I would definitely go with freezebranding, it is really painless and turns the hair white on the brand by killing off the pigment to the hair follicle. Most registries who use freeze branding for identifying a horse use the alpha angle system, which is a system of branding a horse that can never be altered. It only uses numbers, and a symbol of the breed of the horse usually. The first symbol is the breed symbol, the second is a number, one number on top of the other, this is the year of birth of the horse. Then the registraion number to the animal. Some people freezebrand their own "symbol" on their horses but using the alpha angle system is the best way to do it, and on the left side of the neck. If this is a show horse, some breeds do not allow this kind of branding and will count against you for a horse having one.
Go to this link and it explains it all http://www.blm.gov/wo/st/en/prog/wil...rks.print.html