Wellness Wednesday: Equine Infectious Anemia

Thursday, May 11, 2017
Posted by Courtleigh Watson, DVM



(Photo: Mary Phelps)

Whenever a horse loads up on a trailer to travel to a race or a show it needs a health certificate and proof of a negative Coggins Test. To many horse owners this is just an inconvenience - they can’t find the paperwork or they forget to do the test. - and they feel it is just another way for veterinarians and “the State” to squeeze more money out of them. BUT Equine Infectious Anemia (EIA) AKA Swamp Fever is a disease that threatens the world's horse, donkey and mule populations.

Despite testing and measures to eradicate the virus, more than 500 new cases are identified each year in the U.S. There is no cure for EIA; and although most infected horses show no symptoms, they remain contagious for life, endangering the health of other horses.

This is highlighted by a recent case study: “Red” a 10 year old Quarter horse gelding was offered for sale by his owner because of his poor performance and history of “ADR” (Ain’t Doin’ Right). He was up to date on his vaccinations and had been dewormed one month prior to the sale with Ivermectin. However, upon a physical exam Red was found to be lethargic, he had a slightly elevated temperature, and his mucous membranes showed pinpoint hemorrhages. Further testing of his blood revealed minimal platelets and severe thrombocytopenia and the ELISA Coggins Test was positive.

Red’s future is uncertain. There is no effective treatment for EIA. There is no vaccine to prevent it. There is no cure. However, good management can reduce the potential of infection.

If your horse tests positive for the EIA virus, your options are extremely limited. Federal and state health agencies, as well as the American Association of Equine Practitioners, support euthanasia as the most prudent, albeit emotionally difficult, option. Lifelong quarantine in a screened stall is another, less acceptable alternative. EIAV-positive horses will always pose an unnecessary health risk to other horses, whether or not they show signs of illness. Even in the best management situations, blood-sucking insects cannot be totally controlled or eliminated.

mucous membranes showed pinpoint hemorrhages.

Mucous membranes with pinpoint hemorrhages.

EIA may be difficult to diagnose because the symptoms are not specific and may vary from horse to horse. Additionally, individuals may demonstrate no obvious signs (inapparent carriers). Signs may include one or more of the following:

 Fever (temperature may even exceed 105 degrees F)
 Depression
 Mucosal petechial hemorrhages
 Decreased platelet numbers (thrombocytopenia)
 Decreased red blood cell numbers (anemia)
 Swelling of legs, lower chest and abdomen (edema)
 Decreased appetite (anorexia)
 Fatigue, reduced stamina or weakness
 Rapid breathing
 Sweating
 Rapid weight loss
 Nasal bleeding (epistaxis)
 Pale or yellowish (icteric) mucous membranes
 Irregular heartbeat and/or weak pulse
 Colic

The only way to eradicate the disease is to eliminate the carriers. Horses testing positive for EIAV are required by law to be permanently identified via branding or tattooing and be quarantined. Transportation and housing are severely restricted. You should contact your state animal health agency for specific requirements. Owners who choose quarantine must post signs clearly stating: "Quarantined: Equine Infectious Anemia" or "Swamp Fever." Horses should be quarantined at least 200 yards away from all other animals.

Stopping the spread of EIAV is everyone's responsibility. If you suspect a horse has EIA, call your veterinarian or state animal health agency immediately.