- Email: [email protected]
Introduction: The old and the new
Clinical Techniques in
Equine Practice Vol 2, No 4
December 2003
Introduction: The Old and the New uccessful detection of equine lameness does not so much require knowledge of science as it does art.1 When I wrote that sentence in the recently published Diagnosis and Management of Lameness in the Horse, a textbook I edited along with my esteemed colleague, Dr. Sue Dyson, I was reflecting on what had not changed over the last hundreds of years, namely, the need to develop a feel for the horse and to establish the clinical relevance of lameness examination findings. The successfully completed lameness examination is not so much a clinical technique as it is a culmination of years of clinical experience. Basic techniques such as hoof tester application, diagnostic analgesia, and diagnostic imaging can be vital to detecting the authentic source of pain in a lame horse. But nothing replaces the timehonored techniques of asking the right questions when seeking the anamnesis, keen observation and careful palpation, accurate assessment of the lame limb, and meticulous interpretation of these findings to arrive at the correct diagnosis. The racehorse combines the unique characteristics of speed, a rigorous training program, an often unforgiving racing surface, an unrelenting stakes schedule, and a young, immature musculoskeletal system. It is little wonder that a hallmark of the racing industry is the overwhelming importance of lameness. Lameness is the leading cause of poor performance. In 1940, Peters’ early work highlighted this observation.2 In a recent study, 50% of horse operations in the United States with 3 or more horses had 1 or more lame horses, and on any given day, 5% of horses could be expected to be lame.3 In another study, 74% of Standardbred and Thoroughbred racehorses evaluated for poor racing performance had lameness problems contributing to poor performance. Lameness examination was critical in comprehensive sports medicine evaluation.4,5 Lameness was
S
From the Professor of Surgery, University of Pennsylvania, New Bolton Center, Kennett Square, PA 19348-1692. Address reprint requests to Dr. Michael W. Ross, University of Pennsylvania, New Bolton Center, Kennett Square, PA 19348-1692; e-mail: [email protected] Copyright 2004, Elsevier Inc. All rights reserved. 1534-7516/04/0204-0001$35.00/0 doi:10.1053/j.ctep.2004.05.001
the leading cause of wastage in Thoroughbred racehorses.6 Often, overt clinical signs of lameness are minimal and convincing trainers and owners of the relevance of lameness to the horse’s poor performance is difficult. The negative impact of lameness on the racing industry is further defined and highlighted in this issue of Clinical Techniques in Equine Practice by the work of Dr. Sue Stover. If lameness remains the most important cause of poor performance in the racehorse and much of the lameness examination remains the same as it was hundreds of years ago, what has changed? The answer is that we have become much better at understanding the pathogenesis of injuries in the racehorse, or for that matter, most types of sport horses. We can now answer many of the unanswered lameness questions we had years ago. No longer do horses need to be rested, taken out of training, or “turned out” until next year without a diagnosis. The term “colt soreness,” while useful in describing a young racehorse unable to physically endure the rigors of race training, is now known to encompass a myriad of stress-related bone injuries. That many of the common forms of subchondral and cortical fractures in racehorses, once thought to be single-event injuries, are the end result of a continuum of stress-related bone injury is the key to understanding racehorse lameness. Injuries such as small and large carpal osteochondral fractures (chip fractures and slab fractures), third metacarpal and metatarsal bone (McIII/MtIII) condylar fractures, and distal phalanx fractures are not the result of single-event injuries but, rather, common results of stress-related subchondral bone injury. The days of thinking horses are simply galloping down the racetrack and take a bad step are over. Common catastrophic injuries such as complete fractures of the humerus, tibia and pelvis, and McIII and MtIII are now thought to be the dramatic result of existing stressrelated bone changes that have altered morphology and predisposed bone to fracture. I have emphasized this important recent turnaround by soliciting the writings from Dr. Elizabeth Davidson and Dr. Stover. Davidson describes the importance of scintigraphic examination of the lame racehorse. The difficult concept of stress-related subchondral bone injury, often called stress remodeling, or nonadaptive or maladapted bone remodeling, is demonstrated and explained. To understand the con-
Clinical Techniques in Equine Practice, Vol 2, No 4 (December), 2003: pp 293-295
293
