Heart murmur does not indicate imminent heart failure. The murmur, a result of turbulent blood flow in the heart valves, may become more severe as your dog ages. Treatment is based on the severity of the murmur.
Significance of Murmurs
The valve between the left atrium and left ventricle of the heart is called the mitral valve. When this valve is leaking, it causes a murmur or an abnormal heart sound. Blood flows backwards. Most dogs develop the murmur at age 6 or older. Small dogs are more susceptible. Treatment is not necessary until the murmur progresses. The common causes of a murmur are birth defect, heart valve disease and leakage, and anaemia (possibly due to parasites). Murmurs are graded and your veterinarian can hear a murmur as early as grade one. Testing for a heart murmur may involve an electrocardiogram (ECG) to measure heart rate and determine abnormal rhythm, echocardiogram to establish any faulty valves and how well the heart is functioning, and an X-ray, which can ascertain any abnormalities of the cardio-pulmonary system related to heart problems.
As documented on dogslovetoknow.com, there are six grades assigned to a heart murmur. In grades one and two, your veterinarian can detect the abnormal heartbeat through a regular test. Treatment is not necessary during these stages unless your dog develops coughing and lethargy. Grades three and four are more serious and you may note your dog being a lot less active, with a persistent cough that indicates fluid is now collecting in the lungs. Treatment will be required. Grades five and six are the most serious, requiring medication and possibly surgery to repair the heart valves.
According to 2ndchanceinfo.com, treatment includes various medications to help your dog to live comfortably. Your veterinarian begins with medications to eliminate excess fluids leaking from the heart valve. These medications may involve diuretics such as furosemide (Lasix), spironolactone (Aldactone), and thiazide. These medications are very effective in stopping coughs and respiratory distress when lung fluid build-up is the cause of the murmur.
As the murmur progresses and the diuretics no longer work effectively, other medications are prescribed, such as ACE inhibitors (angiotensin-converting enzyme inhibitors), which work on relaxing and expanding blood vessels in the body. The ACE inhibitors reduce the formation of a hormone in the lungs called angiotensin II that increases the workload of your dog's heart. These medications may include enalapril, benazepril and hydralazine.
If these treatments have not worked, medications such as pimobendan (Vetmedin) and digitalis are prescribed to increase the strength of the heart muscle while decreasing the pressure the heart must work against.
Other treatments available in more severe cases may include supplemental oxygen and drainage of fluid from the chest or abdomen. A last resort may be heart surgery to repair the mitral valve.
Diets & Supplements
Nutritional support is important and must consist of a low-sodium diet provided by your veterinarian. This diet is helpful in lessening fluid retention.
Heart conditions can be attributed to eminent vitamin deficiencies, such as L-carnitine, taurine, coenzyme Q, and omega-3 fatty acids. Ask your veterinarian which of these may benefit your dog.
Preventing the onset of a heart problem is not always possible, especially if it is congenital. If your dog is at risk, provide a low-sodium diet along with amino and fatty acids, and keep your dog at the optimum recommended weight for his size and breed. Regular exercise daily is important as well to keep his heart in good working condition.