When i bred rabbits we would freeze milk jugs and 2 litter bottles to put inside of the cages. Maybe you can do that with smaller bottles and put them into the cages of the ones in the highest temperature. Then they could regulate their body temperature by moving closer or further from the frozen bottles. If they are dying, then the bottles sure couldn't hurt to try. You should be able to fit quite a few small bottles into your freezer. Make sure to leave air at the top of the bottles for the ice to expand or they will pop.
Reply With Quote