cept of subchondral bone pain is critical to understanding why lameness can be localized (blocked out), but intraarticular therapy may be of little benefit in so many racehorses with early osteoarthritis. Time-honored beliefs in the racehorse industry are difficult to change. Conventional training programs on dirt racetrack surfaces, shoeing practices and racehorse shoe characteristics, turn-out exercise and thermocautery and blistering have all been recently questioned. What is the ideal conformation of the Thoroughbred and Quarter Horse racehorse? Can you go to a sale and apply the time-honored assumptions of conformation as so many of us do? Cutting-edge analysis of epidemiological data has helped Dr. Wayne McIlwraith and coworkers answer some of these questions and, perhaps, stimulate controversy along the way. Are horses with mild carpus valgus limb conformation really protected from the development of carpal injury? McIlwraith and coworkers also contributed a synopsis of their important recent work detailing the results of a large epidemiological study evaluating radiographs of sales yearlings. Even in a study of this magnitude, finding enough horses with radiographic changes to fulfill statistical requirements can be difficult; thus, some major questions remain unanswered. However, the authors have done marvelous work and have refuted and confirmed some of the time-honored beliefs. Some may disagree with the findings, but a base from which to work has now been established. Dr. W. Theodore (Ted) Hill, a veterinarian whom I greatly admire and respect, has been largely “behind the scenes” in his work with The New York Racing Association. Hill has compiled an incredible knowledge base from his unique experience of examining tens of thousands of racehorses and developed a “feel” for the racehorse that few in the world share. I asked him to contribute original information about his findings in this issue of Clinical Techniques in Equine Practice. What is the best way to reduce the impact of stress-related bone injury in the racehorse? The answer is to reduce the stress. Rest and rehabilitation are the mainstays of therapy for many lameness conditions in the racehorse but, yet, rest can be an ugly 4-letter word in the tough world of racing. While there have been many therapeutic modalities put forth over the years, some have not withstood the test of time. Can extracorporeal shock wave therapy (ESWT) endure? This recent advancement is not well understood and is controversial. Are the beneficial effects simply the result of the analgesic effect or is healing stimulated? Are there differences in the effects of ESWT between soft tissues and bone? Dr. Scott McClure has done interesting and pioneering work in the use of this modality in the horse and I asked him to tackle this topical subject in 2 manuscripts. Difficult questions such as the differences between focused and radial units, management protocols, and supporting experimental and clinical evidence for the use of ESWT are answered. What are the most common lameness conditions in the racehorse? Do Standardbred and Thoroughbred racehorses share common injuries or do differences in breed, gait, equipment, track surface, training methods, and other factors play a role to change lameness distribution between industries? Recently, we asked contributors to our textbook chapters to answer these questions. Arthur and coworkers7 listed the 10 most common lameness conditions in the North American Thoroughbred
294
(most common to least common) as lameness of the foot, lameness of the metacarpophalangeal/metatarsophalangeal joints (MCPJ/MTPJ), carpus, suspensory desmitis, dorsal McIII disease, superficial flexor tendonitis, tibial stress fractures, distal hock joint pain, myositis, and other stress fractures. Mitchell and coworkers8 listed the 10 most common lameness conditions in the North American Standardbred as lameness of the front foot, carpus, MTPJ, distal hock joint pain and other tarsal lameness, suspensory desmitis—forelimb and hindlimb, MCPJ, splint bone disease, stifle join lameness, myositis, and other soft tissue injuries (curb, superficial digital flexor tendonitis). While epidemiological data were not collected, the authors listed their “gut feelings” about what they see in clinical practice. The importance of the foot, in particular the front foot, cannot be overemphasized in both racing breeds and the foot was the most common area of lameness. However, several differences were observed. Cortical bone injury (dorsal McIII and tibial stress fractures) was a common cause of lameness in the Thoroughbred, but not the Standardbred. The MTPJ was a common source of lameness in the Standardbred, highlighting the importance of the hindlimb overall in this racing breed. The forelimb predominated in the Thoroughbred, but the practitioner should not overlook the MTPJ. When Dr. James Orsini asked me to be a Guest Editor for Clinical Techniques in Equine Practice, I had mixed feelings. I am passionate about the lame horse, in particular the racehorse, but had spent considerable time and effort in writing the textbook, in which all of the techniques required to complete and interpret the lameness examination are detailed in considerable length. The basic techniques and specific information regarding lameness in most types of racehorses and nonracehorse sport horses were covered comprehensively. What, then, could be written that would be new, innovative, cutting edge? When writing a textbook of considerable volume, one needs the combined efforts of many authors. I had “gone to the well” many times to solicit the efforts of authors worldwide within the last few years. How, then, could I ask many of the same authors once again to give of their precious time? For this issue of Clinical Techniques in Equine Practice I was able to blend some “old” and some new contributors to share their knowledge and experience. While the basics of the lameness examination have not changed for hundreds of years (the old), this issue of Clinical Techniques in Equine Practice demonstrates just how complex lameness diagnosis has become (the new). The detail with which we can now image the musculoskeletal system of the racehorse, the studies done to examine the epidemiology of racehorse injuries, and the treatment modalities currently available to us for management of lameness in the racehorse should convince all that science has complimented the art in the lameness examination. I thank the contributors and Dr. Orsini for allowing me to continue my quest to expand our knowledge about the important subject, lameness in the horse.
