Heartworm affects hundreds of thousands of dogs every year in the US and has been reported in all 50 states. A heartworm diagnosis is a scary (and potentially costly) thing for a pet owner, but the good news is that with swift treatment, most dogs will make a full recovery from heartworm!

So how do you know if your dog has heartworm?

Heartworm symptoms may take a while to show up. One of the first signs of heartworm is typically fatigue and a reluctance to exercise. This lethargy will often be paired with a persistent mild cough and decreased appetite. As the disease progresses, your dog may develop a distended (swollen) stomach due to fluid build-up in the abdomen.
If your dog is infected with a large number of heartworms, he may also develop a life-threatening blockage in the heart; symptoms of heartworm blockage include sudden labored breathing, dark bloody or brown urine, and pale gums. Dogs with heartworm blockages will require emergency surgery to restore blood flow to the heart.

If you notice any changes in your dog’s normal activity levels or eating habits, or any more serious symptoms of heartworm blockage, take him to the vet immediately. Your vet will perform diagnostic tests (most likely a heartworm antigen test) to confirm diagnosis of heartworm and determine the proper course of treatment.

To learn more about how heartworm is treated and how you can help prevent heartworm infection in your dog, read our Education page: What Is Canine Heartworm, and How Do I Know If My Dog Has Heartworm?