SUB-AORTIC STENOSIS (SAS)

Subvavular aortic stenosis is a common heart defect in dogs and the most common congenital heart disease , some breeds are more prone to it than other breeds.
It is most common in Newfoundlands, Bernese , Golden Retrievers , German Shepards and Rottweilers.
SAS is transmitted genectically.
Any dog with a heart murmur should not be bred from .

The heart anatomically is divided into 4 chambers seperated by 4 valves.
The 4 heart valves ensure that blood only flows in one direction through the heart , the aortic valve sperates the main pumping chamber (left ventricle) from the aorta , a large blood vessel that carries blood from the heart to the body.
Dogs that have SAS have an added tissue below the aortic valve and this abnormal tissue creates an obstruction that the heart has to overcome to pump blood to the body .
With this condition , the stenosis makes the heart work harder than it would normally have to .
Hense a heart murmur is created by blood being pumped across the stenosis into the aorta.

SAS comes in many grades of severity .
The symptoms of SAS can be very subtle and the correct performance of cardiac evaluation by a board certifed veterinary cardiologist is crucial in determining whether a dog is effected or not.

It is graded by the following grade -  
 1) MILD 
 2) MODERATE
 3) SEVERE

Dogs with mild disease may lead a normal life without complications.
For a dog with a moderate murmur there may be a few problems , these problems can get worse due to age , illness ,  excercise and other complications.
 it is difficlut to predict each dog with a moderate murmur and hard to tell what symptoms will occur and how its life will be effected. 
Those dogs who suffer a severe grading are obviously the worse cases , these dogs unfortunately may die suddenly or develop excercise intolerance , fainting and  rear limb weakness .
There are other more severe complications such as fluid in the lungs, this in turn leads to heart failure which is serious .
Heart failure can cause coughing , rapid breathing and shortness of breath .

It is very important however to know that age is important when listening for a murmur as many young pups can have innocent murmurs that are not caused by a heart defect and these will go away by the age of 16 weeks .These innocnet murmurs are hard to differentiate from mild SAS and pups need to be checked at 8 weeks , 12 weeks and then 16 weeks to be sure .
These dogs who have had an innocent murmur detected are advised to be re-examined at a year old to be sure .