Join Date: Oct 2009
Location: Just south of sanity
First, is your horse a registered breed?
If it is, then contact your registry about freeze branding and ask if they have a preferred methodology.
It used to be very big in the Arabian world, but not so much nowadays. My now deceased gelding was freeze branded, and it consisted of an upright 'A' (for purebred) with his registration number in Arabic numerals. Half Arabians had a sideways 'A' and their registration number in Arabic numerals.
Freeze branding is generally their registration number with some sort of other designation, usually for breed.
The hair grows back a different color than the coat, but even if it doesn't, when you get them wet the freeze brand will show up. This is useful information for grey horses, since their brands don't always grow back a different color.