Relocated Katrina dogs turning up heartworm-positive

[Crossfire Bulldogs]

By DENISE FLAIMNewsdayWhen veterinarian Debra Eldredge of Vernon, N.Y., heard about how many transplanted rescue dogs from Hurricane Katrina were turning up heartworm-positive -- as many as 80 percent -- it was déjà vu all over again.

Eldredge's practice checks dogs annually for heartworm, even though none ever tested positive -- until one recent spring.

All three dogs lived within a block of each other, and none had traveled to any areas where heartworm was common. But they did all have a new neighbor.

''It turned out that a family had moved up from Georgia with a dog that was heartworm-positive,'' Eldredge says. And in that year and a half, the dog had been a reservoir for heartworm, which is transmitted by mosquitoes.

Eldredge's concern today is that as Katrina rescues are relocated to other parts of the country, they, too, will bring heartworm with them.
''At least in the Northeast, we have had a very warm, wet fall, and I was still seeing mosquitoes in mid-November, which is very unusual here,'' says Eldredge, author of ''Pills for Pets: The A to Z Guide to Drugs and Medications for Your Animal Companion'' (Citadel, $14.95).
Because heartworm requires a vector (or insect intermediary) to infect new hosts, it does not spread as quickly as a virus or other airborne disease would. In the Northeast, mosquitoes are a problem roughly half the year. But in the Gulf Coast's warm temperatures, heartworm is transmitted year round, and every dog not on preventive medication eventually will be infected.

''Do I think it's a really high risk'' in Northern areas? ''Probably not,'' Eldredge says. ''But is it enough that I would be concerned? Yes.''
She's not the only one. Last month, a consortium of animal-welfare groups donated $150,000 to establish the Hurricane Heartworm Treatment Program (www.aahahelping pets.org/root). Veterinarian Kate Hurley, director of shelter medicine at the University of California-Davis, was so concerned that Katrina animals would give heartworm a foothold in parts of her state where it is not endemic that she drafted guidelines for treatment (www.heartworm society.org/katrina.htm).

Where heartworm is not widespread, veterinary epidemiologists are relatively unconcerned.

''We're such a mobile society nowadays that it's going to be in most areas anyway, and a few more dogs coming in are not going to affect the rates,'' says veterinarian Charles Thomas Nelson of Anniston, Ala., president of the American Heartworm Society. ''The greater issue is that this is such an easily preventable disease, and only about half the dogs are on prevention.''

Heartworm prevention medications are usually administered once a month in chewable tablets. Depending on the brand used, many also protect against intestinal parasites such as roundworms and hookworms.

Part of the difficulty in identifying heartworm-positive dogs is that blood tests do not pick up an infestation until six months after infection.

The heartworm treatment, a drug called Immiticide, is a series of three intramuscular injections, after which the dog must be kept confined and inactive. Not only is the treatment potentially fatal but it does not initially kill the microfilaria, or larvae, which transmit the disease.

''Until a dog is microfilaria negative,'' Eldredge says, ''you have the potential for another dog to be infested.''

For this reason, the American Heartworm Society recommends positive dogs first be given ivermectin, a heartworm preventive that kills microfilaria, followed by Immiticide.

Veterinary epidemiologist Laura Hungerford at the University of Maryland School of Medicine in Baltimore says that relocated heartworm-positive Katrina rescues ''shouldn't have a huge impact'' because heartworm is already present in most of the country.

''The greater issue is as people move, they need to be aware of the disease profiles in different places,'' Hungerford says, noting the 2003 monkeypox outbreak in prairie dogs in the Midwest, caused by contact