The Season 12 episode of Family Guy "Into Harmony's Way" was originally going to be a regular Family Guy episode, scheduled to air on November 24th, 2013 as a follow-up to "Boopa-Dee Bappa-Dee" (the episode where the family goes to Italy), with Brian Griffin listed as being one of the characters in the episode.
However, due to schedule changes, it ended up airing two weeks later as a follow-up to "Life of Brian" and consequentially was notably revised. Because of the events of the previous episode, "Into Harmony's Way" included Vinny the dog in Brian's place. Because Brian's role in the episode was very small, it was easy to paste Vinny over him without effecting the events of the episode. It is possible that, due to this, a number of episodes in the season were "revised" in order to fit after whenever Brian was supposedly going to die.
Brian's "resurection" ends with everything from the end of the first act of the episode "Life of Brian" being retconned, meaning the original cut of this episode is indeed the canon version; however, it was not released on the season 12 DVD and has never been broadcast. It is highly unlikely that anyone except the Family Guy staff has seen the canon cut of the episode, and the evidence of it's existence is extremely sparse, the cast list and original air date being the only true evidence.