What do dogs dream?

I'm curious what dogs dream about because I'm pretty sure Sammy is having a scary or exciting dream right now! She is laying on the couch next to me and all of the sudden she starts breathing really loud...like she's trying to bark, but is obviously in a deep sleep. Anyway...it just made me think. Maybe she was hunting, maybe she was playing with the neighbor's dog (who I think she talks to through the fence).

Btw...I'm not crazy, I'm sort of kidding (at least about the "talking" through the fence). My sammy just really entertains me and I always wonder what's going through her head.

Courtni used to narrate her and Toby while they played. It was hilarious.