Owners and operators on about one-third of farms, ranches, and private residences with horses have not even heard of equine infectious anemia. About another 20 percent have heard of the name of the disease ...Owners and operators on about one-third of farms, ranches, and private residences with horses have not even heard of equine infectious anemia. About another 20 percent have heard of the name of the disease ...
Reprinted from Volume 3, No. 3 Fall 1998 Caution: Horses
Owners and operators on about one-third of farms, ranches, and private residences with horses have not even heard of equine infectious anemia. About another 20 percent have heard of the name of the disease but know little about it. About two-thirds of the owners or operators of boarding/training or breeding facilities were knowledgeable about the disease, but about one-third were not.
This surprising information comes from the National Animal Health Monitoring System of the U.S. Department of Agriculture. USDA recently released a national study of equine health issues. Titled "Equine ’98 Study," this report is a baseline survey of the horse industry in America with particular attention to equine health and management.
What makes these numbers so astonishing is that laws in virtually every state require regular tests of equidae for equine infectious anemia, also known as Swamp Fever or simply EIA. What conclusions are we to draw about those laws, their effectiveness and their enforcement? First, let’s discuss EIA–what it is, how it is spread, and what effects it can have on horses that contract it. Then, we will examine current laws dealing with EIA.
What is Equine Infectious Anemia? Equine infectious anemia is a viral disease that attacks horses and other equidae. It is infectious and incurable. It has a death rate of up to 30 percent of acutely infected animals. A surviving infected animal will remain a carrier of the disease (and, therefore, pose some degree of threat to other horses) for the rest of its life. Currently, there is no vaccination to prevent your horse from catching the disease.
There are three phases of the disease: acute, chronic and inapparent. In acute EIA, which is very rare, the horse’s body temperature is highly elevated and he will exhibit weight loss, anemia, weakness, and edema. The horse may die within two to three weeks. During this phase, the horse may test negative for EIA since there has not yet been time to develop the antibodies the test detects. If the horse survives the acute phase, it may escape being diagnosed with EIA. It may, therefore, be permitted to move freely in the horse population and the presence of EIA will be discovered later, if at all, only with a routine Coggins test. By that time, other horses in the population may have become infected.
If a horse survives its first acute bout of the disease, it may develop chronic clinical signs with intermittent fevers (105 to 108 degrees F) and other acute signs mentioned previously. The horse may also have an irregular heartbeat and a jugular pulse may become evident. The recurrent episodes of illness may last for a few days or for months. There is often some history of a stress episode prior to a flare-up of EIA in a chronically infected horse. The chronic horse will lose condition, and will be lethargic and anorexic. The usefulness of the horse is greatly diminished during flare-ups.
Most horses found to be positive for EIA by routine test are inapparent carriers: they show no overt clinical abnormalities as a result of infection. However, their blood contains the EIA virus. Stress, hard work or the presence of other diseases may advance a carrier to the acute phase.
How is EIA transmitted? EIA is transmitted from animal to animal by horse flies, deer flies, and other biting insects. Flies that are interrupted in their feeding by being flicked or twitched by the horse may fly to a nearby horse to continue feeding. Blood (and the EIA it contains) can be transmitted from one horse to another in that fashion. The disease can also be transmitted by unsterile instruments.
The Hot Zone. Fewer than 1/5th of 1 percent of horses tested for EIA will test positive. However, over 90 percent of horses testing positive in the United States are located in the "hot zone," which is defined as those southern states from Virginia to Texas plus a tier of midwestern states from Missouri and Illinois to Iowa, Minnesota and Wisconsin. The risks are greater in these areas because environmental conditions are ideal for the flies that transmit the disease. However, EIA is also found outside the hot zone. In the summer of 1998, a band of wild horses in Utah was discovered infected with EIA at an alarming rate. See the story in Caution: Horses Summer 1998 page 4.
In the year ending September 30, 1997, there were 1.37 million official Coggins tests conducted, according to the USDA survey. If .02 percent of those tests were positive, which from experience would be expected, it would mean that over 2500 horses tested positive during that fiscal year.
What is a Coggins test? The Coggins (named after the veterinarian who first described it) test is a blood test to determine whether the horse’s blood contains EIA antibodies and, therefore, EIA. A veterinarian takes a sample of the horse’s blood, fills in a form describing the horse and identifying the owner and sends the sample and form off to a specially-approved laboratory for testing. The results are communicated to the owner within one or two days via the veterinarian. Later, the results are placed on the form initially filled out by the veterinarian. That completed form is proof that the horse described in it has tested negative for EIA. Coggins tests are relatively cheap. According to the USDA survey, they average about $25 each, including veterinarian travel charges.
