EIA TESTING, WHY IS IT REQUIRED

We frequently have the opportunity to explain the disease, Equine Infectious Anemia (EIA, for short and for obvious reasons).  It is often referred to as a Coggins test. Coggins is the name of the test used to diagnose EIA.  As is often the case in medicine, a test is named after the person who discovered or formulated it.  Dr. Coggins created the agar diffusion test as a rapid way to test the serum portion of blood.  The test takes 24 hours to run.  A day each way for sending the blood must be considered.  The lab personnel must be certified by the USDA National Veterinary Services Laboratory before they can perform the tests.  In Missouri the blood must be collected by accredited veterinarians.

Recently a new type lab test was released.  The personnel of the lab must also be certified.  The new test is a quick test and takes an hour from the time the serum is added to the reading of the results.  Our clinic was recently approved to perform these quick tests after the training and certification of our personnel and the approval of the lab facilities.

Why do we have to test horses for EIA?  This viral disease is explained by its name, Equine Infectious Anemia.  Equine refers to the horse which is the only animal the virus affects.  Infectious means the virus can be transmitted from horse to horse.  In this case the transmission is through an exchange of blood.  This can be through the use of needles between horses, through the breeding process, and any tears or hair cuts that occur, or by the use of uncleaned surgical instruments.  But the most common method of transmission is the horse fly.  This pest carries a large amount of blood, so it can carry enough virus to infect a horse.  Anemia refers to the most common symptom seen with this disease.  The virus will invade certain white blood cells and use their machinery to reproduce.  Once the cell is “full,” it ruptures and releases virus spores.  Each of these zillions of virus spores will then infect another cell. This is when the horse becomes “sick,” noticed when it runs a fever, becomes depressed, etc.  Now the horse will either die, or start to recover.

If the horse chooses recovery, it will regain its weight and look perfectly healthy.  In times of stress (or other undetermined and mysterious reasons), the horse may again become sick.  It is impossible to predict when this will happen, but this is the time the blood will be loaded with virus.  A passing horse fly can load up on virus-laden blood and infect other horses in the vicinity.  One researcher, apparently with quite a bit of time on his hands, found that the EIA virus will live in the horse fly for as long as it takes to travel 200 yards.  After 200 yards, the virus dies due to different living conditions in the fly compared to the horse.

If the horse tests positive for EIA, the State Veterinarian will visit and put an ID clamp on the tail hairs.  It is illegal to remove this clip (about the size of a postage stamp).  The owner has the option of retesting the horse 30 days after the first test.  If the owner does not choose to retest, or if the second test comes back positive, the owner has three options: 

•	The horse may be sold directly to slaughter.
•	The horse may be euthanized ( and once the horse’s body temperature cools, the virus will die).
•	For the special horse there is the option of a permanent quarantine. That horse must be permanently housed 200 yards from the nearest horse.

So back to the original question: why do we test for EIA?  To summarize, it is because there is no way to prevent it and, for the infected horse, no treatment.  In addition, we happen to border one of the top two states in the nation for infected horses.  And that state borders the other top state.  Just a few facts to wet your appetite and we will expand on these next week.