That's fine. Standard action to remove the spine? Or should it be tougher for a horsey-thing to reach around and pull it out?The spine has to be removed, doing damage unless a DC 20 (?) Heal check is made.
Let's let the shoulder blades act like lances, ie double damage on charging. The bite option should be something like a rend, on a critical only, although it can make hoof attacks normally.
Agreed to all that. I think we had a bite version of a rend recently, too. Maybe in the prehistoric thread?