Of all the diseases affecting dogs, cardiac diseases are relatively common, with acquired cardiac disease comprising the majority of such cases. Auscultation or listening to heart murmurs is the art of diagnosing various cardiac diseases… an insight.
What is a heart murmur?
A heart murmur is a specific sound detected when listening to the heart with a stethoscope. This sound is a result of the blood flowing faster than normal
within the heart itself or in one of the two major blood vessels leaving the heart. As a result of this, an additional sound is present that can vary from a mild pshhh to a loud whoosh, instead of the normal lubb-dupp.
What causes a heart murmur?
A heart murmur is heard because of turbulent blood flow. A heart murmur is a sign, not a disease in itself. In fact, there are many different conditions that can cause heart murmur in dogs, which include: l Improper functioning of valves within the heart – in older dogs.
Diseases of heart muscle – in large breed dogs.
Structural defect of heart since birth – in puppies and young dogs.
What is the significance of a murmur?
The loudness of a murmur reflects the amount of turbulence that is present in the heart. However, the loudness of a heart murmur does not always correlate directly with the severity of disease. Murmurs are graded by their intensity, usually on a scale of I-VI. A Grade I murmur is very soft or quiet, may only be heard intermittently, and is usually heard only in one location on the chest, while a Grade VI murmur is very loud, heard everywhere that the heart can be heard, and can be felt when a person places their hand on the chest in the area of the heart (in cardiac terminology, this is called a ‘thrill’).
Occasionally, a heart murmur can be detected in a young puppy. Though this may indicate the presence of a congenital heart condition (a defect the puppy was born with), in many cases it is what is called an innocent murmur, meaning that it is not related to a heart problem. These murmurs usually disappear by the time the animal is about four months of age.
Symptoms to watch out for
However, if the murmur has been detected in a pet, we should watch for one or more signs:
- Difficult or rapid breathing
- Congestion or ‘noisy’ breathing
- Reluctance to exercise
- Weakness or tiredness
- Fainting episodes
- Bluish gums
- Abdominal distension
Once a murmur is detected, it’s time to determine the cause, which can be done by a number of tests:
- Blood test
- Heartworm test
- Chest X-ray
- Electrocardiogram (ECG)
- Echocardiogram (an ultrasound exam to evaluate heart structure and function)
- Blood pressure test
How a heart murmur can be managed?
Treatment depends on the cause of the heart murmur and dog’s condition. If the dog is not showing any signs of heart disease other than the murmur, treatment is usually not required. In some cases, such as when a heart murmur is caused by heartworm disease, treatment may resolve the heart murmur
completely. If the murmur is caused by a congenital condition, surgery may be recommended. In other cases, the heart murmur may remain, but medications can help make the dog more comfortable and improve his longevity.
(Dr K Satish Kumar is associate professor and head, Veterinary Medicine, Sri Venkateswara Veterinary University, Veterinary Hospital, Warangal, Andhra Pradesh while Dr D Srikala is assistant professor, Veterinary Medicine, CVSc, Tirupati, Andhra Pradesh).