Signs & Symptoms of a Heart Murmur in an Older Dog

Due to natural growth or a combination of problems, dogs could have a serious heart problem, such as a heart murmur, that causes tiredness. A heart murmur is an abnormal sound emitted from the heart. In older dogs, the condition is usually a symptom of another underlying condition, such as heart disease. The presence of a heart murmur usually produces few detectable signs in its early stages; however, when it worsens, symptoms will be apparent.

  1. Overview

    • Just like a human's heart, a dog's heart has four one-way valves -- mitral valve, tricuspid valve, aortic valve and plutonic valve -- that rhythmically open and close to control the flow of blood through it. If any of the valves weaken and do not open or close properly, blood may overflow or rush through the valves, causing abnormal sounds to emit from the heart. These sounds, called murmurs, may be low and only detectable by a stethoscope, or very loud and heard simply by placing your head against a dog's chest. Veterinarians rate murmurs on a scale of 1 to 6 based on their intensity, with a 1 being the lowest sound -- heard faintly through a stethoscope -- and a 6 being the loudest -- clearly audible with or without the use of a stethoscope.

    Causes

    • A murmur in a puppy or younger dog is typically congenital, meaning it is the result of a birth defect. In contrast, a murmur in an older dog is a secondary symptom to some other condition. Congestive heart failure is usually the basis of most heart problems, including murmurs, and it occurs when the heart cannot fulfill its normal duties. Valvular defects, tumors, heartworms and heart disease are all conditions that can cause heart failure, and as a result, the onset of a murmur. Other murmur causes include dental disease, anemia and fever.

    Symptoms

    • Frequent coughing is a common sign of a heart murmur. It happens when a dog's heart valves direct blood into its lungs instead of the proper channels. Another symptom is an abnormal noise emitted from the heart which usually sounds like blood splashing around. The sound may be very low and only detectable through a stethoscope or very loud and heard or felt by listening to or touching the dog's chest. Other symptoms include lack of energy, rapid breathing, poor appetite, a rapid pulse, an enlarged stomach and pale or bluish gums.

    Treatment

    • A murmur in an older dog is usually a symptom of another underlying condition. Consequently, veterinarians treat the initial cause rather than the murmur itself. Depending on the cause, treatment may include medication, surgery and diet changes. If a dog's underlying condition is too advanced or severe, no type of treatment may be available.