Equine infectious anemia is a potentially fatal, viral, blood-borne infection that’s spread between horses primarily through horseflies, deerflies, and other biting insects. There is no vaccine or treatment for the infection, which is a big reason why prevention programs are strictly enforced. Moreover, not all horses show active signs of the infection.
Symptoms of equine infectious anemia include things like fever, anemia, weight loss, swollen limbs, icterus, and general fatigue and weakness. There is also both an acute and chronic onset of EIA. In other words, a horse may contract EIA and die suddenly or the infection may linger, but even chronic symptoms can ultimately prove fatal. Finally, while there is no treatment, a horse may overcome the symptoms and the infection becomes “inapparent.” Nevertheless, the horse is still a carrier of the EIA virus and can infect other nearby horses. You can read more about equine infectious anemia here.