Equine Infectious Anemia (EIA)

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Equine Infectious Anemia

Equine Infectious Anemia, (EIA or swamp fever) is a daunting diagnosis known among horse owners and veterinary professionals. EIA is a blood-borne disease derived from the lentivirus that viciously attacks the red blood cells, causing severe anemia and eventually death in most cases. EIA can infect horses, ponies, donkeys and mules.

Equine Infectious Anemia  is a feared diagnosis due to it’s high mortality rate, so it’s important to be well informed of this disease.


Equine Infectious Anemia


How is it spread?

Equine Infectious Anemia (EIA) is spread through the bite of a horse fly that is infected with the virus. It is also possible to be spread through blood contamination by unsterilized needles, syringes, etc.


  • Anemia
  • Lethargy
  • Weight loss
  • Fever
  • Enlarged spleen
  • Swollen abdomen and legs
  • Decreased athletic performance
  • Death

How do you diagnose Equine Infectious Anemia?

Diagnosis of the disease is done through the performance of a Coggins test, which detects the antibodies of EIA. A Coggins test can be elective, but is required for any horses crossing state lines or performing in any sport.

Is there a treatment for Equine Infectious Anemia?

Unfortunately, there is no treatment for EIA. Most cases of EIA result in death or euthanasia, due to the extreme severity of the disease. In the cases that a horse does survive, they will be a life-long carrier with the possibility of flare ups in the future. If one chooses to keep their positive EIA horse, a special enclosure preventing any exposure to other horses is pertinent. Any confirmed diagnosis of EIA must be reported, due to it’s severity and the potential to spread.

How can you help to prevent Equine Infectious Anemia?

  • Use sterile, disposable needles.
  • Test yearly for EIA, and any time a new horse enters the premises.
  • Implement insect controls.
  • Keep facilities sanitary.
  • Do not participate in events that don’t require a Coggins test upon entry.
  • Quarantine new horses before they have been tested.
  • Never breed a horse that is positive for EIA.

If you enjoyed this article and have an interest in equine medicine, take a look at our blog post, How do you become an Equine Veterinarian?.