West Nile Virus in Horses

About West Nile virus

West Nile virus (WNV) is a viral infectious disease of equids spread by mosquitoes, but humans can also be infected. Wild birds are the natural hosts for WNV, while horses and humans are dead-end hosts, meaning they cannot spread the virus themselves. WNV is characterized by neurologic disease and can be fatal.

Clinical signs

• Fever
• Incoordination
• Stumbling
• Falling
• Weakness
• Muscle twitching
• Seizures
• Drooping lips
• Abnormal sensitivity to touch or sound

Treatment & prevention

There is no specific treatment for West Nile virus, but supportive care can be provided.

AAEP recommends vaccinating horses annually for WNV.

Good mosquito control is necessary for keeping WNV away from your horses:

• Remove standing water
• Clean water containers
• Use insect repellents
• Bring horses inside at dawn and dusk

Actions to take

• Consult your local veterinarian about preventing West Nile virus in your herd or if you suspect your animals may be infected.
• Veterinarians must report WNV to the state veterinarian within 48 hours of first knowledge of the disease.