My Pet World
May 30, 2006

Ticks Traveling, Carrying Disease to Unlikely Cities

By: Steve Dale

It seems everyone comes to the big city to party, even ticks. Historically, you'd never see ticks in Chicago, Boston, New York or San Diego. However, veterinarians in all these cities have confirmed the surprising presence of the disease-carrying suckers.

Dogs that have never traveled out of the concrete jungle are getting ticks, and in some cases, the diseases they transmit.

In many cities, weather plays a role. Ticks usually enjoy reasonably mild winter temperatures and moist springs, according to Dr. Michael Dryden, veterinary parasitologist at Kansas State University College of Veterinary Medicine, Manhatten. "Ticks are a big fan of global warming," he says.

The intersection of suburbia and wildlife is exposing animals daily to raccoons, even squirrels and birds that can carry ticks, but deer are ticks' favorite hosts. Dryden notes that the white-tailed deer population in 1890 was 300,000; in 2004, it reached 24 million.

"We can definitely track the explosion in tick populations by following the deer," says Dr. Edward Breitschwerdt, professor of medicine and infectious diseases at North Carolina State University College of Veterinary Medicine, Raleigh. "The deer have also been responsible for relocating ticks; a racoon might travel a few miles in a lifetime; deer travel much farther." Breitschwerdt says some deer species once found exclusively in the south are now turning up as far north as Minnesota.

Dogs are also importing ticks. Chicagoans going to Wisconsin or New Yorkers heading upstate with their pooches for the weekend may return with a souvenir tick or two. The then ticks drop off in a local park or in your own backyard. A single tick can lay thousands of eggs.

"This is all a changing dynamic," says Dryden. "The bottom line is that pets who didn't previously require protection now need it."

Breitschwerdt and his team of researchers have confirmed what they have suspected for some time: A tick may bite and then infect a dog with several disease pathogens all at once. The dog who has to fight off Lyme disease might do so effectively and have no symptoms. But add a second pathogen, such as the nasty-sounding Anaplasma phagocytophylum, and even healthy dogs can have a far more difficult time.

There are dozens of tick species in America and 15 different tick-transmitted diseases. Two more tick diseases commonly affecting dogs are ehrlichiosis and Rocky Mountain spotted fever.

The news isn't all bad. For one thing, veterinarians will soon have a single blood test that can determine if a dog has three tick-borne diseases (anaplasmosis, Lyme disease and ehrlichiosis canis), as well detect mosquito-carrying heartworm disease.

If your vet doesn't use this tests detecting tick-borne diseases might be tricky.

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