Laird points out that nutrition is very important to muscular health. The muscles cannot be expected to repair themselves if the animal is not maintained properly with adequate nutrition for his performance expectations. This restricted blood supply results in restricted nutrition to the muscle. So, proper nutrition enables the blood supply to carry healing nutrients and oxygen to the muscles and speed healing. Many factors make the equation.
Conformation is one factor to look at.
The animal's age, improper conditioning for the level of performance, trauma by way of slips, falls, kicks, poor shoeing techniques, trailering for lengthy periods without rest. In addition, as Laird points out, certain disciplines seem to encourage certain chiropractic problems. For example, Pleasure horses seem to have more neck and back problems. Perhaps the way of going so popular in the show ring and rewarded so much is actually hurting the animal. Reining horses have more hip and shoulder problems.