REDUCED ABILITY TO EXERCISE (Exercise Intolerance)
Reduced ability to exercise, weakness, fatigue, and lethargy can sometimes develop in dogs and cats with heart disease. Often, reduced exercise ability is incorrectly attributed to old age or arthritis, when the heart is really the cause. Since many animals (particularly cats) do not regularly engage in strenuous activity, noticing a decreased ability to exercise can be difficult.
Dogs with heart disease are often intolerant of hot and humid days. They may get short of breath early or want to cut their walk short or stop to recover during the walk. Exercise intolerance is often only present in dogs with more advanced stages of heart disease. Mild heart disease rarely causes major limitations to normal activity.
Since there is no cure for most forms of heart disease in dogs and cats, the goal is to allow pets to exercise enough to enjoy themselves without putting too much stress on the heart. Short walks are tolerated by most dogs with mild to moderate heart disease, but excessive activity can worsen heart failure or trigger irregular heart rhythms.
If your dog normally pulls on the leash and walks in front of you on a walk, but partway through they now slow down and walk beside you, this might be enough (or probably too much) activity. If your dog falls behind when going for a walk, or if they sit down and need to rest, this was clearly too much activity. Once dogs have heart failure, repetitive or exhausting activities that are initiated by you, such as ball chasing, swimming, and running after other animals, should be eliminated. Animals with significant heart disease should not be pushed to exercise beyond their limits.
In dogs with previously well-controlled heart failure, worsening ability to exercise should trigger a visit to your veterinarian. Changes in medication or diet may improve control of heart failure.