Within a day or so, they should be eating and drinking normally, as well as returning to their normal daily schedule of waking, basking, and activity. Some may be quieter than usual for several more days, especially if the hypothermia occurred when a reptile escaped from its keeper outdoors. When reptiles are subjected to freezing temperatures, extracellular fluids begin to form ice crystals long before the reptile loses consciousness and pain perception. This extracellular freezing creates an osmotic imbalance, drawing water out of cells. The circulation is then impeded which inhibits prevents gas exchange, nutrient uptake, etc.
Ice crystals begin to create small punctures in cell walls.
For more information on euthanasia, see Stephen L. Barten DVM's article, Euthanasia of Reptiles . Hypothermia in Iguanas and Other Reptiles . All rights reserved.