Seeing the dog would help us confirm your worry.

My Old English Bulldogs only eat once a day but they would eat twelve times a day if you fed them that much. They are pigs but feeding the proper amount once a day has them both in great shape. Most people overeat and if they do it they are extremely likely to overfeed their animals as well. Just like we have a large number of obese Americans there is a large number of overweight dogs. A dog shouldn't look like a sausage.....unless it's a dachshund. Lol!

Eating mice may seem weird but there are plenty of people that feed their dogs nothing but raw foods. Mice may be out of the norm(for a dog) but I'm not going to condemn this person as bad dog owner because of it. Plenty of people here give left over mice and rats to their cats so I don't think you should be concerned with that.