Which of the following is a common symptom of heartworm disease in dogs?

Coughing and lethargy are indeed common symptoms of heartworm disease in dogs. As heartworms live in the heart and pulmonary arteries, they can cause significant damage to the cardiovascular system and lungs over time. This condition often leads to inflammation and the resultant fluid buildup in the lungs, which frequently presents as a persistent cough. Additionally, as the disease progresses, many dogs will become less active and show signs of lethargy as their body struggles to cope with the decreased efficiency of the heart and compromised oxygenation.

In contrast, excessive grooming is not typically associated with heartworm disease and is often more indicative of skin irritations or allergies. High energy levels are usually not observed in dogs suffering from heartworm, as the disease typically induces fatigue. Similarly, an improved appetite is uncommon in dogs with this condition, as many affected dogs may lose their appetite due to the overall decline in their health and energy levels.