A horse landing toe first is doing so to avoid pain in the heels. They can have heel pain due to underdeveloped digital cushions, thrush, etc. Trimming to avoid heel pain and promote heel landing is ideal. Supporting a heel sore horse in pads and boots may be necessary to promote a heel first landing.
Toe-first landing can also be caused by the length of the toes. Think about this. As the horse picks up the hoof with long toes it must pick it up higher to clear that toe from the ground and will not "fly" as far forward causing it to land toe first again. But if the toe has appropriate breakover and no heel pain the horse will pick up the hoof and it will "fly" more forward naturally with less initial height and land heel first as it was able to reach capacity at extension.
One of the most important things for successfully going barefoot is a heel first landing. Horses that land toe first are painful whether it is obvious to us or not. Horses are amazing at coping with pain and pushing forward. There is building studies and evidence that horses who land toe first and have worn shoes show a greater likelyhood to develop navicular problems.
