What is Rhino.? When should I Vaccinate my horse to prevent abortions from Rhino.?

General Information

Of the 8 types of herpesvirus that affect horses and donkeys, 2 types cause the most significant disease. These are equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4). Both of these cause the disease known as rhinopneumonitis, which can be manifested as respiratory infections, abortion and neurologic problems.

Horses become infected with equine herpesvirus by inhaling the virus in respiratory droplets from infected horses and by contact with equipment, feed or water contaminated with the virus. Horses are immune to the virus for only 2-3 months after vaccination or infection. In some infected horses, the virus remains dormant and later causes disease when the horse is stressed (latent infection).

Clinical Signs of Herpesvirus Infection

Respiratory Disease: Horses may show a fever (102-106 F), inappetence and a slight nasal discharge 2-10 days after initial infection. Infected foals may develop pneumonia.

Abortion: Abortions caused by herpesvirus usually occur in late pregnancy and may or may not be preceded (days to weeks) by the respiratory infection. Though most foals aborted are dead, those still alive are weak and soon may die. Only a single mare in a group may abort, or an "abortion storm" may sweep through an entire group of pregnant mares. Infected mares can transmit the virus to other horses.

Neurologic Disease: Herpesvirus can cause an altered gait (primarily in the rear legs), a head tilt and front leg problems to the point where the horse goes down and cannot rise. Some horses have difficulty passing urine and manure. Neurologic (nervous system) problems may occur in single horses or in an entire group of horses. Laminitis can be a serious complication in these horses. Vaccination does not prevent this uncommon form of the disease.

While there are several recommendations concerning vaccinations here is some general guidlines:

Foals: vaccinate at 2 months of age and booster 1 month later.

Pregnant Mares: vaccinate at 5, 7, 9 months of pregnancy, mares should be up-to-date on vaccinations before breeding.

Mature horses: usually during the early spring and fall, this varies depending upon risk of exposure.

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