GG had developed cracks in all four feet for a number of reasons. His hooves were lacking the building blocks to grow in healthy, strong wall because his diet was lacking appropriate minerals. The trim schedule was too long, 8-9 weeks between trims. Additionally, the most severe crack had a fungal infection which allowed the entire back quarter of the wall to release from the laminae completely.
We beveled the entire hoof wall every 2 weeks for the first 2 months. Once there was well connected wall growing in, regular trims were set at 4 week intervals. This prevented further damage to the wall while we organized a mineral supplement plan for GG, and minimized pasture access temporarily. Hoof soaks (apple cider vinegar with water) were done every few days for 3 weeks, until the infection cleared up. The damaged hoof grew out within 9 months, meanwhile GG never took an unsound step.
The above photo was taken one year after trimming was addressed. The surface cracks continued until we were able to get GG onto a proper nutrition program. After 3 months you can see that finally the new growth is completely free of cracks.