- Rhinopneumonitis is now recognized to be two distinct diseases caused by equine herpesvirus type 1 (EHV-1) and equine herpesvirus type 4 (EHV-4).
- Both EHV-1 and EHV-4 infect the respiratory tract causing signs of mild fever and transient nasal discharge or more severe influenza-like disease characterized by high fever, lethargy, loss of appetite, nasal discharge and coughing.
- In addition, EHV-1 causes abortion in pregnant mares, the birth of weak foals and a paralytic neurologic disease.
- The primary indications for equine herpesvirus vaccines are
- prevention of EHV-1 abortion in pregnant mares and
- prevention of respiratory disease in foals, weanlings, yearlings and young performance and show horses.
- It is strongly recommended that all pregnant mares be vaccinated during the fifth, seventh and ninth month of gestation using the approved, inactivated EHV-1 vaccine.