Here you can find all the essential information about the West Nile virus (WNV), a potentially serious viral infection that can occur in horses.
What is West Nile virus?
West Nile fever is caused by the West Nile virus, which is primarily transmitted by mosquitoes. In recent years, the incidence of West Nile fever has increased in various regions. Therefore, it is essential for horse owners to be informed about the symptoms, modes of transmission, and prevention options. The main hosts of the virus are wild birds, particularly corvids, birds of prey, and owls.
Transmission of the West Nile virus
West Nile virus is primarily transmitted by the bite of infected mosquitoes. Horses are so-called „dead-end hosts,“ meaning they can become ill but do not produce enough of the virus to infect other horses. Transmission from horse to horse is not possible, nor is transmission from horse to human.
Symptoms of a WNFV infection
The incubation period for West Nile fever is 2 to 14 days. Around 80% of horses that test positive show no symptoms or only mild symptoms. In 8–10% of unvaccinated horses, neurological symptoms may occur, ranging from mild to severe disorders. The most common signs include:
Fever
Loss of appetite
– Weakness or lethargy
– Co-ordination disorders (ataxia)
– Tremors or muscle twitching
– Changes in behaviour
In severe cases, the virus can lead to life-threatening inflammation of the brain (encephalitis). If West Nile virus is suspected, it is important to consult a veterinarian immediately.
West Nile virus vaccination
The best method to protect your horse is vaccination. The WNFV vaccine is a single-animal vaccine that offers protection of up to 12 months after just the second dose. The primary immunisation consists of two doses administered 4-6 weeks apart. An annual booster vaccination is recommended to maintain protection.
The vaccination should take place in spring to provide your horse with optimal protection during the mosquito season. There are no contraindications for vaccinating pregnant or lactating mares.
Current Affairs and Recommendations
Infections have recently been confirmed in horses in several federal states, including Brandenburg, Berlin, Saxony, and Bavaria. The StikoVet (Standing Commission on Vaccination for Veterinary Medicine) recommends completing the basic immunisation before the start of the 2025 mosquito season.
For further information on the current animal disease situation, please visit the website of theFriedrich-Löffler-Institut.
Conclusion
West Nile fever is a serious illness that can be controlled through preventive measures such as vaccinations and education about symptoms and transmission routes. We are available at any time for questions or to schedule an appointment. Protect your horse and get informed by us!
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