I don't think one is necessarily better than the
other for long term soundness. What I would look at is the manner with
which the foot and knee are centered on the leg. If you can drop a
straight line from the middle of the femur, through the knee, through the cannon
and pastern bones to the ground, and it dissects the foot evenly--then you are
ok. If that line deviates from the middle of any of those structures, you
may be looking at forces that will, with time, cause stress. If the foot
toes out or in but the leg still meets the straight line criteria,
then go for it. With a horse whose feet have been improperly trimmed to
correct the toe in or out, there will be a greater amount of the hoof on either
side of your line, but you MAY be able to correct that.
Another good test is to pick up the foot, hold the
leg up by the cannon bone and let the foot fall naturally downward, now sight a
line across the heels, and straight through the cannon bone into the foot, your
lines should be straight and intersect perpendicular. Again, one heel may
be higher or lower, but that may be due to someone trying to 'correct' what
should be left alone.
I have had a good long term horse of each
persuasion--slightly toed in and toed out - both with otherwise straight bone
structure.
