Bovine respiratory disease complex (BRD) treatment is primarily antimicrobial, with drug selection driven by pathogen type and disease severity, since clinical signs alone cannot reliably distinguish the causative pathogen. The Veterinary…

Pathogen-Directed Antimicrobial Selection

For bacterial BRD caused by Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni, antimicrobial therapy is the cornerstone of treatment. MSD Vet Manuals+1 In Canada, labeled options for dairy cows are limited to five antimicrobials: oxytetracycline, trimethoprim-sulfadoxine, ampicillin, penicillin, and ceftiofur. Journal of Dair… Ceftiofur is the most commonly used antimicrobial, accounting for 75% of BRD cases treated in Québec dairy herds. Journal of Dair… Ceftiofur hydrochloride (Excenel) is labeled for BRD at 0.5–1 mg CE/lb (1.1–2.2 mg CE/kg) IM or SC q24h for three consecutive days; Days 4 and 5 may be added for animals that do not show a satisfactory response after the initial three treatments. FDA DailyMed An… For BRD only, an alternate every-other-day regimen of 1 mg CE/lb (2.2 mg CE/kg) IM or SC on Days 1 and 3 is also labeled. FDA DailyMed An… Selection between the 0.5 and 1 mg CE/lb dose levels and between the daily and every-other-day regimens is based on disease severity, pathogen susceptibility, and clinical response. FDA DailyMed An… No more than 15 mL should be injected per injection site. FDA DailyMed An…

For Mycoplasma bovis, standard beta-lactam and many conventional antimicrobials have limited efficacy due to the absence of a cell wall; florfenicol administered by nebulization has been evaluated as an alternative delivery route. BMC Veterinary…+1 Florfenicol by inhalation shortens recovery time compared to subcutaneous administration alone, with clinical improvement observed by Day 2 in nebulization groups versus later in the subcutaneous group. Veterinary Medi… Calves with clinical respiratory scores of 12 or above died across all treatment groups regardless of route. Veterinary Medi… M. bovis was the primary bacterial pathogen and bovine respiratory syncytial virus (BRSV) the primary viral pathogen identified in bronchoalveolar lavage fluid from naturally infected BRD calves in that evaluation. Veterinary Medi…

Severity-Adjusted Dosing

Disease severity at the time of detection should guide both drug choice and dose. Frontiers in Ve… In young bulls, early detection of BRD — defined as ruminal temperature exceeding 40.2°C persisting more than 12 hours with no or mild clinical signs — was treated with marbofloxacin at 2 mg/kg; animals with moderate or severe signs at visual inspection received marbofloxacin at 10 mg/kg. Frontiers in Ve… Animals in both groups were followed for 30 days with relapse treatment administered as needed. Frontiers in Ve… Note that marbofloxacin is a fluoroquinolone; in Québec, third-generation cephalosporins, quinolones, glycopeptides, and polymyxins may only be used when no effective alternative antimicrobial of lower importance in human medicine exists, and all such treatments must be recorded on-farm. Journal of Dair…

Viral Pathogens

No specific antiviral treatment is described for the viral components of BRD — BRSV, bovine viral diarrhea virus (BVDV), bovine parainfluenza virus type 3 (BPIV-3), bovine herpesvirus-1 (BoHV-1), and bovine coronavirus (BCoV). MSD Vet Manuals+2 BRSV is a primary BRD pathogen and also a component of the BRD complex; passively derived immunity does not prevent BRSV infection but decreases disease severity, and initial exposures cause severe disease while subsequent exposures result in mild to subclinical disease. MSD Vet Manuals Dual sequential infections with BVDV and BCoV produce more severe gross and microscopic lung lesions than single-pathogen infections with either virus alone, consistent with mild to moderate interstitial pneumonia. USDA Agricultur… Management of viral BRD is therefore supportive, with antimicrobials directed at secondary bacterial pathogens. MSD Vet Manuals

Ancillary Therapy

Flunixin meglumine IM added to nebulized florfenicol produced a significant decrease in elevated serum haptoglobin values by Day 3 of treatment. Veterinary Medi… No significant difference in lung ultrasonographic scoring or hematology results was observed before versus after treatment within groups. Veterinary Medi…

Antimicrobial Resistance and Stewardship

Treatment failure rates are high, with many cases becoming chronic. The Veterinary… Notable levels of antimicrobial resistance have been found in M. haemolytica and P. multocida in Canadian feedlot cattle. The Veterinary… Antimicrobials licensed for BRD are among the most frequently used on beef rearer and finisher units. The Veterinary… Mixed infections are frequent, and pathogen involvement can rarely be distinguished based on clinical presentation alone, making accurate pathogen identification an important step in selecting appropriate treatment. The Veterinary…

Would you like to review the vaccination protocols available for the viral components of BRD — BRSV, BoHV-1, BVDV, and BPIV-3 — and how they integrate into a herd prevention program?