Agricultural authorities in California are seeking six animals to receive follow-up testing in connection with a California Department of Food and Agriculture (CDFA) Animal Health Branch study of equine infectious anemia (EIA) infections in racing Quarter Horses.

EIA is a viral disease that is attacks the horse’s immune system. EIA is spread animal-to-animal naturally by biting insects, or by the use of contaminated needles or surgical instruments. All EIA-positive horses are either humanely euthanized or placed under lifelong quarantine.

CDFA spokesman Steve Lyle said that CDFA veterinarians began investigating the infections in July 2012 after EIA was confirmed in a racing Quarter Horse during required California Horse Racing Board entry testing. At that time, the horse’s owner acknowledged sharing needles among horses. Subsequent testing of exposed horses on the premises at the time confirmed EIA in a second horse. Another 16 exposed animals tested negative for EIA, Lyle said.

Lyle said that California regulations require the retesting of exposed horses 60 days after initial testing was performed. So far, 10 of the 16 exposed horses have been tested. However, at the time of the retesting, California agricultural authorities were unable to locate the remaining six horses. Lyle said the population of racing Quarter Horses involved in the investigation is considered high-risk due to their potential participation in unsanctioned horse racing