Farms with large acreage and many mares and foals are more likely to have cases of R. 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 in the study, said the associations with farm size and population numbers weren’t that surprising, but the health management factor is puzzling. “This idea of more intensive management increasing the risk of disease was suggested to us by some individuals as resulting from farms where they are interacting a lot with the foals and moving stall-to-stall handling the horses: this activity could provide  greater opportunity to spread the infection from animal to animal,” said Cohen. “Though plausible and possibly true, we think it is unlikely to be the case, because R. equi cases at a farm don’t appear to be clustered in such a way that we’d think it’s highly transferable between foals.

“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