Most people think dogs smile when they pant. They stick their tongue out and pull their lips back, which can look similar to how humans smile. But panting can signal different things. Panting can be a sign of fear, nervousness, anxiety, or simply being too hot. However, there are other facial and body features that can tell you if your dog's panting is happy and relaxed or nervous.
When dogs are happy, you may see their tail wag and ears relax. If they're running, playing, or excited, they might also pant while displaying these other signs of happiness. However, not all dogs will express themselves in the same way.
Dogs can have a “smiling” expression for other reasons, too. You should know the differences and learn how to read your dog’s posture and physical clues to help you determine how they feel.