Spring Vaccination: Every Horse, Every Year!

The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) is reminding horse owners to make an appointment with their veterinarian for spring vaccinations. Consistent with the American Association of Equine Practitioners (AAEP) guidelines on core vaccinations, DATCP recommends all Wisconsin horse owners work with their veterinarian to vaccinate against the following diseases:

• Equine Encephalitis
• West Nile Virus
• Tetanus
• Rabies

Virtually all Wisconsin horses may be exposed to these diseases through their environment, regardless of travel plans or discipline:

• Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV) are transmitted via insects
• Tetanus is transmitted through soil bacteria
• Rabies virus is transmitted through wild mammals

Vaccination offers considerable protection against these serious diseases, most of which have no treatment beyond supportive care, and may cause serious illness or death.

Eastern Equine Encephalitis and West Nile Virus

EEE and WNV may cause brain inflammation, and equine mortality rates approach 90% for EEE and 30% for WNV. While humans may be infected, the viruses do not pass between people and horses. Transmission occurs when mosquitoes carry viruses from infected birds and bite warm-blooded animals. The threat in Wisconsin varies annually, depending on the weather, but normally starts in mid- to late-summer and remains until the first killing frost. Vaccination prior to the start of mosquito season is recommended.

Symptoms are similar for both diseases but tend to be more severe with EEE. They include depression, appetite loss, drooping eyelids and lower lip, fever, weakness, twitching, paralysis or lack of coordination, circling, blindness, seizures, and inability to stand.

In 2024, 19 cases of Wisconsin horses positive for EEE and WNV were reported. No cases were reported in fully vaccinated horses.

In addition to vaccination, DATCP offers these tips to limit horses’ exposure to mosquitoes:

• Remove items that could collect stagnant water (e.g., old tires, buckets, unused troughs).
• Keep rain gutters draining properly; turn wading pools and wheelbarrows upside down.
• Clean and chlorinate pools, outdoor saunas, and hot tubs; drain water from pool covers.
• Empty and replace water in birdbaths at least once a week.
• Consider keeping horses in the barn from dusk to dawn, when mosquitoes are most active.

Following these tips can significantly reduce your horse's risk of exposure. To learn more about Core and Risk-Based Vaccination for horses, talk to your veterinarian and visit the DATCP website or AAEP.org.

Wisconsin Department of Agriculture, Trade and Consumer Protection
Division of Animal Health
https://datcp.wi.gov