Yes, horses are subject to infection with a herpes virus, frequently known as Rhinopneumonitis or Equine Herpes Virus (EHV). This virus is very common in the horse population and it is likely that your horse may have that virus. So why isn't your horse showing signs of an infection? Once in the body, Herpes can lay dormant for long periods of time before it re infects the horse or sheds to other horses.
There are eight different types of EHV, but the most significant ones in the horse are EHV-1 and EHV-4. Both types cause the respiratory version of the disease infecting the lower and upper respiratory tract, hence the name rhinopneumonitis (rhino means nose, pneumo means lungs, and -itis means inflammation).
EHV-1 can also cause abortions in mares and a neurological syndrome. (See the article on "Care of The Pregnant Mare" later in this issue for prevention of abortions.) In the neurological syndrome, the nervous system is attacked and undergoes inflammation. The horse shows signs of weakness and incoordination in the hind legs. The treatment for any of these infections is mainly supportive, in other words make the horse comfortable, prevent secondary bacterial infections and provide fluid and nutritional therapy as needed.
The best way to treat this disease is to prevent it. Prevention is not only by way of proper vaccination, but also by way of quarantining new and sick horses. The quarantine period should be at least three weeks on any new horse with daily monitoring of their temperature and signs of disease. Other types of management changes should include keeping younger horses, (yearlings and up) away from pregnant mares.
If there is any sign of respiratory disease or abortion on your farm, strict isolation of that horse and strict sanitation of the aborted fetus, placenta and fluid associated with the abortion. In any case of an abortion, it is recommended that you have all the tissue tested for EHV, so it is best to call the office as soon as possible, should your mare abort. As for vaccinating for EHV, give the office a call and we would be happy to set up a vaccination schedule tailored for your horses.