The USDA has a program that will have an effect on the Coggins test requirements for horses. Today on the program I am going to discuss equine infectious anemia, or EIA, which we test for with the Coggins test. The disease was first reported in this country in 1888 and there is still no treatment or vaccine is available. The disease can occur in two main forms-an acute and a chronic form. When horses develop acute EIA, they develop severe signs and die in 2 to 3 weeks. Because this form occurs so quickly, it is difficult to diagnose and sometimes the only symptom is an increased temperature.
The USDA indicates that 1 cc of blood from a horse with acute EIA contains enough virus to infect one million horses. In mild cases of the acute form, horses recover and usually do not have other symptoms but will always be positive on the Coggins test. Some horses that recover from the acute form develop the chronic form. Symptoms of the chronic disease include fever that may go as high as 105 to 108 degrees, then drop back down to normal until the next episode. Some horses will also develop small hemorrhages called petechial hemorrhages on the gum line or other mucous membranes. These horses also appear depressed and will usually lose weight but will develop swellings of fluid under the chest and legs. As the name suggests, most horses will develop anemia, which causes horses to be lethargic and have a decreased appetite. However, most horses are inapparent carriers and show no symptoms, although it is possible they could transmit infection. Join us next time when I discuss transmission of EIA.