While the number of incidences is low in Arizona, if you live in America’s Grand Canyon state, it is possible for your pet to get heartworms. Heartworm disease is now found in all 50 states and Canada. Check out this map to see heartworm incidence rates all over the country. And since April is National Heartworm Awareness Month, our vets at Anasazi Animal Clinic in Gilbert want to take this opportunity to talk about heartworm prevention in Arizona.

What Is Heartworm Disease?

Heartworm disease is caused by the mosquito-borne parasite Dirofilaria immitis. The mature heartworm lives in the heart and pulmonary arteries of infected pets and can grow up to 12 inches long. All it takes is one mosquito bite to transmit heartworm to pets, and an infected pet could experience permanent organ damage or even death.


In dogs, a diagnosis is usually made with a combination of blood tests. Cats are more difficult to diagnose. While they are an atypical host for heartworms, even a few worms present in a cat can cause heartworm-associated respiratory distress (HARD) and other life threatening complications.

Signs of Heartworm Disease

The signs of heartworm disease may be subtle at first and can often look like symptoms of other diseases. For these reasons, diagnosis is rarely made based on clinical signs.

Signs of heartworm in dogs:

  • Soft, dry cough
  • Exercise intolerance
  • Lethargy
  • Weight loss
  • Rapid breathing
  • Bulging chest
  • Collapse

Signs of heartworm in cats:

  • Wheezing
  • Sudden onset cough
  • Rapid breathing
  • Vomiting
  • Weight loss
  • Sudden death

Treatment of Heartworm Disease

Treatment for heartworm disease in dogs consists of injections that kill the adult worms over a period of several weeks. Due to the risk of complications, most dogs need to be hospitalized for monitoring after receiving the injections. And all infected dogs need to be on exercise restriction once at home, to reduce these risks during the course of the treatment. Dogs with no signs—or mild signs of heartworm disease, such as cough or exercise intolerance—have a much higher chance of being successfully treated. Dogs with more severe heartworm disease can also be successfully treated, but they face the possibility of more complications.

Unfortunately, the same drug used for dogs has not been approved for use in cats. It can cause serious side effects in cats, including pulmonary failure and death. Options to treat the symptoms in cats include a combination of oxygen therapy, corticosteroids, and other medications as needed. Surgical removal of heartworms is a relatively new treatment option that may become more common in the future.

Prevention is the Best Medicine

Year-round protection against heartworm is essential. Once you and your vet choose a preventive medication, it’s important that you give it to your pet on schedule. Microfilariae take about 51 days to mature to the adult worm stage, and it’s critical to interrupt this process every month to avoid organ damage and other serious complications of the disease. Regardless of what you may have read or heard, there are no “natural” products that are effective for prevention or treatment of heartworm disease. Always use FDA-approved products recommended by our vets at Anasazi Animal Clinic.

Prevention is simple, effective, and much cheaper when compared with the costs and risks of treating heartworm disease. If you have further questions or concerns about heartworm prevention in Arizona, please don’t hesitate to make an appointment with us. At Anasazi Animal Clinic, we understand how much your pets mean to you, which is why we want them to be healthy. Heartworm prevention is an essential part of keeping them both healthy and happy.

Image by JacLou DL from Pixabay