Ag department urges horse owners to keep vaccines updated during mosquito season

ANNAPOLIS — The Maryland Department of Agriculture’s animal-health program encourages all horse owners to have their equines vaccinated for West Nile virus and other mosquito-borne diseases.

The reminder comes after three unvaccinated horses tested positive for West Nile virus in August. Mosquito populations have increased significantly this year due to sustained wet weather, which has lead to an increased risk of mosquito-borne diseases like West Nile virus and eastern equine encephalitis.

At the end of August, three horses tested positive for West Nile virus in Anne Arundel, Carroll and Washington counties. The equines stabled in Anne Arundel and Washington counties are responding to treatment and are expected to recover. The Carroll County horse showed severe neurological signs and was euthanized.

None of the three horses was vaccinated.

West Nile virus vaccination is recommended as a core vaccine and is considered an essential standard of care for all horses by the American Association of Equine Practitioners.

Signs of West Nile virus and eastern equine encephalomyelitis include fever, though not always with West Nile virus; anorexia; head pressing; depression or personality change; wobbling or staggering; weakness; blindness; convulsions; muscle spasms in the head and neck; or hind-limb weakness.

Horse owners can also help during mosquito season by keeping horses inside during dawn and dusk, which are peak mosquito hours, and using topical insect repellents labeled for use on horses.

West Nile virus is a serious and, at times, deadly disease that affects humans and horses. Both species can contract West Nile virus and eastern equine encephalomyelitis if bitten by a mosquito carrying the virus, but the viruses cannot be transmitted between horses or from horses to people.

Because animals and humans contract the virus from the bite of an infected mosquito, the department works closely with the Maryland Department of Health every year to monitor virus activity in equines.

Resources for arboviral and other reportable infectious diseases in equines can be obtained at mda.maryland.gov/animalhealth/pages/diseases.aspx. Equine arbovirus testing information can be found at health.maryland.gov/laboratories/pages/arbovirus-serology.aspx.

More information about the department’s mosquito-control activities can be found at mda.maryland.gov/plants-pests/pages/mosquito_control.aspx.