Heartworm disease is a severe and life-threatening condition for pets, caused by parasitic worms transmitted to a pet from a mosquito bite. The Companion Parasite Control warned in 2022 of increases in heartworm in Tennessee, one of the top ten states for heartworm cases. Fortunately, we can prevent heartworm disease with the proper measures and treatment methods, so it’s essential to understand the signs and symptoms of infection and the steps to prevent infestation.

What is Heartworm Disease?

Heartworm disease is an infectious parasitic disease caused by worms living in the heart and lungs of an animal. These worms reproduce and grow over time, seriously damaging the heart and other major organs. Left untreated, it results in death in dogs. Cats are not as susceptible to infection as dogs. A cat is not a natural host of heartworms because the worms do not thrive as well inside a cat’s body. However, both indoor and outdoor cats are at risk for heartworm disease, and it may lead to death in a cat.

The Heartworm Cycle

When a mosquito bites an animal infected with heartworms, it sucks up the microscopic heartworm larvae (microfilariae). These larvae continue to develop in the mosquito, and the mosquito deposits the parasite into its next victim.

Symptoms of Heartworm Disease

Here is a chart of symptoms for dogs and cats:



Mild persistent cough

Reluctance to exercise

Fatigue after moderate activity

Decreased appetite

Weight loss

Difficulty or labored breathing


Decreased activity.

Loss of appetite

Weight loss



Fluid in the lungs

Diagnosing Heartworm Disease in Pets.

To diagnose heartworm disease in your pet, we typically use a series of tests to determine the presence of adult heartworms or larvae. We have a complete in-house lab capabilities to get results fast. We use an antigen test to detect the presence of proteins released by adult female heartworms. We can also perform an antibody test to check for antibodies created by your pet’s immune system in response to an infected mosquito bite. We use chest X-rays to visualize a pet’s heart and lung tissue. If any of these tests detect the presence of heartworms, we may recommend additional tests to assess the severity of the infection.

Treating Heartworm Disease in Dogs.

We consider your dog’s age, size, and overall health before treating heartworm disease. Generally, standard treatments involve giving closely monitored injections or administering oral medication over a short period. Depending on the severity of the infestation and your pet’s risk factors for developing complications, we may recommend additional testing to monitor the treatment. Regular checkups with your veterinarian are essential for monitoring progress and ensuring the success of a heartworm infection treatment plan.

Unfortunately, there is no approved treatment for cats, making preventative treatment all the more critical for cats, especially in high-risk areas.

Managing Post-Infection Symptoms.

After treatment, your pet will need close monitoring to minimize the risk of further complications. Symptoms such as weight loss, weakness, and lethargy may accompany heartworm infection initially. These may persist for several weeks or months after treatment due to the inflammation and damage caused by the worms in your pet’s body. Depending on the length and severity of the infection, additional treatments may be necessary to ensure continued health post-infection. Regular checkups with your veterinarian are essential in identifying any potential risks.

Heartworm Prevention

Prevention is the best protection against heartworm disease in your pet. Year-round preventive medications can help protect your pet from becoming infected with heartworms.

You can also reduce the risk of infection by avoiding areas with mosquitoes, such as:

Final Words

Heartworm disease is a serious, progressive disease. However, the earlier it is detected, the better the chances a pet will recover. Most importantly, we can prevent heartworm with heartworm medication. It is critical to protect pets year-round with no lapses in medication.

By working together, we can help protect your pet from any serious or fatal consequences of the disease. Please contact us to schedule an exam or preventative treatment.

Your Friendly Team at
Animal Wellness & Rehab Center