EFFECT OF TRANSPORTATION ON LOWER RESPIRATORY-TRACT CONTAMINATION ANDPERIPHERAL-BLOOD NEUTROPHIL FUNCTION

Objective To evaluate the effect of transportation on lower respirator y tract contamination and peripheral blood neutrophil function in hors es and to compare results from transported horses with those obtained in earlier experiments from horses confined with heads elevated. Desig n A prospective study. Procedure Six horses were transported by road f or 12 h. Clinical and haematological examination, transtracheal aspira tion and cell function studies were conducted before and after transpo rtation. Results obtained after transportation were compared to pre-tr ansportation values. Results After transportation, peripheral blood le ucocyte and neutrophil numbers were increased and rectal temperatures were elevated. Transtracheal aspirates showed an accumulation of purul ent respiratory tract secretions with increased numbers of bacteria, p articularly beta-haemolytic Streptococcus spp and members of the Paste urellaceae family. Three horses also had increased numbers of bacteria from the Enterobacteriaceae family relative to corresponding samples from earlier studies. Phagocytosis by peripheral blood neutrophils was significantly reduced, while the oxidative burst activity of peripher al blood leucocytes was either unchanged or enhanced. Clinical Implica tions Bacterial contamination of the lower respiratory tract occurs as a routine consequence of transportation of horses and is likely to be an important determinant in the development of transport-associated r espiratory disease. Inflammatory airway secretions and increased numbe rs of bacteria were rapidly cleared, without clinical evidence of sign ificant pulmonary disease and without additional treatment, in normal horses that were allowed to lower their heads after transportation. Pe ripheral blood neutrophilia and a reduction in neutrophil phagocytic f unction were evident for at least 36 h after transportation, suggestin g that horses may require a number of days to recover from the stress of transportation. As the potential role of bacteria from the Enteroba cteriaceae family in the development of transport-associated respirato ry disease has not been elucidated horses which develop clinical disea se following transportation should undergo thorough bacteriological in vestigation to ensure appropriate treatment.