better to stun or prekill the rat and using tongs, shake it in front of her so she thinks its live. if she is eating it live, and you think it may be biting her, she is likely to be able to constrict it/ take care of the problem herself, and then you check the mouth/ bite site when she is done swallowing and if she is wounded, rinse the area with saline solution and call the vet if any swelling or other problems occur the next day.