When we were raising Scotties, a friend who had one phoned us up all frantic. Their Scottie was going nuts pawing at the sides of his face. They had taken him into the Vet and he couldn't find anything. We went over, pretty well knowing what it was. We opened up his mouth and he had a branch of a rose bush jammed across the roof his his mouth. Because of the color of it, it would have been hard to see if you didn't know what you were looking for but as it is fairly common, the Vet should have found it.