It shouldn't have "burst all over..." so I hope you're thawing properly? In cool/cold water until soft (thawed) throughout, & only then briefly warmed up & offered. (OR, thaw for overnight+ in the refrigerator until soft throughout, etc.) When rodents fall apart easily it means they're spoiled, as when thawed in hot water, allowing spoilage, or if not frozen promptly after it was killed & then allowed to spoil, so it was already rotten as you thawed it.