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Heartworm Treatment: Costs, Coverage, and FAQs Explained

Heartworm disease is a scary condition for any pet parent, especially in advanced stages. While treatment costs can quickly skyrocket beyond a few hundred dollars, many pet insurance plans offer coverage. However, this coverage varies based on the specifics of your policy and provider, so be sure to check yours for more information. Heartworm disease can be avoided by year-round prevention and yearly blood tests.

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What are heartworms in pets?

Heartworm disease in pets is caused by a large parasitic worm called Dirofilaria immitis. The parasite requires an intermediate host — mosquitos — to transmit the parasite from one infected animal to another. When a mosquito bites an infected animal, it picks up the heartworm microfilariae as it feeds.

life cycle of heartworms

The microfilariae develop into larvae within the mosquito, triggering the infective stage of the heartworm’s life cycle. When the infected mosquito feeds on other animals, it transmits those larvae to the healthy animal.

In the new, healthy host, the larvae move through the bloodstream until they reach the heart and pulmonary arteries. The larvae reside in these areas, growing substantially over the next six to seven months, maturing into adults, and producing more microfilaria through mating. Heartworms can grow up to 12 inches in length as they mature and can live for several years. Their presence causes physical damage as well as triggers a significant inflammatory response.

Stages of heartworm disease in pets

There are three primary stages of heartworm disease in pets:

  • Stage one is considered mild heartworm disease and often involves a low number of worms. Some pets may show no symptoms during this stage.
  • Stage two is considered mild to moderate and often brings early signs of the disease, such as coughing, weakness, and exercise intolerance.
  • Stage three is considered severe and often involves serious, potentially life-threatening symptoms, such as labored breathing, coughing, abdominal enlargement, anemia, and heart failure.

Heartworm disease in pets: symptoms

Dogs infected with heartworms often display multiple common symptoms, which may include:

  • Mild but persistent coughing
  • Exercise intolerance
  • Decreased appetite
  • Weight loss

In later stages of the disease, symptoms in dogs may include:

  • Labored breathing
  • Spitting up blood
  • Fainting or collapse
  • Accumulation of fluid in the abdominal cavity due to heart failure
  • Caval syndrome — a life-threatening complication characterized by labored breathing, pale gums, and dark or coffee-colored urine

In cats, heartworm disease may cause coughing, difficulty breathing, vomiting, loss of appetite, and weight loss.

If you notice any of these symptoms with your pet or any abnormal behavior that could indicate heartworm disease, contact your veterinarian as soon as possible. Oftentimes, heartworm disease doesn’t produce symptoms in pets until the mid to later stages, which can be serious and, in some cases, fatal.

So, it’s important to schedule an appointment with your veterinarian immediately to rule out heartworm disease. Catching the disease in the early stages can make a world of difference for your pet, as the worms often cause significant damage to vital organs as they mature. Even better — talk to your vet about year-round prevention.

Tips to prevent heartworm disease in pets

In pets, heartworm disease can be a severe and potentially life-threatening condition, so proper preventative methods are critical. While treatments to combat the disease are available, they’re not 100% successful, especially in advanced cases.

Fortunately, heartworm prevention is simple and effective. Most veterinarians offer medications to protect your pet from heartworms, including topical treatments, chewable tablets, and injections. These medications work by killing the immature heartworms that your pet may have been exposed to before they can develop into adult worms and cause damage.

Beyond medication, you can take steps to reduce your pet’s risk of heartworm disease by minimizing their exposure to mosquitoes. Keep them inside during peak mosquito season and use mosquito repellents formulated for pets when going out. Additionally, eliminate standing water around your home, as mosquitoes breed in stagnant water.

It also doesn’t hurt to schedule regular vet check-ups for routine testing. Veterinarians typically recommend testing your animal for heartworm disease with a simple blood test once a year, even if they are on prevention. Sometimes, these blood tests also screen for tick diseases, such as Lyme’s, Ehrlichia, and Anaplasma.

Taking a few simple precautionary measures can go a long way for your pet, helping you support their health and happiness for years to come.

Understanding heartworm treatment in pets

If your pet tests positive for heartworms, the first step is to confirm the diagnosis through additional testing, which may include bloodwork, X-rays, and echocardiography (ultrasound of the heart). In the days and weeks following the diagnosis, it’s important to restrict your pet’s exercise, as physical exertion can increase the heartworms’ damage rate on the heart and lungs.

Heartworm treatment in dogs

In dogs, the next step is to stabilize the disease before administering treatment, which can look different for every dog based on their health history. When it’s time to treat your dog, your veterinarian will select a treatment protocol suited to their needs.

