Bailey: So, in all my lives as a dog, here's what I've learned. Have fun, obviously. Whenever possible, find someone to save, and save them. Lick the ones you love. Don't get all sad-faced about what happened and scrunchy-faced about what could. Just be here now.
When Bailey, or "buddy" first finds Hannah at his last life, Hannah says that he is not a stray because he has a collar. In the initial shot of the dog it does not have a collar on, but when she reaches to see the tag it appears.