Effects of an Unhealthy Heart
by Dr. Becky Marks
Last month I discussed the effects of a healthy heart in our companion pet.. In this discussion I will describe effects of an unhealthy heart.
Heart disease ultimately results in poor transport of oxygen. Low oxygen to the muscles, kidneys, liver, bone , brain etc. can cause cell death. Cell death means the mitochondria in the cell can no longer carry on electron transfer to oxygen for cell energy. Tissues (groups of cells) then die. Related examples of failure to transport oxygen would be stroke, heart trauma, blood loss, lack of red blood cells (anemia). Primary heart disease is either heart muscle or heart valves in our companion pets. Disease may manifest in several ways. In very young animals there are several heart birth defects or congenital defects. Most defects are physical abnormalities in which the “parts” are formed incorrectly.
Indirect disease occurs in other ways such through infection. Infection is serious enemy of the heart. Infection can enter the bloodstream and lodge on the heart valves. The valves act as a net for bacteria. Once the bacteria take hold the infection can destroy the valve tissue. Good examples of infection are dental disease, prostate infection and Staph infection . Heart disease may be related to stress, high blood pressure, poor nutrition and high thyroid levels. Finally, as the heart ages heart valve disease and heart muscle disease result.
Healthy heart valves act as swinging saloon doors that swing in one direction. This keeps blood flowing forward. Once the valves are diseased or aged they weaken and swing back and forth. This turbulent blood flow is audibly heard. It is called a murmur. More often this occurs in small breed dogs such as poodles, Yorkshire terriers and Chihuahua. Healthy heart muscle acts like a fist which contracts and relaxes to push or “eject” blood forward through the body. Muscle begins to weaken as though the fist has arthritis or as though it is holding Jell-O. Now the ejection of blood is poor. The rhythm of the heart can change when the muscle weakens. This is called an arrhythmia. An arrhythmia pushes blood erratically. If these problems progress the heart begins to fail, usually increases in size and can no longer compensate. Blood pressure will change because the blood ejection is poor but the heart is working even harder to keep blood flowing. With poor blood flow the oxygen delivery is decreased and the heart will work even harder. A vicious cycle begins. This is classified as Heart failure.
Assessing disease can be done with several tools. A stethoscope is the first tool. This usually identifies a problem exists and that further tests are needed. Radiographs (x-rays) assess heart size, ultrasound give a 3 dimensional and cross section of the heart muscle and heart valves, a pulse oximeter measures the effiency of oxygen transport through the blood stream and Magnetic Resonance Imaging( MRI) measures changes in tissue/organ size. Additionally, blood work will check for effects of heart disease on other organs such as the liver and kidneys.
All animals should have a regular annual exam to check the heart. At seven years of age bloodwork and additional testing is recommended to detect early problems before they can impact the heart and cause serious problems. Treatment for heart problems has become very advanced. Many medications are identical to those used in humans. (Many medications were initially tested in our companion pets before they were used in humans.) The result is improved quality of life and a longer life expectancy.