A heart murmur is an abnormal swishing/whooshing sound heard when your veterinarian listens to your dog's chest with a stethoscope. The normal heart sounds in a dog are heard due to the closure of different valves in the heart. A murmur is therefore caused by abnormal turbulent blood flow in the heart.

Some heart problems causing murmurs may be congenital, while others can be degenerative, developing later in life. Sometimes a murmur can occur without heart disease, for example, in dogs with a low red blood cell count or low blood protein count (making the blood 'thin' and causing turbulence). Other murmurs can be 'innocent' or physiologic and have no ill effects.

A grading system is used from 1 - 6 to describe the intensity of a heart murmur, with grade 1 being very quiet and grade 6 being very loud.

When your vet picks up a heart murmur, it does not always mean that the patient has significant heart disease. You will likely be asked a series of questions about your pets' current condition and if you have noticed any clinical signs, including decreased appetite, reduced exercise tolerance, difficulty breathing, especially at night or after laying down and coughing.

If the murmur is found to be moderate or high grade, then further investigation to identify the underlying cause may be required. For some types of heart conditions, it may be beneficial to start treatment before they develop any symptoms of being unwell, so these early investigations are important for your pet's long-term health.