some species of frogs will eat themselves to death. Pacs and African bullfrogs are notorious for that. I have actually seen one do it. Impaction is one risk of this the other is if a pac eats a mouse that is to big the mouse will rot in the frogs stomach before it can digest it. The bacteria from this is pretty much poison and will kill your frog, and fast. This can happen with snakes as well. The symptoms are that of impaction your frog will bloat up like a balloon. Impaction in some cases may be treated with warm water soaks. But if you have a rot situation there is nothing that can be done. Your frog may throw it up. But that is only a matter of luck and your frog may still die. Now this risk is not only with mice it is just the most common. Insects that are also to large can do this.