I have searched my brain (short search) and searched Google (Long Search, but speedier), and I cannot find whose dog Dreyfus was. He was a Saint Bernard, I am sort of sure, but what movie or TV show he appeared in I cannot recall.
Martin Crane's (Frazier) dog was Eddie, and Timmy's dog was Lassie, but whose dog was Dreyfus?
Dennis' dog was Ruff, and Uncle Elby's dog was Napoleon, but whose dog was Dreyfus?
Nelson's dog was Bethoven, and Dagwood's dog was Daisy, but whose dog was Dreyfus?
Nick and Nora Charles' dog (the Thin Man) was Asta, and a famous ventriloquist's dog was Farfel, but whose dog was Dreyfus?
POSTSCRIPT: Thanks to Silk, see comments below, we know Dreyfus was the Saint Bernard-Golden Retreiver mix who belonged to the Westons in Empty Nest. Weston, played by Richard Mulligan, used to have long heart-to-heart conversations with Dreyfus, who responded by looking wise, or, al least, interested.