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Pet parasite infiltrates area

Liberty Lake Animal Clinic veterinarian Marni Quist gives Chester, a Yorkshire terrier mix, a checkup Friday. The clinic recently found a dog and two cats infected with heartworm. (Christopher Anderson / The Spokesman-Review)
By Kandis Carper kandisc@spokesman.com
Liberty Lake Animal Clinic veterinarian Marni Quist gives Chester, a Yorkshire terrier mix, a checkup Friday. The clinic recently found a dog and two cats infected with heartworm. (Christopher Anderson / The Spokesman-Review)

A deadly parasite that kills dogs and cats may have found its way to the Inland Northwest.

Heartworm, a parasitic roundworm spread between animals by mosquitoes, has been discovered in three pets by a Liberty Lake veterinarian. The dog and two cats have never been outside of the Liberty Lake area, which suggests they were infected here.

Now, the Animal Clinic at Liberty Lake is alerting veterinarians throughout the region.

Heartworm afflicts dogs, cats, coyotes, wolves and some other animals, usually in warm weather climates.

Hurricane Katrina dogs, brought here for adoption, may have brought heartworms with them, said Marni Quist, a veterinarian at the clinic.

“It’s present in the area and we never thought it was before. It’s a new condition that we need to be aware of and take the necessary steps to prevent more cases. We’ve got a lot of dogs in the area that have never been exposed before and aren’t on any medication to try to prevent that from happening,” said Quist.

There are three species of mosquitoes in the area that can carry and transmit heartworm, according to Ron Wohrle, the Washington State Department of Health veterinarian. This was discovered through a West Nile virus mosquito survey.

The mosquitoes feed on an infected dog or cat and ingest the baby worms from the infected animal’s bloodstream, and the next dog or cat that the mosquito bites also becomes infected.

The baby worms travel through the bloodstream and become adult worms and settle in the right side of the heart.

“Dogs can have dozens of worms, and those worms can get big – like 10 inches long, so the blood doesn’t flow normally and the dog goes into heart failure. In dogs you’ll see coughing and exercise intolerance,” said Quist.

Cats are usually more resistant because of their immune system. They have a smaller heart and usually just one or two worms, but may also go into heart failure. In cats you’ll see vomiting, said Quist.

An out-of-town laboratory, ANTECH, is being credited with discovery of the local heartworm cases. The lab is used by the Liberty Lake veterinarian, and routinely tests for heartworm even though it has not been a problem in the Pacific Northwest.

Liberty Lake veterinarian Mark Fosberg said he doesn’t know if this is just a Liberty Lake problem or if the region now is at risk.

What can pet owners do to prevent heartworms?

If you have a puppy or kitten that’s less than 6 months old, get it started on heartworm prevention medication through your veterinarian.

If pets are more than 6 months old, they have to be tested to make sure they aren’t already infected. This is generally an inexpensive test.

If the test is negative, start them on preventive medication. This will kill any baby worms that might get into their bloodstream through a heartworm-carrying mosquito bite.

“If the test is positive, there is a drug for dogs that will kill adult worms, but it’s very expensive ($1,000-$2,000) and it’s very dangerous to treat those adult worms. For cats, there’s no effective drug to kill adult worms,” said Quist.