My Brewer's doesn't seem to have a list of famous cats, although the dogs are there, except 8dn minus the 'e'. I have the millennium edition, don't know if the 19th came before or after that.
Farr, I've just checked today's crossword. The preamble specifically mentions the 19th edition of Brewer's, so I think Doc knows some entries are not in some earlier editions.
Farr, the 19th edition is dated 2012 - obviously later than yours! The dog, with its E, is in it. There's a whole page of cats, starting at Bagpuss and finishing at one of today's unclued answers.