Seven control Holstein calves were inoculated intrabronchially with 5.0ml of Dulbecco’s phosphate-buffered saline solution (DPBS). Other seven calves were inoculated with 5´ 10(9) Mannheimia haemolytica organisms/5.0 ml of DPBS. Bronchoalveolar fluid and blood samples were collected immediately before and at 4, 6, 12, and 24 hours after inoculation. Clinical examination was performed at the same time points. Histologically haemorragic and fibrinotic pneumonia was observed. Seven sick calves had lethargy, abdominal respiratory pathern, altered respiratory sounds, hypertemia, increased heart and respiratory rates, and cardiac arrhythmia. Pneumonic calves showed higher packed cell volume and red cell count, suggesting hemoconcentration. Pneumonic calves also had decreased PO2 and increased PCO2 suggesting poor pulmonary ventilation. Neutrophilia and high neutrophil and monocyte counts in bronchoalveolar fluid were detected due to pulmonar inflammation. Blood pH and plasma concentrations of HCO3, Na, and K had no significant changes.
calf; pneumonia; Mannheimia haemolytica; diagnosis
