Do Goats Get West Nile Virus?
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It was recently reported that a goat in Massachusetts was identified with West Nile virus. While this made headline news, it should not be panic-inducing. While the goat tested positive for the virus, to my knowledge, it wasn’t confirmed as a cause of death.
West Nile virus is endemic in North America. It’s a mosquito-borne flavivirus that is primarily spread by Culex sp. mosquitoes. The virus can infect a multitude of species; however, most mammals are considered dead-end hosts — meaning the virus doesn’t replicate enough in the animal to be passed on from them. In the United States, birds are the primary reservoir for disease, with mosquitoes transmitting the virus from birds to other animals. The most susceptible birds to the disease are jays, crows, and ravens, though many other birds can exhibit signs of the disease. Young birds of any variety are much more susceptible to the disease. Mature domestic chickens don’t tend to show signs of illness.
The dead-end hosts of most importance for the West Nile virus are humans. Humans contract the virus through mosquitoes or contact with infected birds. In humans, the virus can cause fever, lethargy, other flu-like symptoms, and even central nervous system inflammation such as meningitis or encephalitis. Though people of any age can be affected, older or immunocompromised individuals are at the greatest risk. Serious disease in humans can even result in death. Unfortunately, there isn’t a vaccine available for humans.
Other dead-end hosts that are of importance are horses and camelids (such as llamas and alpacas). These animals can also develop severe illness from the disease, primarily neurologic in nature. A vaccine has been developed for horses to help prevent disease, and has also been used off-label in camelids.
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Now we circle back to goats and other ruminants. While they can be infected with the virus, they don’t usually show signs of clinical disease. Testing in livestock is generally done to assess for the presence of the virus in the mosquito population, and thus the increased risk to humans. However, in recent years, UC Davis has identified West Nile virus as the cause of encephalitis in sheep. Research performed in other countries has identified the virus at low levels ( <6%) within goat populations. This research aimed to utilize animals and sentinels for signs of the virus within a region, to help reduce the risk of human exposure.
West Nile can cause serious disease and even death in some species. While the virus may affect goats, there is no evidence to implicate it as a common cause of serious illness. However, that doesn’t mean that steps shouldn’t be taken to reduce the risk of the disease occurring. This is especially true, considering the risk the virus poses to humans.
As West Nile virus is spread by mosquitoes, the incidence of the disease is seasonal. Most prevention is aimed at reducing mosquito replication and exposure of humans and animals to mosquitoes. Clearing standing water, cleaning water troughs weekly, and reducing manure load can greatly reduce mosquito burden. Using bug and mosquito repellent daily is also recommended. Reducing vegetation around shelters and pens can also reduce mosquito exposure. In animals that are at risk of disease, administering the West Nile vaccine is recommended. This vaccine is recommended at least annually, and in high-risk regions, like the Southern U.S., at least twice prior to mosquito season. There’s no vaccine approved for use in goats or sheep, so use of a vaccine in these animals should be at the discretion of the herd veterinarian.
West Nile is unlikely to cause serious disease in goats, though it isn’t impossible. Care should be taken to reduce the risk of exposure, not just for goats, but for humans and other livestock as well.
DR. KATIE ESTILL DVM is a veterinarian consultant for Goat Journal and Countryside & Small Stock Journal. She works with goats and other large livestock at Desert Trails Veterinary Services in Winnemucca, Nevada.
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Originally Published in the September 1, 2025 digital issue of Goat Journal
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