Eating mice is references to wild dogs, such as coyotes, also dingoes, wolves and jackals.
They eat mice to stay alive.
Domestic dog is more likely to chase and play with a mouse than it is to eat a mouse, but as long as it can fit in its mouth it can swallow it.
It is not the good idea to let your dog eat mice. Mice carry diseases and worms, you really don’t want your domestic dog eating stuff like that. Your dog can ingested poisoned rat bait which is use to poison the mice.
Also, you don’t want your dog to develop a taste for self-hunting and start to go after rabbits, raccoons and other creatures, even cats.