Information Articles - Heart

Heart disease can either be congenital (the dog was born with it or acquired (a problem occurring later in life). Congenital heart disease usually results in a heart murmur, which can be heard by listening to the heart sounds with a stethoscope. This is because an abnormal opening (like a hole in the heart) or abnormal narrowing of a valve at the great vessels exiting the heart causes turbulence of blood within the heart itself or the great vessels, and the turbulent flow is detected as a cardiac murmur. In many cases, the loudness of the murmur (which is graded out of 6 on a scale 1-6) is correlated with the severity of the heart disease. Many puppies have murmurs, which they grow out of called innocent murmurs. These tend to be very low grade. If these are still present when the puppy is 12-15 weeks old, many veterinary surgeons will want to rule out heart disease. Many athletic dogs also have innocent murmurs called flow murmurs, resulting from the blood leaving the heart. Obviously, there can be a problem distinguishing mild congenital heart disease (which may be significant if the animal is bred) and these innocent murmurs. Further investigation to rule out heart disease is usually required.

MITRAL DYSPLASIA

A number of Bull Terriers have recently been identified with a congenital condition known as Mitral Dysplasia. The mitral valve is leaky in this condition, and when the main pumping chamber, the left ventricle, contracts, instead of all the blood leaving into the aorta, some leaks backwards into the left atrium, causing a murmur. This is known as Mitral Regurgitation. Very rarely, the mitral valve can be narrowed as well as being leaky in some cases — this means it is difficult to let blood pass from the left atrium (the collecting chamber) to the left ventricle (the pumping chamber). This is called Mitral Stenosis.

Bull Terriers with mitral dysplasia may be affected very mildly to very severely. Many dogs will lead normal life styles and be very active. Some may have problems as they get older, possibly because of concurrent acquired valvular disease called valvular endocardiosis. A few dogs will develop heart failure, manifested as coughing, breathlessness, tiring easily on exercise and occasionally, fainting. However, if there is any degree of heart disease present, it is possible this will be passed on to offspring if the dog is bred from.

If a heart murmur is detected in your dog, you must discuss it with your own veterinary surgeon. He or she may decide to investigate the problem further or decide to refer tour dog to a veterinary cardiologist. As well as listening to the murmur, other investigations that may be suggested are:

RADIOGRAPHY

This is a chest x-ray, which will show the hart shadow and the lung fields. Usually two views are taken, with the dog lying on its side and on its front. In most cases without anyone else in the room protecting the owners and veterinary staff from unnecessary radiation.

ELECTROCARDIOGRAPHY

An ECG literally records the electrical activity of the heart from the body surface, usually each leg. This will be especially useful if there is an irregular heart beat (a dysrhythmia).

ECHOCARDIOGRAPHY

This is cardiac ultrasound, available only in the veterinary schools and at a few specialist practices. In most cases, a small square of the coat has to be clipped over the heart on both sides of the chest, to allow good ultrasound. Each chamber and valve of the heart can be viewed as the heart pumps. Measurements can be taken and compared to normal values. A special kind of echocardiography known as Doppler can measure the speed of red blood cells as they move through the heart and tell us if there is any abnormal turbulence in the heart, so if heart disease is present, we can get a good idea of how severe it is. Color Doppler is color coding of moving red blood cells within a section of the heart for their direction of movement and any turbulence.

The beauty of cardiac ultrasound is that it is completely non-invasive and very accurate at defining any heart problem present. However, equipment is expensive and a thorough cardiac ultrasound will take 1-2 hours.

BLOOD SAMPLES

If your dog has a heart problem and requires treatment, blood samples to check kidney and liver function may be taken, and to check drug levels during treatment.

OTHER HEART DISEASE

Some Bull Terriers suffer from other congenital heart disease, such as Sub-aortic Stenosis a narrowing in the area of the aortic valve. The above tests will help diagnose other conditions as well as mitral dysplasia

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