Pin-toes, so named because the toes actually point in towards each other rather than straight forward can be very problematic for the horse and are not just a conformation problem. The normal horse's hoof is made up of the toe or rounded front part, the quarters or sides of the hoof and the heel or back of the hoof. In a correctly conformed horse the toe of the hoof should point directly forward and the hoof wall or the strong outer part of the hoof as well as the frog or spongy cushion of the back of the hoof should allow equal weight distribution as well as correct alignment of the fetlock, knee, stifle, shoulder, hip and pelvic bones.
Usually pin-toes occur on the front feet although they may also occur in the back. Pin-toes are usually congenital, or the foal is born with the inward turning of the feet. Often this is also seen in prior generations within specific lines, but it can also be due to growth problems and joint malformations due to OCD or degenerative joint disease.
As the toe moves to an inward pointing rotation rather than straight position, the horse's weight balance is shifted slightly. The inside quarter of the hoof will often bear more weight than the outside, resulting in uneven hoof wear and damage to the inside quarter. The heel and frog may also be affected, especially if the horse is kept in pastures or areas with dry, abrasive type soil or is worked on hard surfaces. Without proper hoof care this unbalanced wear of the hoof will start to put uneven pressure on the outside and inside areas of the fetlock, knee and shoulder joints, leading to possible inflammation, bone chips and degeneration of one or both sides of the joint.
In some cases where founder and laminitis has been a problem the horse may have some rotation of the hoof due to the shifting or turning of the coffin bone inside the hoof itself. This happens due to a breakdown on the laminae or suspension material that protects the coffin bone and distributes the weight to the outside of the hoof. When this occurs the horse may toe-in to prevent the pain of stepping flat on the hoof.
Correcting pin-toe horses is usually done over time through coordination between the farrier, owner and the vet. Shoes that build up the inside of the hoof and more evenly distribute the pressure across the hoof can greatly help the horse in moving the leg forward rather than placing the leg with the foot turned in. Gradually shaping the hoof and using corrective shoes will take time as the ligaments, muscles and tendons must adjust to the additional stretching. Early treatment rather than waiting longer is always highly recommended by both farriers and vets.