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  • Dr. Hilary Jones

Heartworm Disease in Pets

What is Heartworm Disease?

Heartworm disease is a potentially fatal disease that can affect the heart, lungs and blood vessels. It can be found in dogs, cats and some other domesticated and wild animals. It is caused by a parasite called Dirofilaria immitis. If our pets are bitten by a mosquito carrying this parasite, it can be transmitted to our pets bloodstream during the meal.

How is Heartworm Diagnosed?

There is a blood test that is often performed at your pet’s yearly exam. These tests check for the antigen produced by the parasite. Heartworm tests are not performed on pets typically until 1 year of age. This is based on the parasite's life cycle as well as how the test works. It takes about 6 months of infection to be detected. It is recommended that even if you are diligent with your heartworm preventative that your pet be tested every year.

Signs of Heartworm Disease

In early stages of heartworm disease most dogs do not show any symptoms at all. As it progresses your pet may start to show more signs:

  • Chronic coughing

  • Lethargy

  • Reluctance to exercise

  • Decreased appetite

  • Weight loss

  • If the burden of heartworms increase and the disease progresses past the previous symptoms you may notice

  • Swollen belly from excess fluid in their abdomen

  • A diagnosis of heart disease

  • Sudden onset of labored breathing and pale gums

  • Bloody urine

Preventing Heartworm Disease

Speaking with a veterinarian is the first step. There are many different options of heartworm preventative on the market. Your vet can help you navigate which is best for you and your pet.

Most heartworm preventative is a monthly medication that is recommended to be given every 30 days.

Even pets that are considered to be "indoor" pets can get this disease. Mosquitoes can enter your home and bite your pets.

How to Manage if Your Pet is Heartworm Positive

Your veterinarian will first put your pet on a course of antibiotics and a heartworm preventative to lessen the burden of the immature worms.

During this time further testing will be done that includes

  • radiographs-to check for any damage to the heart or lungs

  • blood work to be sure there aren't any secondary infections or issues with any other organs

  • Urine tests to be sure that they don't have any blood in their urine or an infection

After these tests are performed your pet will most likely receive several injections spaced out over several weeks/months with a medication called Immiticide that will kill the heartworms. During this time your pet will continue with antibiotics and heartworm prevention. Your pet will need to be kept quiet for 1-3 months while the heartworms fade. Any excess activity can cause heart issues, allergic reaction (anaphylaxis), lethargy and respiratory distress.

Six months after treatment finishes, your veterinarian may want to run another heartworm test to check to be sure that the parasite has cleared.

The best thing that you can do for your pet is maintain them on a monthly preventative to prevent this disease. It is much safer and less stressful for your pet than the treatment, and much less expensive for you!


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