Inside a Horse’s Hoof

Okies. Photos here due to a million repeated requests.

The inside bones of a horse’s hoof are something that not many folk get to see (and that’s all good!)
But knowing what is ‘in there’ can often help us understand such things as founder and navicular, etc.

Come with me while we waltz around a horse’s hoof – without the horse.

The coffin bone / pedal bone / third phalanx / hoof bone, P3 – call it what you like. That’s the bit that rotates when it loses connection in a founder case.

The short pastern connected to the hoof bone. Sometimes called P2.
Often when the vet takes x-rays, you hear the terms P1, P2 and P3. Thems are the bones he/she means.

That long thin bone in there is the navicular bone.

Just a close up view of the sesamoid bones (two small ones) and the navicular bone.

Starting from the bottom up:
Coffin bone P3
Navicular bone
Short pastern P2
Long Pastern P1
Sesamoid bones
(and then a bit of the rest of the leg…just to confuse you all.)

Here is the hoof wall, without the hoof bits in it. You can see the top of the upper wall (coronet band) and the spot where the frog belongs. (Excuse the broken bit of sole.)
Along the inside of the hoof wall, we have thousands of little tubulars.

There they are. Think of corrugated iron how the ripples all slot together. This is similar.
When there is a break in the connection – such as inflammation during a laminitis attack, those little tubules lose hold of each other. And let go of hands. Then the pedal bone is swinging by itself…and drops.

That’s a x-ray shot of a dropped pedal bone. As about as dropped as you can get. It broke through the sole and protruded. The yellow line on the bottom shows the base of the hoof sole, the thin silver line marks the hoof wall.
The first photo is a dropped coffin bone. Through the sole. Protruding.
The second photo is a few months later. New growth from the top means new tubules which knits that coffin bone back up where it is meant to be.
But all is not lost. Those tubules can and do get replaced. A new connection comes down from the coronet band, making everything new again. The ‘broken’ or old dead connection will grow out. You know those ridges you see on a founder horse? Everything above is new, everything below is old.
Isn’t the hoof a incredible thing?