References 1. Ross MW: Lameness examination: historical perspective, in Ross MW, Dyson SJ, (eds). Diagnosis and Management of Lameness in the Horse. Philadelphia, Saunders, 2002, pp 2-3 2. Peters JE: Lameness incident to training and racing of the thoroughbred. J Am Vet Med Assoc Feb: 200, 1940 3. Kane AJ, Traub-Dargatz J, Losinger WC, et al: The occurrence and causes of lameness and laminitis in the US horse population. Proc Am Assoc Equine Pract 46:277-280, 2000 INTRODUCTION
4. Seeherman HJ, Morris E, O’Callaghan MW: Comprehensive clinical evaluation of performance, in Auer JA (ed). Equine Surgery. Philadelphia, WB Saunders Company, 1992, p 1133 5. Morris E, Seeherman HJ: Clinical evaluation of poor racing performance in the racehorse: the results of 275 evaluations. Equine Vet J 23:169, 1991 6. Jeffcott LB, Rossdale PD, Freestone J, et al: An assessment of wastage in Thoroughbred racing from conception to 4 years of age. Equine Vet J 14:185, 1982 7. Arthur RM, Ross MW, Moloney PJ, et al: North American Thorough-
MICHAEL W. ROSS
bred, in Ross MW, Dyson SJ (eds): Diagnosis and Management of Lameness in the Horse. Philadelphia, Saunders, 2002, pp 868-879 8. Mitchell JB, Mitchell JS, Nolan PM, et al: The North American Standardbred, in Ross MW, Dyson SJ (eds): Diagnosis and Management of Lameness in the Horse. Philadelphia, Saunders, 2002, pp 895-912
Michael W. Ross, DVM, Diplomate ACVS Guest Editor
295
Equine Practice Vol 2, No 4
December 2003
Introduction: The Old and the New uccessful detection of equine lameness does not so much require knowledge of science as it does art.1 When I wrote that sentence in the recently published Diagnosis and Management of Lameness in the Horse, a textbook I edited along with my esteemed colleague, Dr. Sue Dyson, I was reflecting on what had not changed over the last hundreds of years, namely, the need to develop a feel for the horse and to establish the clinical relevance of lameness examination findings. The successfully completed lameness examination is not so much a clinical technique as it is a culmination of years of clinical experience. Basic techniques such as hoof tester application, diagnostic analgesia, and diagnostic imaging can be vital to detecting the authentic source of pain in a lame horse. But nothing replaces the timehonored techniques of asking the right questions when seeking the anamnesis, keen observation and careful palpation, accurate assessment of the lame limb, and meticulous interpretation of these findings to arrive at the correct diagnosis. The racehorse combines the unique characteristics of speed, a rigorous training program, an often unforgiving racing surface, an unrelenting stakes schedule, and a young, immature musculoskeletal system. It is little wonder that a hallmark of the racing industry is the overwhelming importance of lameness. Lameness is the leading cause of poor performance. In 1940, Peters’ early work highlighted this observation.2 In a recent study, 50% of horse operations in the United States with 3 or more horses had 1 or more lame horses, and on any given day, 5% of horses could be expected to be lame.3 In another study, 74% of Standardbred and Thoroughbred racehorses evaluated for poor racing performance had lameness problems contributing to poor performance. Lameness examination was critical in comprehensive sports medicine evaluation.4,5 Lameness was
S
From the Professor of Surgery, University of Pennsylvania, New Bolton Center, Kennett Square, PA 19348-1692. Address reprint requests to Dr. Michael W. Ross, University of Pennsylvania, New Bolton Center, Kennett Square, PA 19348-1692; e-mail: [email protected] Copyright 2004, Elsevier Inc. All rights reserved. 1534-7516/04/0204-0001$35.00/0 doi:10.1053/j.ctep.2004.05.001
the leading cause of wastage in Thoroughbred racehorses.6 Often, overt clinical signs of lameness are minimal and convincing trainers and owners of the relevance of lameness to the horse’s poor performance is difficult. The negative impact of lameness on the racing industry is further defined and highlighted in this issue of Clinical Techniques in Equine Practice by the work of Dr. Sue Stover. If lameness remains the most important cause of poor performance in the racehorse and much of the lameness examination remains the same as it was hundreds of years ago, what has changed? The answer is that we have become much better at understanding the pathogenesis of injuries in the racehorse, or for that matter, most types of sport horses. We can now answer many of the unanswered lameness questions we had years ago. No longer do horses need to be rested, taken out of training, or “turned out” until next year without a diagnosis. The term “colt soreness,” while useful in describing a young racehorse unable to physically