Squaring the hind toes is a quick fix. In racehorses we'd rather balance the
whole horse because our animals are hitting hard and, above all, need reach
behind. Squaring any toe increases the effects of concussion and, behind,
will go right at the hocks--in racehorses.
Perhaps this kind of thing is OK for endurance horses. Perhaps stride
efficiency is not so important and concussion is not of a magnitude that it
will affect the hocks and stifles. This is out of my realm of experience.
The whole-horse approach, though, is better served by moving toward higher
angles and shorter toes in front, lower angles and longer toes behind. Speed
up in front, slow down behind to correct front to back interference at the
trot and in the rotary gallop.
ti