Even if you can't get your BP switched I don't think it's a big deal. IMO it's better to have them on rats, just one big meal, less work for their meal. I just got a Female normal, she was fed 4-5 mice every two weeks in one sitting by the previous owner. She's 11 or so, so she's survived just fine on mice. She had to work a little more for her food, but when I got her she was very healthy, a little fatty. So if you're worried about the health of your BP, I wouldn't worry too much. That being said... I just switched her over to rats, and she took a small rat no problem.

J. Bissell