Acquired aortic and mitral stenosis characterized by valvular fibroelastosis in a dog.

Acquired fibroelastic valvular stenosis is a rare but important differential for combined aortic and mitral stenosis in dogs.

This case report describes an unusual presentation of acquired combined aortic and mitral stenosis in a 13-year-old neutered male Yorkshire terrier weighing 2.6 kg. The dog presented with left-sided congestive heart failure confirmed by clinical signs and thoracic radiography. Echocardiography demonstrated left atrial enlargement, left ventricular concentric hypertrophy, and stenosis with thickening of both the mitral and aortic valves (AVs). Comorbidities included a hypercoagulable state, chronic kidney disease, and a portal vein thrombus. Medical management combined with balloon valvuloplasty of the AV provided acceptable quality of life for nine months. Disease progression led to recurrent pulmonary edema and acute kidney injury, prompting attempted mitral balloon valvuloplasty, which resulted in cardiac arrest and death. Postmortem and histopathological examination revealed thickening of both valve leaflets with loss of normal stratification, extensive fibroelastic tissue deposition, and myxoid tissue accumulation. Cardiomyocyte hypertrophy was attributed to pressure overload secondary to aortic stenosis rather than primary myocardial disease. These fibroelastic changes were considered atypical compared to more common acquired valvular diseases in dogs, such as myxomatous mitral valve disease. The authors discuss clinical, interventional, and pathological features of this rare condition, drawing comparisons with similar valvular abnormalities reported in other species. This case highlights the importance of histopathology in characterizing unusual valvular diseases and the role of interventional cardiology as a palliative option in complex cases.

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