Mitral valve dysplasia
This defect of the mitral valve leaflets, chordae tendineae or papillary muscles causes mitral valve insufficiency and regurgitation into the left atrium, leading to left atrial and ventricular overload, causing left-sided dilatation, hypertrophic cardiomyopathy, congestive heart failure, arrhythmia and mitral stenosis.
Clinical signs are normally seen in young dogs (1 - 2 years of age) but can present at an older age with symptoms of generalized weakness, exercise intolerance, syncope, ascites and pale mucus membranes. A cough may be present intermittently.
A tentative diagnosis can be established by auscultation of a holosystolic ejection murmur with radiographic evidence of cardiomegaly. Radiographs usually show left-sided cardiomegaly. Cardiogenic pulmonary edema may also be present.
Definitive diagnosis requires use of M-mode and Doppler echocardiography.
A differential diagnosis would include subaortic stenosis, ventricular septal defect, double-chambered right ventricle, hyperthyroidism, cardiomyopathy, Duchenne muscular dystrophy, endocarditis, pulmonic stenosis, mitral valve endocardiosis and infections with Dirofilaria spp.
The prognosis for animals with clinical signs of congestive heart failuree is poor, but mildly affected animals may remain free of clinical signs for several years.
Surgical intervention can be employed in severe cases where financing is not a prohibitive issue. Techniques such as mitral valvular replacement have been employed successfully.
- Cavalier Health
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