>
> I'm curious, does anyone know what would make cow hocks a structural fault
> for a horse but not a dog?

   I don't know the numbers on this, but horses have enormous amounts of
weight on very small hooves.  The lower legs, like other animals that depend
on speed to escape predators, are slim and mostly tendons and bone.  The
muscle is mostly higher up on the leg and body.   So we're talking physics -
the math of mass and angles that have lots of pressure and torque on them.
Think of a horse's leg as a lever, and put a crimp in it.  Suddenly it's not
so strong.
  Doesn't take much to get a hitch in their git-along, as they say.
  A dog weighs a lot less (if they weighed 800-1600 pounds, it might be a
different story) and has bigger bones proportionally and and can tolerate
more torque when they turn and dig in for speed.  A fall of a more flexible
50# body going down 12 inches is different than the fall of a more rigid
1200# body going down 4 feet.

Rini