Those pictures illustrate what we call a “bullnose” hoof: a bulge on the dorsal wall.
A healthy dorsal wall should be straight.
WHAT’S HAPPENING INSIDE?
The coffin bone (referred as P3 on the pic) is tipped back and kind of pushes on the wall, creating an arch to make room for the tip of P3.
▪️ The coffin bone tipping back at the heels leads to Negative Palmar Angle: “heel” of P3 lower than its tip).
▪️ This is often found with a “broken back Hoof Pastern Axis“, or broken back HPA. It means that instead of having the green dotted line parallel to the white line (pastern joint), the green line would end up crossing the white line.
This horse accommodated his HPA by modifying his stance: back feet under him all the time to lower his pastern axis.
This shows how this hoof would have better angles. The black and dotted orange line by the heels are to represent what’s “missing” to the foot.
That’s just a quick drawing, because I would have needed to change the toe, that’s migrated, and it out matches my computer skills 😅
Look at the 3 pictures together and visualise what’s happening inside the 1st & what’s different between the last 2.