Q:A number of horses I’ve seen appear to have asymmetrical muscle development, particularly over the shoulder area, which can make saddle fitting difficult. Many publications seem to say that the larger shoulder indicates that the horse is having to work harder with this leg and that muscle mass has therefore increased–just like with a weight lifter. However, I have also heard that the larger shoulder is actually flaccid muscle, and the contraction of hard-working muscles in the opposite shoulder makes it appear flatter–more like the toned muscles of a sprinter. Which is correct?

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A:Actually, neither might be correct. Developmentally, approximately 80% of horses have a larger, more bulging left shoulder, while 20% have a larger right shoulder. The apparently larger side has the shoulder blade in a position farther back (toward the rear), while the flatter blade is set farther forward. The shoulder joint is also farther forward on the flatter side. The bigger shoulder is usually accompanied by a flatter foot and lower heel, indicating that the horse bears more pressure on the heel, and the farther forward shoulder has a more clubbed foot.

This difference in feet might start at a very young age, as some farriers have noticed that, in grazing foals, the clubby foot is placed back with less weight on the heel, and the flatter foot is forward with more weight on the heels