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Heartworm 101

You’ve probably heard of heartworms, but did you know that heartworms really are worms that live in your dog’s heart? That’s right, dogs with heartworm disease can have worms up to a foot long living in their lungs and heart.

Heartworms in a dog's heart

Photo courtesy of Dr. Joe Hostetler

You’re probably not surprised that this can cause some serious, life-threatening health problems. Fortunately, there are ways to prevent heartworms in dogs. The first step is understanding how infection happens.

How do dogs get heartworms?

When a mosquito bites and feeds on a heartworm-positive dog, it inadvertently ingests baby heartworms, called microfilariae, circulating in the bloodstream. Once the babies are in the mosquito, they grow and develop into larvae. When that mosquito bites another dog, it can pass on these infective larvae. Once a dog is infected, these tiny larvae grow and develop into adult heartworms that live in your dog's lungs and heart, leading to severe consequences and even death if not treated.

Signs of heartworm disease

Even though adult heartworms can cause some big problems, your dog might not show symptoms or illness right away. Eventually you may notice these symptoms of heartworm disease in your dog: fatigue, loss of body condition, a persistent cough and difficulty breathing. As time passes, cardiopulmonary disease, heart failure and kidney disease are possible.

Testing and treatment

To help avoid illness, the American Heartworm Society (AHS) recommends that all dogs are treated with heartworm prevention and that puppies are started on prevention as early as possible and no later than 8 weeks of age. The AHS also recommends all dogs and puppies, even those currently on heartworm prevention, are tested for infection once a year.

Your veterinarian will test a blood sample for the presence of heartworms. Heartworm disease is a serious and progressive illness, and the earlier it’s detected and treated, the better chance dogs have of surviving and limiting permanent damage to their lungs and heart. If your dog tests positive, treatment is expensive and can come with risk. However, treatment will be necessary to save your dog’s life.

What's the key? Prevention

Prevention is the best medicine. Thankfully, there are safe and effective ways to prevent heartworm disease. Ask your veterinarian how to get a prescription for your dog.

Bayer Products

  • Advantage Multi® for Dogs (imidacloprid + moxidectin) packaging

    Advantage Multi® for Dogs (imidacloprid + moxidectin)

    An all-in-one monthly topical that prevents heartworm disease, kills adult fleas and treats roundworms, hookworms and whipworms.

    Advantage Multi® for Dogs (imidacloprid + moxidectin)

    Indicated for:

    HEARTWORMS
    HEARTWORMS
    FLEAS
    FLEAS
    ROUNDWORMS
    ROUNDWORMS
    HOOKWORMS
    HOOKWORMS
    WHIPWORMS
    WHIPWORMS
    SARCOPTIC MANGE
    SARCOPTIC MANGE
    MICROFILARIAE
    MICROFILARIAE

    CAUTION: Federal (U.S.A.) law restricts Advantage Multi® for Dogs (imidacloprid + moxidectin) to use by or on the order of a licensed veterinarian.

  • Advantage® Treatment Shampoo for dogs & puppies.

    Advantage® Treatment Shampoo for dogs & puppies

    A treatment shampoo that kills fleas and ticks on contact.

    Advantage® Treatment Shampoo for dogs & puppies

    Indicated for:

    FLEAS
    FLEAS
    TICKS
    TICKS

  • Advantage<sup>®</sup> Household Spot and Crevice Spray

    Advantage® Household Spot and Crevice Spray

    Kills fleas, dust mites and brown dog ticks in hard-to-reach places in your home.

    Not for use on pets. Use as directed.

    Advantage® Household Spot and Crevice Spray

    Indicated for:

    FLEAS
    FLEAS
    BROWN DOG TICKS
    BROWN DOG TICKS
    DUST MITES
    DUST MITES
    BED BUGS
    BED BUGS