How Much Is Heartworm Treatment for Dogs?

Heartworm treatment for dogs is a serious, multi-step process — and not a cheap one. According to PetMD², the total cost of treating a dog with heartworms ranges from approximately $600 to $3,000 or more depending on disease severity, the dog’s size, and your geographic region. Severe cases involving caval syndrome — where worms block blood flow to the heart — can require emergency surgery costing $3,000–$6,000.² Prevention, by contrast, costs $6–$18 per month.

What Are the Symptoms of Heartworms in Dogs?

Many dogs with heartworm disease show no symptoms early on — which is why annual testing matters even for dogs on preventatives. As infection progresses, symptoms tend to worsen with worm burden and time. Signs of heartworm disease include:

If any of these symptoms are present, veterinary evaluation — including a heartworm test — is warranted immediately.

How Is Heartworm Disease Diagnosed?

Veterinarians use a blood antigen test to detect heartworm proteins in the bloodstream. According to PetMD², a standard heartworm antigen test costs $35–$75. If the initial test is positive, confirmatory testing ($20–$40) is typically recommended alongside chest X-rays ($125–$200) and sometimes an echocardiogram ($300–$1,000) to assess disease severity before treatment begins.

For dogs that have been on heartworm prevention, annual testing remains important — no preventative provides 100% protection, and early detection significantly improves treatment outcomes.

How Much Does Heartworm Treatment Cost for Dogs?

Total treatment costs depend on disease stage, the dog’s weight, and the veterinary practice. Based on PetMD², here is a breakdown of typical costs:

Pre-treatment diagnostics:

Treatment medications:

Total standard treatment range: $600–$3,000+²

Dogs with caval syndrome — a severe form in which worm masses obstruct the tricuspid valve — require surgical worm extraction before standard treatment can proceed. This can add $3,000–$6,000² or more to the total cost.

How Are Heartworms Treated? Step-by-Step

According to VCA Animal Hospitals¹, the recommended treatment protocol involves the following stages:

Step 1 — Doxycycline and steroids (30 days): An antibiotic course kills Wolbachia bacteria that live within the heartworms, reducing inflammatory reactions when the worms die. Steroids minimize immune responses during treatment.

Step 2 — First heartworm preventative dose: Administered to kill circulating microfilariae (juvenile heartworms), typically under veterinary supervision in case of reaction.

Step 3 — Melarsomine injections: The primary adulticide treatment. One injection is given first, followed by a 30-day rest period, then two more injections 24 hours apart. Exercise restriction is mandatory from this point forward.

Step 4 — Microfilariae retest (30 days post-final injection): Confirms juvenile worms have been cleared.

Step 5 — Final heartworm test (9 months post-treatment): Verifies that all adult worms have been eliminated.

According to VCA Animal Hospitals¹, more than 95% of dogs treated with this protocol are successfully cleared of heartworms. Dead worms decompose over several weeks to months, and a persistent cough may continue for up to two months after the final injection in heavily infected dogs.

Exercise restriction is non-negotiable. Increased blood flow during exercise causes dead worm fragments to travel to the lungs, raising the risk of pulmonary embolism. Dogs must be kept calm and leash-only throughout the treatment period.

How Much Does Heartworm Prevention Cost?

Monthly heartworm preventatives typically cost $6–$18 per month² depending on the dog’s weight and product. Injectable preventatives (such as ProHeart 6 and ProHeart 12) provide six to twelve months of protection per dose and are available for dogs at least six months old — often at a lower annual cost than monthly tablets for large breeds.

Given that treatment can cost $600–$3,000² or more, prevention is one of the most cost-effective steps pet parents can make. Most preventatives are available through your vet or a licensed online pharmacy with a prescription.

Does Pet Insurance Cover Heartworm Treatment?

Most accident and illness pet insurance plans help cover heartworm treatment when the infection is not a pre-existing condition. For a detailed look at how heartworm treatment and prevention are handled across different plan types, see does pet insurance cover heartworm treatment.

Because heartworm is detectable before symptoms appear, it’s important to enroll in pet insurance before any positive diagnosis. Once a heartworm infection is identified, it typically becomes a pre-existing condition that future policies exclude. For more on how this works, see pre-existing conditions and pet insurance.

Wellness add-ons can help cover the cost of annual heartworm testing and preventative medications — routine expenses that standard accident and illness plans don’t typically reimburse. For timing guidance, see the best age to insure your pet. For what a routine vet visit runs, see how much does a vet checkup cost.

Frequently Asked Questions

Can heartworms be treated without the melarsomine protocol?

The melarsomine protocol is the standard of care recommended by the American Heartworm Society because it eliminates the highest percentage of adult worms. Alternative approaches — such as keeping dogs on preventatives long-term without melarsomine — are sometimes used when dogs are poor surgical candidates, but they are less effective and not recommended for most cases. Your veterinarian will assess your dog’s individual situation to determine the safest and most effective approach.

How long does heartworm treatment take?

The full treatment protocol, from first doxycycline dose to final confirmation test, spans approximately nine to twelve months. The melarsomine injection phase itself lasts about two months, but the mandatory exercise restriction, monitoring periods, and follow-up testing extend the process significantly. Most pet parents find the exercise restriction requirement — keeping an active dog calm for months — to be one of the most challenging parts of treatment.

Is heartworm treatment painful for dogs?

The melarsomine injections are administered deep into the lumbar muscles and can cause soreness at the injection site, which typically resolves within a few days. Most dogs tolerate treatment well overall. The more significant discomfort comes from the extended rest requirement — many dogs become restless during the activity restriction period. Your veterinarian may prescribe anti-anxiety medication to help keep dogs calm during this phase.

Unexpected vet bills can happen when you least expect them, but pet insurance may help make those costs more manageable. Having coverage in place can help pet parents feel more prepared for emergency care, surgery, diagnostics, and treatment for covered conditions.

Spot Pet Insurance offers dog insurance plans starting at $15/month^ and cat insurance plans starting at $9/month^^, helping to make it easier to find coverage that fits your budget. Spot also makes filing claims simple with a digital claims process that lets pet parents submit a claim in 60 seconds or less. Get a free quote.

_{^ Advertised premium is based on an accident and illness plan with an 80% reimbursement rate, $500 annual deductible, and a $2,500 annual limit for a 2-year-old small mixed dog (11-25lbs) in 32009. Plan costs vary.}

_{^^ Advertised premium is based on an accident and illness plan with an 80% reimbursement rate, $750 annual deductible, and a $2,500 annual limit for a 2-year-old mixed cat in 33801. Plan costs vary.}