Q: At my dog’s last visit to the veterinarian, he mentioned that he heard a heart murmur and that “James” may have the beginning of heart disease. James is a 12 year old boxer. Can you shed some light on the subject?
A: First let me explain a little about the anatomy of the canine heart. The heart is a four chambered organ. The right side of the heart has an upper chamber called the atrium and a bottom chamber called the ventricle. The same applies to the left side of the heart. Between the top and bottom chambers on both sides are valves. The purpose of the valves is to ensure that blood flows in a consistent direction so that no “back flow” occurs. Blood should flow from the body to the right atrium of the heart which directs it towards the right ventricle. From there it is pumped to the lungs where it picks up oxygen rich blood. From the lungs it goes back to the left atrium and then into the left ventricle where it is pumped out into the body.
Since the heart is the most important organ in the body, it plays a crucial role in maintaining health and well-being. Consequently, it is very important that your veterinarian assess the heart at your pet’s physical examinations. Very often the first sign of heart disease that your veterinarian will notice upon examination is called a heart murmur. In dogs this tends to be the valve located between the left atrium and the left ventricle. This valve is called the mitral valve. When the doctor listens to your dog’s chest with his/her stethoscope they will hear a whooshing sound. This whooshing sound is basically the turbulence of blood that is trying to pass smoothly through the valve area from the top atria to the bottom ventricle. Imagine it like a door between two rooms. The murmur occurs when some of the blood regurgitates back from the bottom chamber to the top.
Mitral valve disease is the most common type of heart disease found in canines. It is more common in small dogs, such as poodles, than in larger breed dogs. A very large percentage of dogs over 10 years old will develop a heart murmur. Another type of heart disease that affects dogs is a disease of the heart muscle disease, called cardiomyopathy. This is more common in larger breed dogs such as the Dobermans, Great Danes, German Shepherds and Golden Retrievers.
The symptoms that you might notice from a dog that has heart disease include exercise intolerance, trouble breathing, getting tired faster than normal when at play or taking a walk, coughing, weakness, fainting, pale white or blue gum color, fluid accumulation in the abdomen or a faster than normal heart rate. It is not necessary to have all these signs for heart disease to be present in the dog.The progression of heart disease can vary from months to many years before congestive heart failure develops. Many factors are involved in how the disease progresses. Diagnostic tests are required to get a full evaluation of the heart. The first, auscultation, is listening to the heart with a stethoscope. This will allow the veterinarian to determine the location and intensity of the murmur or if there is an abnormal rhythm (arrhythmia). Secondly, x-rays, called radiographs, are taken of the chest. This allows us to visualize the heart in two dimensions and assess the size and shape of the heart, its blood vessels, and the lungs. The third test, an electrocardiogram or EKG, allows us to determine if the heart is conducting electricity correctly. It helps identify abnormal heart rhythms and it also measures heart rate. The most valuable diagnostic tool in evaluating the function of the heart is the ultrasound examination, called an echocardiogram.
This is a non-invasive technique that allows a three dimensional view of the heart, the valves, the chambers and their walls, as well as, blood flow and how well the heart of contracting.
The recommended treatment of canine heart disease depends, in part, upon which part or parts of the heart is effected, the conduction ability of the heart, the strength of the heart’s pumping ability, and the vessels coming to and from the heart. Many drugs are available to increase the hearts ability to pump blood and oxygen around the body. A Veterinary Cardiologist is the best individual to determine these factors. These veterinarians have had years of additional education and specialize in the Cardiology of pets. As usual, if you suspect that your pet is having some of the above signs, it is imperative that they be examined by a qualified veterinarian as soon as possible. For more information or a consultation to evaluate your pet’s heart status please call for an appointment at my office.