Some animals including horses, cows, bulls, pigs and pheasants can be branded using any at least very hot item. Branding works only when on a deed you are a member of. Once branded, examining the animal shows the village it belongs to and allows members of that village to lead it, no matter where it is.
To brand an animal, activate any item that is 'glowing from heat' such as an [[iron lump]]. Right click the animal and select Brand.