ABSTRACT
OVERVIEW The most common cause of heart failure in the dog is chronic degenerative AV valve disease, also known as endocardiosis, mucoid or myxomatous valvular degeneration, and chronic valvular fibrosis1. The mitral valve is usually affected most, but both AV valves are often involved2. Isolated tricuspid valve degenerative disease is uncommon. Aortic or pulmonic valve thickening is seen in some older animals, but insufficiency is usually only mild. Clinically important degenerative valve lesions are rare in cats.
