A calf with pneumonia needs an antibiotic to fight the bacterial infection, an anti-inflammatory to bring down fever and reduce lung damage, and supportive care to keep the animal hydrated and comfortable while it recovers. Acting quickly matters: calves treated within the first 24 hours of showing symptoms have significantly better outcomes than those where treatment is delayed even a day or two.
Recognizing Pneumonia Early
Before you treat, you need to confirm what you’re dealing with. The University of Wisconsin’s calf respiratory scoring system is a widely used tool that assigns points based on rectal temperature, nasal discharge, cough, eye discharge, and ear position. A total score of 5 or higher signals a calf that needs treatment.
The earliest signs are often subtle: a calf that’s slightly off feed, standing apart from the group, or just not as alert as usual. Fever is the most reliable early indicator, typically between 104°F and 106°F (40–41°C). As the disease progresses, you’ll see nasal discharge that starts clear and turns thick or yellowish, a moist cough, rapid shallow breathing, and one or both ears drooping. A calf breathing with its mouth open or with its head extended and neck stretched out is in serious respiratory distress and needs immediate veterinary attention.
Antibiotics: The Core Treatment
Pneumonia in calves is almost always bacterial, even when a virus triggered the initial infection. The bacteria most commonly involved are Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. Your veterinarian will select an antibiotic based on what’s circulating in your herd and the calf’s treatment history.
The most commonly used antibiotics for calf pneumonia fall into a few major classes. Macrolides, including tulathromycin, are popular because they’re given as a single injection under the skin in the neck. For calves, the dose is based on body weight at roughly 1 mL per 22 pounds. Amphenicols like florfenicol are another common choice, sometimes combined with an anti-inflammatory in a single product. Other options include fluoroquinolones and tetracyclines, though your vet will guide you on what’s appropriate for the specific situation.
One critical principle: if a calf doesn’t improve within 48 to 72 hours of the first antibiotic, the second treatment should come from a different drug class. Switching to another antibiotic within the same class is less likely to work. This is why having a treatment protocol established with your veterinarian before calving season is so valuable.
Anti-Inflammatories for Fever and Lung Protection
Antibiotics kill the bacteria, but they don’t address the inflammation that’s damaging the calf’s lungs. That’s where nonsteroidal anti-inflammatory drugs come in. Giving an anti-inflammatory alongside the antibiotic reduces fever, eases pain, and helps limit the scarring that can permanently reduce lung capacity.
Flunixin meglumine is the most widely labeled option for cattle and works well as a fever reducer. Some combination products pair it directly with an antibiotic in a single injection, which simplifies treatment. Meloxicam is another anti-inflammatory used in cattle that targets inflammation through a slightly different pathway. Research results on meloxicam’s ability to lower fever on its own have been mixed, but its value in reducing lung consolidation when paired with antibiotics is better supported.
The key takeaway: don’t skip the anti-inflammatory. Calves treated with both an antibiotic and an anti-inflammatory consistently have less chronic lung damage than those treated with an antibiotic alone.
Oral Hydration Makes a Real Difference
This is the part many producers overlook. A 2025 study published in Frontiers in Veterinary Science found that calves with pneumonia who received oral hydration for five days alongside their antibiotic and anti-inflammatory had better cure rates, fewer chronic cases, and better growth performance than calves that got medication alone.
The protocol used in the study was straightforward: an electrolyte and glucose solution given orally at 7% of the calf’s body weight per day, divided into multiple feedings with no more than 3 liters per feeding. For a 100-pound calf, that works out to roughly 3 liters total per day. The solution contained glucose, sodium chloride, and potassium phosphate mixed into water.
Why does hydration help a respiratory problem? Proper hydration keeps the mucus lining of the airways fluid and functional. That mucus layer, along with the tiny hair-like structures that sweep debris out of the lungs, is the calf’s first physical defense against infection. When a calf is dehydrated, even mildly, mucus becomes thick and sticky, and those sweeping structures can’t do their job. The glucose in the solution also provides direct energy to the cells lining the respiratory tract. If a calf is too sick to drink voluntarily, tube feeding the solution works. Calves in severe distress with signs of dehydration may need intravenous fluids from a veterinarian.
Keep the Calf Eating
Sick calves often go off feed, but maintaining nutrition during treatment is important for recovery. For nursing calves, keep them with the cow if possible so they can nurse on demand. For bottle-fed calves, offer smaller, more frequent feedings of milk or milk replacer rather than skipping meals entirely. A calf that stops eating loses energy reserves fast, and the immune system is expensive to run. If a calf refuses to nurse for more than 12 hours, that’s a sign the illness may be more severe than it appears.
Environmental Support During Recovery
Where the calf recovers matters almost as much as what you give it. A sick calf is already struggling to breathe, so air quality and temperature regulation become critical.
Bedding should be deep enough for the calf to nest into. Straw is the best choice because of its insulating properties. A simple test: when the calf lies down, can you still see its legs? If so, the bedding isn’t deep enough. In cold weather, nesting conserves body heat that a feverish calf desperately needs.
Ventilation is a balancing act. Calves need fresh air to dilute airborne pathogens, but drafts at calf level will chill a sick animal and worsen the illness. Cornell University’s guidelines recommend indoor ventilation rates of 50 cubic feet per minute per calf in mild weather and 15 cfm in cold weather for young calves, increasing to 60 cfm and 20 cfm respectively for calves two to six months old. In practical terms, you should be able to stand at calf height, feel gentle air movement, and not smell ammonia. If you can smell ammonia, ventilation is inadequate.
Isolating the sick calf from healthy animals reduces the risk of spreading the infection, but complete isolation in a closed-off space with stagnant air does more harm than good. A well-bedded area with good airflow and protection from wind and rain is the goal.
What Recovery Looks Like
With appropriate treatment, you should see improvement within 48 to 72 hours. The fever drops first, then appetite returns, and the calf becomes more alert and active. Nasal discharge may persist for several days after the calf is otherwise improving, which is normal. A lingering cough that gradually becomes less frequent is also expected.
If rectal temperature hasn’t dropped after 48 hours, or the calf’s breathing is getting worse rather than better, the first antibiotic likely isn’t working. This is when you switch to a different class of antibiotic, ideally based on guidance from your veterinarian. Calves that fail two rounds of treatment may have chronic lung damage or a resistant infection and need a veterinary exam to reassess.
Keep in mind that calves who recover from pneumonia often have some permanent lung scarring. These animals may grow more slowly and be more susceptible to future respiratory problems. Research consistently shows that even a single bout of pneumonia can reduce average daily gain enough to have a measurable economic impact over time.
Preventing the Next Case
Intranasal vaccines against bovine respiratory syncytial virus and parainfluenza-3 virus can be given to calves as young as 9 to 10 days of age. These vaccines are delivered directly into the nose, which helps them work even in the presence of antibodies the calf received from its mother’s colostrum. In practice, most calves are vaccinated around 3 to 4 weeks of age. These won’t prevent every case of pneumonia, since bacteria are the ultimate killers, but they reduce the viral infections that often open the door for bacterial invasion.
Beyond vaccination, the most effective prevention comes down to the basics: adequate colostrum within the first hours of life, clean and dry housing with proper ventilation, avoiding overcrowding, and minimizing stress from weaning, transport, or mixing with unfamiliar animals. Stress is the single biggest trigger for respiratory disease outbreaks in calves, and managing it is cheaper than treating the pneumonia that follows.