Bacterial Pneumonia in Cattle: Symptoms, Causes, and Care

Bacterial pneumonia in cattle is a lung infection caused by bacteria that move into the lower airways and trigger inflammation, fluid buildup, and reduced oxygen exchange. It is a major part of bovine respiratory disease, often called BRD, and many cattle producers also know the acute feedlot form as shipping fever. Calves are affected most often, but adult cattle can get it too.

In many cases, bacteria are not acting alone. A recent viral infection, stress from weaning or transport, crowding, dust, or poor ventilation can weaken normal airway defenses first. Once that happens, bacteria that may already be present in the upper respiratory tract can spread deeper into the lungs and cause more serious disease.

This condition can range from mild and treatable to life-threatening. Early cases may show only fever, dull attitude, and reduced appetite. More advanced cases can lead to rapid breathing, open-mouth breathing, pleurisy, chronic poor growth, or death. Because the course can change fast, prompt evaluation by your vet matters.

The most common bacterial causes are Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis. In some outbreaks, Bibersteinia trehalosi may also be involved. These organisms may live in the upper respiratory tract without causing obvious illness until stress or another infection weakens the lungs' normal defenses.

That is why bacterial pneumonia is often part of a bigger respiratory disease picture. Viral infections such as infectious bovine rhinotracheitis, bovine respiratory syncytial virus, parainfluenza-3, and bovine viral diarrhea virus can damage the airway lining or suppress immunity. Once that happens, secondary bacterial infection can move into the lower airways and lungs.

Management and environment matter a great deal. Weaning, transport, sale-barn exposure, mixing cattle from different sources, dust, ammonia, overcrowding, poor ventilation, sudden weather shifts, and nutritional stress all raise risk. In calves and feedlot cattle, these combined pressures are a common setup for BRD. In adult cattle, early lactation stress or concurrent disease can also contribute.

Not every coughing cow has bacterial pneumonia. Lungworm, aspiration, viral pneumonia, toxic lung disease, and other conditions can look similar. That is one reason your vet's exam is important before deciding on a care plan.

Diagnosis starts with history and a hands-on exam. Your vet will ask about age group, recent transport, weaning, new arrivals, vaccination timing, weather changes, and how many animals are affected. On exam, they often look for fever, depression, nasal discharge, cough, increased respiratory rate, and abnormal lung sounds such as crackles, wheezes, or louder bronchial sounds over the front lower lung fields.

In straightforward cases, your vet may make a working diagnosis based on clinical signs and herd history, especially when quick treatment is important. In more complicated cases, they may recommend additional testing such as thoracic ultrasound, bloodwork, nasal or nasopharyngeal swabs, transtracheal wash, culture, PCR testing, or postmortem examination of animals that died. These tests can help identify whether bacteria, viruses, or both are involved.

Imaging and sampling are especially helpful when animals are severely affected, not responding to treatment, relapsing, or showing chronic poor growth. Mycoplasma bovis cases, for example, can be more chronic and may not respond like routine BRD cases. Your vet may also need to rule out pleurisy, lung abscesses, interstitial pneumonia, lungworm, or other herd-level problems.

Because treatment choices, withdrawal times, and prognosis depend on the likely cause and stage of disease, early veterinary diagnosis is usually the most practical and cost-conscious step.

Prevention works best when it combines herd management, environment, and vaccination planning. Good ventilation, dry bedding, lower dust and ammonia exposure, clean water, and avoiding overcrowding all help protect the respiratory tract. Cattle also do better when handling is calm and stress is reduced during weaning, transport, and pen moves.

Preconditioning can make a real difference. Many herds benefit from weaning before shipment, training calves to eat and drink well before transport, and avoiding abrupt mixing with cattle from multiple sources. Clean, disinfected, well-bedded trucks and comfortable receiving pens also help lower disease pressure.

Vaccination may reduce losses, especially when timed before predictable stress periods, but it works best as part of a broader herd plan. Your vet can help decide whether injectable or intranasal products fit your operation, which viral and bacterial targets matter most locally, and when boosters should be given. For feeder calves, respiratory vaccination is often planned 2 to 3 weeks before feedlot entry or other major movement.

Finally, early detection is prevention too. Daily observation, temperature checks in suspect animals, accurate treatment records, and postmortem exams when deaths occur can help your vet spot patterns early and adjust the herd plan before losses grow.