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Equine Infectious Anemia

Equine infectious anemia (EIA) is a viral disease of horses most frequently transmitted by large biting flies between horses in close proximity. There is no vaccine or treatment for EIA. Once a horse is infected, it remains infected for life and is always a potential reservoir for spread of the disease.

EIA infected horses must be permanently quarantined and isolated or be euthanized to prevent the disease from spreading to other horses (Minnesota Rules 1721.0260).

Horses must have a negative test for EIA within 12 months prior to importation or attendance at public exhibitions in Minnesota.

Equine Herpesvirus Myeloencephalopathy

Equine herpesvirus (EHV) is a contagious virus that can cause four clinical presentations including: neurological disease, respiratory disease, neonatal death and abortion. Equine herpesvirus myeloencephalopathy (EHM) is the neurologic disease that develops as a result of EHV infection. The virus has been associated with neurologic cases in llamas and alpacas, but has no effect on people or other types of livestock.

The virus 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. It is killed readily by most disinfectants, ultraviolet light and by drying. Infected horses are generally treated with supportive care. Anti-inflammatory drugs and antiviral medications are often used for those that develop the neurologic form of the disease.

EHM positive horses and EHM exposed horses must be quarantined as outlined in the Board of Animal Health EHM control plan. Board staff members will then work with herd veterinarians and horse owners to carry out the testing and observation protocols defined in the control plan before the quarantines can be released.

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. Testing and treatment protocols must then be completed before quarantines can be released.

Equine Encephalitis Virus and West Nile Virus

Eastern and Western Equine Encephalitis (EEE & WEE) and West Nile Virus are endemic diseases in the United States. Birds serve as the primary hosts for these diseases. These viruses are transmitted from birds to horses or people through the bite of infected mosquitoes. These viruses 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 these diseases.

Vaccines for horses are widely available and have been proven to be effective in preventing infection. Steps can also be taken to reduce the risk of these diseases by reducing mosquito populations. Practices such as changing water in drinking troughs every week, mowing long grass, draining stagnant water puddles, and removing items such as old tires and tin cans may help to eliminate mosquito breeding grounds. Horses and people can also be protected from mosquitoes by using repellents and placing screens over windows and stable doors.

Positive test results for equine encephalitis or West Nile Virus must be reported to the Board of Animal Health.

Confirmed West Nile Virus cases in 2016

8/2/16
Confirmed
Sibley County:  Winthrop, Minnesota.
1.5-year-old Friesian stallion was euthanized on 8/5/16 due to progression of the disease. Not vaccinated.
8/3/16
Confirmed
Mille Lacs County:  Milaca, Minnesota.
Draft horse cross stallion is receiving supportive care and able to stand, eat and drink on its own. Not vaccinated.
8/9/16
Confirmed
Todd County:  Bertha, Minnesota.
6-year-old Standardbred gelding was euthanized on 7/30/16 due to progression of the disease. Not vaccinated.
8/12/16
Confirmed
Polk County:  McIntosh, Minnesota.
4-year-old female draft horse is uncoordinated, and able to stand and walk. Not vaccinated.
8/12/16
Confirmed
Renville County:  Sacred Heart, Minnesota.
8-year-old Quarter horse gelding was euthanized on 8/10/16 due to progression of the disease. Not vaccinated.
8/16/16
Confirmed
Winona County:  Utica, Minnesota.
Morgan horse female is receiving supportive care and is on its feet and slowly improving. Not vaccinated.
8/18/16
Confirmed
Chisago County:  Stanchfield, Minnesota.
8-year-old Appaloosa gelding show horse is having difficulty standing on its own. Not vaccinated.
8/24/16
Confirmed
Kanabec County:  Ogilvie, Minnesota.
7-year-old Belgian female horse slowly recovering from disease.  Not vaccinated.
8/26/16
Confirmed
Clearwater County:  Clearbrook, Minnesota.
7-year-old Fjord female horse.  Died from disease progression.  Vaccination status unknown.
8/26/16
Confirmed
Mower County:  Austin, Minnesota.
10-year-old quarter horse gelding.  Fully recovered.  Vaccinated in spring 2016.
8/26/16
Confirmed
Todd County:  Verndale, Minnesota.
2-year-old Appalossa gelding.  Horse drowned in a pond.  Vaccinated on August 9, 2016.