The 411 On Heartworms


Dr. Mary Beth Tamor

Have you heard of heartworm disease but want to know more? My goal for this blog post is to give you a basic overview. For more information please come see us or talk to your local veterinarian.

What exactly is Heartworm Disease?

Dogs develop heartworm disease when bitten by an infected mosquito carrying heartworm larvae. Once inside the dog, the larvae develop into adults over the course of several months. Adult heartworms can become up to 10 to 12 inches long and then live in the right side of the heart as well as the vessels leading to the lungs (pulmonary arteries). It is here that they cause damage leading to lung disease and heart failure.

Heartworm disease has been diagnosed in all 50 states and risk factors are impossible to predict. Even inside pets are at risk, YES, even if they only go outside to use the bathrooms. We live in south Louisiana; mosquitos are everywhere, even inside our homes!

Clinical signs of Heartworm Disease

Heartworm disease isn’t always easy to see. Some dogs can be infected for years before signs occur. Signs develop as the heartworms slowly cause damage to the pulmonary arteries. Dogs with this level of infection can have a persistent cough, exercise intolerance, decreased appetite and weight loss. Further damage causes decreased blood flow through the lungs and some dogs can develop right sided heart failure. This is typically recognized as a “swollen belly” as fluid builds up in the abdomen. Less commonly, a sudden obstruction of blood flow through the heart and lungs can be caused by a large number of heartworms. This blockage, called caval syndrome, can be life threatening. Be on the lookout for sudden onset of labored breathing, pale gums, dark red/brown urine and severe lethargy. Please seek veterinary care immediately since without quick surgical treatment to remove the heartworm blockage, many dogs will not survive.

Heartworm Testing

The earlier we can detect heartworm disease, the higher the chances of recovery as the disease may be less severe and easier to treat. With just a few drops of blood a test can be ran to detect heartworms either in our clinic or an outside laboratory.

Yearly testing for heartworms is recommended for all dogs to make sure prevention is achieved and maintained. We recommend that all dogs 7 months of age or older be tested for heartworms before starting heartworm prevention. More frequent testing may be required if you have missed a dose of prevention if switching from one prevention to another. At minimum, retesting is recommended 6 months after either first starting prevention or missing a dose, and then annually thereafter.

Treating Heartworms

Heartworm disease will worsen and may lead to more serious illness if left untreated. It is recommended that heartworm positive dogs are treated unless the dog is considered a poore candidate due to other medical reasons.A physical examination, bloodwork and x-rays may be needed before starting treatment to evaluate each dog’s potential for treatment. Your veterinarian can discuss treatment further.

Heartworm Prevention

Heartworm preventative medications are very effective when administered properly on a prescribed schedule. Carefully monitoring your pet’s weight is extremely important as preventatives are prescribed by weight. Heartworm preventatives come in many forms: chews,. tablets, topical serums, & injection. Consult with your veterinarian to determine the proper form of preventative for your pet. Approved heartworm preventions are typically safe, easy to administer, and relatively inexpensive and some even provide additional parasite treatments. Preventing heartworm disease is always safer and more affordable than treating adult heartworm infections.

As a pet owner, you are responsible for giving your dog the heartworm prevention as prescribed. It is recommended you give prevention year round to reduce the risk of heartworm infection in your dog.

Finally, heartworms disease is not subject to only dogs. Heartworms can also infect other common household pets such as cats and ferrets. It is recommended to apply heartworm preventatives to these types of pets as well, though clinical signs of heartworm disease may vary from species to species. Speak to your veterinarian to learn how heartworms may impact your pet’s life.

For more information regarding heartworms and heartworm disease please come see us at Animal Care Center & Pet Care Center or talk with your local veterinarian. As always our staff is happy to assist you with any of your pet related concerns. Please call (985) 542-6300 with questions.