In horses that are not shown, an annual booster is likely sufficient. The resulting disease is an infection similar to the common cold in humans. It is an acute disease with fever, coughing, and flu-like nasal and eye discharge. Rarely, the virus attacks the spinal cord causing neurologic diseases. Additionally, pregnant mares which are infected may abort or give birth to weak foals which die shortly after birth.
Cold symptoms caused by the virus occur primarily in young horses.
Recovered animals can habor the virus and contaminate others. Infection does not protect horses from reinfection at a later date. Prevention begins by isolating contaminated animals and their feed and water, and by using good sanitation management to reduce spread of infection. The virus can survive up to seven weeks in the environment, so sanitation is particularly important. Foals should be vaccinated with two doses about four weeks apart and then annually.