Infective Endocarditis in Pigs

Infective endocarditis is an infection of the inner lining of the heart, usually affecting one or more heart valves. In pigs, bacteria circulating in the bloodstream can attach to damaged valve tissue, form infected clots called vegetations, and gradually interfere with normal blood flow. As the valve becomes thicker and more irregular, the heart may struggle to pump effectively.

This condition is uncommon compared with routine respiratory or digestive disease, but it is serious. In swine medicine, chronic erysipelas is one of the best-known causes of valvular endocarditis, especially in young adult or mature pigs. Other bacteria, including Streptococcus suis, may also cause septicemia and endocarditis.

Some pigs show only subtle signs at first. They may seem tired, grow poorly, or go off feed. Others are found suddenly dead because infected material can break loose and cause emboli, or because the damaged valve leads to cardiac insufficiency. That is why any pig with unexplained fever, weakness, or collapse needs prompt veterinary attention.

Infective endocarditis starts when bacteria enter the bloodstream and settle on heart valve tissue. The valve may already be slightly damaged, or bacteria may attach to tiny platelet-fibrin clots on the valve surface. Once established, the infection creates rough, cauliflower-like vegetations that can destroy the valve and allow infected fragments to travel to other organs.

In pigs, Erysipelothrix rhusiopathiae is a major cause because chronic swine erysipelas can lead to vegetative valvular endocarditis. Streptococcus suis is another important bacterial cause of septicemia and endocarditis in swine. Other bacteria associated with swine disease, including streptococci and Trueperella pyogenes, may also be involved in some cases.

Anything that increases bacteremia can raise risk. That may include skin wounds, navel infections in young pigs, chronic infections elsewhere in the body, poor sanitation, crowding, stress, and gaps in herd vaccination or biosecurity. In many pigs, the heart problem is really the downstream result of a broader infectious disease process, so your vet will usually look for the original source as well.

Diagnosis usually starts with a careful history and physical exam. Your vet may hear a heart murmur, note fever, poor body condition, lameness, or breathing changes, and ask about erysipelas vaccination, recent illness, wounds, and herd-level disease patterns. Because the signs can overlap with pneumonia, septic arthritis, or other septic conditions, infective endocarditis is often a rule-in or rule-out diagnosis rather than something confirmed from one sign alone.

Testing often includes a complete blood count and chemistry panel to look for inflammation, anemia, dehydration, or organ effects from septic emboli. Blood culture can help identify the bacteria and guide antibiotic selection, although cultures are not always positive. If another infected site is present, your vet may culture that area too.

Echocardiography is the most useful imaging test when available because it can show thickened, irregular, vegetative valves and changes in blood flow. Thoracic imaging and ultrasound may also help assess heart enlargement or fluid-related complications. In some pigs, a definite diagnosis is made only after necropsy, when characteristic proliferative lesions on the valves are found.

Prevention focuses on reducing bloodstream infections before they ever reach the heart. Good sanitation, dry bedding, careful wound care, lower stocking stress, and prompt treatment of skin, joint, navel, and respiratory infections all matter. If bacteria are controlled early, the chance of valve infection goes down.

For many pigs, erysipelas prevention is central. Routine vaccination is widely used in at-risk swine populations, and Merck notes that breeding stock are commonly boosted on an ongoing schedule. Your vet can help tailor a vaccine plan based on age, housing, herd exposure, and whether your pig is a companion pig or part of a breeding group.

Biosecurity also matters. Limit exposure to sick pigs, clean equipment between groups, and review herd introductions carefully. If one pig develops signs consistent with erysipelas or septic disease, early veterinary involvement can protect both that pig and the rest of the group.

There is no home prevention plan that replaces veterinary guidance for a suspected heart infection. If your pig has recurrent fever, poor growth, lameness, or unexplained weakness, involve your vet early. Fast action gives you the best chance to identify the source infection before heart damage becomes permanent.