Heart Disease in Dogs

Heart Disease

The heart is a two sided pump that sends blood around the body in a one-way direction through arteries that go away from the heart and veins that return to the heart.  The heart has a right side that pumps blood to the lungs to receive oxygen and exhale carbon dioxide (made when you used food). The left side of the heart then pumps the oxygenated blood and other nutrients to all the tissues and muscles in the body.  Because both sides of the heart are needed to keep the body healthy, if either side of the heart is unable to pump as much blood as the other side, there can be complications. This problem of unequal amounts of blood being pumped to either the lungs or the tissues is called congestive heart failure. There are many other types of heart problems as well as congestive heart failure. I will mention a few of the more common types that affect many different breeds of dogs. Some cats are predisposed to hypertrophic cardiomyopathy, a disease of the heart muscle. Heart disease often lacks symptoms to lay people and a yearly physical exam can detect murmurs or other signs that you may not recognize as symptoms of heart disease. Some more severe signs of potential heart disease are difficulty breathing or exercise intolerance.  Other signs are coughing and weight loss. Fainting in dogs or cats is a symptom that should not be ignored. This could indicate a life-threatening problem.

There are many possible causes of heart disease and many types of heart disease. Often heart disease can result in heart failure. Below I have mentioned a few of the more common causes of heart disease including damage to valves and problems with the muscle cells in the heart. These will be called valvular disease and cardiomyopathies.

Valvular disease is often associated with decreased blood flow to the body because the blood goes backwards (instead of only forward, one-way) and this may result in too few nutrients reaching tissues around the body. Murmurs are often associated with valvular disease. Often the blood pressure will elevate in animals with valvular disease and these animals are put onto one or more medications to help manage the condition. Some medications are used to decrease blood pressure and help prevent progression of the disease include ACE-inhibitors. Additional medications may be given to slow the heart rate and/or increase the efficiency of the heart when it pumps. 

There are also heart changes that are associated with disease of the heart muscle. These are types of cardiomyopathies. The  heart muscle can enlarge in hypertrophic cardiomyopathy or become flabby and weak in dilated cardiomyopathy. These diseases are associated with eventual heart failure and death. They both result in the inability of blood to reach the tissues of the body. Hypertrophy of the heart decreases the amount of blood pumped around the body while dilated cardiomyopathy results in decreased pumping of the heart due to lack of muscle tissue. Medications may prolong the life your pet if diagnosed with either condition.

Often we hear about high blood pressure. Blood pressure is a measure of the force that the arteries feel with each heartbeat. The higher the pressure, the harder the heart must beat to send nutrients around the body. This is why high blood pressure is considered bad; it stresses the heart and causes changes in the size and shape of the heart if left untreated. In some cases, high blood pressure can be associated with heart failure, but it is associated with other diseases as well. In dogs and cats, high blood pressure as often associated with disease rather than occurring spontaneously like it does in people. High blood pressure in the lungs is called pulmonary hypertension and stresses the right side of the heart. Neither systemic or pulmonary hypertension should be left untreated as either can cause progression of heart disease or damage other organs in the body, especially systemic hypertension.

As with human medicine, there are many life-extending medications that can be prescribed for heart problems in pets. These medications can be used to decrease symptoms, prevent progression of the disease process and may help the body to compensate (work better) for the problem the heart is experiencing.. The best course of action with a heart problem is to get a full work up by your veterinarian including x-rays (radiographs), blood pressure measurement, an ultrasound of the heart and ECG as well as. blood work if recommended. Often medications can be given that decrease high blood pressure and help the heart to pump blood around the body. Sometimes diuretics are prescribed to decrease fluid build up in the body.  If your pet is found to have a heart problem, you should discuss any medications that could be prescribed for your pet with your veterinarian. For many clients, cost is often of concern. Fortunately, many medications are relatively cheap and can sometimes add years to the life of your pet, depending upon when diagnosis is made in the course of the heart disease.

Heart disease can be very scary,  An early diagnosis of the problem can often lead to a positive, preventative approach to the disease that allows your pet to maintain a good quality of life with few symptoms.  I have personally been involved with supporting several canine patients for over 3 years using 1 or more relatively inexpensive medications to decrease severity of murmurs and prevent progression of valvular heart disease. Some pets can live for years after a diagnosis. You should discuss any problems your pet is experiencing with your veterinarian. Remember, heart problems in pets are often hidden until later in the disease because our pets cannot tell us when they do not feel well. Yearly physical exams help to find these problems early and improve the life of our pets with affordable treatments when they are needed.

S. Mason, DVM

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