Name a clinical sign of heartworm disease in dogs?

Coughing is a clinical sign of heartworm disease in dogs and is often one of the first symptoms that pet owners notice. This occurs because as the heartworms mature and multiply within the heart and pulmonary arteries, they can cause inflammation, and subsequently result in coughing due to the irritation of the bronchial tubes.

Pet owners might observe their dogs experiencing a persistent cough that doesn't seem to be related to other common respiratory issues. In advanced stages of the disease, the coughing may worsen and can be accompanied by other symptoms such as lethargy, difficulty breathing, and weight loss.

While excessive barking can occur for various reasons, it is not a specific sign of heartworm disease. Loss of appetite can be a symptom of many health issues and is not unique to heartworm infection. Increased energy is typically not a sign associated with heartworm disease; affected dogs usually show decreased energy and increased fatigue due to reduced cardiac efficiency and compromised oxygen delivery.