The disease develops among foals from the age of one to six months and typically occurs during their first year of life. The frontal edge of the hoof cracks and splits. Pieces of hoof wall chip off in bits. This cracking, chipping and peeling may involve the whole of the dorsal hoof wall. The deficit means that when the hoof wall reaches the ground (and weight bearing load) the wall breaks away from above the level of the sole. Thus the affected pony has to walk on the sole of the hoof with no support provided by the dorsal hoof wall. All four feet are similarly affected. This can be very painful for the animal.

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Glushus protect the outer hoof wall from continual trauma and allow the growth of the horn. Special inserts can also be used the support the sole.