This story appears in the May 2019 issue of National Geographic magazine.
When it comes to horseshoes, one size—or shape—hardly fits all. There are thousands of styles worldwide, and Arvin Reynolds is familiar with many of them. Reynolds is a farrier, or “horseshoe-er,” as he sometimes puts it. Based in Washington, D.C., he cares for hundreds of equine feet, including those belonging to the horses of the United States Park Police. Checkups are typically every six weeks, says Reynolds, and not because the animals get sick frequently or need new shoes. Rather, hooves, like human toenails, grow continually and require regular trimming.