endure the rigors of race training, is now known to encompass a myriad of stress-related bone injuries. That many of the common forms of subchondral and cortical fractures in racehorses, once thought to be single-event injuries, are the end result of a continuum of stress-related bone injury is the key to understanding racehorse lameness. Injuries such as small and large carpal osteochondral fractures (chip fractures and slab fractures), third metacarpal and metatarsal bone (McIII/MtIII) condylar fractures, and distal phalanx fractures are not the result of single-event injuries but, rather, common results of stress-related subchondral bone injury. The days of thinking horses are simply galloping down the racetrack and take a bad step are over. Common catastrophic injuries such as complete fractures of the humerus, tibia and pelvis, and McIII and MtIII are now thought to be the dramatic result of existing stressrelated bone changes that have altered morphology and predisposed bone to fracture. I have emphasized this important recent turnaround by soliciting the writings from Dr. Elizabeth Davidson and Dr. Stover. Davidson describes the importance of scintigraphic examination of the lame racehorse. The difficult concept of stress-related subchondral bone injury, often called stress remodeling, or nonadaptive or maladapted bone remodeling, is demonstrated and explained. To understand the con-
Clinical Techniques in Equine Practice, Vol 2, No 4 (December), 2003: pp 293-295
293
cept of subchondral bone pain is critical to understanding why lameness can be localized (blocked out), but intraarticular therapy may be of little benefit in so many racehorses with early osteoarthritis. Time-honored beliefs in the racehorse industry are difficult to change. Conventional training programs on dirt racetrack surfaces, shoeing practices and racehorse shoe characteristics, turn-out exercise and thermocautery and blistering have all been recently questioned. What is the ideal conformation of the Thoroughbred and Quarter Horse racehorse? Can you go to a sale and apply the time-honored assumptions of conformation as so many of us do? Cutting-edge analysis of epidemiological data has helped Dr. Wayne McIlwraith and coworkers answer some of these questions and, perhaps, stimulate controversy along the way. Are horses with mild carpus valgus limb conformation really protected from the development of carpal injury? McIlwraith and coworkers also contributed a synopsis of their important recent work detailing the results of a large epidemiological study evaluating radiographs of sales yearlings. Even in a study of this magnitude, finding enough horses with radiographic changes to fulfill statistical requirements can be difficult; thus, some major questions remain unanswered. However, the authors have done marvelous work and have refuted and confirmed some of the time-honored beliefs. Some may disagree with the findings, but a base from which to work has now been established. Dr. W. Theodore (Ted) Hill, a veterinarian whom I greatly admire and respect, has been largely “behind the scenes” in his work with The New York Racing Association. Hill has compiled an incredible knowledge base from his unique experience of examining tens of thousands of racehorses and developed a “feel” for the racehorse that few in the world share. I asked him to contribute original information about his findings in this issue of Clinical Techniques in Equine Practice. What is the best way to reduce the impact of stress-related bone injury in the racehorse? The answer is to reduce the stress. Rest and rehabilitation are the mainstays of therapy for many lameness conditions in the racehorse but, yet, rest can be an ugly 4-letter word in the tough world of racing. While there have been many therapeutic modalities put forth over the years, some have not withstood the test of time. Can extracorporeal shock wave therapy (ESWT) endure? This recent advancement is not well understood and is controversial. Are the beneficial effects simply the result of the analgesic effect or is healing stimulated? Are there differences in the effects of ESWT between soft tissues and bone? Dr. Scott McClure has done interesting and pioneering work in the use of this modality in the horse and I asked him to tackle this topical subject in 2 manuscripts. Difficult questions such as the differences between focused and radial units, management protocols, and supporting experimental and clinical evidence for the use of ESWT are answered. What are the most common lameness conditions in the racehorse? Do Standardbred and Thoroughbred racehorses share common injuries or do differences in breed, gait, equipment, track surface, training methods, and other factors play a role to change lameness distribution between industries? Recently, we asked contributors to our textbook chapters to answer these questions. Arthur and coworkers7 listed the 10 most common lameness conditions in the North American Thoroughbred
