Embolic Pneumonia in Cattle: Causes, Signs, and Prognosis
- See your vet immediately. Embolic pneumonia in cattle is usually a severe, secondary lung infection caused by septic clots traveling through the bloodstream and lodging in the lungs.
- A common pathway is rumenitis from high-grain feeding, followed by liver abscesses, caudal vena caval thrombosis, and then metastatic or embolic pneumonia. It can also occur with bacterial endocarditis.
- Common signs include rapid or labored breathing, cough, fever, poor appetite, weight loss, reduced milk production, abnormal lung sounds, and sometimes sudden nosebleeds if pulmonary aneurysms rupture.
- Prognosis is guarded to poor in many cases because the lung lesions are often multifocal and the original source of infection can be hard to reverse. Early veterinary assessment helps clarify whether treatment is reasonable or humane culling is the safer option.
What Is Embolic Pneumonia in Cattle?
Embolic pneumonia is a serious form of lung infection that happens when infected material in the bloodstream breaks loose and travels to the lungs. Those septic emboli block small pulmonary vessels and seed multiple pockets of infection, so the lungs develop scattered abscesses, inflammation, and damaged blood vessels.
In cattle, this condition is often discussed alongside vena caval thrombosis and metastatic pneumonia. A classic pattern starts with ruminal acidosis and rumenitis, then liver abscesses, then a septic clot in the caudal vena cava, and finally infected emboli showering the lungs. In some cattle, embolic pneumonia can also develop from bacterial endocarditis, especially when infected material sheds from the right side of the heart.
This is not the same as routine shipping fever or a simple bacterial bronchopneumonia. Embolic pneumonia usually means there is a deeper source of infection elsewhere in the body, and that matters because treatment decisions depend on both the lung damage and the original source.
Because the disease can progress quickly and may lead to respiratory distress or fatal bleeding from pulmonary aneurysms, cattle with suspected embolic pneumonia need prompt veterinary attention.
Symptoms of Embolic Pneumonia in Cattle
- Rapid breathing
- Labored breathing or open-mouth breathing
- Cough
- Fever
- Poor appetite and drop in production
- Weight loss and chronic poor thrift
- Abnormal lung sounds
- Nosebleeds or blood from the nose
- Sudden weakness or collapse
See your vet immediately if a cow has fast breathing, obvious effort to breathe, fever, marked depression, or blood from the nose. In embolic pneumonia, signs can look like other respiratory diseases at first, but the combination of chronic poor condition plus severe breathing changes raises concern for a bloodstream source of infection.
Some cattle show a slower course with weight loss, intermittent fever, and reduced production before the respiratory signs become dramatic. Others may first be noticed after a sudden nosebleed or abrupt respiratory distress. Because this condition can be life-threatening and may affect food-animal treatment decisions, early veterinary evaluation is important.
What Causes Embolic Pneumonia in Cattle?
Embolic pneumonia is caused by septic emboli, which are infected clots or fragments of infected material that travel through the bloodstream to the lungs. Once they lodge in pulmonary vessels, they trigger multiple small areas of infection, abscess formation, and inflammation.
In adult cattle, one of the best-known causes is caudal vena caval thrombosis. This often begins with ruminal acidosis and rumenitis, especially in cattle on high-carbohydrate or poorly adapted high-grain diets. Bacteria can then move through damaged rumen tissue to the liver, where abscesses form. If a liver abscess erodes into the caudal vena cava, a septic thrombus can develop and send infected emboli to the lungs.
Another cause is bacterial endocarditis, especially involving the right side of the heart. In that situation, infected material can break off from the valve lesion and travel directly into the pulmonary circulation. Chronic infections elsewhere in the body may also seed the bloodstream, although the vena caval thrombosis pathway is the classic pattern in cattle.
The key point is that embolic pneumonia is usually a secondary disease, not a primary lung infection. That is why your vet will often look beyond the lungs for the original source of infection before discussing prognosis and treatment options.
How Is Embolic Pneumonia in Cattle Diagnosed?
Diagnosis starts with a farm-call exam and a careful history. Your vet will ask about diet changes, high-grain feeding, recent illness, chronic weight loss, milk drop, fever patterns, and any history that could suggest liver abscesses, rumen acidosis, or endocarditis. On exam, they may find fever, increased respiratory rate and effort, abnormal lung sounds, poor body condition, or signs of chronic systemic infection.
