What you would expect to see in an ideal mini hoof should be exactly the same thing you would expect to see in any other breed of horse. The principals are the same. The hoof wall should be parallel with an
imaginary line drawn through the middle of the long and short pastern bones. (You can see that illustrated in one of the drawings on this topic)
The problem is that each horse, and even each breed, can have conformation issues, hoof growth characteristics, or physical wear that, if left uncorrected, can cause the hoof to grow in ways that upset the
alignment. As was already stated, draft horses tend to have very flat, splayed out, feet because of their heavy weight. Minis tend to have more upright hooves (both when looked at from the side and when looked at from the front) than most ‘big’ horses, because of their light weight.
So, the challenge is to find a farrier or hoof trimmer that looks at the individual animal and trims it the way IT needs to be trimmed. On some horses, you may take off a lot of toe and very little heel, on others; you may only need to trim heel, and no toe. It depends on how the hoof grows, and on how the hoof is being worn off.
In my area, (SW Oklahoma) there is a very popular farrier. He swears by never taking any heel off, as his Grandaddy said you didn’t need to. Most of his business is Quarter Horses, and on most of them, it is true,
and the horses look great. But, the problem is that he does the ‘same’ trim on all horse. So, when he works on ‘other’ horses, ones that tend to grow more heel, he doesn’t take enough off, so their heels keep
getting longer and their feet get too upright. I have seen him do it on some big horses, and on lots of minis.
From my experience, I would say that all the photos currently posted on this topic, (at least the ones that show a side view), have more heel than is ideal. The ones that had been neglected still look like they have quite a way to go before their heels are back at the correct length. It will take a few more trims before they can be brought back to ‘ideal’.
Even Littlegoesalongway’s horse has some heel issues. And ,I don’t mean to ‘pick’ on her gelding, as his feet are pretty good, he is obviously well cared for, and he is getting close to being ready for another trim.
But, from what I can see, from the side view particularly, even his heels seem too long.
Because of that, where his heel touchs the ground is quite a bit forward of the back of his foot. I would say he has ‘under-run heels’, because the back of the heel is too far forward, and the angle at the back of the hoof is more slanted than the angle at the front. But, because he has ‘good’ feet, his heels have not collapsed. (Many horses with under-run heels also have the back quarters of their feet collapse under from the sides, rather than having a healthy, more vertical alignment, as her gelding does).
I think this article does a good job of explaining, and illustrating, what ‘underrun’ heels are:
http://dressagewannabes.blogspot.com/2011/06/hoof-pathology-underrun-heels.html
I have trimmed a lot of minis, but I am not a certified farrier or hoof care specialist, so these are just my observations.