Re: cannon bone size

["David M. Garlinghouse, Esq." <suendavid@worldnet.att.net>]

Jack_Weaver@cc.chiron.com wrote:

> I was also informed by Lynette that the weight of the horse can also be
> considered.   I think this was also Susan's  formula.
> 
> > If you add up the total mass of the horse's body weight plus the
> > weight of the rider and tack, and divide that number by the cannon
> > bone circumference, and then divide that number by two; the resulting
> > number should not exceed 80 lbs per inch of cannon bone
> > circumference, and ideally should be 75 or less.  Horses that have to
> > carry more than 80 pounds of weight per inch of cannon bone had a
> > higher incidence of lameness.

Lynette is referring to a formula I presented as a hypothesis at a talk
I gave last spring---at first, the formula looked like it might have
some value in predicting performance based on weight, CBC, etc.  After
adding to the database and then running the numbers through statistical
tests, the above formula did NOT meet criteria as a valid formula.  Body
weight of the horse did have an effect on lameness, but there is no
quick-and-dirty formula, as of yet.

> 
> I presume an overall average for an endurance type Arab would be around
> a 7.5" circumference since body weight would not be that different, but
> the weight formula would be a little more accurate.

Actually, the ranges for body weight among the Tevis horses had a pretty
wide range, even among purebreds.  Low weight was around 700 lbs, top
weight around 1050 or so, I think.  Although there aren't any published
studies measuring typical CBCs in a random population, based on
unpublished data, 7.5" is above the average for the general population. 
Part of that might also be due to increases in bone circumference in
response to consistent conditioning.
> 
> Ok, there are other factors.  I would think that cannon bone length
> would also be a factor because of leverage (torque).  Two horses of
> equal height can have cannon bones of different length.  I think I would
> prefer the horse with longer upper leg (a larger bone) and shorter
> cannon bones.  Has there been a study of cannon bone length?

Not in endurance horses.


Good luck with him.

Susan Garlinghouse