Source of equine infectious anemia outbreak in Arkansas still eludes veterinarians

Clarksville, Ark.

— Eighty horses on a ranch in the Clarksville area are under quarantine after a “substantial and alarming” outbreak of equine infectious anemia (EIA) was discovered there.

The first case surfaced three weeks ago, and a full herd test was completed last week, says Arkansas State Veterinarian Pat Badley. Forty of the herd’s 80 horses tested positive for EIA. Of those, two died and 38 were euthanized, Badley says. The owner of the horses must re-test the remainder of the herd after 60 days to release the ranch from quarantine, but Badley says she will likely test before that to make sure there aren’t any undetected cases.

The horses originally were used for show, but Badley says the owner stopped showing in 2004. Since then, the herd has stayed on the ranch, but there have been some additions. The last addition was in early 2011, but Badley says the Arkansas Livestock and Poultry Commission traced the origin of that horse and did not find any positive EIA cases at its original ranch. Ranches around the quarantined location also have not produced any positive tests to date, Badley says.

The source of the outbreak remains unknown, he adds, but there have been no new cases. The owner hadn’t done a complete herd test in four or five years, testing only five to 10 horses each year. EIA could have been in incubation in unaffected carriers within the herd for several years now, Badley says.