Myxomatous mitral valve disease is the most common cardiac condition in dogs, particularly small breeds, requiring careful monitoring and welfare-focused medical management.
MMVD causes progressive respiratory compromise as the heart loses efficiency. Dogs in early heart failure experience exercise intolerance and coughing from pulmonary oedema — a distressing sensation of breathlessness that owners may initially misattribute to aging. Acute decompensated heart failure, with severe respiratory distress, cyanosis, and fear, is one of the most distressing emergency presentations in small animal practice. Appropriate staged treatment significantly delays this deterioration and maintains quality of life. End-of-life planning for MMVD patients should include clear discussion of what constitutes unacceptable quality of life — refractory dyspnoea at rest is a recognised humane euthanasia threshold that owners should understand before reaching that point.