PENDLETON (AP) — Symptoms of a contagious animal disease called pigeon fever have been found in dozens of horses in Eastern Oregon this fall.

Despite the name, the disease is not spread by the bird. Rather, the bacterial infection can cause abscesses that lead a horse’s chest to swell like a pigeon’s.

Dr. Fred Robinson of Riverside Veterinary Clinic in Pendleton said he has seen an increasing number of cases this fall, just as he did in 2005.

“There were 80 or so horses treated then, and at this point, with the season not over, we’re approaching 50 horses.”

The disease can cause swelling anywhere on the horse’s body. The animal feels pain when touched on a swollen area, so owners and caretakers must look for the swelling because horses don’t give any clues.