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Mitral Valve Defect
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Selective IgA Deficiency
Spina Bifida
Symetrical Lupoid Onychodystrophy
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Tricuspid Dysplasia
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  Mitral Valve Defect


Common names or abbreviations:

bulletMitral Valve Defect

Description or definition:


Mitral Valve Defect (MVD) is any defect in the valve that separates the left atrium and the left ventricle.  Depending on the defect, the condition can range from mild to severe.


The left ventricle contracts and sends the blood out into the arteries to take oxygen and nutrients to the rest of the body.  The valve between the left atrium and left ventricle is called the mitral valve.  A defect in the mitral valve generally prevents the valve from properly doing its job to keep blood from flowing back into the left atrium when the left ventricle contracts.  This backflow of blood is called mitral regurgitation.

bulletMitral valve defects cause a reduced blood supply to the body.  They also cause a larger than normal volume of blood to accumulate in the left atrium.  As a result, the left atrium begins to expand or “bulge” to accommodate this greater volume of blood.  This chronic stretching of the heart muscle fibers eventually causes the heart to beat abnormally.  The body also attempts to compensate for the reduced blood flow to the body by increasing the heart rate and constricting blood vessels to increase blood pressure and maintain normal body function.  This decreased blood supply causes the exercise intolerance that is commonly observed in dogs with mitral valve defects.  If the left atrium enlarges enough, it will compress and injure the left mainstem bronchus of the lung and cause a hacking cough.  In more severe cases this condition can lead to heart failure.

Mitral Valve Dysplasia:  This form of mitral valve defect is congenital (present at birth) and is the result of abnormal development (dysplasia) of the mitral valve.  If the dysfunction is mild it may never present a clinical problem.  In moderate cases, the dog may not begin to experience any signs or symptoms of the disease until it ages.  In the most severe cases the condition can lead to heart failure.  An older dog with asymptomatic mitral valve dysplasia is more prone than a normal dog to develop congestive heart failure.


Mitral Stenosis: This defect is caused by narrowing of the mitral valve that separates the left atrium and the left ventricle.  When the mitral valve is narrowed, it is difficult for the blood to leave the left atrium.  Like other mitral valve defects, dogs with mitral valve stenosis can be affected either mildly or severely.  Most dogs can live active normal lives, but with age the condition can progressively worsen.


Mitral Valve Insufficiency.  This term is often used to indicate a degeneration of the mitral valve leaflets that results in valve insufficiency (leaks) in aging or geriatric dogs.

bulletMitral valve prolapse (MVP): is when the mitral valve flaps do not close properly.  As pressure builds inside the left ventricle it pushes the mitral valve back into the left atrium which may cause a small leak.



Reduced tolerance for exercise, difficulty breathing, coughing at night or when at rest (these symptoms occur because of a build-up of fluid in the lungs), heart murmur, abnormal heart rhythm (cardiac arrhythmia).  Signs of a gradually failing heart include fainting, weakness, or collapse.



Most experienced veterinarians can diagnose a heart murmur simply by listening with a stethoscope.  If a heart murmur is detected in a young dog, an echocardiogram (ultrasound), electrocardiograph (ECG/EKG), and raidiographs (X Ray) should be done to confirm the diagnosis and stage the disease.  These tests can often reveal some of the changes that occur in the heart over time, as it works harder to compensate for the insufficiency of the mitral valve.  These changes may include enlargement of the left side of the heart, enlargement of blood vessels in the lungs, and cardiac arrhythmias.

Check here for OFA heart clinics in your area: http://www.offa.org/clinics.html



Treatment depends on the stage of heart disease and the severity of the condition.  Dogs with very mild cases may live a normal life without the need for any veterinary intervention.  Treatment may include a special sodium-restricted diet, exercise restriction, diuretics, and medication to support the failing heart.  There are also cardiac drugs available that may be beneficial to this condition.


 For more information on heart disease, or if you are concerned about whether your dog has a heart condition, contact your veterinarian.

Links to sites about this disease:













This summary provided by:

bulletJessica S

Wildfire Kennel



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Copyright © 1998 - 2009. Shiloh Shepherd Dog™ Club of America.
All rights reserved. Revised: January 2008

The information on this website was written by ISSR breeders and other concerned individuals, however we are are NOT veterinarians. This information is being provided as a general overview, from information we were able to find about each disease through our own research. These summaries are not intended to be relied upon as medical or veterinary advice, nor do we consider ourselves experts in the veterinary field or in any of these conditions. While we do our best to provide the most up to date information, new research is constantly being done on these diseases. We recommend that you do further study and talk to your veterinarian on any topics you see here, as we cannot guarantee that the information posted here is the most current information available.  This site was originally designed and maintained by Debbie Knatz.