Heartworm in Dogs: Prevention, Treatment, and Insurance Coverage

Yes, pet insurance can help cover heartworm treatment costs if heartworm is not a pre-existing condition and the waiting period has passed. According to PetMD¹, treatment typically costs $600-$3,000+ depending on severity—but prevention typically costs just $16/month. Spot Pet Insurance plans offer up to 90% reimbursement on eligible veterinary expenses, including heartworm diagnosis and treatment.

What Is Heartworm Disease?

Heartworms are parasitic worms called Dirofilaria immitis that can grow up to a foot long. According to the American Heartworm Society³, heartworms are transmitted through infected mosquito bites. Once inside a pet’s body, the larvae migrate through tissue and develop into adults over approximately 6-7 months.

Adult heartworms lodge in the blood vessels serving the heart and lungs, causing inflammation and potentially leading to heart failure. The AVMA reports⁴ that heartworm incidence continues climbing despite preventive efforts, making awareness and prevention critical for pet parents.

Heartworms in Dogs vs. Cats

Heartworms in Dogs

Dogs are natural hosts for heartworms, allowing the parasites to thrive and reproduce.³ Without treatment, a single dog can harbor several hundred worms. Adult heartworms survive 5-7 years in dogs, causing progressive damage to the heart, lungs, and arteries.

Key facts about heartworm in dogs:

Learn more about heartworm treatment costs for dogs.

Heartworms in Cats

Unlike dogs, cats are not natural hosts for heartworms.³ Most heartworms don’t survive to adulthood in cats, which is why feline heartworm disease is frequently misdiagnosed. However, even immature worms cause serious complications.

Cats face unique risks including:

Because cats cannot be safely treated for adult heartworms, prevention is even more important than for dogs.

Signs and Symptoms of Heartworm in Dogs

Heartworm symptoms depend on infection severity and which organs are affected. According to PetMD⁵, many dogs show few or no symptoms in early stages, making regular testing essential.

Early-stage symptoms: - Mild persistent cough - Decreased appetite - Mild weight loss - Reluctance to exercise

Advanced-stage symptoms: - Severe coughing - Exercise intolerance - Fatigue after mild activity - Difficulty breathing - Pale or bluish gums

Caval syndrome (severe infestation): - Sudden collapse - Labored breathing - Dark or coffee-colored urine - Abdominal swelling from fluid accumulation

Caval syndrome requires emergency surgical intervention and can be fatal within days if untreated.

How Is Heartworm Diagnosed?

Veterinarians diagnose heartworm through blood tests and imaging:

The American Heartworm Society recommends annual testing for all dogs, even those on prevention. Puppies should be tested at 6 months, again at 12 months, then annually thereafter.³

Heartworm Treatment for Dogs

Treatment is a multi-step process that can take several months. According to PetMD¹, the standard protocol includes:

1. Stabilization Dogs with severe infections may need stabilization before treatment can begin safely. This may include medications to reduce inflammation and improve heart function.

2. Antibiotics A 30-day course of doxycycline targets Wolbachia, a bacteria living inside heartworms. Eliminating this bacteria weakens the worms and reduces inflammation when they die.

3. Melarsomine Injections The FDA-approved treatment involves a series of 3 deep muscle injections administered over several weeks. The medication kills adult heartworms, which are then absorbed by the body.

4. Activity Restriction This is crucial—physical activity increases the risk of dead worms causing blockages. Dogs must remain confined and calm for 6-8 weeks during and after treatment.

5. Preventive Medication Monthly preventives stop new infections while treatment addresses existing worms.

Learn more about heartworm prevention and treatment.

How Much Does Heartworm Treatment Cost?

Heartworm treatment costs vary significantly based on infection severity, dog size, and geographic location. According to PetMD¹:

Dogs with caval syndrome may not be candidates for standard treatment and require emergency surgery to physically remove worms from the heart.

Heartworm Prevention: A Cost-Effective Alternative

According to CareCredit², monthly heartworm prevention costs approximately $16—making annual prevention around $192 compared to treatment costs of $600-$3,000+.

Prevention options include: - Monthly chewable tablets - Monthly topical applications - Injectable preventives (every 6-12 months)

The American Heartworm Society advocates “Think 12”—testing every 12 months and providing prevention for all 12 months of the year, regardless of geographic location.³

Why year-round prevention matters: - Mosquitoes can survive indoors during winter - Climate variability makes seasonal prediction unreliable - A single missed dose creates vulnerability - Year-round compliance is easier to maintain than seasonal

Can Pet Insurance Help Cover Heartworm Treatment?

Yes, pet insurance can help cover heartworm treatment expenses—with important conditions:

What Spot Pet Insurance Plans Cover

Spot’s accident and illness plans can help cover eligible heartworm treatment costs, including:

Spot plans offer customizable coverage with:

Learn more about what pet insurance covers.

When Heartworm Treatment Is NOT Covered

Heartworm will not be covered if it’s considered a pre-existing condition—meaning your pet showed signs, symptoms, or was diagnosed before coverage began or during the waiting period.

Important timing considerations: - Spot’s standard waiting period is 14 days for illnesses - Any symptoms observed during the waiting period may be excluded - Regular testing BEFORE enrolling helps establish baseline health

The best approach: enroll your pet in insurance while healthy, maintain regular veterinary testing, and keep up with monthly prevention.

Can Pet Insurance Help Cover Heartworm Prevention?

Standard accident and illness plans typically do not cover routine prevention. However, Spot’s optional preventive care add-ons can help cover eligible wellness expenses including:

Learn more about preventive care coverage options.

Frequently Asked Questions

How long can a dog live with heartworms?

Without treatment, heartworm disease is often fatal. Adult worms can survive 5-7 years in dogs, progressively damaging the heart and lungs.³ With treatment, most dogs with mild to moderate infections recover, though some permanent damage may occur.

Can heartworm be cured completely?

Yes, most dogs can be cleared of heartworm infection with proper treatment. However, the damage caused by heartworms (to the heart, lungs, and blood vessels) may not be fully reversible, especially in severe cases.

Is heartworm testing covered by pet insurance?

Diagnostic testing for heartworm is typically covered when performed to diagnose a suspected illness. Routine annual screening may be covered under preventive care add-ons but not standard accident and illness plans.

How soon after getting pet insurance is heartworm covered?

After Spot’s 14-day illness waiting period, new heartworm infections would be eligible for coverage. Infections diagnosed during or before the waiting period would be considered pre-existing.

Should I get my dog tested before buying pet insurance?

Yes. A clean bill of health before enrollment ensures that conditions like heartworm won’t be classified as pre-existing. Regular testing also catches infections early when treatment is less complicated and less expensive.