Spring in California: 
Every year at the beginning of spring here in California our horses feet do some weird things. I have noticed that every year when our horses shed hair, their feet go through a tremendous growth spurt. This not only gets their feet out of balance but it also creates a lot of panic among the human owners.
I don’t know the exact science for this act of nature. Perhaps it has something to do with the keratin production that grew hair now goes to the feet? Maybe it has something to do with the pituitary gland and how that affects the remolding enzymes that grow the feet off? At the same time the ground here is changing from wet to dry, the longer daylight hours and warmer weather can bake our primarily clay soil to the consistency of concrete. Wet to dry transitions are hard on feet. Wet feet want to expand and dry feet want to contract, this can cause shoes to get loose and ultimately lost.
Back to this abnormal growth thing; Most feet do not grow an even hoof capsule. It all depends on how the capsule is weighted by the conformation of the leg through ‘center of rotation’. Center of rotation is located in the center of the condyle of the second phalanx and it is the mechanics around this which acts like the axle of a wheel that the foot rotates about. The weight of the horse is above and the ground is below, every force has an equal and opposing force. The part of the foot that is less weighted will grow faster than the more weighted part of the foot. This is due to blood flow (more on this at a later date). So the foot grows around center of rotation; it can grow more hoof forward to
center of rotation in the entire toe or on one side of the foot. If the foot is a club foot it will grow extra foot behind center of rotation. This extra foot produces a mechanical wedge that causes weight distribution to the opposite side of the foot.
5 mm of growth on one side of the foot can cause a 2° effect to the opposite or diagonal side of the foot.
Growth can be a good thing but it can also upset the apple cart. Unbalanced growth combined with wet to dry conditions can have quite an effect on the feet and in some horses, soundness. Don’t panic, get the feet reorganized and go on, this usually last about one shoeing cycle.