Need a pick-me-up today? Watch a video of a smiling dog – it should do the trick. You could go for the dog smiling as his owner takes a selfie or the one where the owner is training their puppy ...

When we offer up a big, goofy grin, she matches us with a smile of her own. But are our dogs really "smiling" the way humans do? We asked a veterinarian about what our canine friends are trying to ...