Bovine · Respiratory · Infectious disease
Bovine respiratory disease complex
Recently transported, commingled feedlot calf with fever, depression, and cranioventral lung consolidation. It is a management disease as much as an infectious one.
Viral insult from BRSV, BVDV, IBR, or PI3 damages mucociliary clearance and lets Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, or Mycoplasma bovis colonize the lung. Risk is driven by weaning stress, transport, dust, ration change, and commingling. Early detection using rectal temperature plus depression scoring outperforms waiting for coughing. Antimicrobial selection should follow label, withdrawal times, and local susceptibility patterns; metaphylaxis is justified only in high-risk groups. Prevention means preconditioning, timely vaccination well before shipment, low-stress handling, and adequate bunk and water space. Chronic poor-doers with Mycoplasma often have arthritis and otitis and respond poorly.