Treating bovine respiratory disease (BRD) starts with early detection, followed by the right antibiotic choice and supportive care to reduce lung damage and get the animal back on feed. BRD is the leading cause of illness and death in feedlot cattle, and how quickly and effectively you treat it determines not just survival but long-term performance and carcass quality. Here’s what works, what doesn’t, and how to make better treatment decisions on the ground.
Spotting BRD Early With Clinical Scoring
The sooner you catch BRD, the better your treatment outcomes. Pen riders and calf managers often rely on general observation, but structured scoring systems improve consistency. The University of Wisconsin BRD scoring system, widely used in pre-weaned dairy calves, assigns points across several categories: nasal discharge (from none to copious bilateral mucopurulent discharge), ear and head carriage (from normal to head tilt or bilateral ear droop), rectal temperature, cough, and eye discharge. The total score is the sum of nasal, temperature, and cough scores plus whichever is higher between the eye discharge and ear/head scores.
In practice, you’re looking for the combination of depression, reduced feed intake, nasal discharge, elevated temperature (typically above 104°F), and labored breathing. A single sign like a cough might not warrant pulling an animal, but stacking two or three of these signs together should trigger treatment. Animals that stand off from the group, have drooping ears, or show a noticeable head tilt are often further along than they appear.
Choosing the Right Antibiotic
Antibiotics approved for BRD treatment in the United States fall into two broad categories. Bactericidal drugs, which directly kill bacteria, include beta-lactams like ceftiofur, fluoroquinolones like enrofloxacin and danofloxacin, and aminoglycosides. Bacteriostatic drugs, which stop bacteria from multiplying and let the immune system finish the job, include macrolides (tilmicosin, tulathromycin), florfenicol, and oxytetracycline.
The choice between these classes matters more than many producers realize. A large feedlot study published in the Journal of Animal Science found that calves treated with bactericidal drugs for both their first and second BRD treatments had significantly better outcomes than calves started on bacteriostatic drugs. Only about 50% of calves receiving two rounds of bactericidal antibiotics needed four or more treatments, compared to roughly 72-74% of calves that received bacteriostatic drugs first. Calves on the bactericidal-first protocol also gained more weight, averaging 1.11 kg/day versus 0.84 kg/day for calves treated twice with bacteriostatic drugs. At slaughter, the bactericidal-treated group had a higher probability of grading Choice (36%) compared to the bacteriostatic-first group (28%).
This doesn’t mean macrolides and florfenicol are poor drugs. They remain effective tools, especially in metaphylaxis and in operations where resistance patterns favor them. But when an animal is visibly sick and you’re choosing a first-line treatment, the data supports starting with a bactericidal option and reserving bacteriostatic drugs for follow-up or prevention rather than the other way around.
Why Treatment Fails
BRD treatment failure is frustratingly common, and it’s rarely caused by a single factor. The disease itself results from complex interactions between the animal’s immune system, the pathogens involved, and environmental stressors like transport, commingling, weather swings, and dust. Treatment failure follows the same pattern: it’s an interaction between the host, the pathogen, the environment, the drug, and the person giving the drug.
On the pathogen side, the bacteria causing BRD vary in severity. Mannheimia haemolytica causes the most aggressive form, producing severe hemorrhagic pneumonia with extensive dead tissue in the lungs, clotting in blood vessels, and fibrin deposits on the lung surface. This type of infection can destroy lung tissue so rapidly that even the right antibiotic given at the right time can’t reverse the damage. Pasteurella multocida, by contrast, tends to cause a milder pneumonia with less tissue destruction and more airway inflammation. Animals infected primarily with Pasteurella generally respond better to treatment.
On the drug administration side, common errors include incorrect dosing, wrong injection site, using a drug past its withdrawal period from a previous treatment, or simply treating too late. Antimicrobial resistance is a growing concern as well, particularly in operations that rely heavily on one drug class for both prevention and treatment. If you’ve used a macrolide for metaphylaxis on arrival, switching to a different class for individual treatment makes sense both biologically and from a resistance standpoint.
The Role of Anti-Inflammatory Drugs
Because fever, pain, and lung inflammation drive much of BRD’s impact on the animal, anti-inflammatory drugs (NSAIDs) are commonly used alongside antibiotics. Meloxicam and flunixin meglumine are the most frequently discussed options. The logic is straightforward: reducing inflammation should limit lung damage and help the animal feel well enough to return to feed and water sooner.
The evidence, however, is more nuanced than the theory suggests. A controlled study in calves infected with bovine respiratory syncytial virus (one of the key viral triggers of BRD) tested both meloxicam and aspirin against untreated controls. Neither NSAID had a significant effect on virus replication, clinical signs, or the extent of lung lesions. This doesn’t mean NSAIDs are useless in every BRD scenario, since the study looked specifically at viral infection rather than the secondary bacterial pneumonia where most lung damage occurs. But it does suggest that anti-inflammatories alone won’t rescue a poor antibiotic choice or a late diagnosis. They’re best thought of as comfort care that may help animals eat and drink sooner, not as a treatment that changes the disease trajectory on its own.
When to Treat the Whole Group
Metaphylaxis, treating an entire group of cattle with antibiotics on arrival rather than waiting for individuals to get sick, is a standard practice for high-risk cattle. “High risk” typically means freshly weaned calves, animals that have been commingled from multiple sources, or groups with unknown vaccination history that have been through a stressful transport.
The economic math drives the decision. One analysis estimated that when metaphylaxis costs around $18 per animal, the expected morbidity rate in the group needs to exceed roughly 40% for the practice to pay for itself. Below that threshold, you’re spending more on mass treatment than you’d lose from treating individual sick animals. Above it, the cost of pulling, treating, and retreating individuals (plus the performance drag on animals that get sick) makes group treatment the better investment.
For medium-risk cattle, the decision is harder. If you have good arrival processing protocols, solid vaccination programs, and experienced pen riders who catch illness early, you can often manage these groups with individual treatment. If your infrastructure or labor makes early detection unreliable, metaphylaxis becomes a more defensible choice even at moderate risk levels.
Practical Treatment Protocols
A solid BRD treatment protocol on any operation should include three layers. First, define clear pull criteria so that everyone working cattle uses the same threshold for deciding an animal needs treatment. A clinical scoring system, even a simplified version, reduces the variability between pen riders and ensures animals get treated at a consistent disease stage.
Second, establish a treatment sequence. Your first-line drug should be your most effective option for the pathogens common in your operation. Work with your veterinarian to review necropsy results and lab cultures from previous outbreaks, since this tells you which bacteria are dominant and which drugs they’re still sensitive to. Assign a second-line and third-line drug from different classes for retreatment. Switching classes between treatments gives you the best chance of overcoming partial resistance or reaching bacteria that the first drug didn’t fully clear.
Third, set a post-treatment observation interval. Most BRD antibiotics need 48 to 72 hours to show clinical improvement. Retreating too soon wastes drugs and exposes bacteria to subtherapeutic levels. If an animal hasn’t improved after the labeled post-treatment interval, move to your second-line drug. If it fails a third treatment, the prognosis drops significantly, and the cost of continued treatment rarely pays back in performance.
Record keeping ties everything together. Tracking which drug was used, when, and whether the animal responded lets you evaluate your protocol over time. Operations that track treatment success rates by drug, by lot, and by season can spot resistance trends and adjust before they become expensive problems.