Preventing communicable diseases from striking horses should be the goal of every horse owner. Despite our best efforts, however, there are going to be occasions when a communicable malady afflicts one or more horses at a private farm or public stable. When that occurs, efforts must be made to treat the afflicted animals and to prevent the disease from spreading to others on the premises or in the vicinity.

Just what preventive steps should be taken depend on the disease being combatted. Preventing the spread of bacterial disease requiring physical contact for transmission, for example, might be quite different from preventing vector-borne or airborne transmission.

In some cases, isolation or quarantine might be the answer, but here, too, the approach will depend on the facilities involved and the space available. The approach taken at a large commercial breeding farm might be far different from that taken at a small facility of an acre or two with one barn and a couple of paddocks. At a large farm, ill horses might be moved to another barn or section of the farm to prevent contact with other horses. At a small facility, there simply might not be room to do this.

Andrew Clark, DVM, state veterinarian for Oregon, says that the word "quarantine" originated in the Middle Ages in Italy. When a ship came into one of the ports--he believes it was Naples--the sailors aboard were confined to the craft for 40 days for fear that they would introduce smallpox or the plague. If no one on the ship showed symptoms of either after 40 days, they were allowed to come ashore. The Italian word to describe that time, he said, was later Anglicized to "quarantine." Thus, the word quarantine means to curtail movement to prevent the spread of disease.

To better understand the role that quarantine can play in the prevention of disease transmission as well as some of the costs involved, we'll take a look at the approach from the top down. On top are the federal regulations involving horses and equine semen imported into the United States. In the middle are state regulations, and on the bottom--but no less important to the horse owner--is quarantine on the farm.

Federal Authority

Quarantine at the federal level is designed to keep horses from bringing disease into this country. The following information on the federal approach is from Freeda Isaac, DVM, staff veterinarian at the National Center for Import/Export in Riverdale, Md., as well as from directors at USDA-operated Animal Import Centers (AIC).

There are three animal import centers in the U.S. The busiest of the three is the New York Animal Import Center in Rock Tavern, N.Y., where some 4,000 horses annually enter the U.S. The other two are in Los Angeles, Calif., and Miami, Fla.

The New York facility, says Director Joe Hansen, DVM, has a capacity of 150 horses in a series of barns that range in size from five-stall facilities up to 34 stalls. Each of the barns is equipped with double-screened windows to prevent the entrance or exit of insects, and each is designed for complete security so that horses in quarantine can't be removed from the barn until the quarantine period has elapsed.

While the capacity is 150 horses, Hansen says that really doesn't represent population capability. If a group of horses from Country A are in a given barn, for example, no other horses are allowed into that particular facility until the incumbent horses have been removed and the premises disinfected. This means that if 10 horses from Country A are in a 20-stall facility and 10 more horses arrive from Country B, the new arrivals will be stabled in a different facility and 10 of the stalls in the 20-stall barn containing horses from Country A will remain vacant until the 10 Country A horses leave.

Generally speaking, the quarantine periods are for three, seven, or 60 days, depending on the country of origin and the diseases endemic in those countries. All horses coming into this country must be accompanied by a proper veterinary health certificate issued by a full-time veterinary officer of the national government of the exporting country. That certificate must state that the horses being imported have:

  • Been in that country for 60 days immediately preceding importation. If not, they must be accompanied by a like certificate issued by a full-time salaried veterinary officer of the national government of each country in which the horses have been during the 60 days immediately preceding shipment to the U.S.;
  • Been inspected and found to be free of contagious diseases and, as far as can be determined, exposure thereto during the 60 days immediately preceding exportation;
  • Not have been vaccinated with a live, attenuated, or inactivated vaccine during the 14 days immediately preceding exportation;
  • Not have been on a premises where African horse sickness or a number of other itemized diseases have occurred during the 60 days immediately preceding exportation;
  • Not been in a country where contagious equine metritis (CEM) is known to exist, nor have had contact, breeding or otherwise, with horses from such a country for the 12 months preceding exportation; and
  • Been inspected and found to be free from ectoparasites (i.e., ticks).

Horses meeting those criteria will be in quarantine at one of the import centers for three days, the time it takes to get results from tests for equine infectious anemia (EIA), glanders, dourine, and piroplasmosis. A horse testing positive for any of these diseases will be refused entry into the United States.

(Equine infectious anemia, commonly known as swamp fever, is a viral disease that attacks the horse's immune system. Glanders is a very old disease, described as early as 400 BC, that in its most virulent form attacks the respiratory system and often causes death. Dourine is a disease of the reproductive system with a high mortality rate, and it is transmitted through breeding. Piroplasmosis is a tick-borne disease that destroys the red blood cells.)

The three-day quarantine stay at the import station is not cheap. The daily fee is $264 per horse, or a minimum of $792 for the three days.

Horses which require the seven-day quarantine are those which meet the above criteria, but are from countries not recognized by the USDA as being free from Venezuelan equine encephalitis (VEE) or screwworms. This includes all countries in the Western Hemisphere except for Canada, Mexico, Bermuda, and the British Virgin Islands.

The only good news for owners of these horses is that they get a price break. The cost remains at $264 per day for the first three days, then drops to $191 per day per horse for the next four days. If the horse is required to remain longer than seven days, says Hansen, there often is another lowering of the daily fee.

There is logic behind the rate structure, says Hansen. When each group of quarantined horses from a shipment leaves the station, the barn where they stayed must be thoroughly disinfected. This can be a one- to two-day project, and the barn can't be used during that time, thus raising labor costs and reducing income for short stays.

