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Equine Infectious Anemia Controversy

Donna Campbell Smith is an author, freelance writer, and photographer. She has an AAS degree in equine tech and is a certified instructor.

"I had a Coggins pulled in April. Unknown to me, he became infected in September. I took him to a show in October, and in November with a negative Coggins. Though he had a fever for a day or so, we contributed it to a low-grade infection. I didn't find out he was positive till January of the next year," Sally, a FRIENDS member who lives in Florida, tells about her experience when her horse tested positive for equine infectious anemia.

Commonly called swamp fever, EIA is a disease caused by a blood born virus transmitted to horses by biting insects, use of contaminated needles or surgical instruments, and even farrier tools. There is no cure for EIA, and in North America there is no vaccine. What does surround EIA is a great deal of controversy.

Two friends live in quarantine at FRIENDS in Florida

Two friends live in quarantine at FRIENDS in Florida

The reasons for the controversy have to do with the Coggins test and the methods used to control the disease. The Coggins test is used to detect the virus, and was developed by Dr. Leroy Coggins in 1970. There is a newer test called the ELISA test, which takes much less time to run. It is not as reliable as the Coggins, so a positive reading is double checked with the Coggins.

But many people question the reliability of the Coggins. As in Sally's case, the test is clearly only good the day the blood is pulled. With an annual test being the norm, a horse can be exposed the very next day to EIA and go a year commingling with other horses.

So, why is the Coggins in the middle of so much debate? The debate is because of what happens when a horse tests positive. In most states if your horse is test-positive it must be either quarantined or euthanized. Some states have test and destroy as the only options, other states have no regulations at all.

Naturally this puts the issue in a very emotional light. There are stories of breeders losing whole herds when they complied with their state's laws. But, whether the positive horse is an expensive show horse or a backyard 4-H project horse, it is disheartening to lose a horse to EIA.

"But, are we losing them to EIA or the Coggins test?" ask many protesters.

Equine infectious anemia is manifested in three basic forms, acute, chronic and latent or inapparent carriers.

In the acute form of the disease the horse usually dies within days of the onset of contracting the virus. The horse runs a high fever (104 -108 degrees), exhibits severe depression, loses his appetite, and his physical condition deteriorates rapidly. There are heavy concentrations of the virus in the animal's bloodstream. A sub acute form is similar to the acute, but less severe. Most horses recover after a week or two and remain well for several weeks or months. They become weak and unthrifty and anemic, especially when under stress. Then the virus reappears, causing death.

In the chronic form the horse has reoccurring bouts of illness following an acute or sub acute stage. They also have a high concentration of the virus in their bloodstream.

The inapparent carrier is the center of the disagreement over the laws concerning EIA. In this form the horse carries the virus in his bloodstream, but is not sick. The virus count is very low, which can be determined by a test called the SID test.

A sideroleucocyte negative horse is not contagious according to a paper presented by Dr. S. McConnell and Dr. Masami Katada, "Management of Equine Infectious Anemia". The SID negative horses appear to have recovered completely and can live a fully productive life. The problem lies in knowing the difference between the chronic sufferer and the inapparent carrier. The Coggins test does not make that distinction.

In addition, the inapparent carrier shows no signs of illness, whereas the chronic horse is unthrifty, showing loss of fat, and muscle mass. The inapparent carrier does not have a fever. Owners of those horses in the Florida refuge have their temperatures monitored regularly.

"It has been estimated that 85% to 90% of horses infected with EIAV, present as sub clinical infections without ever having shown observable clinical signs of the disease. Furthermore, many of these horses have long productive lives and survive long periods without febrile episodes being induced by EIAV in spite of their being AGID (Coggins test) positive," writes Drs. McConnell and Katada.

Many horse owners have their horses tested as per state laws with little understanding of what the test is for, or the consequences of their horse testing positive. Some even think the Coggins is a vaccination. According to a 1998 survey done by the USDA's National Animal Health Monitoring System 30.3% of horse operations had never heard of EIA, 16.3% recognized the name, but not much else, and 22.5% knew some basics. Only 30.9% were really knowledgeable about EIA.


