Imagine a tribe of nomads where all the males have the blessing of being were-stallions. The tribe would not need to have ordinary horses to move around, all mounted warriors would be female and a curious custom could be that when a couple gets married, the girl rides her chosen to the altar.
When someone befriends an animal, s/he obtains the ability to unite their souls together and take on the form of that animal as well as its abilities. S/he also gain some properties of that animal even when they are no keener t transformed, such as resistence to cold or senses. If s/he really wants to s/he can half transforms taking on characteristics of the animal and their normal form