Reprinted from petcaretips.net
Equine Rhinopneumonitis (Contagious or Viral Abortion, Snots) is a disease caused by equine herpes virus Type 1 (EHV-1). Each subtype produces different symptoms: Sub-type 1 is the strain that causes abortions, respiratory, and neurologic disease, while sub-type 2 is just a respiratory strain. Rhinopneumonitis occurs in horses of all ages but is more common in horses less than three years old. Sporadic outbreaks come from inhalation of the virus particles. After incubation of two to 10 days, symptoms for the respiratory subtype are a fever of 102o to 107o F with a bacterial infection or "snots." Recovery provides immunity for only two to three months. Respiratory problems are more severe in foals, with infections near birth producing weak foals that die within 24 hours. Following a respiratory infection, the virus can cause abortions. Death of the fetus occurs two weeks to four months after exposure to the virus, or during the last three months of pregnancy. Abortion storms have a sudden onset with no additional clinical signs. The foal dies from asphyxiation by the premature separation of the placenta. Occasionally, the virus attacks the central nervous system, causing mild incoordination, paralysis of the rear legs or complete recumbency. Two vaccines are available: a killed vaccine and a modified-live vaccine. The killed vaccine is given to pregnant mares during the fifth, seventh and ninth months of pregnancy. The modified-live vaccine can be given every three months. Foals should be vaccinated at three months of age and again at four months. Horses should be given boosters every year. Prevention includes isolating arrivals and dividing the horses into small groups. The disease is difficult to confirm by diagnostic procedures unless proper tissue and blood samples are available.