TOTAL AND RESPIRABLE AIRBORNE DUST ENDOTOXIN CONCENTRATIONS IN 3 EQUINE MANAGEMENT-SYSTEMS

The concentrations of total and respirable airborne endotoxin in the b reathing zone of a pony in 3 different management systems, on 8 occasi ons, are reported. Airborne endotoxin concentrations in all 3 systems were lower than those reported for many other agricultural environment s. However, total airborne endotoxin concentrations in many of the con ventional stables exceeded those which can induce pulmonary inflammati on and bronchial hyper-responsiveness in normal human subjects, and ex ceeded those which can induce bronchoconstriction in humans with pre-e xisting pulmonary inflammation. Therefore, airborne endotoxin may cont ribute to the development of airway inflammation and dysfunction in co nventionally stabled horses. Potentially detrimental effects of airbor ne endotoxins on the welfare and exercise performance of stabled horse s can be reduced by maintaining horses in 'low dust' stables or at pas ture, since these environments had significantly lower airborne dust a nd endotoxin concentrations.