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Heartworm Prevention

Heartworm disease is a serious and potentially fatal disease in pets in the United States and many other parts of the world. Heartworm disease is spread by mosquitoes that bite your pet. In Texas, heartworm disease is more common due to the weather conditions that provide a perfect environment for mosquitoes and this disease to spread.

The disease originates when the mosquito bites your pet and leaves immature heartworms under the skin.  These immature heartworms take months to develop into adult heartworms in your dog’s heart and pulmonary vessels.  Heartworm disease affects dogs, cats and ferrets, but heartworms also live in other mammal species.  The worms can grow to be a foot-long and 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 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.

According to the American Heartworm Society, annual testing is an integral part of ensuring that prevention is achieved and maintained.  Should an infection be diagnosed, more timely treatment can be provided to minimize the disease process.

Some heartworm preventatives can be detrimental to a pet that has undetected heartworm disease.  These pets are at risk for having an anaphylactic reaction which could be fatal.  Therefore, we strongly recommend annual physical examinations and heartworm test for patients before prescribing heartworm prevention.

Why do we test annually?

Every heartworm prevention currently marketed in every form of administration (oral, topical, or injectable) is not 100% perfect. It is important to monitor a pet’s status to prevent the disease instead of reacting and treating a serious condition.  Additionally, many factors play a role in the success of the prevention including:

  • It wasn’t absorbed properly
  • It wasn’t applied properly
  • It wasn’t chewed
  • The pet vomited
  • Heartworm resistance
  • Pet parent forgot to give the medication


While heartworms are one of the most damaging and dangerous parasites, they are also almost entirely preventable with regular testing and year-round use of preventive medications. Pets that have this disease may not show any signs for years. For this reason, prevention is by far the best option.

ZippiVet offers options for heartworm prevention for both cats and dogs.  Please discuss this disease and your pet’s risk with your veterinarian.

In the event that your pet is positive for heartworms, ZippiVet veterinarians will formulate a treatment plan guided by the American Heartworm Society Guidelines. You can find more information about Heartworm Disease and Testing on the American Heartworm Society website at https://www.heartwormsociety.org.

For additional questions, speak with our veterinary professionals by contacting us online or calling (512) 596-3749.

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