Species: Dog

Specimen:
Heart atrioventricular valve

Shown:
Myxomatous valvular degeneration (Endocardiosis)

Pathology:
Endocardiosis

• Most common cardiovascular lesion in dogs, frequently an incidental finding on necropsy
• Prevalence of disease increases with age
• Primarily affects the left atrioventricular valve
• Cause is unknown but likely a genetically influenced degeneration of connective tissue

• Shortened and thickening cusps with a rounded edge or prominent nodules, valves are opaque and white with no evidence of inflammation
•  May see secondary dilation of the atria of the corresponding atrium and dilation of the corresponding ventricle in cases with AV valvular insufficiency
• May see "jet lesions" in the atrium, indicating regurgitation