Monday, May 19, 2008

Short heel, long toe: No, No!

The long toe, underslung heel trait is the most common hoof abnormality in horses. Here are ten reasons to take corrective measures for this conformation flaw, especially in the competition horse. Most are from Daniel Mark's Conformation and Soundness in the AAEP Proceedings, vol 46, 2000, p. 39.

Ten reasons to trim the toe

  1. In a study of racehorses, researchers found that as the length of the toe increased by 1 inch, the odds of sustaining a carpal chip fracture increased by a factor of 40. (C. W. McIlwraith, Role of Conformation in Musculoskeletal Problems in the Racing Thoroughbred and Racing Quarter Horse, AAEP Proceedings, 2003).
  2. Low hoof angles cause the heel to bear more weight, resulting in joint stress and heel pain. When the hoof angle is at a 39 degree angle, 75% of the weight goes to the heel; at 55 degrees, 43% is borne by the heels. The widest part of the foot is where the horse should land to effectively balance the hoof around the coffin bone.

  3. Horses with long toes tend to land toe-first. Horses that land toe-first are those that are "closer to lameness" and considered by some veterinarians to be a grade one lame.

  4. A toe-first landing means that the stride is shorter than normal (Ovnicek, G., How Hoof Form Relates to Hoof Function: Part 2, 9th Congress on Equine Medicine & Surgery).

  5. Low hoof angles increase tension on the deep digital flexor tendon and compresses the navicular bone and rotary forces on the p3 bone (see picture above right--click on it to enlarge).

  6. Underrun heels crush the digital cushion. The digital cushion does not regenerate well once significantly crushed. The longer the problem continues, the greater the overall damage to internal and external structures


  7. The greater the weightbearing on a portion of hoof, the slower the growth (a vicious cycle).


  8. Hoof tubules run from the top to the bottom of the hoof, and form the outer structure. Ideally they should be closer to vertical than horizontal. On underrun heels the tubules are bent forward, making the them less able to resist compression.

  9. In a study of racehorse shoeing and hoof traits, researchers found that when there is disparity between the toe angle and heel angle, suspensory apparatus failure is more likely to occur. (Kane, A., Hoof balance characteristiscs associated with catastrophic injury of Thoroughbreds, AAEP Proceedings 1998).

  10. Breakover is significantly delayed when the horse has a long toe and low hoof angle. The toe acts as a long lever arm, requiring more time and effort to rotate the heel around the toe. Imagine a athletic shoe (with a rolled toe) versus a clown shoe. The cross- trainer's shorter length and its breakover design allow for easier locomotion.


4 comments:

  1. All good tips. Boy am I glad I have a great farrier, who knows what he's doing, as this is one of the areas, I'm not to knowledgeable in.

    ReplyDelete
  2. Stacey- as always- good post. Please visit Oh HorseFeathers! when you have a moment to pick up an award for your fantastic work here on your blog. ;)

    On to the post here- I have one issue (as a hoof care provider in my professional life) with the picture shown, depicting the toe angle. I wish that it also showed the heel portion of the hoof being underrun. Had they drawn that line there, it would have been much easier for people to see what an underrun heel actually is.

    The long toe illustrated is a small portion of a large problem, in which the solution is not adding a shoe, as a shoe creates leverage on the heel, increasing pressure on the heel, crushing it farther forward. We see a HUGE amount of this in our practice, and it is always a wonderful, realtively easy fix to get the hoof capsule back up under the horse, where it belongs.

    If you get the chance, watch Gene O's video depicting how the bony structure moves in a heel first landing, VS a toe first landing. It will make you cringe, and explain things even more. (Gene is a great teacher, and I enjoy his works tremendously.)

    Thanks again!

    ReplyDelete
  3. Thanks Mrs. Mom! I'm at work now but tonight I try to revise the article to reflect your comments.

    Is the Gene O video on Youtube?

    Finally, a dumb question -- how do I pick up the award? Just grab the image (a really nice image)...

    Stacey

    ReplyDelete
  4. Hmmm, since I spend zero time on youtube, I really do not know. I watched his VHS tape about 7 years ago now, and had to set down my lunch after really getting to understand what is going on in that foot and leg....

    I see you got the award :) Looks Great on here!

    ReplyDelete

Hi Guys, Your comments are valued and appreciated -- until recently I never rejected a post. Please note that I reserve the right to reject an anonymous post.