Dogs will flick their tongue as an appeasement signal but also as a signal theyre relaxing. While similar each signal has subtle differences. I will do posts on both. , The tongue flick is a signal Understanding Your Dog's Quivering Tongue Your dogs tongue could be warning you are you paying attention? , Expert Halo Dog Trainer Charlie Chun breaks down the early signs of heatstroke in dogs just by reading their tongue. , From Day 22: Tongue Flick = Uncomfortable?