West Nile and Your Pets
FAQs on West Nile Virus for Small Animal Veterinarians

September 19, 2002


Q: Can West Nile virus (WNV) 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: What advice should I give to my clients to protect their pet dog or cat?
A:

* 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: Yes. There are a few products that are approved for safe use in dogs. Products may be available at local pet stores/feedstores or veterinary offices. We have recommend pet owner to contact their veterinarian regarding the use of these products.

According to the most recent Veterinary PDR®, the following products have been approved for use in dogs to prevent or repel mosquitoes. (Note: several of these are horse products that are also approved for use in dogs.)

* Flysect Super 7 by Equicare
* Petguard gel by Virbac
* VIP Fly Repellent Ointment by VPL
* Flea and Tick Mist by Davis
* Adams Flea and Tick Mist by VPL
* Happy Jack® Flea-Tick Spray by Happy Jack
* Ultrashield by Absorbine

In addition, applying a pyrethrin-based flea spray in accordance with the label directions for that species may be the safest method to try to repel mosquitoes on pets. Reapplication of the spray may be necessary for animals that will spend much time outdoors.

Q: Is it safe to use a mosquito insect repellent meant for humans on pets or to use a product containing DEET(N,N-diethyl-m-toluamide, N,N-diethyl-3-methylbenzamide)?
A: No, only approved mosquito repellents should be used on pets. Clients should be told to read the label first to determine if the product is approved for use in pets and then follow label instructions for applications. Topically applied DEET may be absorbed dermally as well as orally when pets groom themselves, increasing exposure and the potential for problems. 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 that 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 (especially distemper, rabies, and brain neoplasia) therefore it is very important to consider these as well.

Q: Is there a vaccine available for pets?
A: No, the only vaccine currently available is for horses.

Q: What is the treatment for WNV in pets?
A: Treatment is supportive and consistent with standard veterinary practices for animals infected with a viral agent.

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.

Q: If I suspect a patient may have WNV based on clinical signs, is an ante-mortem test available?
A: Currently, there are only a few laboratories that will accept samples from dogs and then only if they are clinically ill. National Veterinary Services Laboratories (NVSL) is one of those laboratories. Please note that NVSL is inundated with sera from sick horses all around the country and is not establishing a high priority on the dog sera. Therefore, veterinarians will likely not get results from NVSL on dogs for several weeks. By that time, the dog will either have recovered or, in the unlikely case, died. Also the serology test for dogs measures IgG which may last for years, therefore, positive serology results for WNV on canine serum may not indicate recent infection.

The New York State Animal Health Diagnostic Laboratory will also accept samples for serology, PCR testing of blood and virus isolation. The laboratory should be contacted before submitting specimens to ensure proper packaging and submission, to ensure that they are currently receiving out-of-state specimens, advice on how to interpret the serology results and to obtain current fee information.

Q: Is there a way to diagnose WNV post-mortem?
A: If death occurs, the diagnosis of WNV may be established through post-mortem examination and examination of the brain and other tissues by histology and immunohistochemistry (IHC). Contact your diagnostic laboratory regarding specific information on submitting post-mortem samples for these tests. Currently in Illinois both the Galesburg and the U of Illinois diagnostic laboratories are performing the IHC test.

Created September 19, 2002; prepared by Dr. Christine Merle, Small Animal Extension Veterinarian, University of Illinois College of Veterinary Medicine, Continuing Education and Public Service Unit/Extension.

http://www.cvm.uiuc.edu/ceps/wnvpetvets.html