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Article by Dr. Nancy Kay, DVM | Found on PetHealthNetwork

If ever there was a year to be vigilant about heartworm prevention, this is it. The number of dogs and cats diagnosed with heartworm disease within the United States is expected to increase this year because of above-average precipitation and temperatures. These are ideal conditions for the propagation of mosquitoes that transmit heartworms to our pets. 

The nonprofit organization, Companion Animal Parasite Council (CAPC), tracks trends for various infectious diseases within the United States, including heartworm disease, Lyme disease, anaplasmosis, and ehrlichiosis. A CAPC announcement released earlier this year states, “Given the ongoing trend toward above average temperatures and rainfall, CAPC is forecasting high levels of heartworm disease activity in 2017 for most of the country, with an especially active year for the Western United States.”

Geography of heartworm disease
According to an American Heartworm Society survey, the number of cases of heartworm disease seen per veterinary clinic was 22 percent higher in 2016 than in 2013. The five states with the highest incidence of heartworm infections in 2016 were, in order:

  • Mississippi
  • Louisiana
  • Arkansas
  • Texas
  • Tennessee

The CAPC is predicting more heartworm disease this year in the lower Mississippi Valley as well as in the Rockies and westward. The incidence is also expected to be higher than usual in the Upper Midwest, the Ohio River Valley, New England, and the Atlantic Coast States. Interestingly, the CAPC predicts that West Texas, from Amarillo to Laredo is expected to have no increase and may have a decline in heartworm disease cases. (Texas readers, please do not take this is an invitation to back off on heartworm prevention!)

What this means for you and your pets
Don’t forget to keep up with your heartworm prevention medication for your dogs and cats.

Heartworm infection is a “poster disease” for the old adage, “An ounce of prevention is worth a pound of cure.” Treatment of heartworm disease is risky, pricey, and quite miserable for both pet and pet caretaker. A pet who isn’t treated for heartworm disease experiences some pretty darned awful symptoms, along with a significantly decreased life expectancy.

There used to be areas within the United States considered to be “safe zones” where heartworm disease didn’t exist and prevention wasn’t necessary. This is no longer the case. Heartworm disease has been diagnosed in all 50 states.

If you aren’t already giving your dog or cat heartworm prevention medication, consult with your veterinarian right away to get the ball rolling. The first thing your pet will need is a heartworm test to make sure that infection hasn’t already occurred. Keep in mind that animals typically show no symptoms of this disease for the first six months or more following infection.

If you’ve been giving preventive medication to your pet, but not on a regular basis, it’s time to create a reminder system. Talk with your veterinarian about whether or not heartworm testing is warranted to make sure that a heartworm-carrying mosquito didn’t sneak up on your pet during a lapse in medication.

The American Heartworm Society website provides a great resource should you want to learn more about heartworm disease.


Laurelwood Animal Hospital,located near Jesuit High School on Beaverton-Hillsdale Highway offers a full range of companion animal services, including surgery, nutrition and behavior counseling, parasite control and preventative medicine. The hospital also offers advanced imaging through an all-digital spiral CT scanner, a comprehensive dental program and laser treatment.

If you’re looking for quality, compassionate veterinary care in Beaverton, Oregon, come visit us at Laurelwood Animal Hospital.

Laurelwood Animal Hospital

9315 SW Beaverton-Hillsdale Highway
Beaverton, Oregon 97005

Phone: (971) 244-4230
Fax: (503) 292-6808

E-mail: [email protected]