How to check if your dog has heartworms?

Heartworms aren’t just a scary term—they’re a silent threat that can creep into your pup’s life without fanfare. These tiny parasites, transmitted by mosquitoes, grow inside the heart and blood vessels, and by the time obvious signs show up, they might have already caused damage. Knowing what to watch for could make all the difference for your dog’s health—and it’s part of keeping them happy, healthy, and in line with local guidelines that often emphasize prevention and early detection.​

Watching for little changes in their energy or behavior is usually the first clue. Does your dog get winded faster on walks, even if they’re still young? Maybe they’ve started coughing after playtime, or they’re napping more than usual. Some pups lose their appetite or drop weight without explanation. These aren’t always heartworms, of course—they could be other issues—but they’re worth noting. Just remember, in many areas, keeping an eye on these signs is part of responsible pet ownership, right alongside regular check-ins.​

When those little red flags pop up, it’s time to call your vet. They’ll probably start with a blood test—this is the only surefire way to know. Most clinics use an antigen test to detect proteins from adult female heartworms, and sometimes a microfilaria test to check for baby worms in the blood. Depending on your dog’s history, they might also suggest imaging like X-rays to see if there’s damage to the heart or lungs. Skipping these tests? It might not just risk your pup’s health—some regions require proof of regular heartworm checks to comply with local animal welfare regulations.​

Early detection matters more than you might think. Heartworms can take months to mature, so by the time symptoms are obvious, treatment gets harder and costlier. Your vet can catch them in those early stages, when managing the issue is gentler on your dog. Plus, staying on top of these checks keeps you aligned with the kind of preventive care that’s standard in most communities—no one wants to miss a simple test that could save their pup from discomfort.​

Prevention and detection go hand in hand, too. Even if your dog is on monthly preventatives (and let’s be honest, most vets in populated areas recommend them), regular checks are a must. Mosquitoes don’t care about schedules, and sometimes preventatives can be missed or washed off. A quick test once or twice a year is a small step that fits right into the routine of keeping your dog healthy—something every pet parent can get behind.​

If you’re ever unsure about a symptom, don’t wait. That cough after chasing a squirrel might be nothing, but it could be something. Your vet knows the ins and outs of heartworm patterns in your area, from which seasons pose more risk to what tests work best locally. Trusting their guidance isn’t just smart—it’s part of being the responsible owner your dog deserves.​

At the end of the day, heartworm checks are about more than just checking a box. They’re about keeping that tail wagging, those zoomies happening, and those snuggles going strong. So note the little changes, book that vet visit, and rest easy knowing you’re doing right by your best friend.