Adding on to what was said above, we sadly cannot add things like this to the game. The creator of FH, KovuLKD, left and has been gone for a very long time. When he left, he took the source code with him which is what is used to modify the game. It is now up to the current admins to keep the game running.
But, the idea is lovely. Horse models would be a very interesting addition which many users would love. c:
I kind of like this little idea you got there, I wished I've seen this sooner. ^^
The idea of horses sounds pretty neat & even though it doesn't really 'fit' as some say with the theme of the game it still sounds like a nice little touch. Adds some little variety & it brings something new to the table as well. Makes it more....wild, per say and I've already seen some horses running around in-game by some people's characters. So again, Like the way you're thinking there. . . .
Use your imagination c; - Le Nuzzles -