What should you do if you get a positive test result? If your horse’s routine Coggins test results are positive, what are your options? First, you can insist that the horse be re-tested, if you make that demand promptly. You should insist on a re-test, just to verify the bad news. If the re-test results are positive, then your legal choices are (1) euthanization, (2) sale for immediate slaughter, or (3) lifetime quarantine. Quarantine requires keeping the horse several hundred yards from any other horse, which is outside the feeding range of the insects that transmit the disease. Under most state laws, a quarantined horse must be identified as a "reactor" by a hot iron, chemical brand, or freezemarking. There is a uniform identification system in which each state has its own two digit number. That number with a capital A is placed prominently on the left side of the horse’s neck to identify it for life as a reactor.
Individual state laws prescribe quarantine requirements. Some states require a separation from non-reactors of as much as 500 yards, while other states permit them to be as close as 100 yards. If the horse is stalled, the stall must be enclosed in fly-proof screening. Apparently, many owners who initially opt for quarantine later decide that euthanasia or sale for slaughter is their best option.
There are special legal rules for foals. A foal born of a reacting mare may have obtained the EIA antibodies from the mother’s colostrum and may test positive for EIA but not in fact have the disease, only the antibody.. Accurate testing can be done only after the foal is 6 months old. For these reasons, many state laws do not require Coggins tests of horses younger than 6 months old.
What about horses that were exposed to the infected horse? State laws vary enormously in their definitions of "exposed" with its mandatory quarantining and testing. Some states require proximity of less than 200 yards from a reactor to count as exposed, while in other states any horses within 3 miles of a reactor are regarded as exposed. Exposed horses must be quarantined from other horses and must be tested for EIA. Positive horses must be separated from the others. The negative group must be re-tested every 30 to 60 days until new cases fail to appear. At that point, those that have not tested positive are regarded as safe.
What does the law require about testing? Federal law does not require Coggins tests prior to the interstate movement of horses. It does prohibit the interstate movement of an EIA reactor except to a slaughterhouse, research facility, or home farm of the horse. Any such horse moved from state to state must, by federal law, be identified as an EIA reactor by brand, freezemarking or lip tattoo.
State laws vary from state to state. Most states require a health certificate before a horse can be brought into the state. Usually, this requirement includes a negative Coggins certificate. Most states require that the test be within 12 months of entry, but a few states require more recent tests, such as 60 or even 30 days. In 1995, a woman was convicted and fined for transporting horses into Ohio without the required EIA certificates. In addition to the criminal penalties, her horses were quarantined for 30 days at her expense in another state.
After a horse has entered a state, there are different requirements for Coggins tests. Many states require proof of a negative Coggins test before a horse can be exhibited at a fair, shown, raced, or even trail ridden in the company of other horses. Some states require a negative Coggins before a horse can be sold by private treaty while in others a Coggins is required only for sales at regularly-scheduled auctions and still others require a Coggins before any sale. A few states require a negative Coggins before a horse can be moved within the state from place to place for any purpose. A few states require that all horses within the state be tested once a year.
A conscientious horse owner should have an annual Coggins test of all of his horses. Even if the horse has not left the property, if other horses have come on the property and into proximity with the resident horse, there is a potential for transmission. The resident horse might become an inapparent carrier that could be a source of infection for other resident horses. If you are really unlucky, you could end up losing all your horses to EIA.
According to the USDA study, over 40 percent of the Coggins tests are conducted in connection with the exhibition of horses, another 20 percent in connection with the interstate movement of horses, about 15 percent for the personal knowledge of the owner, and about 10 percent for change of ownership within the state. Less than 4 percent of the Coggins tests are conducted on the recommendation of a veterinarian as a diagnostic aid.
For more information. The AAHS web site contains state statutes and administrative regulations for almost 40 states dealing with equine infectious anemia. If your state is there, you can locate and download your law with ease. Go the web site at www.law.utexas.edu/dawson/. Once there, go to the category Equine Infectious Anemia under Statutes for Horsemen and there you may find the legal requirements for your state. You should be cautioned, however, that these laws change and may have changed after they were put on the web site. You should check with your veterinarian or state regulatory agency for current legal requirements. You can jump directly to the statutes by clicking on Equine Infectious Anemia Statutes.
Finally, if your state has a statute or administrative regulation relating to equine infectious anemia that we don’t have on our web site, please send it to us so we can include it to benefit others.