Mitral annular disjunction and myxomatous mitral valve disease in a dog.

Mitral annular disjunction (MAD) has been defined as a structural abnormality with separation between the posterior leaflet of the mitral valve and the left atrial wall. It is commonly associated with myxomatous mitral valve disease (MMVD), mitral valve prolapse (MVP), ventricular arrhythmias, and sudden cardiac death in humans, but has not been described in veterinary medicine despite the high prevalence of MMVD in the canine population. The echocardiographic findings in a Chihuahua with MAD, MMVD, and MVP are described. Diagnostic methods and criteria are reviewed and adapted.