How To Wash A Dog ... Eight-year-old Bobs Watson demonstrates with Betty, the 14-year-old spaniel which appears with him in Metro-Goldwyn-Mayer's "On Borrowed Time." This, incidentally, is the first film in which Botty ever appeared. When it is completed, she will return to her home in North Hollywood. Bobs appears in the plum child role of the year in the film, as Pud, grandson of Lionel Barrymore. Other principals include Sir Cedric Hardwicke, Beulah Bondi, Eily Malyon and Una Merkel. Harold S