How to treat heartworm in dogs?

Heartworm isn't just a scary word—it's a serious threat that sneaks up on even the most careful pup parents. Those tiny parasites, spread by mosquitoes, can grow into foot-long worms in your dog's heart and lungs, causing damage before you notice a thing. Let's talk about what to do if your vet drops that diagnosis—no panic, just clear steps.​

First, stay calm. Modern treatments work, but they require patience. Your vet will start with a full checkup, maybe blood work and X-rays, to see how bad the infestation is. Severity matters—mild cases (a few worms, no lung damage) have simpler paths than advanced ones. This isn't a “wait and see” situation, though; delaying treatment lets worms multiply, making recovery harder.​

The core of treatment usually involves a series of injections—often melarsomine, the go-to medication. These shots target adult worms, but they're tough on your dog's system. That's why vets often recommend 4-6 weeks of rest first. No roughhousing, no long walks—just gentle potty breaks. Think of it like bed rest after surgery; their bodies need to conserve energy to fight off the dying worms.​

Here's the tricky part: as worms die, they break down and can block blood flow if your dog gets too active. That's why strict rest isn't optional—it's a safety measure. Some owners find crate rest helpful during this phase, especially for high-energy breeds. Your vet might also prescribe antibiotics or anti-inflammatories to ease lung irritation—follow those doses exactly, even if your dog seems fine.​

Puppies under 6 months get special consideration. Their smaller bodies handle certain medications differently, so your vet might suggest a modified schedule. It's rare, but some areas have regulations about reporting heartworm cases to local animal health boards—your clinic will handle that, so you can focus on your pup.​

After treatment, follow-up tests are non-negotiable. Most vets check at 6 months to ensure all worms are gone. This is also when you'll lock in prevention—monthly chewables, topical treatments, or injections that stop new infections. Skipping prevention is how this cycle repeats, and in many places, regular heartworm tests (usually annual) are part of routine care—smart to stay on top of.​

Watch for warning signs during recovery: coughing, lethargy, or loss of appetite. These could mean complications, so call your vet right away. It's normal for dogs to be a little under the weather for a week or two post-injection, but anything more needs attention.​

Recovery isn't quick, but it's worth it. Seeing your dog chase a squirrel again, tail wagging without hesitation—that's the goal. And prevention? It's cheaper, easier, and keeps them out of this mess entirely. Talk to your vet about what fits your lifestyle—there's a reason those monthly meds are so widely recommended.