I have tried switching to larger mice and even frozen. Given their age, my snakes are pretty set in their ways and won't eat them. With the larger mice, we had an incident where Rosie was scratched pretty bad and needed antibiotic injections and Iodine baths. So, my uncle (the Vet) said to keep them on smaller (more helpless) mice, as they give less of a struggle...lol that sounded so horrible.