Thinking of bringing a new horse into your herd or taking your horse to an event? Make sure you know what to do to do keep your horses protected from equine infectiousanemia (EIA). EIA does not affect humans.
Clusters of biting flies on horse's face
With recurring bouts of Equine Infectious Anemia, weight loss and edema in the chest and legs will become apparent and infected horses may die from direct effects of the virus or from secondary infections.
© 2020 by Carien Schippers New window.
Equine Guelph has prepared an EIA Horse Infograph that addresses the many facets of this disease which can be faltal to horses.
Basic Information about Equine Infectious Anemia
When horseflies or deerflies bite a horse infected with equine infectious anemia, the flies get blood from the infected horse on their mouth parts and then carry the infection on to other horses. In some cases, the initial clinical signs of equine infectious anemia are mild and go unnoticed, but other horses may become seriously ill within one to three weeks.
The initial clinical sign is usually a high fever, up to 105 degrees or more. As the disease develops, the immune system, via antibodies, attacks and destroys the horse's red blood cells leading to anemia.
Vital organs such as bone marrow, liver, heart and kidney may be damaged by accompanying inflammation and secondary infections such as pneumonia may occur because of suppression of the immune system.
Three distinct types of illness make up the progression of equine infectious anemia, but symptoms overlap: The acute illness is characterized by high fever, severe anemia, weakness, swelling of abdomen and legs, a weak pulse and an irregular heart beat. The rapid breakdown and destruction of red blood cells results in severe anemia and death may be the first indication of the disease.
Less serious cases of the illness progress more slowly and are less severe. In the less severe form of the disease similar symptoms occur, but they are not nearly as serious as in the acute form of the illness. The horse may become jaundiced and an enlarged spleen may be felt with a rectal examination.
The chronic illness is characterized by recurrent fever and anemia. The horse tires easily and is lethargic and depressed.
After the first bout with the disease, most horses suffer recurrent episodes of illness accompanied by fever, loss of appetite and lethargy. A blood test will usually reveal decreased red blood cells and decreased platelets. With recurring bouts, weight loss and edema in the chest and legs will become apparent. EIA infected horses may die from direct effects of the virus or from secondary infections.
Some infected horses never show any signs of the illness. Although a horse can live with the virus, that horse can be a source of infection for other horses. This fact makes testing very important. The Coggins test that checks for EIA antibodies in the horse's blood is often used. Blood samples are sent to a state-approved laboratory. Some states require the test before a horse can be transported or sold.