Aortic (subaortic) stenosis is a narrowing of the pathway for blood leaving the heart. The narrowing is usually beneath the aortic valve of the left ventricle; the condition is then called subvalvular aortic stenosis or SAS for short. SAS is a genetically predetermined disease that affects dogs. The condition is rare in cats. The mode of inheritance, or the genetic cause, is not simple and healthy carriers of the disease genes are common.

A number of breeds are predisposed, including golden retrievers, Newfoundlands, boxers, German shepherds, Rottweilers, shar-peis, bull terriers, English bulldogs and Bouvier de Flanders.

Mild cases of SAS have little impact on the dog other than causing a heart murmur and rendering the dog unsuitable for breeding. Moderate to severe cases are at risk for exercise intolerance, fainting, heart failure, irregular heart rhythms, infections on the heart valve and sudden death.

What to Watch For

The presence of a murmur in a puppy, especially in breeds at risk

Poor exercise capacity

Cough

Difficult breathing

Collapsing

Fainting

Illness with fever