The Kentucky Department of Agriculture (KDA) is reporting today that during the past two weeks, four horses in Western Kentucky’s Marshall County have tested positive for equine infectious anemia (EIA). These are the first Kentucky horses found positive for the viral disease since 2007.

A private veterinarian tested and found the initial horse positive, with the remaining three (3) cases discovered through testing conducted as part of a KDA investigation. Each of the horses were confirmed positive by additional testing and have since been humanely destroyed and buried. Seven additional “cohorts” tested negative on the initial testing. These seven remain under quarantine and will be sampled periodically during the next 60 days.

Though authorities are unable to definitively determine the route of transmission, they have not ruled out iatrogenic (inadvertent veterinary) transmission. The fact that one group of seven horses were commingled in a confined location the past 10 months with no evidence of transmission minimizes chance of natural transmission having occurred.

The horses testing positive are described as pleasure riding horses that have resided on one of two farms for several years and range in age from 6 to 21 years. When the KDA evaluated the positive horses, they found them to be asymptomatic (not showing clinical signs) and in good body condition. The older horses were all reported to have been purchased through livestock markets, and as such would have been tested negative at the time of purchase. These pleasure horses have not regularly participated in events that would require they be routinely tested and are defined as representing the “untested population.”

Equine infectious anemia is a viral disease that attacks horses’ immune systems and is most commonly detected with the Coggins test. The virus is transmitted through the exchange of body fluids from an infected to a noninfected animal, often by blood-feeding insects such as horseflies, and more rarely through the use of blood-contaminated instruments or needles. Once an animal is infected with EIA, it is infected for life and can be a reservoir for the spread of disease. Obvious clinical signs of the disease include progressive loss of condition along with muscle weakness and poor stamina. An affected horse also could show fever, depression, and anemia.

More information about Kentucky’s EIA Surveillance and Control Program that includes annual testing stats can be found at www.kyagr.com/statevet/equine-infectious-diseases.html.

TheHorse.com will provide updates as new information becomes available.