One group of people who are anxious to educated people on the disease and the testing process is FRIENDS in Florida. FRIENDS offer refuge to inapparent carriers. The organization began in 1972 by Sue Young. Innumerable horses have gone through their gates in thirty years. The ranch, which meets Florida's quarantine standards, also acts as a "living lab" for veterinarians and researchers to study the horses.

Membership fees and private donations support the organization. The horses are "adopted" by someone willing to pay a small fee and commit to working on the ranch to care for the animals. Horse lovers who cannot afford to buy a horse find this a perfect compromise. They also pay for the horse's feed and hay.

At the time of this writing FRIENDS has not had an acute or chronic case of EIA since the early 70's. One horse tested positive the first two years on the ranch, and now tests negative. The positive horses are run with some negative horses. The negative horses have yet to test positive. Kim, board member of FRIENDS, says the likelihood of an inapparent carrier passing the disease to another horse is one in six million.

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Learn more about the work FRIENDS is doing and how you can help at

Alternate Strategy

Dr. McConnell outlines an alternate strategy for handling the EIA problem, as sited in T.B. Crawford and S.L. Kittleson's paper, "A reappraisal of EIA Regulation". It suggests that horses with active EIA should be removed from the horse population. They say owners with horses that are asymptomatic have the right to use their horses in the presence of other horses, provide the owners know they are test positive. And in addition they state that owners of expensive horses have the right to protect their horses from any chance of exposure to EIAV infected horses.

Another controversy that has come up is news that the Chinese developed a vaccine against EIA. In fact they made this announcement in 1983, but the general horse owning population was not informed of this fact. The Chinese claim to have eradicated EIA in their country. But, American researchers and veterinarians fear that bringing the vaccine into our country could wreak havoc by introducing a mutant strain of the disease.

The Chinese vaccine is a modified live virus vaccine, which means it could possibly cause a horse to become infected. Ours accuse the regulatory agencies of playing politics, or that a cure would hurt veterinarians financially.

While many question the truth of the vaccine press releases have confirmed its existence. The Australian Associated Press announced on February 2, 1998 that researchers from the Academy of Preventive Medicine are working with the Harbin Veterinary Institute of the Chinese Academy of Agricultural Sciences to apply knowledge gained in developing the EIA vaccine to HIV. The Telegram Gazette of Worcester, Mass. reported on March 7, 2000 that the China Animal Husbandry Industry Co. was considering launching a business in Worchester to develop a vaccine, already in use in China, for EIA. Research on the vaccine would also apply to HIV and gene therapy. The same paper later reported that the company would invest $500,000 to start the business.

So, it seems the vaccine is a reality. Further research offers hope that eventually we will be able to prevent equine infectious anemia by using the vaccine. No one can predict how long that will take. Meanwhile, the equine community is at odds on how to handle the problem of EIA.

FRIENDS members believe education and money are key factors in saving horses from either the disease or the regulations that leave owners of test-positive horses with little alternative but to have those horses destroyed.

The figures from the USDA survey support their feelings that horse owners need to be educated about EIA. The same survey tells us that we spend $34 million on EIA testing. None of that money is earmarked for research. Some activists suggest that a percentage of the fees collected for Coggins testing should be set aside for research. They also believe more quarantine stations like FRIENDS would give owners of inapparent carriers another option, while providing animals for research.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2008 Donna Campbell Smith


Donna Campbell Smith (author) from Central North Carolina on April 12, 2019:

Shirleyvh, check the link at the end of my article an it will take you to their site.

Shirleyvh on April 12, 2019:

Does FRIENDS still do this EIA work. I haven't been able to find out from them. I use to contribute.

Pat Hutchins on October 04, 2010:

I am currently associated with a veterinarian who is in the midst of a court battle with the Mass. Dept of Agricultural Research over this subject. He has been researching EIA for over 40 years and has made amazing progress. He has breakthrough findings in the field and has worked hand in hand with the chinese scientists and the vaccine. He has proved that the quarantine and destroy method of dealing with EIA is totally inadequate. But now the MDAR is trying to destroy one horse in particular, Nora, which we are fighting. The following is the most recent article to appear concering Dr. Tashjian and his findings.

