ny symptoms you would notice.
Many veterinarians have noticed that small breeds of dogs that eat soft food and table scraps eventually develop chronic mouth infections or periodontal disease. It is very common for these pets to also have a heart murmur related to their mitral valve. Dentists and many veterinarians believe that bacteria break loose from oral tissue, move through the blood stream and attach to the heart valves to cause a condition called endocarditis that eventually scar the heart valves. When a mitral valve wears out, its two flaps become blunted, shriveled and scarred so that they do not open or close properly. When this happens, blood does not flow in the normal pattern but leaks back in to the left atrium and/or fails to fully fill the left ventricle before the heart beats. With time, increased back pressure causes one or more chambers of the heart to enlarge. As the chambers of the heart enlarge they press on the windpipe resulting in a dry, hacking cough. The enlarged heart also stretches the nerve fibers that control heart rhythm. That can resulting in abnormal heart beats or arrhythmias. As blood backs up, it pools in the lungs as edema that makes the cough even worse. Particularly when the pet is lying down or at rest.
Less frequently than left side heart failure, it is the right side of the heart that fails to move blood adequately. When that occurs, blood backs up between the heart and the lungs. You can read more about that problem through the previous links .
Puppies and kittens are sometimes born with abnormal hearts. This is congenital heart diseases – errors in heart construction .
Errors In Heart Development:
Subaortic Stenosis (SAS):
This problem is most common in big dogs (Rottweilers, Boxers, Newfoundlands, Golden retrievers, Great Danes etc.). Stenosis means narrowing. In cases of subaortic stenosis the puppy is born with an abnormally narrow passageway leading from its heart to its aorta. The problem comes in all degrees of severity – from very mild case, requiring no treatment to life-endangering seriousness.
When you take your puppy or kitten to your veterinarian for its first vaccinations, your veterinarian should listen to the pet’s heart. In a puppy with SAS, there will usually be a heart murmur over chest near the left base of its heart. When a puppy is not severely anemic from hookworms, SAS and/or a patent (=open) foramen ovale are probably the most common anatomical reasons for these pediatric murmurs. (read here) This murmur is how most cases of SAS are first diagnosed. When discovered later in life the complaint is likely to be tiring after mild to moderate exertion. Not every puppy with a heart murmur has SAS or anything that serious. Puppies often outgrow heart murmurs without veterinarians really knowing what caused them in the first place. Only complicated tests can tell which murmur is important and which is not ( benign or innocent heart murmurs ). But if your pet still has the murmur when it is ~6 months old, the problem need veterinary attention.
When a puppy has a significant degree of SAS passageway narrowing, its heart has to work harder to force the blood through the narrow area just below the aortic valve. With time, the heart muscles will get thicker due to this extra effort. As the heart walls thicken, the full heart holds less and less blood and needs more and more oxygen. Eventually, the heart can begin to fail. Unlike older dogs with congestive heart failure, puppies with seriously narrowing SAS often die suddenly when clots form in the heart muscle or the heart’s electrical system fails. Neither the parent of an SAS puppy (nor the puppy itself) should ever be bred again.
What Signs Of SAS Might I See In My Puppy?
Most often, you will see no signs at all in your puppy. But as time goes by and the puppy’s heart muscles thicken, problems in the electrical system of the heart might cause fainting or even unexpected sudden death.
What Tests Might My Veterinarian Perform?
To decide how serious a heart murmur really is, your pet needs to have an echocardiograpy 