Why did mouse suddenly die after dog caught it in its mouth but let it go with no signs of injury?

Answer 1

It probably died of shock.

My cat managed to catch a mouse, but it did not do any damage to the critter. In fact, the only injury to the mouse was broken ego and a wet back where the cat licked it. The point is that the mouse survived 100% even though it was captured. It is likely that this mouse you asked about had an internal injury. You would not see internal bleeding under all the fur, so the mouse may have bled out. Besides the pain where the injury was, I imagine that the mouse would have just fallen unconscious and died peacefully. My pet mouse dies of shock. I took him to the vet to get some spot on for a minor pest infestation and he went into shock and died when the vet restrained him so she could see what she was dealing with. Mice are fragile I'm afraid.