To determine whether road transport affected pulmonary phagocyte activity, 7 healthy Thoroughbred horses were shipped 1,160 kilometers over 36 hours. Fluid collected by bronchoalveolar lavage (BAL) 12 hours, and 7 and 14 days after transport was analyzed. Results were compared to those from the same horses pre-transport, and 7 non-transported control horses that had BAL performed at the same times as the transported horses. Of cells recovered with BAL the percentage of viable pulmonary alveolar macrophages (PAMs) declined from 90.0 +/- 0.9% pre-transport to 80.0 +/- 3.7% by 2 weeks post transport. Although the ability of PAMs to inhibit the growth of Staphylococcus epidermidis had decreased by 2 weeks post-transport (19.2 +/- 3.7% vs. 8.8 +/- 2.3% inhibition) this could not be attributed to transport as a similar effect occurred in the control group. In contrast, the ability of PAMs to phagocytose sheep erythrocytes labelled with rabbit anti-erythrocyte antibodies increased from 74.0 +/- 8.1% to 92.3 +/- 1.5% by 12 hours post-transport. As all variables were unchanged or only mildly altered following transport, we conclude that this form of transport did not alter the PAM functions we assessed.