GLENDALE, Ariz. -- Veteran right-hander Chad Gaudin, competing to make the roster as a long reliever, has been shut down with discomfort in his right arm.Gaudin was warming up to pitch in a minor-league game Thursday when he felt a tingling sensation in his arm, the same sensation that shut down his previous outing. Los Angeles Dodgers manager Don Mattingly said Gaudin will undergo an MRI. His chances of making the Opening Day roster appear now to be slim.