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Are Pets at Risk to West Nile? Owners Take Precautions

Denise Flaim | Animal House

May 27, 2003

Memorial Day weekend means summer, which means warm weather, which means mosquitoes. And that - for the worriers among us - means renewed concerns about the West Nile virus.

West Nile, for those who haven't punched in since before the Giuliani administration, is an infectious disease spread through the bites of infected mosquitoes. It can cause encephalitis, or inflammation of the brain, with symptoms that may include fever, tremors, listlessness, muscle weakness, paralysis and, in some cases, death.

Because the West Nile outbreak in North America began in our metropolitan area, most New Yorkers are savvy about the precautions they should take. But what about our animal companions? Are they at risk?

The answer is: It depends on the animal.

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Horses, for example, are very susceptible to West Nile; according to the Centers for Disease Control and Prevention, 40 percent of horses that contract it die.

An equine vaccine is in widespread use. "The company says it is 95 percent effective, and that's reasonably accurate," says veterinarian Gregory Ferraro, director of the Center for Equine Health at the University of California, Davis.

Initially, the vaccine manufacturer recommended two shots, given three to four weeks apart, at about six weeks before the horse would be exposed to West Nile, followed by an annual booster, Ferraro says. "But everyone in the horse business is recommending a booster twice yearly, if not every four months."

Adverse reactions to the Fort Dodge vaccine, says Ferraro, are "lower than we would expect."

Dogs and cats, it turns out, are unlikely to contract West Nile. The CDC confirms only one dog and one cat death each since the disease was discovered in this country in 1999. "Other than horses, most domesticated animals can get infected with the virus, but they don't get the clinical disease," Ferraro says. "And it's rare that you see any symptoms."

Birds are the natural host for West Nile, with the CDC reporting that it has been detected in at least 138 species. But the federal agency says that most infected birds survive. And parrot owners shouldn't assume that their birds will be as susceptible as other species, such as crows.

"While there have been anecdotal reports of West Nile in the occasional companion bird, it's not the disaster that we thought it would be," says veterinarian Margaret Wissman of Wesley Chapel, Fla., one of approximately 150 board-certified bird specialists in the world. "We kept waiting for the shoe to fall in Florida, because here everybody breeds their parrots outside. But nothing's happening" - including in her own aviary. Wissman has 50 pairs of parrots, and all are seemingly unaffected.

"For the most part, birds are mostly feathered, which is a good protection system against mosquitoes," Wissman notes. Other areas are covered with scales, although she points out that some parrots, such as African greys and macaws, have exposed skin on their faces.

That's not to say that some bird people aren't being extra-cautious. "At conferences, there's definitely been talk about vaccinating, especially for rare birds," such as the California condor, she says. The vaccine under consideration is the equine one, since an avian vaccine is still in the works.

But, Wissman adds, studies of birds inoculated with the horse vaccine aren't that promising. "While it didn't hurt the birds, it didn't seem to give them any extra protection," she says. "In the face of impending disease, it's probably not going to really help."

Bottom line: While horses and humans seem to have a susceptibility to West Nile, dogs, cats, parrots and most of our other companion animals are relatively resilient. And following the common-sense precautions - keeping your backyard free of standing water and your animals indoors during the late afternoon and early evening, when mosquitoes feed - should be adequate.

But as with humans, animals that are elderly and immuno-compromised are at a greater risk for the disease, "and those are the animals you really want to protect against mosquitoes," Wissman stresses. In those high-risk cases, she suggests investing in an outdoor product like SonicWeb, which attracts biting insects and then traps them.

Write to Denise Flaim, Newsday, 235 Pinelawn Rd., Melville, NY 11747 or dflaim@newsday.com.