EIA: Equine Infectious Anemia


EIAEquine infectious anemia (EIA), also known as “Swamp Fever” is an incurable, potentially fatal viral disease affecting all equines (i.e. horses, ponies, donkeys, mules and zebras). There is no vaccine available. EIA is caused by a blood-borne virus that affects the horse’s immune system. The virus is transmitted by large biting insects, primarily horse- and deerflies; however, virus transmission occurs when blood-contaminated products, such as needles and surgical equipment, are used on multiple horses.


Clinical signs of EIA vary and are generally non-specific. They can range from being absent, to a horse having a transient mild fever, to sudden death. Three phases of EIA can be identified: the acute phase is the most infective and the horse may display symptoms such as fever and anorexia. Chronic infection is characterized by recurring bouts of clinical disease with asymptomatic periods in between. The signs displayed during the symptomatic chronic phase include: anemia, weight-loss, depression and petechial haemorrhaging on the mucous membranes. Many horses infected with EIA never display any symptoms yet remain infectious, endangering the lives of other horses.


An agar gel immunodiffusion test, commonly called the Coggins test, used to be the first-line of testing for EIA. Recently Coggins testing has been replaced as the primary test for EIA by a faster ELISA-based assay; however, a Coggins test remains the gold standard for testing and is still used to confirm a positive result. The process of testing for EIA is still generally known as “getting a Coggins”.


Horses are at increased risk of contracting EIA when they live in close proximity to outbreak areas, in swampy areas, in close proximity to feral horses and/or at facilities where there is a high turnover rate of horses, particularly if the facility does not require a negative EIA test certificate. Horses are also at increased risk if they travel to shows, rodeos, sales etc.; this risk increases if a negative EIA test certificate is not required by the event.


Since there is neither a vaccine nor a cure for EIA protection through management practices is critically important. You can take the following measures to help protect your horse from contracting EIA:

  • Test all horses on the property for EIA at least annually
  • Do not re-use needles or syringes
  • Sterilize surgical and farrier equipment in between uses
  • Test all newly purchased horses prior to bringing them on to your premises
  • Isolate new horses for at least 45 days and monitor them for signs of illness
  • Manage your stable and pasture areas to discourage insects from breeding
  • Facility owners and event organizers should require a negative EIA test certificate from all horses on their property

Equine infectious anemia is endemic in the Canadian horse population and is a federally reportable disease. Canada has a program in place aimed at eradicating EIA from the Canadian herd by breaking the cycle of disease. The program relies on owners to voluntarily pay for their horse(s) to be tested. In the event of a positive test the Canadian Food Inspection Agency (CFIA) will respond by quarantining the premises on which an infected horse resides as well as any horse(s) who have come into contact with an infected horse within thirty days of the positive test result. Horses who are infected and are showing symptoms of the disease are humanely destroyed; asymptomatic carrier horses are either placed in quarantine for life or are humanely destroyed.

There has been considerable success with EIA eradication programs in Eastern Canada; however disease outbreaks continue to occur in Western Canada and progress in disease eradication has been slow due to poor participation in surveillance programs. Since 2011, Saskatchewan has had the highest number of individual cases of EIA in Canada. Voluntary testing of horses has increased in Saskatchewan in recent years. Current numbers estimate that 2,742 of Saskatchewan’s 100,000 horses are voluntarily tested for EIA.


Alberta Veterinary Medical Association. Equine Infectious Anemia.
Available Online: 
Accessed April 2016.

American Association of Equine Practitioners. Equine Infectious Anemia: The only protection is prevention.
Available Online: http://www.aaep.org/info/horse-health?publication=756
Accessed April 2016.

Canadian Food Inspection Agency. 2011 Equine Infectious Anemia.
Available Online: http://www.inspection.gc.ca/
Accessed April 2016.

Canadian Food Inspection Agency. 2012a Equine Infectious Anemia.
Available Online: http://www.inspection.gc.ca/
Accessed April 2016.

Canadian Food Inspection Agency. 2012b Equine Infectious Anemia Control Programs.
Available Online: http://www.inspection.gc.ca/animals/terrestrial-animals/diseases/reportable/eia/control-program/eng/
Accessed April 2016.

Canadian Food Inspection Agency. 2013 Equine Infectious Anemia.
Available Online: http://www.inspection.gc.ca/
Accessed April 2016.

Canadian Food Inspection Agency. 2014 Equine Infectious Anemia.
Available Online: http://www.inspection.gc.ca/animals/
Accessed April 2016.

Canadian Food Inspection Agency. 2015a. Equine Infectious Anemia.
Available Online: http://www.inspection.gc.ca/animals/terrestrialanimals/diseases/reportable/eia/eng/13296987 49489/1329703176989
Accessed April 2016.

Canadian Food Inspection Agency. 2015b. Proposed risk management strategy for EIA control in Canada.
Available Online: http://svma.sk.ca/~svma/uploads/pdf/EIA_-_Equine_Infectious_Anemia__Proposed_Risk_Management_Strategy_for_EIA

Accessed April 2016.

Equine Canada. Equine infectious anemia: Owners need to test for equine infectious anemia.
Available Online: http://www.equinecanada.ca/industry/index.php?option=com_content&view=category& id=280&Itemid=556&lang=en
Accessed April 2016.

Government of Saskatchewan. Equine Infectious Anemia.
Available Online: http://publications.gov.sk.ca/
Accessed April 2016.

Issel, C.J., R.F. Cook, R.H. Mealey and D.W. Horohov. 2014. Equine infectious anemia 2014: Live with it or eradicate it?
Veterinary Clinics of North America: Equine Practice. 30:561-577.

Ontario Ministry of Food, Agriculture and Rural Affairs. 2016. Horse disease surveillance factsheet.
Available Online: http://www.omafra.gov.on.ca/english/livestock/horses/facts/09-047.htm
Accessed April 2016.

Van Wyk. Equine infectious anemia threat for horses.
Available Online: http://www.usask.ca/vmc/
Accessed April 2016.

Wilkins. W. Equine infectious anemia a growing concern in Saskatchewan.
Available Online: http://www.agriculture.gov.sk.ca/
Accessed April 2016.

Filed Under: