The evolution of the horse from a tiny, four-toed animal, perhaps no more than one foot tall, to the variety of equines in existence today, is one of the wonders of nature. During that process of change, the horse evolved over many thousands of years from an animal that predators hunted for food to an animal that became a servant and friend for mankind.

Today’s horses are designed to do one of two things–pull a load with their shoulders or carry riders on their backs. The type of horses utilized for these respective tasks varies a good deal; one is large and ponderous and the other is lighter-boned with less muscle mass. Even within these two types, there are significant differences. For example, the conformation of a roping or cutting horse is different from that of the American Saddlebred. Yet there is a basic sameness to anatomy.

In this opening article of our 12-part series on equine anatomy and physiology, we will attempt to paint a picture of how today’s horse is constructed and what this means in the realm of form to function. We will not be quoting a lot of sources, for the most part, because the information to be presented is an amalgamation of what has been recorded in thousands of scientific papers, textbooks, and manuals as knowledge has been gained and disseminated through the years. However, we would be remiss in not calling attention to two valuable sources upon which we shall draw heavily. Both are written at the layman level. They are Horses and Horsemanship by the late M.E. Ensminger, BS, MA, PhD, and The Coloring Atlas of Horse Anatomy by Robert A. Kainer, DVM, MS, and Thomas O. McCracken, MS, both of whom were at Colorado State University.