Infection in Pet Mammals and Livestock

Although disease associated with WNV infection is most common in horses, birds, and people, infection with WNV has been reported sporadically in other animal species. One to a few cases have been described in dogs, cats, rabbits, sheep, mountain goats, alpacas, llamas, donkeys, mules, reindeer (captive), squirrels, chipmunks, skunks, bats, harbor seals, and even alligators. Although this may be alarming to clients who own some of these animals, the remarkably low number of reports of WNV-associated illness in these species should serve to indicate a relatively strong resistance. Dogs, for example, may be just as likely to be bitten by a WNV-carrying mosquito as a horse is, but only a small number of canine cases of WNV infection have been reported.

Clinical signs and pathologic findings of WNV infection have not been thoroughly described in most of these animal species. In cases where description is given, both clinical illness and pathology refer to the nervous system. Therefore, it seems that WNV-associated disease in both equidae and other mammals is primarily a neurological disease.

To the best of our understanding, dogs and cats are very resistant to the West Nile Virus. While a very small number of dog illnesses and possible deaths have been reported across the country, in at least one case the dog in question was unhealthy prior to becoming ill with WNV. This very likely made the dog more susceptible to the virus and also probably contributed to the severity of its illness.

In early September of 2003, a dog from Kent County was confirmed positive for West Nile virus. The owners noted neck stiffness and mild depression in this 10 year old Irish Setter during late July. The examining veterinarian, suspecting WNV, collected blood specimens for testing and then initiated supportive treatment. The dog developed intermittent seizures and rear limb weakness early in the course of the infection, but has since recovered completely. The blood specimens showed increasing levels of antibody to WNV which, coupled with the obvious physical disorders, are considered diagnostic for WNV infection. The dog lives in a community on and around lakes and marshes in eastern Kent County, and was not known to be ill or debilitated prior to this incident. As noted elsewhere dogs, cats, and other domestic mammals are considered to be very resistant to WNV encephalitis, a belief supported by the very low numbers of ill animals.

A second dog, a 5 year old golden retriever from Calhoun county was also confirmed positive for West Nile virus in 2003. This dog had chronic immune system dysfunction and was in poor heath prior to infection. The dog was treated and appears to be in recovery.

According to the CDC, there has been only one dog and one cat death attributed to West Nile virus infection since 1999. The dog was in poor health prior to becoming infected. There is no evidence that a dog or cat can transmit West Nile virus to a human, nor is there evidence that a dog or cat develops enough of the virus in their bloodstream to infect additional mosquitoes. Refer to the CDC's Link: Information on WNV Infection in Dogs and Cats for more information on WNV in pets.

A pet infected with West Nile virus suggests that there are infected mosquitoes in the area. You should take appropriate measures to avoid being bitten.

Protecting Your Pets (click for link)

Infection in Pet Birds

WNV infection has been reported occasionally in caged bird species, suggesting that all avian species are at risk. However, as with non-equine mammals, it appears that non-corvid pet (corvids are crows, blue jays, ravens) avian species are relatively resistant to disease caused by the virus. Owners are advised to keep pet birds indoors during mosquito season; insect repellants are not approved for use in these species, and should not be used.

CDC: Experimental Infection of Cats and Dogs with West Nile virus

Link to Results of WNV Domestic Animal (excludes horses) Lab Testing