'Family Guy' kills off major character

• The character had been with the animated series since its pilot in 1999
• A new character voiced by Tony Sirico of %27The Sopranos%27 was introduced in Sunday%27s episode
• %27Family Guy%27 is in its 12th season

Warning: This story contains spoilers from Sunday night's episode of Family Guy

Family Guy viewers paid a shocking visit to Quahog on Sunday night, as they witnessed the death of one of the show's main characters.

A regular on Seth MacFarlane's popular animated series since its pilot in 1999, Brian the family dog was hit and killed by a car during the Season 12 episode Life of Brian, in which Stewie destroyed his time machine and the Griffins adopted a new pet. The show's executive producer Steve Callaghan spoke to E! Online about the painful decision, which forced the family to say teary goodbyes to their bruised and bloodied dog.

"We thought it could be a fun way to shake things up," Callaghan says. "It seemed more in the realm of a reality that a dog would get hit by a car. 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."

Shortly after Brian's death, the Griffins adopted a fast-talking new dog named Vinny, who is voiced by The Sopranos' Tony Sirico, and helps comfort Stewie in the wake of his devastating loss.

"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 says. "He'll call Stewie out on his b.s. freely."

Cast members such as Mila Kunis and Seth Green were surprised to learn of the character shakeup, which has already sparked the hashtag #BringBackBrian on Twitter. Aside from his belief that Vinny will add a new dynamic to the Griffin family, Callaghan isn't worried about any major post-Brian backlash in the long term.

"Our fans are smart enough and have been loyal to our show for long enough to know that they can trust us," Callaghan says. "We always make choices that always work to the greatest benefit of the series."