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Health & Care


What Is Heartworm?

Unfortunately, it's as scary as it sounds: worms that live in your dog's heart! Heartworm disease can readily kill dogs, but it's also readily preventable.

How Do Dogs Get Heartworm?

Mosquitoes transmit the disease to dogs by injecting tiny heartworm larvae into their skin.

The larvae develop in the tissues and migrate to the heart where they grow into adult worms.

The adults live in the heart and the large blood vessels surrounding the heart.

They reproduce and release more larval offspring into the dog's blood stream.

These larvae can then be taken by a mosquito and transmitted to another dog or cat.

What Are Signs My Dog May Have Heartworm?

Due to the stress that adult worms have on a dog's heart, there are often clinical signs of heart disease or heart failure such as:

  • Lethargy
  • Tiring easily with exercise
  • Coughing
  • Loss of appetite
  • Enlarged abdomen

How Do Vets Check For Heartworm?

  • A blood test to see if adult heartworms or their offspring are present
  • Chest radiographs and ultrasound may also be used

How Can I Treat Heartworm?

Heartworm can be treated, but it carries risks for your dog and there are no guarantees of success. Your dog may need a series of arsenic-based injections or even surgery to remove the adult worms from their heart. As with most of these sorts of things, prevention is better than cure.

When Should I Start My Puppy On A Heartworm Prevention Program?

Start within the first few months of their life.

Additional Information

To download a fact sheet about heartworm disease, click here.

Companion Animal Parasite Council

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