I wanted to post this picture as an example of the difference between a hoof, that is cut to specific parameters as given, for example, by the ABC trimming manual, and a foot that is managed by the horse's need. The ABC trimming manual mandates all horses heels to be backed up to the "baseline", which corresponds to the widest part of the frog and also most of the time to the position where the periople skin curls up (indicated by the red arrows in the picture below). I have previously written a
blog post about the heel height.
I have trimmed my horses heels back to that landmark when I first started out trimming my horse's feet, in 2011. When the heel is so low, the toe needs to be brought back also very substantially, which meant in my case that I needed to remove a lot of toe, basically removing pretty much all toe wall and some sole in the toe.
As a result of this trim, my horses were basically unable to master hard terrain. They were fine as long as they stayed on their sand paddocks and pastures, but they were very uncomfortable on any sort of hard ground.
Long story very short, on the right part of the picture below, you can see my geldings front left hoof as he presents it today compared to the "ABC" trimmed hoof in 2011. It is pretty obvious that today he has a much more massive heel (it is roughly at the height that Cheryl Henderson thinks should belong to a draft horse) and much more massive bar, supporting that heel. Also, he is no longer walking on his sole but has some wall support all throughout his foot.
The difference in function between those feet is like night and day. He can now master any terrain without any hoof protection once again, something he was also able to do before I started the ABC trim, but never during the time of the ABC trim.
When I started trimming myself according to the ABC trim, I was always told that bar had migrated over my horses sole and circled around the frog. This caused me to shorten bars and "dig out" supposed bar material for months without end, only to find the foot growing back the exact same way as I found it before.
My horses live on a sand dune. The (mostly wet) sand compresses in their solar concavity and in the area right under the coffin bone, the pressure on sole is largest so that the texture of that sole changes slightly. It basically becomes much harder sole right underneath the coffin bone, than further out, where no coffin bone is pressing on the sole anymore. This is the one and only reason, why, on my horses in their environment, the sole around the frog looks slightly different from anywhere else. There never was any bar "smeared" or "pooled" or "migrated" anywhere else than where the bar was supposed to be, at the back of the foot. This whole concept was so wrong and caused me and my horses so much sorrow, that I hope with this post maybe someone will be deterred from that notion of bar pooling, migrating or smearing and find other ways to understand the hoof than following blindly such misinformation.