Many dogs, especially small breed dogs, as they age will develop degenerative changes to their mitral valve. The mitral valve is composed of three leaflets which open and close to control the blood flow between the left ventricle and left atrium.
With the aging process these valve leaflets deteriorate and then begin to leak, which allows for the back flow of blood from the left ventricle to the left atrium. As this progresses the backflow of blood eventually builds and leads to fluid buildup in the lungs. Once fluid begins to accumulate in the lungs, the patient becomes symptomatic, and the condition is called congestive heart failure (CHF).
The first indication of CHF noted at home would be an increased Resting Respiratory Rate (RRR). This can be measured by counting the number of breathes per minute when the patient is at rest. A normal RRR should be 20 breathes or less per minute. If the RRR gets to 30 or more this is a clear sign of lung congestion and warrants a visit to the veterinarian. This is usually the time at which heart medications are discussed and started.
The veterinary visit will likely include physical exam, chest radiographs, and possibly blood work and ultrasound of the heart and lungs. Once the appropriate data base is collected then traditionally three heart medications would be started.
These heart meds include a diuretic, an ACE inhibitor, and a drug called Pimobendan. The diuretic helps to pull fluid away from the lung, angiotensin converting enzyme inhibitor relaxes the veins and arteries and lowers blood pressure, and the Pimobendan helps the heart be a stronger pump.
These meds have worked very well together over the past 10 years, and now the “The American College of Internal Medicine” is recommending a fourth medication. This additional med is called spironolactone. Spironolactone is an old drug but has come back into popularity. Spironolactone helps to block aldosterone, a hormone made in the adrenal gland, which can cause increase sodium levels and heart fibrosis.
It turns out this combination of all four drugs provides better outcomes for heart patients and is the newest recommendation by specialists in the veterinary field. Cardalis is a new FDA approved heart medication that combines spironolactone and the ACE inhibitor, benazepril, in one tablet. This is a once per day medication and will make the administration of these four medication easier for the pet owner.
In general patients with CHF secondary to mitral valve disease can improve on medication, and some will live nicely for several years.