Squaring toes of hind hooves

["guest@endurance.net" <guest@endurance.net>]

Corky Unclecorkysgirl@aol.com
Can anybody tell me if it is damaging to square the toes 
on my horse's hind feet? (She wears shoes in the back, too)

If she goes for 25 miles, at least twice in that time,
I feel her hind end collapsing while at a trot. (It feels 
like she's losing her hind end.) She'll collapse 3 times in 
a row, with each stride, then back to a normal trot.

The reason my blacksmith started squaring the toes was 
because she was starting to forge, and this stopped the forging.  She never used to lose her hind end last year,
just forged after 20 miles or so, I think because of 
laziness.  She's 8 years old, and very fit, but a lazy
girl.
Thanks for any advise on this,
Corky