Field diagnostics often include bloodwork and sometimes thoracic ultrasound. Ultrasound can help identify superficial lung consolidation, pleural changes, or abscess-like lesions, although it cannot see every lesion deep in the lung. If the history points toward vena caval thrombosis, your vet may also use ultrasonography of the liver and caudal vena cava to look for liver abscesses, a thrombus, or a dilated vena cava.
When practical, your vet may recommend airway sampling such as a transtracheal wash for bacterial culture and susceptibility testing, especially if treatment is being considered. In some cases, diagnosis remains presumptive while your vet rules out other causes of respiratory distress, including typical bacterial pneumonia, aspiration pneumonia, pleuritis, or other chronic thoracic disease.
A confirmed diagnosis is sometimes made only after necropsy, because embolic pneumonia can create many scattered lesions throughout the lungs. Even so, combining history, exam findings, ultrasound, and the search for a primary septic source often gives enough information to guide realistic decisions.
Treatment Options for Embolic Pneumonia in Cattle
Spectrum of Care means you have options. Here are treatment tiers at different price points.
Budget-Conscious Care
- Farm-call exam and respiratory assessment
- Temperature, heart rate, and lung auscultation
- Focused discussion of likely source such as rumenitis, liver abscessation, or endocarditis
- One labeled or extra-label antimicrobial plan when appropriate under a valid veterinary-client-patient relationship
- NSAID/anti-inflammatory support when appropriate
- Short-term monitoring plan with clear recheck or humane-endpoint guidance
Recommended Standard Treatment
- Farm-call or hospital exam
- CBC/chemistry or other bloodwork as available
- Thoracic ultrasound to assess accessible lung lesions
- Ultrasound of liver/caudal vena cava when vena caval thrombosis is suspected
- Targeted antimicrobial plan based on likely pathogens, label restrictions, and food-animal considerations
- NSAID support, hydration planning, and nursing recommendations
- Recheck visit to assess breathing, appetite, and treatment response
Advanced / Critical Care
- Referral-level hospitalization when feasible
- Serial ultrasound and repeated examinations
- Airway sampling such as transtracheal wash for culture/PCR when practical
- IV fluids or more intensive supportive care if indicated
- Oxygen support or close respiratory monitoring in selected cases
- Expanded workup for concurrent endocarditis, severe septicemia, or other systemic disease
- Detailed food-animal drug-use and withdrawal planning with your vet
Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.
Questions to Ask Your Vet About Embolic Pneumonia in Cattle
Bring these questions to your vet appointment to get the most out of your visit.
- Does this look more like embolic pneumonia than routine bacterial pneumonia?
- What primary source of infection do you suspect, such as liver abscesses, vena caval thrombosis, or endocarditis?
- Would thoracic ultrasound or liver/vena cava ultrasound change the treatment plan or prognosis?
- Is treatment likely to help this cow, or is humane culling the more realistic option?
- Which antimicrobials are appropriate for this animal, and what food-animal withdrawal times apply?
- What signs would mean the condition is worsening, especially risk of severe respiratory distress or bleeding?
- Could herd feeding practices be contributing to rumenitis and liver abscess risk?
- What prevention steps should we take for the rest of the group if high-grain feeding is part of the problem?
How to Prevent Embolic Pneumonia in Cattle
Prevention focuses on stopping the primary septic source before infected clots ever reach the lungs. In many herds, that means reducing the risk of ruminal acidosis, rumenitis, and liver abscesses. Careful adaptation to high-grain diets, consistent bunk management, adequate effective fiber, and avoiding sudden ration changes are central herd-level steps.
Your vet and nutritionist can help review feeding programs for cattle at risk, especially adult dairy cattle and feedlot cattle on energy-dense rations. Merck notes that control of vena caval thrombosis is largely achieved through careful feeding management, and liver abscess prevention depends on minimizing rumenitis and managing acidosis risk.
Prevention also includes prompt attention to chronic infections elsewhere in the body. Cattle with persistent fever, poor thrift, reduced production, heart murmurs, chronic lameness, or other signs of ongoing infection should be examined early, because untreated septic conditions can occasionally seed the lungs.
There is no single vaccine that prevents embolic pneumonia itself. Instead, prevention is about good ration transitions, strong herd-health oversight, and early veterinary evaluation of chronic disease so the bloodstream source of infection is addressed before severe lung damage develops.