West Nile Virus

The good news is that West Nile encephalitis isn’t likely to affect dogs or cats. The bad news is that people with outside or indoor/outdoor aviaries for pet birds need to protect their feathered friends. Of course, the West Nile virus can kill horses, and some people have died as well.

“So, far studies offer no evidence that the health of a dog or cat may be impacted by West Nile encephalitis,” says Dr. Lisa Conti, a veterinary epidemiologist, with the office of Florida State Public Health in Tallahassee. Having said that, in 1982, according to a published report, a dog in Botswana was identified with West Nile. The virus has also been described in several dead cats.

“We don’t really believe West Nile is a threat to dogs or cats,” adds Conti. “In fact, it appears they may have resistance to the virus.”

Still, Conti suggests if you live in Louisiana, Florida, Texas, Georgia or any mosquito-laden hot bed, keep your pets indoors when mosquitoes are most active at mid-day and in the evening. Also, don’t walk your dog around standing bodies of water where mosquitoes breed, for your own safety as much as your pet’s safety.

Some researchers believe that when a dog or cat eats a dead bird that was infected with the disease, that dog or cat can become ill. However, there is no research currently available to confirm this theory. If you’re concerned, however, monitor your pet so dead birds don’t become a snack.

West Nile is spread with the help of unwilling birds. An infected mosquito zaps a bird and gives the bird the virus. Meanwhile, another mosquito comes along, takes a blood sample and now carries the disease elsewhere, such as to a person or to a horse. Dr. Peter Timoney, chair of the Gluck Equine Research Center at the University of Kentucky ” Lexington, explains that one of two things happen when a bird is zapped by an infected mosquito. Some birds succumb to the disease (it’s thought some species, including blue jays and crows are more susceptible than others, such as sparrows), others are able to fight it off, and even develop a resistance.

“This creates a disease cycle,” says John Roehrig, PhD at the Aborvirus (a name for viruses spread by insects and ticks) Diseases Branch of the Centers for Disease Control and Prevention, Ft. Collins, CO. The good news is that as more birds become resistant, they can’t help to perpetuate the spread of West Nile.”

However, pet birds ” often members of the parrot or finch families ” may not develop a resistance. Conti warns owners with outdoor aviaries to protect their feathered friends with mosquito netting. While mosquitoes can get indoors, draping mosquito netting over an indoor cage may create behavior problems, particularly in parrots. Instead, secure screen windows and make sure the kids close outside doors quickly, lessening the likelihood of intruding mosquitoes. Don’t use mosquito repellents near pet birds, such sprays may be fatal.

Meanwhile, Timoney notes West Nile continues to spread, quietly establishing itself in Canada, as far as Manitoba. As of August 8, according to the CDC, 87 horses have been reported with the virus in the U.S. The states most heavily hit include 23 cases in Florida, 18 in Texas, six in both Louisiana and Mississippi, and three in Texas. However, horses are also being impacted where the national media has not reported incidences of encephalitis, in states you’d least expect, 11 cases in North Dakota, and seven incidents in both South Dakota and Minnesota.

“Certainly, where West Niles affects horses, there’s a clear potential for the threat for people,” Roehrig adds. “The good news is that only a miniscule percent of mosquitoes carry the disease, even where there are outbreaks. Still, people need to protect their horses and themselves in these places.”

Timoney explained that most horses, maybe more than 90 per cent, that are bitten by an infected bug never become ill. However, of those horses who do become sick, about 33 percent either succumb or are ultimately euthanized. Many of the horses who die of West Nile are old or are already suffering from another illness.

Still, Timoney says protection for horses begins with a vaccine. So far, about two million doses have been given with few side effects. Dr. Steve Connell is a director of professional services at Ft. Dodge Animal Health, the Overland Park, KS company that manufacturers the vaccine. The vaccine, which is still new, remains conditionally licensed by the United States Department of Agriculture. Efficacy testing has been conducted so the vaccine will soon enjoy a full license. Connell says he hopes the vaccine will prove to be about 90 percent effective. The vaccine is a preventative, and will not help animals who are already infected. However, no single vaccine is 100 per cent guaranteed. This is why Timoney recommends extra protection for horses, particularly in places for West Nile has been identified.

Here are some tips:

  • Do not spray barns or the horses themselves with products containing pesticides without veterinary approval. However, you can rub Avon Skin-So-Soft on Your Horse.
  • Some barns now have places behind screen doors where mosquito invasions are less likely.
  • Have your horses graze at dusk and dawn when mosquitoes aren’t as active.
  • Replace standing water where horses drink on a daily basis. Mosquitoes breed in water. If possible, keep horses away from swampy areas, or ponds.

One more note, horses are a large target for hungry mosquitoes ” even if the horse is vaccinated, the mosquitoes don’t know it. This is why if you live where you know there are infected mosquitoes, be sure to carefully protect yourself when you go riding or walking with equine company. There’s more information at www.cdc.gov and www.avma.org.


Note: This article is copyrighted by Steve Dale and can be used as source material and for reference only. It cannot be reprinted verbatim. Please contact Steve Dale at petworld@aol.com if you have any questions.


Comments are closed.