If it's summer, shearing off the excess fur from last winter is useful and good... but for the love of Christ, a dog is NOT a canvas! So what if maybe the dog didn't protest? Telling a dog, "Now sit still, I'm dyeing your fur so you'll look like a panda..." is like giving that same proposition to an infant and proceeding to throw a few buckets of paint at it.
Just because an animal can't say 'NO', that doesn't mean it doesn't deserve dignity. If people are so desperate to create art, there's thousands of other ways to do that... heck, nowadays even taking a crap and sticking a small American flag in it passes as daring art for some people.