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Contagious Equine Metritis

Contagious Equine Metritis (CEM) is a venereal disease of horses caused by a bacterium called Taylorella equigenitalis. CEM may be spread through natural breeding, artificial insemination, and contaminated equipment. Mares infected with CEM may show mild or more severe degrees of uterine inflammation and vulvar discharge. Abortion and permanent infertility can occur. Stallions and mares infected with CEM may not show symptoms, but can carry and spread the disease for years. Infected horses can be successfully treated with antibiotics and disinfectants.

CEM is considered a foreign animal disease, not endemic in the United States. If a horse in Minnesota is infected or exposed to the disease, the Board will place the horse under quarantine. During that time, our district veterinarians will work with USDA and the herd veterinarian to complete required testing and treatment protocols before the quarantine can be lifted. Testing for CEM includes blood tests and bacterial culture.

Any case of CEM in horses must be reported to the Board by calling 651-201-6804.

Eastern and Western Equine Encephalitis

Eastern and Western Equine Encephalitis (EEE & WEE) are viral diseases in which birds serve as the primary hosts. Both diseases can be transmitted to horses and people through the bite of infected mosquitoes. These diseases can cause encephalitis, an inflammation of the brain and spinal cord. Infected horses may or may not show neurological symptoms and many recover completely from the disease.

You can help prevent EEE and WEE in horses by taking the following steps:

  • Vaccinate your horses for the diseases
  • Eliminate “mosquito zones” by mowing long grass, draining stagnant water puddles, and removing items such as old tires and tin cans that can serve as breeding grounds for mosquitoes.
  • Change water in drinking troughs at least once a week to prevent mosquito breeding.
  • Use mosquito repellents and place screens in stables.

Any case of EEE or WEE in horses must be reported to the Board by calling 651-201-6804.

Equine Herpesvirus April 18, 2014

Equine herpesvirus-1 (EHV-1) non-neuropathogenic strain has recently been identified in horses in parts of Minnesota. This is not uncommon. The disease occurs in horses throughout the U.S. each year. However, it is unusual to see multiple cases in horses with EHV-1 that show neurologic signs. This virus has no effect on people. Equine herpesvirus has been associated with neurologic cases in llamas and alpacas, but has no affect on other types of livestock.

The Board of Animal Health has followed seven cases of EHV-1 in Minnesota. The affected horses had neurologic signs and tested positive for EHV-1 non-neuropathogenic strain. The last positive case reported in Minnesota was on March 29 in a horse in Wright County.

Equine herpesvirus is usually spread in nasal secretions between horses that are in close contact with each other or that share water or feed pails. The virus does not typically survive very long in the environment or on people or equipment. This virus is killed readily by most disinfectants, ultraviolet light and by drying.

The Minnesota Board of Animal Health continually encourages horse owners to consult their veterinarians on ways to protect their animals.

Equine Infectious Anemia

Equine infectious anemia (EIA) is a viral disease of horses. It is usually spread through blood transfer caused by large biting insects such as horseflies and deerflies. The disease causes immune suppression. Horses infected with EIA may develop acute symptoms and die within weeks of transmission or they may have slowly progressing symptoms and live many years. Because there is no vaccine or treatment for EIA, an infected horse will always be a reservoir for spread of the disease.

In Minnesota, all horses that are infected with or exposed to EIA are placed under quarantine. All exposed horses will be required to complete EIA testing protocols before the quarantine can be lifted. Infected horses must be isolated and remain under quarantine for the duration of their life.

Any case of EIA in horses must be reported to the Board by calling 651-201-6804.

West Nile Virus

West Nile Virus (WNV) was first identified in the United States in 1999. WNV is now endemic in the entire continental United States. Most cases of WNV in Minnesota occur from August until the first killing frost in the fall.

Birds serve as the primary host for the virus, which is spread by mosquitoes to other birds and a wide range of susceptible animals including horses and humans. The disease can cause encephalitis, an inflammation of the brain and spinal cord. Infected horses may or may not show neurological symptoms, and many recover completely from the disease.

You can help prevent WNV in horses by taking the following steps:

  • Vaccinate your horses for WNV
  • Eliminate “mosquito zones” by mowing long grass, draining stagnant water puddles, and removing items such as old tires and tin cans that can serve as breeding grounds for mosquitoes.
  • Change water in drinking troughs at least once a week to prevent mosquito breeding.
  • Use mosquito repellents and place screens in stables.

Any case of WNV in horses must be reported to the Board by calling 651-201-6804.