Endocarditis in Sheep: Infection of the Heart Valves
- See your vet immediately. Endocarditis is a bacterial infection of the heart valves and can become life-threatening.
- Common clues include fever, weight loss, weakness, poor appetite, exercise intolerance, and a new or louder heart murmur.
- Sheep may also show fast breathing, swelling under the jaw or belly, intermittent lameness, or sudden collapse if heart failure or septic emboli develop.
- Diagnosis usually requires a farm exam plus bloodwork, and may include blood culture and echocardiography when available.
- Treatment often involves prolonged antibiotics and supportive care, but prognosis is guarded to poor in many cases, especially when diagnosis is delayed.
What Is Endocarditis in Sheep?
Endocarditis is an infection and inflammation of the inner lining of the heart, most often affecting one or more heart valves. In sheep, it is usually bacterial endocarditis, meaning bacteria enter the bloodstream and attach to damaged valve tissue. Over time, infected clumps of bacteria, fibrin, and inflammatory debris form on the valve. These lesions can interfere with normal blood flow and make the valve leak.
This condition is uncommon compared with pneumonia, foot problems, or digestive disease, but it is serious when it happens. Affected sheep may look vaguely ill at first, with fever, weight loss, or reduced thrift, then worsen as the heart and other organs are affected. Pieces of infected material can also break off and travel through the bloodstream, causing septic emboli in the lungs, kidneys, joints, or other tissues.
For pet parents and flock managers, the challenge is that early signs are often nonspecific. A sheep may seem "off," lag behind, or fail to improve after treatment for another infection. Because endocarditis can progress quietly, a prompt exam by your vet matters whenever a sheep has persistent fever, poor body condition, or a newly detected murmur.
Symptoms of Endocarditis in Sheep
- Persistent or intermittent fever
- Weight loss or poor body condition
- Lethargy, weakness, or lagging behind the flock
- Reduced appetite
- Heart murmur
- Fast breathing or breathing effort
- Swelling under the jaw, chest, or belly
- Intermittent lameness or joint pain
- Sudden collapse or death
When to worry: call your vet promptly for any sheep with fever that keeps returning, unexplained weight loss, weakness, or poor response to treatment for another infection. A same-day exam is especially important if your sheep has breathing changes, visible swelling, collapse, or your vet has previously heard a murmur. Because signs can overlap with pneumonia, abscesses, chronic foot infection, and other flock diseases, your vet will need to sort out the cause.
What Causes Endocarditis in Sheep?
Endocarditis usually starts when bacteria gain access to the bloodstream and then settle on a heart valve. This is more likely if the valve surface has already been irritated or damaged, but infection can also develop during significant bacteremia. In large animals, chronic infections elsewhere in the body are important risk factors because they provide a steady source of bacteria.
In sheep, possible sources include infected wounds, navel infections in lambs, joint infections, foot infections, abscesses, pneumonia, mastitis, uterine infection, or complications after procedures that allow bacterial contamination. Opportunistic bacteria such as Trueperella pyogenes, streptococci, staphylococci, and other organisms may be involved, depending on the source infection and the flock environment.
Good flock management lowers risk, but it cannot eliminate it completely. Clean lambing areas, prompt care of wounds, careful hygiene during injections and procedures, and early treatment of primary infections all help reduce the chance that bacteria will spread through the bloodstream. If one sheep has chronic fever or repeated illness after an earlier infection, your vet may consider endocarditis as part of the workup.
How Is Endocarditis in Sheep Diagnosed?
Diagnosis starts with a careful history and physical exam. Your vet will ask about recent illness, lambing history, wounds, lameness, pneumonia, mastitis, injections, and any prior antibiotic use. On exam, findings that raise concern include fever, poor body condition, abnormal heart sounds or a murmur, fast heart rate, fast breathing, and signs of fluid buildup.
Bloodwork may show inflammation, infection, anemia, or organ changes related to chronic disease. If feasible, blood culture can help identify the bacteria involved, although prior antibiotic treatment may reduce the chance of a positive result. In some cases, your vet may also recommend testing for other causes of chronic fever and weight loss.
Echocardiography is one of the most useful tests when available because it can help visualize vegetative lesions on the valves and assess how well the heart is functioning. Thoracic ultrasound or radiographs may be used to look for heart enlargement, fluid, or lung involvement. In field settings, diagnosis is sometimes presumptive, based on the combination of chronic infection signs, a murmur, and poor response to routine treatment. Unfortunately, some cases are only confirmed at necropsy.
Treatment Options for Endocarditis in Sheep
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm call or clinic exam
- Basic physical exam with heart and lung assessment
- Targeted bloodwork if available
- Empiric long-course antibiotics chosen by your vet based on likely source infection
- NSAID or other supportive care if appropriate
- Isolation or reduced exertion and close monitoring
- Discussion of humane culling or euthanasia if the sheep is declining
Recommended Standard Treatment
- Comprehensive exam by your vet
- CBC and chemistry panel
- Blood culture when feasible
- Echocardiography or referral imaging if accessible
- Culture-guided or best-judgment prolonged antibiotic therapy
- Anti-inflammatory and supportive care
- Recheck exam to assess murmur, fever, appetite, and body condition
Advanced / Critical Care
- Referral or hospital-level evaluation
- Detailed echocardiography
- Serial bloodwork and repeated cultures as indicated
- IV fluids or intensive supportive care when appropriate
- Oxygen or additional cardiopulmonary support if respiratory distress is present
- Management of complications such as heart failure, septic emboli, or severe systemic infection
- Necropsy planning if the sheep dies or euthanasia is elected for flock health information
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Endocarditis in Sheep
Bring these questions to your vet appointment to get the most out of your visit.
- What findings make you suspect endocarditis instead of pneumonia, abscess disease, or another chronic infection?
- Did you hear a murmur, and if so, what might that mean for this sheep's heart function?
- Which tests are most useful in this case, and which ones are realistic to do on-farm versus by referral?
- Is blood culture or echocardiography likely to change the treatment plan for this sheep?
- What antibiotic options fit this sheep's situation, and how long might treatment need to continue?
- Are there signs of heart failure, septic emboli, or other complications that change prognosis?
- What monitoring should I do at home for appetite, breathing, swelling, temperature, and activity?
- Given this sheep's role in the flock, what are the most practical care options, including treatment, isolation, culling, or euthanasia?
How to Prevent Endocarditis in Sheep
Prevention focuses on reducing bloodstream infections. That means keeping lambing and housing areas as clean and dry as possible, disinfecting equipment, using good injection technique, and addressing wounds early. Navel care in newborn lambs, prompt treatment of lameness and joint infections, and good mastitis control are especially important because these problems can provide a route for bacteria to spread.
Routine flock health work also matters. Work with your vet on vaccination plans, parasite control, nutrition, stocking density, and foot health so sheep are less likely to develop the chronic infections that can seed the heart. If you notice a sheep with recurring fever, poor thrift, or a lingering infection that does not respond as expected, ask your vet to reassess rather than repeating the same treatment plan.
Necropsy can be an important prevention tool for the rest of the flock. If a sheep dies after chronic illness, a postmortem exam may confirm endocarditis and help identify the original infection source. That information can guide changes in hygiene, lamb care, wound management, and overall flock protocols.