West Nile Virus in Dogs

Melissa Boldan, DVM
By Melissa Boldan, DVM on Jan. 25, 2024
A Duck Tolling Retriever walks through a wooded area.

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What Is West Nile Virus in Dogs?

West Nile is a virus that can cause encephalitis, an inflammation of the brain. It’s spread by mosquitoes and is more common in warmer regions of the world that have high mosquito populations.

While humans can contract West Nile virus, most don’t develop any symptoms. One person out of five will get a fever, and only one in 150 will develop a serious illness where they experience encephalitis or meningitis (inflammation of the membranes surrounding the brain and spinal cord).

Dogs experience even fewer symptoms than people—most dogs never show any signs of the virus. This disease, however, is especially dangerous to horses, and vaccination against West Nile virus is recommended for all horses in North America.

West Nile virus is very uncommon in dogs and is not considered a medical emergency. Pups who do get the virus are typically immunocompromised, senior, or very young. These symptoms mimic a mild virus and it is not considered to be a fatal virus in dogs.

Symptoms of West Nile Virus in Dogs

While most dogs infected with West Nile virus will have no symptoms, those who do may experience any of the following: 

Causes of West Nile Virus in Dogs

The West Nile virus is carried by birds. Crows, raptors, and jays are particularly susceptible to getting the disease.

When a mosquito feeds on an infected bird, it contracts the virus and can then spread it to other animals—including dogs. A dog is more likely to be exposed to West Nile virus if exposed to lots of mosquitoes.

How Veterinarians Diagnose West Nile Virus in Dogs

If your dog is experiencing symptoms, your veterinarian will start by getting a thorough medical history.

Let your vet know if you have noticed unusual signs or behaviors in your dog at home and when you first noticed any changes. Be sure to share if your pet has had a high mosquito exposure.

After getting a history, your vet will perform a physical exam. Based on the exam findings, they may elect to do bloodwork. Your vet may also do additional special blood tests if West Nile virus is suspected.

One test looks for antibodies to the virus circulating in the bloodstream. Sometimes the virus is diagnosed by testing of the cerebrospinal fluid (CSF). This fluid is obtained by a veterinarian who collects a sterile sample of spinal fluid while your pup is under anesthesia.

Treatment of West Nile Virus in Dogs

There are no specific treatments for West Nile virus. Most treatment is geared toward supportive care, as with many other viruses.

It’s important to keep your dog well hydrated and maintain adequate nutrition. Sometimes, anti-inflammatory medications such as carprofen or meloxicam are prescribed if your dog has a fever.

Occasionally, hospitalization is recommended if more intense supportive care is needed. Hospitalization would usually entail IV fluids and possible supported feeding.

Fortunately, it is uncommon for dogs to become severely ill from West Nile virus, and hospitalization is not common.

Recovery and Management of West Nile Virus in Dogs

Recovery from West Nile virus is usually smooth and uneventful, with most pet parents never knowing their dog was even infected. However, if your dog is diagnosed with West Nile virus and does become ill with a fever or other clinical signs, supportive care can often be done at home.

If this is the case, make sure your dog has easy access to fresh food and water. Rarely, hand feeding may be necessary to encourage intake.

If your dog is acting lethargic or not as excited about their food following a diagnosis of West Nile virus, it may be helpful to track their temperature.

Consider purchasing a digital thermometer if you don’t already have one. If they are running a fever, your vet may prescribe dog-safe, anti-inflammatory pain medications for use during recovery. Remember—never give over-the-counter human medications to dogs without speaking with your veterinarian first.

Most affected dogs recover within a couple of weeks. The rare, severely affected pup with neurological signs (such as lack of coordination or balance issues) may take months to recover. 

Prevention of West Nile Virus in Dogs

The best way to prevent West Nile virus is to avoid exposing your dogs to mosquitoes as much as possible.

Try to eliminate any mosquito habitat on your property. Mosquitoes like to lay their eggs in standing water, so regularly empty or turn over any items that hold water, such as planters, birdbaths, and trash containers.

Tightly cover water storage containers like buckets and rain barrels so that mosquitoes are unable to get in and lay their eggs. Consider having a pest control company treat your home’s outdoor areas for mosquito adults and larvae.

DEET-containing products are not safe for dogs and should never be used.

Talk to your veterinarian about dog-safe mosquito repellents or consider a topical product labeled for dogs, such as Elanco™ K9 Advantix™ II.

West Nile Virus in Dogs FAQ

Do dogs get vaccinated for West Nile virus?

Because West Nile virus is extremely rare in dogs and is unlikely to cause any symptoms, there’s no vaccine for dogs.

Featured Image: Anna-av/iStock / Getty Images Plus via Getty Images


Centers for Disease Control and Prevention. West Nile Virus (2023).

Cornell University College of Veterinary Medicine. West Nile Virus Diagnostic Testing.

Gardiner, J. UC Davis Veterinary Medicine Health Topics. West Nile Virus. (2019)

Lichtensteiger, C., et al. PubMed. West Nile Virus Encephalitis and Myocarditis in Wolf and Dog. (2003)


Melissa Boldan, DVM


Melissa Boldan, DVM


Dr. Melissa Boldan graduated from the University of Missouri College of Veterinary Medicine in 2012. She initially practiced mixed animal...

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