Taco Belle Times: "Tails" of a Baby Boomer Veterinarian: Heart Disease: Mitral Valve Insufficiency (regurgitation) in Dogs

A very dear veterinary colleague underwent mitral valve replacement surgery this week in a rather prolonged procedure. He had his valve replaced with a pig valve rather than an artificial one for the simple reason he did not want to be on blood thinners the remainder of his life. The surgeon theorized eight to 10 years of longevity for the implanted valves. What are the options in dogs when this same valve failure?

What is the mitral valve of the heart and the association with congestive heart failure?

There are four chambers of the heart. Each one has a valve to keep blood flowing in one direction. On the left side of the heart the upper atrium is separated from the lower ventricle by the mitral valve. When this valve begins to deteriorate, blood backs up to the upper left heart (atrial) chamber causing it to gradually enlarge. Eventually this will lead to fluid accumulation in the lungs. See more at: http://www.akcchf.org/canine-health/your-dogs-health/disease-information/mitral-valve-disease.html#.dpuf

How does a veterinarian detect a valve is deteriorating and the concern?

One of the more common findings is the detection of a heart murmur (think "rap song beat") with a stethoscope.

Are there some common factors associated with this disease?

Greater than 1/3rd of small/ toy breeds around 10 years of age or older will acquire this disease, although it is possible in any breed. The percentage rises up to 75 percent at 16 yeara of age. Cavalier King Charles Spaniels appear to have an increased risk.

Since most pet owners do not keep a stethoscope at home, are there potential signs in dogs at risk?

-coughing, especially after laying down

- sleeping more or having difficulty sleeping

- panting, difficulty breathing, and increased respiratory rate

- fainting or collapse

Does the intensity of the heart murmur correlate with the severity of the valve deterioration?

No

Once a heart valve condition is suspected, what are the next steps?

Chest radiographs (x-rays), bloodwork, blood pressure, and sound waves (echocardiogram) are recommended. These may be performed at Creature Comforts or by referral to a veterinary cardiologist.

What are the stages of heart disease with a murmur classified by veterinary cardiologists?

Stage A: murmur and no other signs- recheck every 6 to 12 months

Stage B1: radiographic changes- recheck every 3 to 9 months

Stage B2: cough, elevated heart rate, and often an irregular heart beat- start medication and recheck within 2 weeks then every 3 to 6 months

Stage C: early onset heart failure, possible collapse adding maximum drug therapy

Stage D: end stage heart failure, cage rest and possible oxygen therapy initially, with a guarded prognosis

Can mitral valve disease be treated in dogs?

While mitral valve disease cannot be cured there are protocols that may extend life a year or longer based on the degree of damage when treatment is initiated. These include medications, exercise, and a healthy diet.

What are these medications?

- diuretic to remove fluid from the lungs via the kidneys(ex. Furosemide )

-an angiotensin converting enzyme (ACE) inhibitor, to dilate arteries and veins increasing blood flow (ex. Enalapril or Benazepril)

-medication to lower heart rate leading to increased strength of each heart contraction (pimobendin)

Are there other condition(s) that hasten the onset of heart disease?

Severe dental disease harbors bacteria that can get to the blood stream and setting up bacterial infections of the heart valves and sudden death. It is very important that heart patients or dogs at risk maintain a healthy mouth.