Experimentally, the virus has caused disease in laboratory cats and guinea pigs but not in mice, rabbits, chickens, or dogs. In horses, the incubation period ranges from 8 to 11 days after exposure. There is no known treatment or cure. Initially, infected horses may lose their appetite and appear depressed. Respiration may become labored, rapid, and shallow.
Mucous membranes can become dark and congested.
Headpressing may occur. The legs, sheath, and angle of the jaw may also swell. The last sign to appear is usually a substantial, frothy nasal discharge. Death occurs approximately two days after clinical signs appear. After death, humans and horses show similar pathology.