Symptoms Related to Heartworm Disease in Dogs


Worms that are parasites cause heartworm disease in dogs, affecting many major organs of the body. Mosquitoes transmit these worms to dogs in their larvae stage. These larvae begin to grow and multiply and then move to the heart and lungs through the blood vessels and live there. These worms can grow up to a foot long in the dog’s body. When dogs are infected with heartworms, they may exhibit various symptoms that indicate their health is compromised. These heartworm symptoms in dogs can include coughing, difficulty breathing, fatigue, and even weight loss. Recognizing these symptoms is crucial for early detection and intervention. Heartworm disease can be a serious threat to a dog’s well-being, and being vigilant about observing any changes in their behavior and health can make a significant difference in providing timely care.

heartworm symptoms in dogs

Heartworm Symptoms in dogs

Persistent Dry Cough

When the heartworms reach the lungs, they begin to multiply in the lungs and the connected blood vessels. Your dog starts to cough after any mild activity and it can become persistent. Sometimes there may be fainting spells associated with severe coughing.

Difficulty in Breathing

Once the lungs are affected by heartworms, it can lead to respiratory problems. Your dog may experience difficulty in breathing, which is apparent from constant panting. The space around the lungs gets filled with fluid, making the dog harder to draw breaths.

Swollen Belly or Chest

Fluid also begins to accumulate in the abdomen of the dog, along with chest, as the disease advances into next stage. This can make the dog’s belly and chest appear bulged or swollen.

Tiredness and lethargy

Your dog seems to lose interest in accompanying you to daily walks and other activities. Heartworm disease can make the dogs weak and they will mostly remain inactive throughout the day.

Weight loss

As the disease progresses, your dog may struggle to finish its meals and may lose appetite. The dog loses weight as well. If you notice this, you should immediately see your vet to diagnose the issue.


When the disease reaches to a final stage where heartworm population has increased to a great extent, the worms inhabit the heart and its blood vessels. This can block the blood flow and cause damage to red blood cells. Your dog starts collapsing because of the severity of internal damage and may soon die. If you notice any changes in your dogs usual behavior, you should seek your vet’s advice, because it’s better to catch heartworm disease at an early stage and treat it to avoid complications. Blood tests help in diagnosing this issue in dogs.


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