Thank you guys very much for your help. I'm hearing that small rats should be fine (great to know, I will pick one up and see if he takes it), and that it could also be an issue with thawing. The latter was interesting to me because I actually have been experimenting with slightly different prep methods and maybe I should spend some more time making sure I'm doing this correctly. I used to, after thawing the rat in cool water, leave it under his CHE for 15 minutes to warm it up, and he loved that because it also got his tank nice and smelly and he would be very excited to eat. Now I've changed from a wire cage to a dome for his CHE and increased the wattage so I have been nervous about using it to warm rats as it gets much hotter at that distance. I have tried using a hair dryer but felt like they were cooling off very quickly and the heat wasn't penetrating enough. I've also tried putting the rat under the dome for like, 3 minutes - it gets very hot on the surface but I could still be having the same issue with not heating it all the way through. I will experiment with this a little more and find what works best. Thanks for your thoughts, all.