The Rise of Heartworm Disease & Jet City’s Plan for Prevention!

Hello Medical Family of Jet City Animal Clinic –

Heartworm disease is on the rise here in Washington!  Heartworm disease is a serious and potentially fatal disease in pets in the United States and many other parts of the world. It is caused by foot-long worms (heartworms) that live in the heart, lungs and associated blood vessels of affected pets, causing severe lung disease, heart failure and damage to other organs in the body. Heartworm disease affects dogs, cats and ferrets, but heartworms also live in other mammal species, including wolves, coyotes, foxes, sea lions and—in rare instances—humans. Because wild species such as foxes and coyotes live in proximity to many urban areas, they are considered important carriers of the disease.

Dogs. The dog is a natural host for heartworms, which means that heartworms that live inside the dog mature into adults, mate and produce offspring. If untreated, their numbers can increase, and dogs have been known to harbor several hundred worms in their bodies. Heartworm disease causes lasting damage to the heart, lungs and arteries, and can affect the dog’s health and quality of life long after the parasites are gone. For this reason, heartworm prevention for dogs is by far the best option, and treatment—when needed—should be administered as early in the course of the disease as possible. Learn more about heartworm medicine for dogs. (1)

Cats. Heartworm disease in cats is very different from heartworm disease in dogs. The cat is an atypical host for heartworms, and most worms in cats do not survive to the adult stage. Cats with adult heartworms typically have just one to three worms, and many cats affected by heartworms have no adult worms. While this means heartworm disease often goes undiagnosed in cats, it’s important to understand that even immature worms cause real damage in the form of a condition known as heartworm associated respiratory disease (HARD). Moreover, the medication used to treat heartworm infections in dogs cannot be used in cats, so prevention is the only means of protecting cats from the effects of heartworm disease. (1)

When hurricane Katrina hit the Gulf Coast, many of the dogs from that region were surrendered to shelters and adopted across the country – many of these dogs had heartworm disease.  This unfortunate circumstance caused heartworm disease to be spread around the country and since 2005 it has been steadily increasing everywhere.  We have the right species of mosquito here in Washington and until the past few years, there hasn’t been enough heartworm positive dogs for the mosquitos to pick it up from.  However – with more folks adopting dogs from Heartworm endemic areas – it is definitely becoming a problem. Climate change is also impacting our heartworm problem – mosquito season is longer and more intense.

We have increased our heartworm testing in May and June and have already found FOUR positive dogs!  This is dismaying to say the least. Because of this we are changing our heartworm policy to follow the American Heartworm Association’s recommendations. This may be surprising and frustration for many of our clients as we will no longer be filling heartworm prescriptions without a current test and will require 6 month following up testing if a dog has been off heartworm prevention for more than 2 months.  We promise we are not trying to hassle you – only to help you provide the best protection from this devastating disease as possible.

Jet City Animal Clinic’s Updated Heartworm Policy
(based on recommendations from the American Heartworm Assocation)

1 – All dogs, whether on preventative or not should be tested annually.  Annual testing is necessary, even when dogs are on heartworm prevention year-round, to ensure that the prevention program is working. Heartworm medications are highly effective, but dogs can still become infected. If you miss just one dose of a monthly medication—or give it late—it can leave your dog unprotected. Even if you give the medication as recommended, your dog may spit out or vomit a heartworm pill—or rub off a topical medication. Heartworm preventives are highly effective, but not 100 percent effective. If you don’t get your dog test, you won’t know your dog needs treatment. (1)

2 – Puppies under 7 months of age can be started on heartworm prevention without a heartworm test (it takes at least 6 months for a dog to test positive after it has been infected), but should be tested 6 months after your initial visit, tested again 6 months later and yearly after that to ensure they are heartworm-free.

3 – Adult dogs over 7 months of age and previously not on a preventive need to be tested prior to starting heartworm prevention.  They, too, need to be tested 6 months and 12 months later and annually after that. The reason for re-testing is that heartworms must be approximately 7 months old before the infection can be diagnosed.

4 – Any cat that is coughing should be heart worm tested.  Heartworm infection in cats is harder to detect than in dogs, because cats are much less likely than dogs to have adult heartworms. The preferred method for screening cats includes the use of both an antigen and an antibody test (the “antibody” test detects exposure to heartworm larvae). Your veterinarian may also use x-rays or ultrasound to look for heartworm infection. Cats should be tested before being put on prevention and re-tested as the veterinarian deems appropriate to document continued exposure and risk. Because there is no approved treatment for heartworm infection in cats, prevention is critical. Revolution is the current heartworm prevention recommended for cats -both indoor and esp outdoor cats.  Revolution will also protect your cat from fleas, ticks, ear mites, roundworms and hookworms.

We encourage you to explore the American Heartworm Associations
information website –

Please contact our team if you have questions and/or want to get your pet scheduled for a heartworm test.  Thank you for your patience while we update our protocols to help you take the best possible care of your pets!

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Shana Kitchen | Associate Veterinarian


Category: News

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