20/02/2017
When clients complain and say that their horses constantly have sore backs, problems in the high suspensory apparatus, hamstring problems/injuries, hock pain, stifle pain and swollen legs, the probable and most often the most overlooked culprit is Negative Pedal Bone angle, which can be caused by Conformation, Trimming or the Lack their off, disease or an injury.
The photographs below are of a horse which I was asked to work on. A few issues were observed during the initial assessment; - the horse was standing underneath himself and was slightly sickle hocked. The feet looked long, the coronet band hair line angle was more upright than normal āpointed to the abdominal area instead of the knees,ā and had a semi bull nose look on the dorsal part of the hoof capsule. . The Center of Pressure and the heels were too far āin frontā of the bony column, it should be more underneath the bony column. I believe if these issues are present and the horse is not lame, - if left uncorrected it will eventually lead to lameness in most horses.
Without X-rays to confirm my suspicion of a negative pedal bone angle to the ground, the next best method I use to give me insight on whatās going on inside is to measure the collateral groove. As I was presented with a straight collateral groove, I cleaned, opened and measured the ādepthā of the collateral groove at the back part of the foot and at the apex of the live frog where it meets the live sole.
It was obvious that the apex of the frog depth was much deeper as measured from the ground surface thanthe colateral groove at the back of the heels. Therefore a good indication that there was most probabily a negative angle of the pedal bone in relation to the ground.
Example x-ray: A negative angle pedal bone. . One should always be deeper at the back of the foot than at the Apex of the frog.
It is generally accepted that the healthiest and soundest feet are those with a positive angle, and that an acceptable range for the pedal bone positive angle is between 1.5 to 6.0 degrees.
The problem with negative pedal angle is overloading of the rear of the hoof. The soft tissues of the digital cushion, lateral cartilages, frog, etc., are being crushed. The heel bulb areas will look flatter and the frog may be pr*****ed. Horses with negative plantar angles often stand underneath themselves, which leads to soreness through the stifles, hocks, hamstrings and up into the croup and sacroiliac area.
Sickle hocked horses and horses with Degenerative Suspensory Ligament disease are predisposed to a more negative pedal bone angle, it is therefore imperative to keep their angles correct all the time.
A good depth for the collateral grooves from the ground is about 1,8cm or deeper, - as measured from ground level. The bigger the horse the deeper it should be. This is directly linked to how far the internal āsensitiveā structures are from the ground. Shallow collateral grooves equal a low arch and Low internal structures. With a depth of 1 cm or less the sole does not have a healthy blood flow supply and the circumflex vessels and solar papillae are compressed. These horses may appear sound, but they are working with a major blood flow deficit. These feet will bruise easily, and often develop quarter cracks on the deficient quarter and will heal slowly.
When I work towards correcting a negative pedal bone angle and the heel depth is 1,5 cm or less, I do not touch the heels and only work on the toe area but care must be taken to not lower the toe to much as it will leave your horse sensitive structures to close to the ground. So a wedge pad will be needed to achieve the correct pedal bone angle in relation to the ground.
A healthy digital cushion, frog and lateral cartilages are essential for a good healthy āback of the foot supportā and will go a long way to help with a good natural HP angle. When these structures fail due to conformation or undue pressure, one can easily have a negative pedal bone angle. First thing is to trim correctly for this condition. If the problem didn't originate in the hooves but rather as a result of a conformational issue, disease or an injury, we are limited in how much permanent change we can make at the hoof.
Working mainly on a better HP angle and more positive pedal bone angle, by doing this one will: spread the load more evenly around the hoof capsule, unload the back part of the foot, bring the bony column more under the hoof capsule more, promote better blood circulation and lessen unnecessary tension on tendons, ligaments, muscles, stifle, hocks and the horses back.
Constant Good trimming and ground work will help return the hoof to normal functionality, it will promote a healthy digital cushion and good arch at the back of the foot.
I luckily had enough hoof to work with which allowed me to lower the toe area. After the trim I had a slightly deeper heel collateral groove than the apex of the frog.
