People smile, so human beings are animals that smile, so some animals smile. If you had added the topic Evolutionary Biology to your qestion I would have simply written people smile, so some animals smile.
Bonobos smile: .
This can be a little controversial for someone that has learned that great apes make fear grins similar to smiles when they area scared, but in the case of bonobos they can do both things "fear grins" and big open smiles.
Chimpanzes smile, or make playfaces:
About cats and dogs, I have cats, they show their social open mind and good humour in many ways, but never showing a smile, al least in my experience.
I have not fear to throw myself in the outerskirts of the so called antropomorphic fallacy, in my experience the greater fallacy is to permit your prejudices prevent you listening to what a well observer can tell you, and seeing what you can see with your own eyes. So, as they saying goes in Spanish: soy todo orejas -I am open to listen- if anybody has a testimony about a dog or a cat wearing a expression similar to a smile to show good humour.