Skip to Main Content Skip to Footer

Heartworm Prevention For Dogs

Video: "Heartworm Disease" (3:00)—Dr. Scribano talks about how pets get heartworms, their effects, and how we can help prevent them.

Featured Quote: "The oral once-a-month prevention methods are good, but they're only good if you give it every single month and most of us are human, not superhuman."

Hi, I'm Dr. Scribano from Northeast Animal Hospital. Today, we're going to review some things about heartworm disease.

Dr. Scribano, how do our dogs and cats get heartworms?

Heartworms are transmitted through a mosquito bite. Even if I took blood out of an infected animal and injected into another animal, they won't get heartworms. It has to go through the mosquito. The products that we sell have to be in their bloodstream, so that when a mosquito feeds and deposits larvae that they won't make it to be an adult.

How do heartworms affect our pets?

Heartworms accumulate in the heart and the large vessels causing coughing and exercise intolerance. The problem is that those symptoms that you will see are far into the disease and it affects the large organs as well.

How do I know which product is the best to prevent heartworms?

That's a great question, especially now. We are using more of the injectable form just from a compliance standpoint. The oral once-a-month prevention methods are good, but they're only good if you give it every single month and most of us are human, not superhuman. When we do the statistics - when we read about them - it’s not favorable. The last one I heard was that 93% of all dogs that are positive, the owners say, "Well yes, but they've been on a preventative." That kind of told me that they forgot when they forgot. Maybe six months ago you forgot to give it, or maybe he got right back on it, but it let them be open to the mosquito bite six months ago. The orals work right, but you have to give them every month and the animal has to keep it down. Sometimes they might have an upset stomach or something like that or you might find them under your sofa. There are all kinds of reasons, but the statistics don't lie.

In the other compliance studies I've seen, they say that we're successful somewhere around six or seven doses out of the entire year. I'm very much promoting the injectable form so that I know they have guaranteed protection.

Do I need to use prevention year-round?

Yes. Maybe in Canada or something of the Northern climates, the mosquitoes aren't out, and so you can go off prevention certain times of the year and they'll educate you on that. But here in Florida, absolutely, year-round, lifelong.

How often should my pet have a heartworm test?

We test dogs annually and we do that through their annual blood work. The heartworm test is included when we do annual blood work. Not only do we get the benefit of an internal exam, but we can let you know if they are positive for heartworms. In the cat, it is not as significant because we can't treat heartworms in the cat anyway.

Cause of Heartworms in Dogs

Heartworms are long, thin parasites that infect cats, dogs, and ferrets. The only way a dog can contract heartworm disease is from a mosquito bite. After a mosquito bites an infected pet, the tiny young of the heartworm are ingested—with the animal’s blood—into the mosquito. Then, when the mosquito bites another pet, infective larvae enter the pet through the bite wound.

Infective larvae then grow over the next six months into adult heartworms, taking up residence in the dog’s heart, lungs, or arteries. This is heartworm disease. It can lead to heart failure, lung disease, damage to other body organs, and eventually death—even sudden death with no apparent symptoms of the disease. How does your veterinarian test for and treat heartworm disease in dogs?

Diagnosis and Treatment of Heartworms in Dogs

The most commonly performed heartworm test detects the presence of adult female worms by screening a dog’s blood for specific antigens. If tests are positive, preventive measures should not begin until the existing disease is treated by your dog’s veterinarian. As mentioned above, preventatives can cause complications in an already infected pet.

Your veterinarian can treat heartworm disease in your dog through medications. Treating the disease is a hardship, though, both on your precious pet and your finances. In advanced pet heartworm disease, the only treatment may be surgical removal of the worms. However, full recovery is rare because serious damage to internal organs has already occurred. For these reasons, we recommend annual testing for heartworms while your dog is on regular heartworm prevention.

Symptoms and Prevention of Dog Heartworms

Dog heartworm prevention, however, does not eliminate adult worms, nor does it address the symptoms and damage that heartworms cause. Regular tests should be performed after prevention has begun—annually, as recommended—to determine whether the dosage of prevention is adequate for your dog’s unique, ever-changing circumstances.

Symptoms of heartworm disease in dogs depend on the severity of the disease. There may be no symptoms at all in the early stages. Later, dogs may develop a cough, fatigue, loss of weight, loss of muscle, and labored breathing. Symptoms can vary in intensity depending on activity levels and other health conditions. In later stages of heartworm disease, dogs may not survive. So prevention, early detection, and treatment are vital.

Wellness exams by your veterinarian include standard tests for detecting the presence of internal parasites in your dog. So please make sure to schedule regular exams. With the treatments and preventatives prescribed by your vet, your dog can live a happy, healthy life with your family—parasite-free.

As indicated above, the prevention of heartworms is paramount. Please let the veterinarians at Northeast Animal Hospital help your dog stay free of these dreadful parasites.

Return to Preventive Care for Dogs >

Northeast Animal Hospital