For my money, one of the greatest dogs in fiction disapproves his way through P.G. Wodehouse's Stiff Upper Lip, Jeeves. He's Bartholomew, the surly Aberdeen terrier belonging to Stiffy Byng, and he "biteth like a serpent and stingeth like an adder." He is also reported as "looking like a Scotch elder rebuking sin," biting the butler, and Bertie Wooster adds that at one point Bartholomew "gave me an unpleasantly superior look as they moved off, as if asking me if I were saved."
Bartholomew is based on an Aberdeen terrier called Angus, one of the many dogs Wodehouse gathered round himself in his long life. In 1966 he and his wife Ethel gave $20,000 to the Bide-A-Wee Association to build the P G Wodehouse Shelter for stray animals at Westhampton.
You really should read the book.