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[RC] Barefoot/circulation and studies - Candace Kahn

Hi Heidi,
     In one of your last posts on this subject you asked me for case studies.  I have done some investigating and submit the following:
 
> "I'd sure like to see studies that back up this notion that the
> expansion is limited.

Equine Vet J Suppl. 2001 Apr;(33):54-7 In vivo and in vitro heel
expansion in relation to shoeing and frog pressure. Roepstorff L,
Johnston C, Drevemo S.

You have to pay to get the fulltext of the paper but you can view the
abstract here:

<http://www.ncbinlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11721569>

The mean values given for heel expansion in a live (not cadaver) fore hoof were:

unshod walk: 0.44 mm
shod walk: 0.34 mm

unshod trot: 0.67 mm
shod trot: 0.51 mm


>  I've yet to see anything convincing on this
> subject, other than horses with happy, healthy feet with good
> circulation who have worn shoes for much of their lives.  (Yes, I'm
> aware of cadaver studies that don't take into account whether the
> shoes were properly applied, or whether the horses did anything in
> their lives besides stand in a paddock--lack of exercise is far more
> apt to cause decreased circulation than are properly applied shoes!)
>      I've watched the tapes of treadmill studies in which one can
> SEE the expansion and contraction as it occurs--and one can't see
> one whit of difference between properly shod and unshod feet on
> those.
> Additionally, one can see that most of the expansion occurs
> posterior to the quarters--which is only logical, given that there
> is no "opening" at the toe, as there is at the heel.  How can there
> be restriction if there is nothing whatsoever inhibiting the hoof
> wall posterior to the quarters?

Equine Vet J Suppl. 1998 Sep;(26):86-95. Variation in surface strain on
the equine hoof wall at the midstep with shoeing, gait, substrate,
direction of travel, and hoof shape. Thomason JJ.

The abstract is here:

<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=9932098>

The main difference is in the way the hoof capule expands, it's amount
reduced in a shod hoof, and the deformed shape is different, that is
what the term "strain reorientation" in the abstract means.

>      With regard to the degree of expansion--on many of our horses,
> the edge of the shoes are often as much as 3/8" outside the non-
> expanded hoof wall at the heels--and sometimes we STILL have issues
> with so much expansion that the feet will overgrow the outsides of
> the shoes when the horses are very active.   That's because they are
 > expanding PAST the edges of the shoes at the heels.  And one can
 > verify that with the wear marks.

The hoof becoming larger than the shoe is not caused by the same
(elastic) expansion mechanism as above but by growth of the hoof in its
natural concical shape. Any farriery text should point this out.
 

 
 
Candace Kahn
Naturally Bare Hoof Care
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