West Nile Virus: Dogs and Cats

Q: Can West Nile virus cause illness in dogs or cats?
A: West Nile virus was isolated from one cat in New Jersey in 1999 and two cats in upstate New York in 2000. All were severely ill and died. A study in Queens in 1999 showed that from 5% to 11% of dogs tested had been exposed to West Nile virus, though none was clinically ill. It is important to remember that pets with neurologic disease should be first evaluated for other, more likely, causes of illness, including rabies.

Q: Can infected dogs or cats be carriers and transmitters of West Nile virus to humans?
A: West Nile virus is transmitted by infectious mosquitoes. There is no evidence that any mammals, including humans, dogs, and cats, can transmit West Nile virus. Veterinarians should take normal infection control precautions when caring for an animal suspected of having West Nile or any other viral infection.

Q: How do dogs or cats become infected with West Nile virus?
A: Dogs and cats become infected the same way humans become infected: by the bite of an infected mosquito.

Q: Can a dog or cat infected with West Nile virus infect other dogs or cats?
A: No. There is no documented evidence that West Nile virus is transmitted between dogs and cats.

Q: How long can a dog or cat be infected with West Nile virus?
A: The answer is not known at this time.

Q: What should I do if I think my dog, cat, or other pet might have West Nile virus?
A: While dogs and cats do not appear to suffer clinical illness from West Nile virus, if you think your pet is ill you should see your veterinarian promptly. Pets can develop neurologic diseases from many other causes, and these should be ruled out before testing for West Nile virus is considered. Veterinarians should contact their local state health department to arrange for testing of pets suspected of having West Nile virus infection.

Q: Should a dog or cat infected with West Nile virus be euthanized?
A: No. As animals infected with West Nile do not transmit the virus to people or other animals, there is no reason to euthanize an infected animal. Treatment would be supportive and consistent with standard veterinary practices for animals infected with any viral agent.

Source: New York City Department of Health