This sounds very much like bile caused by an empty stomach. My Teddy did this when he was younger. Easy solution: give a late night snack. All Teddy required was a few kibble before bed time.
We played "tricks for treats" where the doggies would perform tricks for the kibble.
Your dog may have a fast metabolism which makes it difficult to go too long without food. It is common in Yorkies.
__________________ Kristin, Max and Teddy  |