HAND OUT SHEET ON BOXER HEART MURMURS
FOR NEW PUPPY OWNERS (UK)

Heart murmurs have been found to be common among boxers.

It should be emphasised that these do not affect health in the great majority (95%) of dogs.

The few dogs with very loud murmurs, however, may be subject to fainting, and there even may be sudden death.

Aortic stenosis is the heart condition most commonly associated with these heart murmurs, but cases of pulmonic stenosis and cardiomyopathy, as found in other breeds, have also been detected.

Typically, clinical signs of aortic stenosis first appear in the young adult although, rarely, puppies can be affected.

It should be stressed that minor "flow" murmurs are commonly found in young Boxer puppies, as in other breeds, but most disappear by about 16 weeks of age. Even if they persist there may be no cause for alarm if they are quiet. Such genuine "flow" murmurs" are not associated with heart disease in the adult.

The incidence of Boxers with severe aortic stenosis has increased in recent years, although the number of cases is still very low in relation to the number of dogs bred.

To rectify the situation the Boxer Breed Council has, with the aid of veterinary cardiologists throughout the country, developed a system of testing based on simple stethescopic examination by the cardiologists. A breeding control scheme has also been established.

Therefore, should a heart murmur, or any heart condition other than a genuine puppy "flow" murmur, be recognised in a Boxer it should be referred to one of the cardiologists. The breeder and the Breed Council geneticist should be informed of the result.

Dependant upon the findings the condition may be treatable.

If a puppy "flow" murmur is loud and persists, the vet in charge may recommend that further advice be sought from a specialist cardiologist.

CONSULTANT CARDIOLOGIST: Anne French, MVB DVC MRCVS, Lecturer in Veterinary Cardiology, The University of Edinburgh, Summerhall, Edinburgh EH9 1QH. Tel. 0131 6506061

SECRETARY TO THE BOXER BREED COUNCIL: Mrs Wendy Brooks, Jinnybrux Bungalow, Alford Road, Mablethorpe, Lincs LN12 1PX. Tel. 01507 472156

VETERINARY ADVISOR TO BREED COUNCIL: Walker G Miller BVMS DBR MRCVS. Walkon Boxers, High Kirkland, Leswalt, Stranraer, DG9 0RH Tel. 01776 870211

Normal Heart

The following describes BRIEFLY how the heart works:-

The Heart has four chambers. The upper two chambers are called atria (atrium - single), the lower two chambers are called ventricles. The heart is also considered to have a left and right side. i.e left and right atria, left and right ventricles. In addition to these chambers, the heart also has a series of valves which control the flow of blood.

Blood flows from the body into the right atrium. It is stored there briefly, before being pumped into the right ventricle. The right ventricle pumps blood into the lungs, where it becomes oxygenated. It flows from the lungs into the left atrium, it is held here briefly before going into the left ventricle. The left ventricle contains the largest muscle within the heart and this is used to pump blood to all parts of the body.

Aortic Stenosis

The following describes BRIEFLY what Aortic Stenosis is:-

A heart murmur is the sound produced when blood flow through the heart becomes turbulent. Murmur's are graded in severity from 0 to 6 where 0 is murmur free and 6 is severe. Aortic Stenosis is a congenital narrowing at the entrance of the aorta which supplies blood to the body. It usually takes the form of a fibrous ring below the aortic valve (Sub-Aortic Stenosis).

The left ventricle has to pump with greater force to push the blood past the narrow valve. This results in a thickening of the heart muscle wall, it enlarges just like any other muscle because it is working harder. As a result of the thickening, the narrowing is made worse. Blood supply to the muscle itself is restricted, thus the muscle is working harder but with restricted blood flow.