Warning: This article contains spoilers from Sunday's episode of Family Guy.

Last night, Family Guy viewers were forced to say good-bye to Brian, the family dog that has been a major character in Fox's animated series since it premiered in 1999. For 12 seasons, Family Guy creator Seth MacFarlane voiced the wise, smart-cracking, cocktail-sipping dog. Now fans are left with one question: Why?

Steve Callaghan, Family Guy executive producer, discussed reasons behind the loss of one of Family Guy's most important characters.

"...this was an idea that got pitched in the writers room, and it sort of caught fire and we thought it could be a fun way to shake things up," Callaghan told E! Online. "As soon as this idea came up, we started talking about what the next couple episodes could be, and we got very excited about the way this change will affect the family dynamics and the characters."

Death is definitely a way to keep a long-running show fresh, but why Brian?

"It seemed more in the realm of reality that a dog would get hit by a car, than if one of the kids died," 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."

Family Guy producers are not scared about how fans will react.

"I'm not [scared], only because our fans are smart enough and have been loyal to our show for long enough to know that they can trust us. We always make choices that always work to the greatest benefit of the series," Callghan said.

In "Life of Brian," Brian is replaced by a new dog named Vinny, voiced by Tony Sirico of The Sopranos.

"I think it was Seth's idea actually to get Tony to come in. He's a big fan of The Sopranos and always loved Tony Sirico in particular, and he thought it would be fun to write a character based around his voice and his personality ...," Callaghan said. "Brian was very smart and studious and intellectual, and Vinny is just a lot more of a rough around the edges. Vinny is a really good match for Stewie. 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. He'll call Stewie out on his B.S. freely."

Fans will have to find their own way to mourn because according to Callaghan, the next new episode of Family Guy is "just a regular, run-of-the mill episode."

Related