Heart Disease In Dogs
The heart has four chambers. The upper chambers are called atria (singular: atrium) and the lower chambers are called ventricles. The heart is also divided into right and left sides.
Unoxygenated blood flows from the body into the right atrium. It is stored there briefly and then pumped into the right ventricle. The right ventricle pumps blood into the lungs where it receives oxygen. It flows from the lungs into the left atrium where it is held before flowing into the left ventricle. The left ventricle is surrounded by the largest and strongest of the heart muscles. This large muscle is necessary to pump blood throughout the body.
Each side of the heart has a one-way valve to keep blood from going backward from the ventricles to the atria. The valve between the left atrium and left ventricle is called the mitral valve. Because of the high pressure created when the left ventricle contracts, the mitral valve will begin to leak or "wear out" in many dogs. This is known as mitral valve insufficiency and is often associated with a heart murmur.
The earliest sign of a leaking mitral valve is a heart murmur. This is produced when some of the blood goes backward through the leaking valve into the left atrium. Many dogs develop a murmur from the mitral valve as early as six years of age. This problem is especially common in small breeds of dogs. A heart murmur does not mean that heart failure is imminent. But as time goes on, the leak becomes more severe and more and more blood flows backwards. This results in reduced pumping efficiency and, eventually, congestive heart failure. From the time a murmur develops, it may be a few months to several years until heart failure occurs.
When the heart is not properly pumping blood, the blood moves more slowly through the lungs. This results in small amounts of fluid leaking out of the capillaries into the air passageways. This fluid collection produces the earliest signs of heart failure: gagging as if trying to clear the throat, a chronic, hacking cough, and lack of stamina.
Congestive heart failure begins when the body is unable to provide the tissues with adequate oxygen. Without adequate oxygen, the body's cells become desperate and trigger a series of responses. Various hormones are released in an attempt to correct the problem. These hormones conserve fluid in an effort to increase blood volume and the output of blood and oxygen by the heart. For several months, these compensatory responses help the situation.
Eventually the increased fluid retention becomes a detriment as more and more fluid leaks out of capillaries and into the lungs, abdomen and other body tissues. Fluid in the lungs is called pulmonary edema, fluid below the skin is called peripheral or limb edema, and fluid in the abdomen is called ascites. When these are present, congestive heart failure is present.
1. Auscultation which is listening with a stethoscope. This allows us to identify murmurs due to the improper closure of heart valves based on the murmur's location and intensity. In addition, we can detect abnormal heart rhythms (arrhythmias and dysrhythmias) and evaluate lung sounds.
2. Blood and urine tests. We are especially concerned about liver and kidney function because these organs are often impaired in heart disease.
3. Chest X-rays. Chest radiographs allow us to examine the lungs and measure the size and shape of the heart. Many forms of heart disease cause obvious enlargement of the heart, particularly the left side.
4. Electrocardiogram (ECG). This is an assessment based on the electrical activity of the heart. It allows us to accurately determine heart rate and to diagnose any abnormal rhythms.
5. Ultrasound examination (echocardiogram). This gives the most accurate determination of each heart chamber's size and thickness of the heart walls. Measurements of the heart contractions can be taken to evaluate the heart's pumping efficiency.
The combination of all of these tests gives the best evaluation of the dog and its heart function.
SEE YOUR VETERINARIAN. If your pet is displaying signs of heart disease (the coughing and exercise intolerance), then you must have an examination and workup to determine the root of the problem. If your pet is in obvious distress (heavy breathing, blue gums), then go right away. I always begin by treating pets with conventional medication, and add in holistic treatment. If your pet is diagnosed with heartworm then she can be treated with medication (Immiticide) to kill the adults immediately.
HERBAL HELP. Hawthorn has been shown to increase the ability of the heart to contract, as well as causing the outside blood vessels to dilate, making heart contraction easier.