Rhodococcus Equi Pneumonia Linked to Large Farms, Lots of Horses

Farms with large acreage and many mares and foals are more likely to have cases of Rhodococcus equi foal pneumonia than smaller farms with fewer horses, according to a recently published Texas A&M University (TAMU) study. Additionally, farms that are intensively managed and use what are considered desirable practices to prevent disease are more likely to have R. equi cases.

R. equi is the most common cause of severe pneumonia in foals. Many breeding farms in Central Kentucky and other states are R. equi endemic, meaning the disease is present at a given farm on a recurrent basis. The study examined variables on 138 farms (65 affected and 73 unaffected) and appeared in the Feb. 1 issue of the Journal of the American Veterinary Medical Association.

Noah Cohen, VMD, PhD, Dipl. ACVIM, professor of equine medicine at TAMU's College of Veterinary Medicine and lead author on the study, said the associations with farm size and numbers weren't that surprising, but the health management factor is puzzling.

"Our current thinking is that it (the association of disease with intensivity of management) probably indicates that those practices, while desirable for other infectious diseases, are not adequate for resolving this problem," he added.

Other risk factors identified in the study included concrete flooring in foaling stalls, regular deworming, administration of R. equi hyperimmune plasma (considered to be a result of the disease rather than a cause), and using a manure removal program. Cohen thinks these might be merely markers for larger, well-managed farms. Also, the farms tended to be Thoroughbred operations.

Studies have shown that some foals are innately more susceptible to R. equi and the researchers are targeting a possible genetic cause. For more information on current and future R. equi studies, see www.TheHorse.com/ViewArticle.aspx?id=5624.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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