Valvular aortic 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. In moderate to severe cases, femoral pulse strength is diminished.
A tentative diagnosis can be established by auscultation of a harsh holosystolic ejection murmur at the left cardiac apex. The intensity of the murmur correlates fairly well with the degree of stenosis and may increase as animals mature, reflecting progressive stenosis. Puppies without detectable murmurs should not be considered free of disease until they reach 6 months of age.
Radiographically, there is variable left ventricular enlargement and poststenotic dilatation of the aorta.
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. Balloon valvuloplasty (typically not very effective) and surgical resection have been performed, with variable coutcomes.
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