Diagnosis and management of a more advanced stage of preclinical myxomatous mitral valve disease in dogs without echocardiography

Myxomatous mitral valve disease (MMVD) is the most common cardiac disease in dogs. Appropriate diagnosis and staging can be performed by means of an echocardiographic examination. Early disease stages might be accompanied by valvular insufficiency and, in more advanced phases, by cardiac dilatation. A correct diagnosis of this preclinical phase and identification of cardiac enlargement should be carried out in order to advise appropriate medical treatment. When echocardiography is not available or declined by the dog's owners, alternative methods to identify the disease and predict clinically relevant cardiomegaly, can be performed. Among these, cardiac auscultation and assessment of heart murmur intensity, cardiac dimensions obtained by thoracic radiography, by means of vertebral heart size, and cardiac biomarkers, in particular N-terminal pro-B-type natriuretic peptide (NT-proBNP), can be carried out as single tests or in combination, in order to identify dogs with increased risk of congestive heart failure, and needing an early treatment with pimobendan. In particular, a heart murmur intensity ≥3/6 (moderate or louder), a vertebral heart size ≥11,5 units obtained from a latero-lateral thoracic radiographic view, and plasma concentrations of N-terminal pro-B-type natriuretic peptide value > 1100 pmol/l, are findings that might suggest presence of clinically relevant cardiomegaly with a good specificity. A practical algorithm to guide clinicians in managing dogs with suspicion of valvular disease has been created, starting from clinical examination, and using the aforementioned additional tests in order to advise the appropriate controls and therapy.