A Purdue University veterinarian is advising Indiana equestrians to be alert to clinical signs of Potomac horse fever (PHF) in their animals after a horse was diagnosed with the disease last month.

Janice Kritchevsky, DVM, professor of large animal internal medicine at Purdue, said PHF is a bacterial disease carried by insects such as freshwater snails, caddisflies, mayflies, and dragonflies. Horses come in contact with the causative bacterium when they consume pasture grass, hay, or water contaminated by dead insects. Clinical signs of PHF include colic, dehydration, and diarrhea. Treatment includes antibiotics, fluids, and non-steroidal anti-inflammatory drugs. Untreated, the disease can result in permanent lameness, shock, or death.

Indiana horses are not usually at high risk for contracting PHF until late August, Kritchevsky said. However, this year’s warmer-than-usual winter and spring temperatures might have promoted the early hatchings of the insects that carry the disease.

"The (earliest) we’ve ever seen (Potomac fever) is late July," Kritchevsky said. "So when this horse presented with the disease in early June, we wanted to make sure to alert horse owners about it