by Kathy Jermaine, DVM
Part of every routine exam of your dog or cat by their veterinarian is listening to the heart with a stethoscope. But what does it mean when you are told Fluffy’s heart sounds good? Or a heart murmur was heard? Does a normal sounding heart mean there is no disease? Is a murmur serious? Life-threatening?
A murmur is essentially a sound that is heard when there is turbulent blood flow through the heart (i.e. due to a leaky valve). This is often an indication of heart disease. But as you might have guessed, there is no one simple answer to the questions listed above! Murmurs come with a variety of classifications including loudness, location and more. And although the loudness of the murmur can sometimes correlate with the severity of disease, this isn’t always the case. Particularly in cats; approximately 20% of cats have a physiologic, or non-pathologic, heart murmur. Furthermore, some cats with severe heart disease have no murmur at all!
Most cases of heart disease, particularly in middle-aged to older pets, tend to be a chronic, progressive condition. They are often secondary to either degeneration of the valve(s) or changes to the heart muscle itself. Mild changes don’t necessarily cause direct problems for the animal, but over time, can lead to life-threatening consequences such as heart failure. Not all animals diagnosed with heart disease will end up with heart failure. It typically depends on multiple factors such as the animal’s age, severity of when heart disease starts, what part of the heart is affected, etc.
When a heart murmur is first heard in a pet, a few diagnostics may be considered to find out more information. Chest x-rays can be useful to evaluate the overall size and shape of the heart. They are also very important to look for evidence of heart failure. Other times an echocardiogram (ultrasound) is more useful, to look for specific changes in the heart. In severe cases, medications may be indicated based upon changes seen on imaging.
Whether or not your pet has a heart murmur, it’s important to be aware of what signs to look for that may indicate heart failure. Early heart failure can be detected by observing an increase in your pet’s respiratory rate while asleep. As signs progress, respiratory rate and effort increase when the pet is awake and she often loses interest in normal activities such as eating, playing, etc. Cats will often hide more. Once this happens, respiratory distress can progress quickly, so it is important to treat it as an emergency until proven otherwise. Other signs to be aware of are: coughing, exercise intolerance, syncope (fainting), or lethargy. Signs of cardiac disease or failure are not always specific. Since our pets can’t talk, a thorough exam by a veterinarian is required to determine what tests and treatments are required.
Another consideration is which pets are at risk for heart disease, and what can be done to prevent or slow changes in the heart. Genetics are a major factor in heart disease in dogs and cats. For example, the Cavalier King Charles Spaniel tends to be the poster child for valvular heart disease in dogs. While larger breed dogs such as the Doberman Pincher or Boxer tend to be at risk for cardiomyopathy. The Maine Coon is a classic example of a cat breed at risk for cardiomyopathy. The best thing we can do to help prevent heart disease in these breeds (or any animal) is to have any potential breeding animal evaluated by a cardiologist and to not breed any animal with a familial history of cardiac disease. Feeding a well-balanced diet (i.e. pet food that meets AFFCO requirements) is also important to prevent certain deficiencies that can lead to heart defects. Because dogs and cats don’t tend to get the classic heart attack from atherosclerosis like people do, weight, cholesterol, etc. don’t tend to be an important risk factor. However a thin, fit pet will likely fare better with an impaired heart compared to an overweight pet.
The key to managing and preventing heart disease, as with most diseases, is to keep your pet lean and active, with a well-balanced diet. Knowing what is normal for your pet is also important for early recognition of when something is off. And most importantly, follow up with your veterinarian if you ever have any concerns about how your pet is doing.
Dr. Kathy Jermaine attended Western University of Health Sciences Veterinary School in Pomona, Calif. During a rotating internship at California Veterinary Specialists she worked side by side with emergency/critical care, surgery and internal medicine specialists. She worked at a small animal practice and emergency hospital before moving here to join University Veterinary Hospital and Diagnostic Center in Salt Lake City. Her professional interests include emergency medicine, soft tissue and preventative medicine.