CTS: befriending a horse turns it into a boar
Mount and dismount a horse
Click on horse with Player Tool 6
Type /cts befriend
Click on 'Animal Companion' (feat activation)
Say hello to the comically named boar. (ok, you don't need this last bit)
Companion Training System.
After riding a horse for a while, my PC dismounted, and befriended the horse. The horse was replaced with a boar with the name "CTS Boar Fylgia Template". Horse was a henchman at the time which may have been part of the problem.
Also - I then released the boar (/cts release) without naming it. And it doesn't go anywhere, leaving a creature with an improbable floaty name in the world.
[Can I just say YAY HORSES. Only just figured how to ride one!!]