Short answer: Heartworm in dogs is treated by killing the worms with a veterinarian-supervised protocol from the American Heartworm Society (AHS) — a monthly heartworm preventive, a 28-day course of the antibiotic doxycycline, and then a series of three melarsomine injections that kill the adult worms. Just as important is strict rest for several months so the dying worms don't cause dangerous complications. There is no safe at-home cure; treatment has to run through your vet.
I'm Preston Smith, co-founder of Bully Sticks Central. I'm not a veterinarian, so treat this as a plain-English overview to help you talk to your vet — not medical advice. Heartworm is serious, but it's both treatable and, better yet, preventable.
What Is Heartworm Disease?
Heartworm disease is caused by a parasitic worm, Dirofilaria immitis, that's spread through the bite of an infected mosquito. The worms mature and live in the arteries of the lungs and the right side of the heart, where adults can grow up to a foot long and survive five to seven years in a dog. Left untreated, they damage the lungs, heart, and arteries and can be fatal, according to the American Heartworm Society.
What Are the Symptoms of Heartworm in Dogs?
Early on, many dogs show no signs at all. As the disease progresses, common symptoms include a mild persistent cough, reluctance to exercise, tiring quickly after activity, decreased appetite, and weight loss. In advanced cases dogs can develop a swollen belly from fluid buildup or, rarely, a sudden life-threatening blockage of blood flow called caval syndrome. Because early infections are silent, a yearly blood test is the only reliable way to catch it, per the American Kennel Club.
How Is Heartworm in Dogs Treated?
The AHS recommends the same core protocol for most dogs. It typically looks like this:
- Confirm and stage the infection. Your vet confirms with a second blood test and often chest X-rays and bloodwork to see how advanced it is.
- Stabilize and start a preventive. Dogs are usually started on a monthly heartworm preventive to stop new larvae, sometimes with a steroid to reduce inflammation.
- Doxycycline. A 28-day course of the antibiotic doxycycline weakens the worms by killing Wolbachia, bacteria the worms depend on, and reduces lung damage during treatment.
- Melarsomine injections. A three-dose series of melarsomine (the drug that actually kills the adult worms) — one injection, then two more about a month later on consecutive days. This three-injection schedule kills more than 98% of worms.
- Retest. Your dog is tested again about six months later to confirm the worms are gone.
From first antibiotic to final injection, the process usually spans several months. Your veterinarian tailors the exact schedule to your dog.
Why Exercise Restriction Matters So Much
This is the part owners underestimate. As the worms die, they break apart and can lodge in the lungs. A racing heart and heavy breathing raise the risk of dangerous, even fatal, complications — so vets require strict rest, often for a couple of months, with no running, jumping, or hard play. VCA Animal Hospitals stresses that keeping a dog calm during treatment is essential.
Keeping an energetic dog quiet for weeks is genuinely hard. Mental stimulation and safe, long-lasting chews are your friend here. At Bully Sticks Central we make single-ingredient chews that are 100% natural, 100% real meat, fully digestible, and no rawhide — the kind of quiet, low-key enrichment that helps a dog settle on crate rest. Our bully sticks are a go-to, and softer options like beef trachea give the same calm chewing time. Always match the chew to your dog and check with your vet on treats during recovery.
Can You Treat Heartworm at Home or Without the Shots?
Some people ask about the "slow-kill" method — using only monthly preventives to gradually clear worms without melarsomine injections. The AHS does not recommend it as a first choice: it can take years, allows ongoing lung and heart damage, and may contribute to drug resistance. The injection-based protocol is faster and clears more worms. Either way, there is no safe do-it-yourself cure — heartworm treatment belongs with your veterinarian.
How Do You Prevent Heartworm in Dogs?
Prevention is far cheaper, safer, and easier than treatment. Give a vet-prescribed monthly preventive (pill, topical, or an injection that lasts several months) year-round, test your dog once a year even if they're on prevention, and reduce mosquito exposure where you can. Puppies should start prevention early — see our guide on chews and care for puppies for more on those first months.
The Bottom Line
Heartworm is treated with a vet-run protocol of doxycycline and three melarsomine injections, backed by months of strict rest — and it works in the vast majority of dogs when caught early. But the smarter play is prevention: a monthly preventive and a yearly test keep your dog off the treatment table entirely. If you notice a lingering cough or unusual tiredness, get your dog tested and talk to your vet.
Bully Sticks Central makes 100% natural, single-ingredient dog chews — 100% real meat, fully digestible, no rawhide, ethically sourced from grass-fed American and Argentinean farms, and 100% high-quality guaranteed.
This post was last updated at August 6, 2026 23:30
