Frostbite is when the extreme cold has caused the water in cells freeze and then expand causing the cell to rupture. Usually frostbite occurs on the extremities like the toes, tail, and ears. These areas are the first to get frostbitten because the body in extreme cold will divert blood flow and heat to the core area including the heart and lungs. If these areas are not rewarmed it will lead to the cells dying for good and possibly causing that part of the body having to be surgically removed. Make sure that you consult your vet the same day of the frostbite occurrence.