Please remember!

The information presented on this blog represents "learning in progress" on my part, a horse owner, who was not satisfied with professional farriers and took matters in my own hands. As far as I am aware at the time of the post, the information presented is correct, but may change with me understanding more about hooves, in which case I will edit or remove the post. In order to follow my learning and understand everything about Molly's hoof, you need to start reading at the bottom.

Monday, January 14, 2013

negative palmar angle on hind feet

My next post will investigate the relationship between dorsal wall angles and palmar coffin bone angle on front and hind feet.

Heike Bean, who is a collector of coffin bones, found that the hind foot coffin bone has a steeper dorsal angle than the front coffin bone, on most horses (not all!). Below is an example (taken from here:

Note that these two bones do not stem from the same horse. Yet, the difference in dorsal angle is comparable to bones that do stem from the same horse. 

This difference between dorsal angle of coffin bones was also noticed by Dr. Hildrud Strasser, which lead her to formulate her strict rule that all horses' hind feet needed to be trimmed to a dorsal wall angle (DWA) of 55 degrees and all horses' front feet needed to be trimmed to a dorsal wall angle of 45 degrees. In recent years, these dorsal hoof wall angles have been proven wrong (due to the fact that the coffin bone does not sit in a ground parallel position in the hoof capsule) but what remains correct is the difference in dorsal angles between front and hind coffin bones.  By extrapolation from Dr. Strassers rule, this difference should be as great as 10 degrees.

Nobody really knows exactly which palmar elevation of the coffin bone in the hoof capsule is the best for a horse's comfort and performance. To my knowledge, noone has measured (by X-ray) the palmar elevation of hind feet coffin bones in free living mustangs. However, it is reasonable to assume that both, front and hind feet should have similar palmar elevations of the coffin bone. This palmar elevation could be anywhere between 2 degrees and 8 degrees positive angle. For example, on a front foot a dorsal wall angle of 50 degree translates in a 3 degree positive palmar angle (see below, top row).

However, given the difference dorsal angles of coffin bones between fronts and hinds shown above, a dorsal hoof wall angle of 50 degrees on a hind foot results in a negative palmar angle of the coffin bone in that foot, as can be prominently seen on the lower part of the picture below.

While the horse in the picture below is not lame or sore, it is expected to perform much better once the palmar elevation of front and hind feet match. The hind feet need to be correctively trimmed to achieve a higher palmar coffin bone angle. This corrective trim is not so trivial. 

Most people do not have x-rays at their disposal to guide their trimming techniques. Thus, a good rule of thumb should be that the dorsal hoof wall angle of the hind feet should at least be slightly steeper than on the front feet.

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