“Family Guy” viewers on Sunday witnessed the shocking demise of Brian, the Griffin family’s pet dog and one of the show's longtime main characters. Many fans of the Fox animated sitcom, now in its 12th season, are questioning why the series' producers killed him off in the episode titled "Life of Brian."

Here are four reasons why they decided to axe Brian Griffin:

EASIER TO KILL

Producer Steve Callaghan told E! News on Sunday that despite the fact that Brian was a main character for years and the show's general lack of realistic plots, it seemed a more plausible story line for the Griffins' family pet to die than one of the Griffins. “It seemed more in the realm of reality that a dog would get hit by a car,” he said, adding, “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.”

SHAKE THINGS UP

“Family Guy” producers said it was time for a change, and the death of the Griffins' family pet was reportedly at the top of their morbid to-do list.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,” he said. “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."

CAST APPROVED

Despite losing a key character, members of the “Family Guy” team reportedly approved of including the shocking death in the series latest episode. “I think they were glad it wasn’t them,” said Callaghan, who confirmed the cast (specifically, voice actors Mila Kunis and Seth Green) was still saddened by the plot twist. “I think they were pretty stunned this far into the show,” he added.

NEW FAMILY DOG

While fans are still mourning the death of Brian Griffin, producers have already brought on former “The Sopranos” actor Tony Sirico to voice the family's new dog, Vinny. Why so soon? According to Callaghan, producers felt that it was important to keep the show's formula the same as it was when it originally premiered under the leadership of creator Seth MacFarlane in 1999. “By losing Brian, it felt like a void needed to be filled, both comically and also for the interpersonal relationships between all the characters,” he said.“We felt that we needed to fill that role.”

Are you sad to see Brian go? Do you want “Family Guy” producers do bring him back?