What is a common characteristic of heart failure in dogs as presented in the scenario?

A common characteristic of heart failure in dogs is exercise intolerance. This condition is primarily caused by the heart's inability to effectively pump blood, which leads to inadequate oxygen delivery to the muscles and tissues. Dogs with heart failure may display signs of fatigue during normal activities or become quickly exhausted during play or exercise.

In heart failure, various compensatory mechanisms are activated to maintain blood flow, but as the disease progresses, these can become insufficient, resulting in a noticeable reduction in the dog's stamina. Additionally, other signs often accompany this symptom, such as coughing or difficulty breathing, particularly during exertion or when lying down, which further signifies compromised cardiac function.

While ventral lung edema indicates fluid accumulation in the lungs and can occur with heart failure, exercise intolerance more directly affects a dog's daily activity level and is a primary complaint among dog owners observing their pets' behavior. This symptom serves as a crucial indicator for veterinarians assessing a dog suspected of having heart issues.