Equine infectious anemia nearly always requires a horse to be put downWhen I first gained my release from veterinary school, I was hired by a general large animal practice in another state. I was there about 1 1/2 years and the exposure to other species thrust upon me only made me appreciate horses more. I also learned there was more emotional involvement with horses than with other large animals.
There, as in all practices that include horses, I guess, Coggins testing was a big part of what we did. A Coggins test is diagnostic for equine infectious anemia (EIA), an untreatable, incurable disease in which infected horses probably will not die but will remain carriers. EIA was a problem in the area and I was glad to finally leave there.
A lot of the horse work in the practice was pleasure horses and the boarding farms usually required at least annual and often semi-annual Coggins tests for all their boarders. One such farm was owned and operated by an old lady who had probably forgotten more about horses than most of us who care for their health ever know. She required six-month testing and anyone who did not like it could take his or her horse elsewhere. Now.
Boarded on this farm was a Thoroughbred gelding of some ten or 11 years that was owned by an attractive, tall young woman of maybe 18 or 19. This girl, though, had a severe socialization problem. She had been born without a left hand; whether she perceived herself as different because of this and her height (about 61) or was made to feel that way by her parents and/or schoolmates I do not know, but she chose to have her horse and the old lady as her only friends. The horse was truly her life. She spent every moment she could find with himriding him, grooming him, just talking to him.

A positive
The time came for the drawing of blood for the Coggins tests on the 20 or so horses on the farm. The girls horse had been there for several yearsthree or fourand had been negative twice a year for that entire period, but this time he came back positive. The first I knew of it was when I received a phone call from a person at first so hysterical that I could not understand who it was or what was being said. After several minutes, though, the story unfolded.
It was the girl. The state veterinarian had called her and told her that her horses Coggins test was positive and that he would have to be put down or quarantined 200 yards from any other horses. He also said he would be out the next day to take another blood sample to recheck.
Early in the call she accused me of switching samples, of mislabeling tubes, of contaminating her horses sample with some other horses blood. Then she stabilized a little and asked if there were ever false positives. Could there be a laboratory error? Would the laboratory see the name on the retest and not even bother to run it, just mark it positive? Were there other labs?
I agreed to submit a sample to another lab. I did not know what else to do. I went there immediately to draw the sample and mailed it right away, before the state veterinarian even came to draw his for the retest.
Well, of course, my second sample and the state vets were both positive. The old ladys farm was only 20-some acres and there was no way the girls gelding could be kept 200 yards away from the rest of the animals. The girl called every farmliterallyin a several-county area and no one had, or would create, a quarantine facility and, anyhow, no one would take a Coggins-positive horse.
The horse was put down, but I could not do it. It had to be done by a vet made of sterner stuff. Neither I nor the old lady ever saw or heard from the girl again.

More positives
As I said, EIA was a problem in this area. We would find the occasional positivemaybe one out of every 80and no one was ever happy but they understood.
Just before I left the area, a young couple, at my suggestion, had Coggins tests run on their 11 Quarter Horsesa stallion, six mares, and four yearlings. It was their third year in operation; two years before they had bought the stallion and mares and bred them, then foaled them out the next year. This was in early March, all six mares were in foal, and the couple were preparing to begin foaling. They were planning their future around the income these yearlings would bring.
All 11 came back positive. The couple were devastated and grabbing for straws the same way the girl was. I do not know the outcome, though; I left for Kentucky at this point. I could have learned what happened, but I did not want to hear about 11 horses being destroyed.

Causes, spread, and clinical signs
EIA occurs the world over. It is a viral disease spread by biting insects, particularly horse flies, although the most famous outbreak and the one that brought the disease to everyones awareness was eventually traced to the usage of one hypodermic needle on many horses at Suffolk Downs several years ago.
A week to a month after an animal is exposed to EIA, the signs first appear but they are not really specific and may even go unnoticed. These early signs include transient fever, depression, and petechial hemorrhages (minute hemorrhages that appear on the skin or membranes). Later, however, there are recurrences, the first usually within a year. Again there is fever and depression and also anemia, icterus, edema, and weight loss. Subsequent recurrences are progressively less severe but the horses condition is never fully regained. Death is rare.
The historychronic weight loss and recurrent bouts of fever and depressionshould cause one to consider EIA, but the only way to diagnose the disease is with a Coggins test.

Control
There is no treatment or prevention and the virus cannot be eliminated from an infected horse. I have never been on a farm that could reasonably keep a horse 200 yards from other horses and I am not sure neighboring farms would necessarily trust the local flies to not have a 201-yard range, so, in practicality, euthanasia is the only course to follow to safely prevent spread.
Your racehorses, show horses, trail horses, out-of-state boarders, etc., are tested annually (or more often in certain states), but what about your mares that do not go anywhere but the breeding shed? Your young horses before they enter training? Your pensioners? Your teaser? Good management should include at least annual Coggins tests on all horses in your care.