Horses imported from countries where African horse sickness exists must be quarantined for 60 days and can only be placed in the import center barns in New York. Countries included in this category are Oman, Saudi Arabia, Yemen Arab Republic, and all countries on the continent of Africa except Morocco. (African horse sickness is a highly fatal and infectious disease that is caused by a virus and is transmitted by insects. It affects the pulmonary system and, in the acute form, is almost always fatal. It does not exist in the U.S. See page 18 for more information.)

All three of the import/export centers in the United States are relatively isolated from other horse facilities. Proposed rules for federally approved private quarantine centers call for them to be located at least one-half mile from any equine facility.

The goal in quarantining imported horses is obvious--to prevent diseases that are endemic in other countries from being introduced into the United States.

Semen Import Regulation

Special rules and regulations also apply to the importation of semen, although quarantine isn't involved. There is one set of requirements for countries free of CEM, and another, more elaborate set of requirements, for countries not free of CEM. The requirements deal with everything from sanitation procedures for the stallion to the extenders used. For example, if milk is used as a semen extender, it must originate from a country recognized by the USDA as being free of foot and mouth disease. If eggs are used as a semen extender, they must originate from poultry flocks that are certified free of exotic Newcastle disease by the national veterinary authorities in the country of origin.

A fee of $94 is charged for a transported semen permit application. If a shipment arrives in the United States without a permit, an additional fee of $66 is charged for "import compliance assistance."

State/Local Quarantines

We move now to the state level, where quarantine is sometimes invoked by regulatory officials. While not all states have the same regulations, many will be very similar. A prime example where quarantine at the state level might be involved, says Clark, is equine infectious anemia (EIA).

EIA, or swamp fever, is a very serious blood disease of horses and mules that has also been known as mountain fever, slow fever, and malarial fever. Once the horse is afflicted with EIA, he becomes a carrier of the causative virus for a long period of time, often for life. The virus is transmitted by biting insects, so a carrier horse can be a reservoir that potentially could result in many horses being infected.

For this reason, a diagnosis of EIA is a virtual death sentence for the afflicted horse. A horse positive for EIA is immediately quarantined on his home farm, says Clark. The owner then has the option of keeping the horse in quarantine under highly restrictive conditions, possibly for life, or having him euthanized. The restrictive conditions include confining the horse full-time to a stall that is double-screened so that insects cannot get in or out.

This simply isn't practical from either an economic or humane approach, says Clark, so the euthanasia option is almost always the solution of choice.

All states require horses traveling from one state to another to have a certificate that shows they have been tested for EIA and found to be free of the malady (Coggins test certificate). The only exception to the rule, says Clark, involves equine travel between Oregon and Washington. As long as the horse or horses travel only from Washington to Oregon or Oregon to Washington, a negative EIA test certificate is not required. The reason, he says, is that the two states are almost free of EIA.

There have been times when states' regulatory agencies have implemented quarantine due to a disease outbreak. In 2001, a form of equine herpesvirus type 1 afflicted a group of horses at a dude ranch in the Big Horn Mountains near Buffalo, Wyo. All horses at the dude ranch, says Jim Logan, DVM, Wyoming State Veterinarian, were restricted from being moved from the ranch and no horses were allowed access to it until well after the disease had run its course.

A similar outbreak occurred among horses stabled at the nearby Sheridan, Wyo., fairgrounds. The county fair board cancelled horse activities at the upcoming fair and quarantined all horses on the grounds.

The quarantine approach worked in both instances. The disease ran its course, and normal operations were soon resumed by the dude ranch and the fairgrounds.

Quarantine at Home

We come now to the matter of handling the situation at a private farm when one of the horses is diagnosed with a communicable disease. The type of quarantine depends on the disease, say both Logan and Clark. If the disease involves bacteria spread by contact, the approach will be different than if it is an affliction that can be airborne or spread by insects.

If the disease is, for example, strangles or some type of influenza, where bacteria is transmitted via contaminated water, buckets, feed, bedding, and even the clothing of the person handling the horse or horses, the transmission preventive measures are more labor-oriented than cost-oriented.

First, the affected horses should be kept from physical contact with other horses, says Logan. Next, the utensils, tools, feed buckets, and water tubs that come into contact with the ill horses should be kept out of reach of healthy animals and disinfected regularly. Contaminated bedding should be incinerated or buried.

When the disease is respiratory in nature and might be transmitted through the air, such as rhinopneumonitis and some forms of influenza, Logan says, an effort should be made to keep the affected horse at least 100 yards from other equines. "The greater the distance, the better," he says.

The problem is that not every horse facility has this capability. A very small farm or a crowded public stable, for example, might not have the space to isolate an afflicted horse or horses. When that is the case, it might be necessary to place the animal at a veterinary clinic with quarantine capability, thus increasing the cost of treatment and prevention, but reducing the risk to other horses on the farm.

If the horse is not quarantined and the disease spreads to other horses on the farm, the cost could be much greater.

Take-Home Message

The owner or caretaker is often the first person to notice a health problem with a horse. It is that person's responsibility to recognize something's wrong and call a veterinarian, who will make a diagnosis. If the problem just poses risks for the horses at that farm, your veterinarian can help you determine what measures to take to prevent spread of the disease. If the disease is reportable to state and federal authorities and requires quarantine of the horse(s) or farm, the veterinarian will help you work with state and federal officials.

Be vigilant, and don't be afraid to report something unusual to your veterinarian and ask questions. Outbreaks of serious disease can be halted in this manner, and preventive quarantine of new horses can protect your own animals from a costly illness that could spread through your farm.

About the Author

Les Sellnow

Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at or by calling 800/582-5604.

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