Cynthia G. MacKenzie, DVM, senior equine technical services veterinarian for Merck Animal Health. In this role, she provides continuing education to equine practitioners and horse owners, composes technical literature, and conducts field trials. Prior to joining Merck Animal Health, MacKenzie served as a veterinary associate for Mark Secor, DVM, Inc., in San Juan Capistrano, Calif., and at Rood & Riddle in Lexington, Ky. She was also the resident veterinarian for 700 horses at Lane’s End Farm in Versailles, Ky.

Alan Ruggles, DVM, Dipl. ACVS, is a surgeon and partner at Rood & Riddle Equine Hospital in Lexington, Ky., where he specializes in orthopedic surgery and lameness. Previously he taught at the New Bolton Center at the University of Pennsylvania and The Ohio State University. He is the author or co-author of more than 20 peer reviewed papers and eight book chapters concerning equine orthopedic problems.