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== Introduction ==

== Introduction ==

[[Image:AV valve dysplasia cat.jpg|right|thumb|200px|<small><center>'''Mitral dyplasia'''. Courtesy of A. Jefferies</center></small>]]

Myxomatous degeneration of the mitral valve is the most common acquired cardiac disease in the dog. Degenerative mitral valve disease (DMVD) is a progressive disease and subtle changes in valve structure precede the development of clinically significant disease.  

Endocardiosis is a valvular insufficiency. The most commonly affected site is the mitral valve. The condition results in slowly developing [[:Category:Heart Failure|heart failure]] as the valves become swollen and shortened/misshapen, so the heart cannot pump blood effectively from the left ventricle to the circulation.  

 

The aetiology of DMVD is unknown. Genetic predisposition for development of the disease is likely, however the inheritance is complex.  

 

The mitral apparatus consists of the mitral valve leaflets, valve annulus, chordae tendinae and papillary muscles.  

Blood passes back into the left atrium, compromising the filling from the pulmonary vein, which leads to back pressure on the pulmonary capillaries. Resultant [[Oedema|oedema]] forms in the lungs, and can be heard as moist sounds on auscultation. This reduces the oxygenation of blood leading to exercise intolerance. Failure of the left side eventually compromises the function of the right side. In [[Heart Failure, Right-Sided|right sided heart failure]] there is a pooling of blood in the venous system i.e. in the [[Liver - Anatomy & Physiology|liver]]. In some cases a jet lesion can occur, where a small stream of blood passes back into the left atrium and contacts the atrial wall.  

Blood passes back into the left atrium, compromising the filling from the pulmonary vein, which leads to back pressure on the pulmonary capillaries. Resultant [[Oedema|oedema]] forms in the lungs, and can be heard as moist sounds on auscultation. This reduces the oxygenation of blood leading to exercise intolerance. Failure of the left side eventually compromises the function of the right side. In [[Heart Failure, Right-Sided|right sided heart failure]] there is a pooling of blood in the venous system i.e. in the [[Liver - Anatomy & Physiology|liver]]. In some cases a jet lesion can occur, where a small stream of blood passes back into the left atrium and contacts the atrial wall.