The short answer
Roughly $1,500 to $3,000 or more for the full course of treatment in Canada, depending on your dog’s size and the severity of infection. Some dogs need a second round. Compare that to prevention at around $10 to $20 a month. You can get years of prevention for the price of one treatment.
What treatment involves
Heartworm treatment is not a single pill or injection. It’s a months-long process with strict restrictions on your dog’s activity. Here’s what a typical protocol looks like:
Diagnosis and staging come first. Blood tests, chest X-rays, and sometimes an echocardiogram to assess how advanced the infection is and whether the heart and lungs have sustained damage. This workup alone can run $200 to $500.
A course of doxycycline (an antibiotic) for about 30 days. This targets Wolbachia, a bacterium that lives inside heartworms and makes them harder to kill. Cost is roughly $30 to $150.
Then come the melarsomine injections. This is the actual adulticide treatment. The standard protocol is three deep intramuscular injections: one on day 60, then two more 24 hours apart on days 90 and 91. Each injection costs several hundred dollars. The drug itself, melarsomine (brand name Immiticide), is expensive and periodically faces supply shortages.
Steroids and anti-inflammatories are usually prescribed alongside to manage the inflammatory response as the worms die.
Strict exercise restriction for the entire treatment period and for weeks after. As the adult worms die, fragments travel through the bloodstream to the lungs. Physical activity increases blood flow and the risk of a fatal pulmonary embolism. This means crate rest, leash-only bathroom breaks, and no running, playing, or excitement for roughly 2 to 3 months.
The cost breakdown
These figures vary by clinic and region, but in Canada you can expect roughly: diagnostics and workup ($300 to $600), doxycycline ($50 to $200), melarsomine injections ($700 to $1,500+), supportive medications ($50 to $200), and follow-up testing ($100 to $300). Total: roughly $1,500 to $3,000 or higher for large dogs or complicated cases.
Some dogs don’t clear the infection on the first round and need repeat treatment, which can double the cost.
Prevention by comparison
Monthly prevention costs around $10 to $20 per dose in Canada. Over a 6-month Ontario heartworm season, that’s roughly $60 to $120 per year. Many prevention products also cover ticks and intestinal parasites, so you’re getting multi-parasite protection for the same price.
An annual heartworm test adds another $40 to $80. Total annual cost of responsible prevention: well under $200.
Key takeaways
- Full heartworm treatment runs roughly $1,500 to $3,000+ in Canada, potentially double if a second round is needed.
- Treatment involves weeks of antibiotics, three injections of melarsomine, and months of strict exercise restriction.
- Prevention costs roughly $60 to $120 per season in Canada, a fraction of treatment cost.
- The exercise restriction during treatment is hard on dogs and owners. Prevention avoids the entire ordeal.
- Annual testing catches infections early, when treatment outcomes are best.
References
- PetMD. “How Much Does Heartworm Treatment Cost for Dogs?” petmd.com
- Vetster. “The Cost of Heartworm Prevention vs. Treatment in Dogs.” vetster.com
- GoodRx. “How Much Does Heartworm Treatment Cost for Dogs?” goodrx.com
- American Heartworm Society. “Heartworms in Dogs.” heartwormsociety.org