Clinical bronchography in the horse: development of a method using barium sulphate powder

A method for performing bronchography in standing nonanaesthetized horses was developed. Bronchography was performed by insufflating the previously intubated trachea with a mixture of 120 to 200 g of finely powdered barium sulphate mixed with 3 to 7 g of powdered methyl cellulose. The mixture was delivered from an ether vaporiser into which compressed air was blown. Premedication with atropine sulphate immediately before insufflation minimised bronchoconstriction. Satisfactory bronchograms with contrast visible down to the seventh and eighth bronchial divisions were obtained in 80 per cent of the 26 horses tested. Poor results were obtained if there were delays in taking exposures. Total clearance of the barium sulphate from the lung fields was extremely rapid, averaging 4 h. No significant clinical side effects were noted and histology of the lungs, in animals sacrificed sequentially over a period of 2 weeks, demonstrated a minimal cellular response. In one clinical case, with chronic bronchitis, loss of parallelism of the bronchial walls and moderate bronchial dilatation between branches was demonstrated. It was concluded that although the value of bronchography as a diagnostic procedure in equine radiology has yet to be proven, the method of powder insufflation with barium sulphate provides a safe and accurate means of investigating bronchial conditions in the horse.