Three cases of Potomac horse fever were reported in July at the Star Equestrian Center on Greencastle Pike near Hagerstown.
Ginny Gaylor, director of the Star Equestrian Center, said one of the horses was put down. None the center's horses are infected with the disease at this time, she said.
Potomac horse fever is spread to horses by aquatic insects. Its symptoms include diarrhea, depression, fever and lethargy.
