemiological study, investigate early diagnostics and effective treatments for placental disease, and conduct a retrospective study on the athletic success of foals born to mares that had been successfully treated for placentitis.

In July the KTA agreed to fund an investigation into the route of infection for nocardioform placentitis, and Gluck Center investigators have performed preliminary research to determine an infective dose of the bacteria. Thirty mares at the University of Kentucky Maine Chance Equine Campus will be involved in the study that is expected to produce results when the mares foal next year.

In addition, Hagyard Equine Medical Institute and Woodford Equine Hospital clinicians have collected more than 200 samples from mares that were bred during the 2011 breeding season. These samples are currently being analyzed for the presence of nocardioform placentitis' causative bacteria.

Researchers also are collaborating with David P. Labeda, ARS, with the United States Department of Agriculture, National Center for Agricultural Utilization Research, in Illinois. A national expert on nocardioform bacteria, Labeda has provided recommendations regarding the study design and will provide advice as results are produced.

The UKVDL itself funded a detailed epidemiological study to identify risk factors associated with nocardioform placentitis. Eighty Central Kentucky farms responded to an initial survey. A redesigned survey making questions farm-focused rather than mare-focused is in the works.

Farms with high incidence and those with very low incidence of abortions are being investigated to identify potential risk factors. The Gluck Center hopes these initial research steps will provide valuable information on how to limit nocardioform placentitis outbreaks in Central Kentucky and elsewhere and lead to future research on how to effectively diagnose and treat this form of abortion and premature birth.

Mats Troedsson, DVM, PhD, Dipl. ACT, director of the Gluck Center and chair of the department of veterinary science at the University of Kentucky, submitted this information.

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