A heart murmur is an abnormal heart sound that is heard when listening to the heart with a stethoscope. Heart murmurs in dogs can be classified into two broad categories: innocent or physiologic murmurs and acquired murmurs. Innocent murmurs are benign and have no impact on the dogs health. They are common in young puppies, especially large breed puppies, and usually outgrow them by about 4-5 months of age. Acquired murmurs, on the other hand, are caused by structural heart disease or an extracardiac problem. The most common cause of an acquired heart murmur in dogs is mitral insufficiency, a condition in which the mitral valve becomes thickened and begins leaking. Other causes of an acquired heart murmur in older dogs include bacterial endocarditis caused by a bacterial infection that localizes on a heart valve and dilated cardiomyopathy (DCM).

The symptoms of a heart murmur depend on the underlying heart condition that is affecting the dog. Some common symptoms of heart diseases and disorders include:

• Irregular heartbeat or racing pulse
• Hacking, persistent cough
• Excessive panting even when resting
• Lack of energy or appetite
• Collapsing or fainting
• Gums and/or tongue are bluish in color
• Severe water retention

If your veterinarian detects an abnormal rhythm to the heartbeat or finds that your dog has a heart murmur, they may recommend further evaluation and treatment[[1]](https://vc...