I'll stay off the soap box for a moment and merely say in a well written work (Film, novel, etc) any death be it animal or human should further the plot. As long as the piece is well written (and though I may ball) if the death adds to the story than I'm ok with it. If it's for mere shock value than many of you are right, get it the heck out of there.

With this being said there is one movie I can think of off the top of my head that I won't watch because of the violence toward the canine. If anyone has seen 'The Butterfly Effect' than they know what I'm talking about. If you haven't seen the movie, skip it.