During the last century and today, the Tennessee walking horse has been used primarily for pleasure and show competition. Unique and natural to the breed is a smooth four-beat "running walk" gait. In the 1950s the accentuated or exaggerated running walk, known as the "big lick" became popular at high-level competitions. The combination of exaggerated high-action step in front and long stride behind is still considered desirable in today's horse show competitions, and it is often achieved through soring. Soring is the practice of applying a substance or mechanical device to the lower limb of a horse that will create enough pain that the horse will exaggerate its gait to relieve the discomfort. In 1970 Congress put into law the Horse Protection Act (HPA) to specifically address the practice of soring by prohibiting the showing, exhibition, or sale of Tennessee walking horses that are found to be sore. Sadly, soring is still being done even after 50 years of HPA enforcement. This report reviews the methods for detecting soreness in horses, in hopes of advancing the goal of ultimately eliminating the act of soring in horses and improving the welfare of Tennessee walking horses. A Review of Methods for Detecting Soreness in Horses examines what is known about the quality and consistency of available methods to identify soreness in horses; identifies potential new and emerging methods, approaches, and technologies for detecting hoof and pastern pain and its causes; and identifies research and technology needs to improve the reliability of methods to detect soreness. This independent study will help ensure that HPA inspection protocols are based on sound scientific principles that can be applied with consistency and objectivity. Table of Contents Front Matter Summary 1 Introduction 2 Methods Used to Identify Soreness in Walking Horses 3 New and Emerging Methods, Approaches, and Technologies for Detecting Pain and Its Causes 4 Review of the Scar Rule for Determining Compliance with the Horse Protection Act Appendix A: Biographical Sketches of Committee Members Appendix B: Open Session and Webinar Agendas Appendix C: The Horse Protection Act of 1970 - Regulations