The University of Arkansas System Division of Agriculture said in a release Monday cases were reported Friday by horse owners near Fort Smith in the northwestern region of the state and near El Paso in central Arkansas.
"Pigeon fever is not very common in Arkansas," said Mark Russell, assistant professor-equine extension at the university. "It's more prevalent in drier climates, but the recent drought in parts of Arkansas may be why we're seeing it now."
The university said more than 30 cases were also reported in Louisiana in December, and KXAS-TV, Dallas, said the disease was on the rise in northern Texas with dozens of cases reported last month.
Jeremy Powell, a university extension veterinarian, said cattle are also susceptible to the disease, which causes pectoral abscesses, but humans are not.
The abscesses "cause the appearance of a protruding breast like a pigeon breast -- which accounts for the name of the disease," Powell said. "These can also occur in along the belly and the lower neck region or on a front or rear limb. Often an owner will think the horse has been injured due to a kick from another horse."
The abscesses also can appear on the horse's face and, less frequently, deep ones can occur in lungs, kidneys or liver. Affected horses may appear weak and exhibit stiffness or lameness.
The disease is transmitted by insects, primarily flies, though horse-to-horse contact or contaminated soil also can spread it.