I haven't a clue what's turned this slightly nippy rat so dangerously mean but irregardless she's being put down humanely today. It's not fair to her pups, dangerous to the kids if they are helping feed the rat colony and in the end not much fun for this rat as she'd have to be kept away from the rest of the colony the rest of her life. She can't even retire to pet status as the other breeders do here when their breeding cycles are done. A quick end is better for all concerned.

As to issues....she's treated wonderfully as our all our breeders, not stressed with back to back breeding, in the prime of her breeding life and in perfect condition, her litter wasn't all that large and it was her second so there is no reason I can see for her going rogue like this. Guess it just happens sometimes.