Horses are rarely anemic during this stage. This phase may last several days and is the stage during which the horse is most likely to transmit the disease to nearby horses. The second phase is characterized by weight loss, recurring fevers and general weakness. Anemia is likely to be present, and mares can abort during this stage. An owner may report that a horse is a poor keeper, and the animal may be mildly anemic.
Infected mares can transmit the disease to their foals.
A horse infected with the EIA virus will be a carrier of the disease for life. Although horses in the chronic stage appear normal, they become ill again if subjected to stress, such as shipping or severe weather. Blood samples must be sent to a state approved laboratory. It is to prove to others your horse is safe to be around their horses. The only exception to this rule is unweaned foals traveling with their dams.