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

• A. Rapid weight gain
• B. Exercise intolerance
• C. Ventral lung edema
• D. Decreased appetite

Answer: (B)

Exercise intolerance best captures how heart failure commonly presents in dogs. When the heart can’t pump effectively, tissues don’t receive enough blood during activity, so the muscles can’t meet the body's increased demands. This leads to fatigue, quicker onset of tiring during walks, and a reluctance to exercise, which owners often notice first. While fluid retention can cause rapid weight gain and left-sided failure can produce lung edema with coughing or labored breathing, those signs are more about specific consequences of the disease rather than the everyday limitation dogs experience during activity. Decreased appetite can occur but is nonspecific. So, the hallmark observable change is the dog’s reduced ability to tolerate and enjoy normal activity.