A grin for animals is not a smile. Usually, they show aggression to other creatures in this way. But pets, living with people and adopting their habits, including facial expressions, sometimes copy their owners.
The owner adopted a dog named Titlist from a shelter. When they found her, she was hungry and exhausted. It took the Titlist a long time to recover and start trusting people. But now she lives in France and she is doing well.
Video:
She does not stop smiling and making the owner laugh with her muzzle.
