Equine viral arteritis (EVA) is a disease of horses caused by Alphaarterivirus equid. The virus which causes EVA was first isolated in 1953, but the disease has afflicted equine animals worldwide for centuries. It has been more common in some breeds of horses in the United States, but there is no breed “immunity”. In the UK, it is a notifiable disease. There is no known human hazard.
The signs shown depend on the horse’s age, the strain of the infecting virus, the condition of the horse and the route by which it was infected. Most horses with EVA infection don’t show any signs; if a horse does show symptoms, these can vary greatly in severity. Following infection, the first sign is fever, peaking at 41 °C (106 °F), followed by various signs such as Lethargy, nasal discharge, “pink eye” (conjunctivitis), swelling over the eye (supraorbital edema), urticaria, and swelling of the limbs and under the belly (the ventral abdomen) which may extend to the udder in mares or the scrotum of male horses. More unusual signs include spontaneous abortion in pregnant mares, and, most likely in foals, severe respiratory distress and death.