Heartworm cases up, veterinarians worried

Marty, a golden retriever who was once infected with heartworms, gazes lovingly at his owner.

More dogs in Oregon are contracting heartworm, a deadly parasite that veterinarians say used to be relatively rare in the state.

According to data compiled by the Companion Animal Parasite Council, 193 dogs in Oregon tested positive for heartworm in 2016. That’s compared to just 128 cases in 2012.

Five years ago, most of Oregon’s cases were in the southern part of the state, particularly in Josephine County, where nearly a third of the cases were diagnosed.

Last year, although heartworm continued to be prevalent in Josephine County, there were a lot more cases reported in the Portland-metro area.

Washington County, for example, saw 40 heartworm cases last year, a number that has been steadily increasing since 2012, when the county only saw six cases.

Oregon’s State Public Health Veterinarian, Dr. Emilio DeBess, is worried about the spread of the parasite.

“It’s no longer localized to a particular area of the state,” DeBess said. “It should be a concern for everybody.”

Heartworms can cause permanent and deadly damage to a dog’s heart and lungs. They are spread through mosquitoes, which can ingest baby worms by biting a dog, and spread them to another animal with their next bite.

DeBess said global warming (warmer summers in particular) has made the Pacific Northwest a more hospitable area for mosquitoes over the past decade, and that is likely why Oregon is seeing more heartworm cases crop up.

Dr. Ariel Grubb, the medical director at VCA Raleigh Hills, agrees.

“I actually found a mosquito in my own bathroom this winter in Portland, and that’s concerning because indoor dogs and cats are at risk," Grubb said.

She warns that heartworm can be hard to spot in dogs.

“A lot of times [heartworm] can go undetected until there’s multiple heartworms living in the heart,” Grubb said.

She said symptoms to watch for include coughing, getting winded easily, and weight loss.

Grubb said she has personally seen two cases of heartworm over the past couple years.

“When I went to vet school, which was not too long ago, we were told heartworm really didn’t exist in the Northwest," Grubb said.

Treating a dog that has heartworm, she said, is not easy.

“Treatment involves a series of injections that slowly kill off the adult worm," Grubb said. “Those injections are painful. They’re not cheap.”

Instead, she recommends talking to your veterinarian about preventative heartworm medication, which she said can be as cheap as $30.

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