Freeze Marks are the chosen method of the Bureau of Land Mangement (BLM) to mark a horse or burro as a wild horse managed on Federally protected land. Also know as “freezebranding.” A “freezing” branding iron is used to mark the hide of an animal. Freeze branding uses extreme cold to kill the cells in the animal’s skin that produce pigmentation (color). A freeze branded animal will have white hair where the freeze branding iron touched the skin. A permanent mark, freeze branding a horse (or cow or other animal) is done for identification purposes.