Any time a dog is happy, he has relaxed body language.
His muscles are relaxed, his tail and ears are held in their natural positions, and he seems neither large nor small for his physique. He may possibly wag his tail from side to side or in a circular motion. His facial expression is neutral or he looks happy — the muscles in his face are relaxed, his mouth is closed or slightly opened, and he may be panting with a regular pace. The corners of his mouth may be turned upwards a bit like he’s smiling.
Look at Elliot… He’s happy whenever he receives a treat… And he even says ‘Mom’!