Fight the Bite! Preventing West Nile Virus
About West Nile Prevention Insect Repellent Pets & Livestock For Kids

Pets & Livestock

FAQs on West Nile Virus for Pet Owners

Q: Can West Nile virus infect dogs and cats?

A: Yes, however, infection rates in epidemic areas are low. WNV does not usually cause severe illness.

Q: Which dogs and cats are likely to be the most susceptible?

A: Based on the most recent animal cases seen at the University of Illinois College of Veterinary Medicine Veterinary Diagnostic Laboratory, young, old, and immune-compromised pets would seem to be at a higher risk.

Q: How do dogs and cats become infected with West Nile virus?

A: The same way humans become infected: by the bite of infectious mosquitoes. It is possible that dogs and cats could become infected by eating dead infected animals such as birds, but this is unproven.

Q: How can I protect my pet?


  • Keep pets indoors during peak mosquito hours--dawn, dusk, and early evening.
  • Eliminate standing water around your home.
  • Prevent pets from coming into contact with dead birds or squirrels that may have died as the result of the virus.
  • Contact your local veterinarian if your pet exhibits any neurological signs, such as incoordination, depression, decreased appetite, difficulty walking, tremors, abnormal head posture, circling, and convulsions.
  • Use only approved mosquito repellent on your pet; make sure to read the label first to determine if the product is approved for use in pets.

Q: Is there a mosquito repellent available that is safe to use in dogs?

A: Currently there are a few products labeled for use in pets to repel mosquitoes. Products may be available at local pet stores/feedstores or veterinary offices. Contact your veterinarian if you have any questions regarding using a specific repellant on your individual pet.

Q: Can I use a mosquito insect repellent meant for humans on my pet?

A: No, only approved mosquito repellents should be used on your pet, make sure to read the label first to determine if the product is approved for use in pets and then follow label instructions for applications.

Q: Can I use DEET (N,N-diethyl-m-toluamide, N,N-diethyl-3-methylbenzamide) mosquito repellent on my pet?

A: The use of DEET on animals is not recommended and should be avoided. DEET has been associated with serious adverse effects when used on dogs and cats. Citrus oil extracts and other essential oils are also not recommended due to the extreme sensitivity of some animals to these products.

Q: What are the signs of WNV in dogs?

A: Neurological signs are similar to those seen in horses, such as incoordination, depression, decreased appetite, difficulty walking, tremors, abnormal head posture, circling, and convulsions. These signs can mimic other diseases; therefore, it is very important to contact your veterinarian if your pet is exhibiting any of these signs.

Q: Is there a vaccine available for dogs and cats?

A: No, there is currently only a vaccine available for horses.

Q: What is the treatment for WNV in pets?

A: There is no specific treatment other than supportive care provided by your veterinarian.

Q: Can pets transmit the WNV to humans or other pets?

A: There is no documented evidence that animal-to-animal or animal-to-person transmission can occur. There is no reason to destroy an animal because it has been infected with WNV.

Source: University of Illinois College of Veterinary Medicine

West Nile Virus and Horses

As of August 28, 2002, West Nile Virus (WNV) had been reported in 95 of 101 Illinois counties. Horses and humans have been infected, and some have died from WNV in 2002. A fact sheet and maps of the spread of WNV through Illinois can be found on the College Web site.

Photo Clusters of equine WNV cases have been reported in Illinois in the summer of 2002. WNV signs may progress rapidly to include hyperaesthesia (increased responsiveness to external stimuli), depression, decreased appetite, muscle fasiculations, skin tremors, visual problems, and recumbency. Horses which become recumbent have a much poorer chance of survival. Early clinical signs include those typical of any spinal disease in horses, and Equine Protozoal Myelitis (EPM) cannot be ruled out.

The virus is spread by many different mosquito species and therefore is more likely to be transmitted where mosquito activity is high. Direct horse-to-horse and horse-to-human transmission does not occur. Any farm sustaining multiple cases of rapid-onset neurological disease should have WNV considered as the most likely diagnosis, with Equine Herpesvirus Myelitis, EPM, eastern and western encephalitis viruses, and rabies virus as secondary but important diagnoses.

Preventive measures include mosquito control and vaccination. Horses should not be turned out at dawn and dusk when mosquitoes are most active. Standing water should be eliminated, such as in old tires, wading pools, and infrequently-used buckets. Insect repellants or fly sprays may also be helpful.

A WNV vaccine is available for horses. It is conditionally-licensed, meaning that complete efficacy data are not yet available. From field outbreaks in Florida in 2001, it appears that the vaccine is protective, but only once the horse has received both the primary and secondary (booster) injections at least 3 weeks apart prior to exposure to WNV.

We are recommending the use of this vaccine. It appears to be safe, and localized muscle-soreness reactions are no more common than with other equine vaccines.

Source: University of Illinois College of Veterinary Medicine