294
(most common to least common) as lameness of the foot, lameness of the metacarpophalangeal/metatarsophalangeal joints (MCPJ/MTPJ), carpus, suspensory desmitis, dorsal McIII disease, superficial flexor tendonitis, tibial stress fractures, distal hock joint pain, myositis, and other stress fractures. Mitchell and coworkers8 listed the 10 most common lameness conditions in the North American Standardbred as lameness of the front foot, carpus, MTPJ, distal hock joint pain and other tarsal lameness, suspensory desmitis—forelimb and hindlimb, MCPJ, splint bone disease, stifle join lameness, myositis, and other soft tissue injuries (curb, superficial digital flexor tendonitis). While epidemiological data were not collected, the authors listed their “gut feelings” about what they see in clinical practice. The importance of the foot, in particular the front foot, cannot be overemphasized in both racing breeds and the foot was the most common area of lameness. However, several differences were observed. Cortical bone injury (dorsal McIII and tibial stress fractures) was a common cause of lameness in the Thoroughbred, but not the Standardbred. The MTPJ was a common source of lameness in the Standardbred, highlighting the importance of the hindlimb overall in this racing breed. The forelimb predominated in the Thoroughbred, but the practitioner should not overlook the MTPJ. When Dr. James Orsini asked me to be a Guest Editor for Clinical Techniques in Equine Practice, I had mixed feelings. I am passionate about the lame horse, in particular the racehorse, but had spent considerable time and effort in writing the textbook, in which all of the techniques required to complete and interpret the lameness examination are detailed in considerable length. The basic techniques and specific information regarding lameness in most types of racehorses and nonracehorse sport horses were covered comprehensively. What, then, could be written that would be new, innovative, cutting edge? When writing a textbook of considerable volume, one needs the combined efforts of many authors. I had “gone to the well” many times to solicit the efforts of authors worldwide within the last few years. How, then, could I ask many of the same authors once again to give of their precious time? For this issue of Clinical Techniques in Equine Practice I was able to blend some “old” and some new contributors to share their knowledge and experience. While the basics of the lameness examination have not changed for hundreds of years (the old), this issue of Clinical Techniques in Equine Practice demonstrates just how complex lameness diagnosis has become (the new). The detail with which we can now image the musculoskeletal system of the racehorse, the studies done to examine the epidemiology of racehorse injuries, and the treatment modalities currently available to us for management of lameness in the racehorse should convince all that science has complimented the art in the lameness examination. I thank the contributors and Dr. Orsini for allowing me to continue my quest to expand our knowledge about the important subject, lameness in the horse.
References 1. Ross MW: Lameness examination: historical perspective, in Ross MW, Dyson SJ, (eds). Diagnosis and Management of Lameness in the Horse. Philadelphia, Saunders, 2002, pp 2-3 2. Peters JE: Lameness incident to training and racing of the thoroughbred. J Am Vet Med Assoc Feb: 200, 1940 3. Kane AJ, Traub-Dargatz J, Losinger WC, et al: The occurrence and causes of lameness and laminitis in the US horse population. Proc Am Assoc Equine Pract 46:277-280, 2000 INTRODUCTION
4. Seeherman HJ, Morris E, O’Callaghan MW: Comprehensive clinical evaluation of performance, in Auer JA (ed). Equine Surgery. Philadelphia, WB Saunders Company, 1992, p 1133 5. Morris E, Seeherman HJ: Clinical evaluation of poor racing performance in the racehorse: the results of 275 evaluations. Equine Vet J 23:169, 1991 6. Jeffcott LB, Rossdale PD, Freestone J, et al: An assessment of wastage in Thoroughbred racing from conception to 4 years of age. Equine Vet J 14:185, 1982 7. Arthur RM, Ross MW, Moloney PJ, et al: North American Thorough-
MICHAEL W. ROSS
bred, in Ross MW, Dyson SJ (eds): Diagnosis and Management of Lameness in the Horse. Philadelphia, Saunders, 2002, pp 868-879 8. Mitchell JB, Mitchell JS, Nolan PM, et al: The North American Standardbred, in Ross MW, Dyson SJ (eds): Diagnosis and Management of Lameness in the Horse. Philadelphia, Saunders, 2002, pp 895-912
Michael W. Ross, DVM, Diplomate ACVS Guest Editor
295