"We thought it could be a fun way to shake things up," executive producer Steve Callaghan told US media. To voice the new family dog, Vinny: Tony Sirico. It had been suggested in the show's writer's room that a member of the family be killed off and after a length discussion it was decided that it would be Brian. "It seemed more in the realm of a reality that a dog would get hit by a car," Callaghan said. "As much as we love Brian, and as much as everyone loves their pets, we felt it would be more traumatic to lose one of the kids, rather than the family pet."

Compounding the surprise, the Griffins almost immediately adopted a new dog named Vinny, who is voiced by actor Tony Sirico (The Sopranos). "Where Brian was sort of a match for Stewie intellectually, Vinny is a good match for Stewie because he doesn't let Stewie get away with any crap," Callaghan said. Although the producers are confident they have made the right call, fans are less certain and a backlash is already brewing. "Our fans are smart enough and have been loyal to our show for long enough to know that they can trust us," Callaghan said. "We always make choices that always work to the greatest benefit of the series."

Cartoon shows have capitalised on killing off characters and the marketing which goes with it for many years. The Simpsons killed off family neighbour Maude Flanders and is planning to kill off another "major character" early in 2014. But shows - even animated shows - rarely kill off a main character. A hashtag pushing for the producers to repeal the decision, #BringBackBrian, has already surfaced on the social network Twitter. And an online petition at change.org created by fan Aaron Thompson from Tuscaloosa, Alabama, has drawn more than 2000 signatures.

"Brian Griffin was an important part of our viewing experience," Thompson wrote. "He added a witty and sophisticated element to the show. Family Guy and Fox Broadcasting will lose viewers if Brian Griffin is not brought back to the show." Another page, a Facebook page titled RIP Brian Griffin From Family Guy, has drawn more than 110,000 "likes" and is still growing. 20th Century Fox has not commented on the backlash. MacFarlane issued a brief statement to the trade newspaper Variety saying only "this is the first time I’ve ever gotten positive feedback from [comedian] Tina Fey."

The episode, Life of Brian, will air in Australia on the digital channel 7mate.