The treatment involves a drug called melarsomine dihydrochloride, an arsenical compound, which is administered in a two-dose or three-dose injection protocol to kill adult heartworms. Many veterinarians opt for the three-dose protocol, as it may be safer and more efficient.

The two-dose protocol involves two doses administered 24 hours apart. In the three-dose protocol, the first dose is given, and after a month, the second and third doses are given 24 hours apart.

Other treatment options are available, including prednisone, doxycycline, and the continuation of preventative medications. During all of these treatments, it's important to follow your veterinarian's strict rest instructions to help your pet recover as smoothly as possible.

Heartworm treatment in other pets

Unfortunately, there is no FDA-approved drug for treating heartworms for many household pets, including cats and ferrets. This doesn’t necessarily mean the pet will die, as there are options to help stabilize the animal. Your veterinarian can help determine a suitable plan of action based on your pet’s medical history and the severity of their disease.

Possible side effects of heartworm treatment

Like most medications and treatments, heartworm treatment and the medications involved can present various side effects, including:

  • Soreness and swelling around the injection site
  • Abscess at the injection site
  • Lack of appetite
  • Coughing
  • Spitting up blood
  • Labored or rapid breathing
  • Lethargy
  • Vomiting or diarrhea

Soreness and swelling around the injection site are normal. However, the other side effects can be signs of post-treatment complications. These complications typically stem from a too-active pet after the treatment, as the mass of dying worms can cause problems in dogs that aren’t properly confined to restrict activity. In these instances, cage confinement, oxygen treatment, and drugs to reduce blood clotting and limit inflammation may be necessary.

If you notice any significant or persistent signs in your pet’s behavior, call your veterinarian immediately.

Is heartworm treatment included in pet insurance coverage?

“My dog has heartworms, and I can’t afford the treatment.” It’s a scary thought for any pet parent, regardless of what kind of pet you have or what type of disease your pet is facing. Luckily, most pet insurance providers cover heartworm treatment as long as the disease isn’t a pre-existing condition and doesn’t occur during the waiting period.

If your pet shows signs of or is diagnosed with heartworm disease before purchasing the policy or during the waiting period, your pet insurance policy likely will not cover the cost of treatment.

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Policy types and heartworm coverage

Most pet insurance providers offer several policy options to accommodate varying pet needs and budgets. It’s important to note that pet insurance heartworm coverage can vary based on the policy you have.

For example, if you have an accident-only plan, heartworm treatment will likely fall outside the scope of coverage. Conversely, if you have an accident and illness policy or a similar comprehensive plan, it will likely cover the treatment if the disease isn’t pre-existing.

If you have a wellness or preventative care plan (typically an add-on), which usually covers expenses like vaccines, you may have coverage for heartworm prevention but not heartworm treatment.

There are dozens of pet insurance providers offering various policies with different coverage options. Many pet insurance providers may cover heartworm treatment as long as it isn’t a pre-existing condition and have wellness packages that cover heartworm prevention.

InsurerHeartworm treatment coverage availableHeartworm prevention coverage available
Pets BestNoYes

*Will likely cover heartworm treatment if it isn't a pre-existing condition.

How to find pet insurance that covers heartworm treatment

If you want to ensure you purchase pet insurance that covers heartworm treatment to be on the safe side, check the fine print of each policy you consider. Generally, you’ll find specific exclusions, terms, and conditions in the fine print, and, in some cases, you may find information pertaining to heartworm treatment.

If you can’t find what you’re looking for, contact the insurer directly via phone, email, or other contact options they offer. You can even ask your veterinarian for provider suggestions personalized to your pet’s needs.

How much does heartworm treatment cost?

The cost of heartworm treatment depends on factors specific to you and your pet, including your veterinary clinic, the size of your pet, and the severity of the disease. On average, most pet parents pay between $500 and $1,500 for heartworm treatment.

If your pet insurance policy covers heartworm treatment, your costs may be as little as your deductible plus your coinsurance, if any. Remember to factor in your reimbursement rate, too, as this will also impact the final cost you pay.

For example, suppose heartworm treatment for your dog costs $1,000. Your pet insurance policy has a $250 deductible, no coinsurance, and a 90% reimbursement rate. Your insurer would pay 90% of the remaining $750 after your deductible, which comes out to $675, so your out-of-pocket costs would be $325.

All in all, whether your pet insurance policy will cover heartworm treatment varies based on your policy and pet. While many policies cover heartworm treatment if the disease isn’t a pre-existing condition, there are a few exceptions, so it’s important to check your policy to learn about the coverage that applies to you.


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