My dog keep terrorizing my pet mouse. how to train dog to not panic pet mouse?

i have white mouse as pet and a 2 year old male shepherd mix. The poor mouse has suffered lots of intimidation, fear and panic because the dog keeps charging at the mouse. As a result the mouse suffered digestive and respiratory problems due to the excessive anxiety and stress caused by the dog. I took mouse to vet and vet said that constant panic and fear will weaken its heart rapidly and at one stage the mouse can die simply of shock. I put the mouse in his cage but my dog keeps trying to shove his nose inside the mouse, terrifying it. The shepherd has also shaken the cage a lot. For now I keep the mouse in another room, where the dog has no access. However, I want to train my dog not to har and scare the mouse. How to do it?