Barium swallow as an aid to the diagnosis of grass sickness.

Twenty-five horses, suspected on clinical grounds of having grass sickness, were given a barium swallow. Using image intensification the passage of the barium bolus was followed radiographically from the pharynx to the stomach. All 18 horses in which grass sickness was later confirmed at post mortem examination showed defective oesophageal motility. Although the specificity of the abnormality could not be proven, the technique offers a valuable aid to the ante mortem diagnosis of grass sickness.