Groundbreaking Horse in Retroviral Research Slated to Be Killed

WEST BOYLSTON, Mass., Sept. 20, 2010 — American Veterinary Medical Frontiers (AVMF) announces a breakthrough in the field of retroviral research with the confirmation of a successfully bred horse with natural immunity to the deadly Equine Infectious Anemia Virus (EIA). Dr. Robert J. Tashjian, an internationally recognized expert in EIA, announces this exciting finding, the culmination of his over 40 years research on the virus. “This breakthrough adds an important component to the understanding of retroviruses, and may have implications for the understanding of Human Immunodeficiency Virus (HIV), the causative agent of AIDS,” according to Dr. Tashjian.

Lentiviruses are a class of retroviruses that damage the immune system of horses (EIA), simians (SIV), humans (HIV) and cats (FIV). In the 1970s, Dr. Robert J. Tashjian observed that an EIA-positive herd of horses lived side by side with EIA-negative horses, without a statistical increase in mortality among the negative horses. Dr. Tashjian brought a small herd of seemingly resistant horses to West Boylston and started a breeding program. The intent of the breeding program was to amplify and document the natural immunity that he had observed anecdotally decades before. That natural immunity was recently confirmed when “Nora” tested negative for EIA despite significant exposure to the virus.

The Division of Animal Health of the Massachusetts Division of Agricultural Resources, which had killed another AVMF research horse last year, has now ordered the destruction of this unique horse named “Nora,” out of fear it may infect other horses. Per their prior order, “Nora” lives in quarantine on the Malden Brook Farm. She has lived a happy, disease-free life of 10 years.

Current USDA approved tests for EIA include the Coggins and ELISA tests. “Nora” has tested negative twice on both the Coggins and ELISA tests. A subsequent immunoblot test showed a minor immune response to the virus, which may reflect exposure. This test is not USDA approved as definitive for EIA exposure, nor is it predictive of disease.

Today, “Nora” is a healthy, well-cared-for, friendly horse. “Nora” represents an exciting opportunity in the field of virology. This is the first time that a horse has been bred for immunity to a retrovirus. In addition, “Nora’s” destruction would be tragic, as she is disease-free.

“Dr. Tashjian, an international authority on EIA, began studying this infection many years ago when he was Director of the New York Animal Medical Center. The virus that causes EIA is closely related to the Human Immunodeficiency Virus (HIV), the cause of Acquired Immunodeficiency Syndrome (AIDS). I greatly respect the scientific contributions and accomplishments of Dr. Tashjian.” — Leonard J. Morse, MD, Commissioner of Public Health, City of Worcester Massachusetts

“Over the past 40 years Dr. Tashjian, through his cutting-edge research, has become one of a very few internationally recognized experts in EIA. His collaborative work has led to a number of breakthroughs in the understanding of this retrovirus. The culmination of this research is the idea that a vaccine for EIA, similar in structure and action to human HIV, may be possible. He has managed to discover, through relentless study, that a horse can be exposed to EIA, demonstrate that exposure, yet never manifest the disease. This naturally developed immunity is instrumental to the development of a vaccine for this retroviral disease, and may lead to the creation of the same for HIV. The living model of this immunity is ‘Nora,’ the very horse in question now.”

Glenn Andrews on January 26, 2010:

The test and slaughter policy is a fraud perpetrated by The USDA bureaucrats and vets who profit from this superstition that this policy protects horses. The Chinese vaccine should be imported and used. All horses that are mingled with other horse should have their temperature taken, and those with elevated fever should be temporarily quarantined. That’s all the policy that is needed, and that policy will save more horses.

Donna Campbell Smith (author) from Central North Carolina on May 23, 2008:

This is a VERY contraversal subject. I had this article assigned twice and the publication didn't use it. Some think it is political. In my opinion a Coggins test is useless ten minutes after the blood is drawn, and certainly by the time the results come back ten days later. Feel free to send it to your vet friend. It is not new at all, and she is aware of the contraversy I am sure. The Coggins is mandated under Federal laws as well as states.

Rochelle Frank from California Gold Country on May 23, 2008:

Is this something new, Donna? Are most veterinarians aware of this?

I have a vet friend who deals with horses. I might want to forward this link

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