Endocarditis:

• Endocarditis refers to inflammation of endocardium (inner lining of heart).
• This disease affects inner lining of heart as well as valves within it
• It may be acute or chronic in nature.
• Most cases of endocarditis in farm animals are caused by bacterial infection but route of infection is uncertain whether it is through ingestion or hematogenous spread of bacteria form one part of body to heart via blood.

Etiology:

Most common infectious causes in farm animals are listed below:

Cattle: Alpha-hemolytic streptococci, Actinomyces or Corneybacterium pyogenes, Micrococcus, Staphylococcus spp., Pseudomonas spp., Clostridium chauvoei, Mycoplasma mycoides, Erysipelothrix rheusopathiae (insidiosa– rare)

Horses: Actinobacillus equuli, Streptococcus equi, Streptococcus zooepidemicus, Pasteurella spp., Pseudomonas spp., Migrating larvae of strongylus

Sheep and Pig: Erysipelothrix rheusopathiae (insidiosa), Streptococcus equisimilis, Streptococcus dysgalactia, Streptococcus suis, Escherichia coli, A. pyogenes.

Pathogenesis:

Endocarditis arise from implantation of bacteria onto endocardium from bloodstream or by bacterial embolism of valve capillaries. Endocarditis is predisposed by trauma to the endothelial surface exposing collagen and leading to binding of platelets, activation of the extrinsic coagulation cascade with deposition of fibrin and the formation of sterile platelet-fibrin deposits.

Following infection, bacteria from other system gets dislodged, enters the blood and circulates in bloodstream.

Bacteria then settles in healthy valves and inner lining and starts to produce pathological changes.

Vegetation are formed on endo-cardial surface of valves. They are formed by platelets, fibrin, bacteria and inflammatory cells.

These infections then extend to myocardium causing infarction in smaller areas to occlusion of small branches.

Infection further extends to pericardium and finally cardiac rhythm disrupts due to toxaemia and septicaemia.

Clinical Findings:

• In cattle, endocarditis most commonly occurs in right atrio-ventricular (tricuspid) valve.
• In horse, common site of predilection is aortic valve, then second site left atrio-ventricular valve and third site is right atrio-ventricular valve.
• Most important finding is murmur on auscultation of heart or thrill on palpation of cardiac area.
• Constant moderate, fluctuating fever
• Peripheral lymphadenitis
• Pneumonia
• Arthritis, tenosynovitis
• Loss of condition, pale mucus membrane
• Increased heart rate
• It is one of cause of acute heart failure and sudden death in sows.
• Weakness, progressive loss of body weight

Laboratory Findings:

• Anemia and leukocytosis present at blood examination

Diagnosis:

• On basis of history and clinical findings
• On basis of laboratory findings
• Radiography and echocardiography of heart
• ECG findings: sinus tachycardia, decreased amplitude of QRS complex
• PM findings: Cauliflower-like growth on valves; shrunken, distorted and thickened valves at edges

Differential Diagnosis:

• Pericarditis
• Brisket disease of cattle
• Cardiac lymphosarcoma

Treatment:

• Intravenous administration of high doses of specific antibiotics. Crystalline penicillin upto 20 times is indicated at 4-6 hours’ interval
• Supportive therapy should be given to correct anemia.
• Administration of iron injection to correct anaemia.
• High protein diet should be provided to animals to avoid fluid buildup.
• Vitamin C and folic acid are given as supplements for fastening healing process
• Continuous treatment for 4 months is required and it is uneconomic in food animals.
• Relapse of infection is common and treatment is expensive.