Was the mouse warm enough? That's a really common action when the prey is too cold or still frozen in the middle. They hit that spot and then spit it right out. It's even more dangerous when you and the animals doesn't notice and it eats it and them goes into shock because of the cold spot in their bellys. Try again next feeding day and make sure the mouse is about 100.f and it's totally thawed or warmed through.
Whats you're thawing regimine?
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