West Nile Virus (WNV)

Article West Nile

West Nile virus (WNV) first appeared in North America in 1999. Spread by infected mosquitoes, the virus often creates no symptoms or mild symptoms that last several days to several weeks. However, if the disease enters the brain, it causes an inflammation called encephalitis, which can be debilitating or fatal in a small portion of infected people and animals. A physical exam, health history, and laboratory tests can diagnose WNV in people or in their companion animals.

How WNV Infects Dogs and Cats

West Nile virus resides inside the carrier mosquito’s salivary glands. The mosquito transfers the virus when it feeds on the blood of your dog, cat, or horse—or even you. Mosquitoes are by far the most common transmitters of WNV to humans or their companion animals. Mosquitoes acquire the virus after feeding on infected wild birds, and they then transmit the virus through bites to people, animals, and other birds. WNV does not transfer directly from pet to pet or from pet to human. Although some laboratory experiments show that cats and dogs can acquire the disease by eating infected birds, no transmissions of this type of have been documented by health authorities.

Consequences of WNV for Dogs and Cats

Although the virus can infect dogs and cats, neither seems to develop active infections easily. This is in contrast to horses, humans, and some bird species, which are much more likely to develop active West Nile infections than our canine and feline friends. Horses are especially susceptible and may suffer serious neurological effects that can be permanent. For animals of any sort, the young, the old, and immune compromised are most likely to develop symptoms of WNV, which include depression, decreased appetite, difficulty walking, muscle weakness, spasms, and fever.

No vaccine is available for humans or companion animals. (Four vaccines are available for horses.) If you suspect that your pet may be infected with WNV, see your regular veterinarian. Your vet will treat an infected dog or cat as for any viral infection—by relieving the symptoms.

Protection From WNV

To protect your pets from WNV, particularly during outdoor activities for dogs, take the same measures that you would to protect yourself:

  • Eliminate mosquito breeding sites, including overgrown grass and weeds, as well as standing water. Even a flower pot, soda can, or coffee cup that partially fills with rainwater can breed mosquitoes.
  • Install or repair screens on windows and doors to keep mosquitoes outside.
  • Use effective mosquito repellents made for pets to boost protection when outside in heavy mosquito conditions. Only use repellent products specifically labeled for use on your pet.
  • Treat your yard with an Adams™ Plus Yard Spray to kill mosquitoes in your lawn, trees & shrubs, roses and flowers. Protect your home from mosquitoes that may carry WNV with the Adams™ Flea & Tick Home Spray or Indoor Fogger. Protect your pet with an Adams™ Flea & Tick Spot On® product that kills and repels mosquitoes.
  • Remember that mosquitoes are most active from dusk to dawn. Limiting outside time to bright sunny periods reduces your pets’ risks of suffering bites.

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Pet Health and Wellness