Dog getting heartworm medication chewable tablet.

What is Heartworm Disease and How Can It Affect My Dog?

Heartworm disease, also known as dirofilariasis, is a severe and potentially fatal disease caused by a blood-borne parasite known as Dirofilaria immitis. The adult heartworms inhabit infected dogs' hearts, pulmonary arteries, and adjacent large blood vessels. They can live for five to seven years, and a single dog may host as many as 300 worms. Female heartworms produce millions of offspring called microfilariae, which mainly reside in the small vessels of the bloodstream.

Heartworm disease can cause lasting damage to the heart, lungs, and arteries affecting the dog’s health and quality of life long after the parasites are gone.

How Would My Dog Catch Heartworm?

Heartworm disease is spread via the bite of an infected mosquito. When a mosquito bites a dog, it transmits the infective larvae into the dog’s bloodstream. These larvae then migrate to the heart and adjacent blood vessels, where they mature into adult heartworms, mate, and produce offspring.

Heartworm disease has been reported in all 50 states of the U.S. but is most commonly found along the Atlantic and Gulf coasts from the Gulf of Mexico to New Jersey and along the Mississippi River and its major tributaries.

Can Dog Heartworm Be Prevented?

Preventing heartworm disease is the best defense against this serious health risk. Preventive medications are available only by prescription from veterinarians and come in various forms, including monthly chewable, and injectable medications given every 12 months. Some preventives only protect against heartworms, while others protect against other parasites, including heartworms, intestinal worms, fleas, ticks, and mites. Consult their vet to discuss the most suitable option for your canine companion.

Regular veterinary check-ups are also essential in the early detection and prevention of heartworm disease, as vets can detect signs and symptoms of heartworms that the pet owner may miss. 

Microfilaria of dog heartworm under microscope

What Are the Early Signs of Heartworm in Dogs?

The first signs of heartworms in dogs can be subtle and don’t usually manifest immediately after infection. Most infected dogs show signs and symptoms in five to six months. A soft, dry, persistent cough is one of the earliest signs of heartworms in dogs. This occurs because the adult worms interfere with breathing by residing in the lungs and associated blood vessels.

Other early signs of heartworm disease can include difficulty breathing, decreased appetite, fatigue, and exercise intolerance.

What Are The Middle to Late-Stage Symptoms of Heartworm?

If the disease is left untreated, it will progress to more severe and potentially fatal stages. Symptoms of heartworms in the middle to late stages can include abnormal sounds when breathing, weight loss, lack of appetite, coughing, lethargy, enlarged liver, bulging ribs, heart murmur, and abdominal swelling.

In extreme cases, heartworm disease can cause a sudden blockage of the pulmonary artery, leading to shock or sudden death. Heartworm-associated respiratory distress (HARD) occurs when there are too many worms in the lung arteries for them to be cleared by medication. This can cause severe shortness of breath and pain that may require emergency surgery.

What Can Be Done to Stabilize My Dog’s Heartworm Disease?

heartwormBefore starting heartworm treatment, your dog may need to be stabilized with appropriate therapy. Treatment options include topical and intravenous drugs, with the specific plan depending on the severity and stage of the disease. In severe cases, surgical removal of the heartworms may be necessary.

The goal of any treatment is completely removing all worms from the dog’s body and preventing further infection. Treating dogs infected with heartworms usually requires a combination of two or more medications to reduce adult worm numbers before killing them off with an adulticidal. Your veterinarian will help you better understand your dog’s treatment options.

How Soon Should I Bring My Dog to the Vet for Heartworm Prevention?

Puppies can begin heartworm preventative medication as young as 6-8 weeks old. If your pup is a little older, they need a heartworm test before starting preventative medication.

You must also administer the preventive medication on time, every time, to ensure its effectiveness. Even if you don’t live in an area where mosquitoes carry heartworms, your dog should still be on preventive medication year-round.

How Will a Veterinarian Diagnose If My Dog Has Heartworm?

A simple blood test is the most common way to diagnose heartworm disease. This test detects the presence of antigens produced by adult female heartworms. We recommend having your dog tested for heartworms annually.

If your dog tests positive for heartworms, additional tests may be needed to determine the severity of the disease and the best course of treatment. These tests may include X-rays, ultrasounds, electrocardiograms (ECG), and other specialized laboratory tests to evaluate organ function.

Why Is Early Detection and Diagnosis of Heartworm Important

Early detection and diagnosis are essential for preventive and curative heartworm treatments. Treatment is much easier, faster, and less expensive when the parasites are detected early. Early detection can also help prevent further damage to the heart, lungs, and other organs.

It’s important to be aware of the signs and symptoms of heartworm in dogs so you can seek veterinary care at the earliest sign of infection. Regular check-ups with your veterinarian are essential to ensure proper diagnosis and treatment before the disease progresses.

Conclusion

Heartworm disease is serious and potentially fatal for dogs, and knowing how to prevent, detect, and treat it is vital. Preventing heartworm disease is the best way to protect your pet from this health risk, so talk to your vet. Regular veterinary check-ups are also essential for the early detection of heartworm in dogs.

At All Creatures Veterinary Care Center, we are committed to providing the highest quality and best service to pet owners, and we believe that educating pet owners about heartworm disease is the best way to keep their dogs healthy. Our experienced veterinarians can help you select the most suitable preventive product for your pet and will advise you on proper administration. Schedule an appointment today to protect your dog from heartworm!