Endocarditis

Definition

• Endocaditis means inflammation of endocardium of heart

Occurrence

• Common in animals – Swine are more frequently affected

Types

• Inflammation of valves is common and is called valvular endocarditis
• Inflammation of septal endocardium is called mural endocarditis

Sites of occurrence

Species	Frequent site
Horse	Aortic valve
Cattle	Right A-V valve
Dog and Pigs	Left A-V valve

Sources of infection

• Septicaemic infections
• Oral infection
• Umbilical infection
• Suppurative metritis and mastitis
• Traumatic reticulopericarditis (TRP) in cattle
• Liver abscess, peritoneal abscess
• Streptococci of intestinal origin (white scours in calves) or oral origin (in dogs)

Etiology

• Bacteria
  • Erysipelothrix rhusiopathiae in swine
  • Streptococcus equi (Strangles in horses), Shigella equirulis
  • Streptococci in cattle, swine and dogs
  • Leptospirosis in dogs
  • Corynebacterium pyogenes in cattle
• Parasites
  • Migrating larvae of Strongylus in horses
• Pathological
  • Chronic septicaemic diseases

Pathogenesis

• The valves are more often affected as they are exposed to the circulating bacteria and the force of blood.
• The auricular side of valves is damaged usually. In the valves it is the edges of valves that are frequently affected.

•  The enlarged valves injure the adjacent valves during its movement and the thrombi may break off and form emboli.

Gross pathology

• The thrombus is cauliflower like and friable and is called as vegetation . Endocarditis in which these vegetations are present is called vegetative endocarditis .
• In swine excessive vegetations are common
• In cattle affected with black quarter, roughening of left auricular endocardium occurs
• In dogs with leptospirosis and uraemia, ulcerative endocarditis is common. Greenish ulcers are present in the left auricle and ventricle, pulmonary artery and aorta. 

Histopathology

• The lesion consists of a thrombus with central bacterial clumps

• Leucocytes are present in the intima
• From the basal area of the valve fibrous tissue invades the thrombus. But as long as the organisms are alive, complete organization and healing does not take place
• In cattle C. pyogenes causes excessive fibrosis