The effects of stressful exercise on leukocytes in cattle with experimental pneumonic pasteurellosis.

Seven yearling bulls were treated with stressful exercise and intrabronchial Pasteurella haemolytica A1. Group 1 bulls (nos. 1–4) underwent treadmill exercise and, 24 days later, intrabronchial instillation of P. haemolytica A1. Group 2 bulls (nos. 5–7) underwent treadmill exercise, followed 30 min later by intrabronchial P. haemolytica A1. Blood lactic acid values were raised (p<0.05) by treadmill exercise only, but plasma cortisol was raised (p<0.05) by treadmill exercise and by P. haemolytica A1 infection. Neutrophils in bronchoalveolar lavage (BAL) differed from control values 24 h after treadmill exercise, and 1 h and 4 h after P. haemolytica A1 infection.