The equine spine has individual vertebrae connected by ligaments and muscle. Each vertebra has a bony processes that sticks up. The processes should be evenly spaced. This allows the horse to work over their back. They are able to flex and extend the back. If the horse doesn’t have mechanical support from their hooves, the back drops. The even spacing between the processes closes. The horse now has pain, stiffness and even muscle spasm. This is often disagnosed as kissing spines.
Below is horse with a dropped back and closed spinal process. The horse was getting the typical farrier trim. Low heels and long toe. The after pic is the Apex trim and how the trim lifts the back. The horse is now able to lift and engage his back. He is now more correct in support and ability work over his back. Support from the hooves directly effects your top line and skeletal system.