I don't know a whole heck of a lot about dogs, but isn't "smiling" a human emotion and not a dog behavour at all. I have never known any dog to "smile" but I have seen a ton of very happy dogs in my day. Tail wagging has always been a sign to me that a dog is happy (among other things). Just a thought though.
usually smiling with dogs is not open mouthed as previously thought. usually the upper lip will go up and they will show teeth and the nose will crinkle. it sometimes looks like a snarl.. i have actually trained my dog to smile on command...
I've had dogs that smile. Not all dogs do it. Some breeds are known for it and some are not. It can be open or closed mouth. Ours smiled by pulling back the corners of their mouths just like people do and did not wrinkle their noses. With our dogs it has meant: 1. I'm very happy, accompanied by lots of vigorous tail wagging. 2. I'm very pleased with something I've done, short tail wags. 3. I'm worried you are angry-please don't be, tail straight down. Our boxer/pit mix did it more than any dog we've ever had.
sorry, what breed was this? labrador retrievers are known to "smile". it is like a snarl, does not look like a human smile. as stated by some one else, the upper lip curls, they look as if they are about to bite. my doberman pinscher has only done this once/twice, but it was no big deal. be firm, let them know that it is bad. tell them "NO".