Adams and Stashak's Lameness in Horses

Gary M. Baxter, VMD, MS, DACVS, is Associate Dean for Clinical Services at the University of Georgia College of Veterinary Medicine in Athens, Georgia, USA.

• List of Contributors xvPreface to the Seventh Edition xixPreface to the Sixth Edition xxiPreface to the Fifth Edition xxiiiPreface to the Fourth Edition xxvAcknowledgments xxviiCommon Terminologies and Abbreviations xxixAbout the Companion Website xxxi1 Functional Anatomy of the Equine Musculoskeletal System 1Anna Dee FailsAnatomic Nomenclature and Usage 1Thoracic Limb 1Hindlimb 34Axial Components 60Acknowledgment 642 Examination for Lameness 67History, Visual Exam, and Conformation 67Gary M. Baxter and Ted S. StashakIntroduction 67Adaptive Strategies of Lame Horses 67Classification of Lameness 68Signalment and Use 71History (Anamnesis) 71Visual Examination at Rest 71Conformation 72Conformation Components and Traits 74Acknowledgment 91Palpation and Manipulation 93Gary M. Baxter and Ted S. StashakFoot 93Pastern 96Fetlock 97Metacarpus/Metatarsus (MC/MT) 97Suspensory Ligament 99Flexor Tendons 100Carpus 100Forearm (Antebrachium) and Elbow 101Shoulder and Scapula 102Tarsus (Hock) 105Tibia 107Stifle 109Femur 112Hip 112Pelvis 113Back 113Neck 115Flexion Tests/Manipulation 115Distal Limb/Phalangeal/Fetlock Flexion 115Carpal Flexion 117Elbow Flexion 117Shoulder/Upper Forelimb Flexion 117Tarsal/Hock Flexion 117Stifle Flexion 119Full‐Limb Forelimb and Hindlimb Flexion 119Navicular Wedge Test 119Direct or Local Pressure plus Movement 120Subjective Assessment of Lameness 123Kevin G. KeeganEvaluation of the Horse for Lameness at the Walk 124Evaluation of the Horse at the Trot 126Evaluation of Vertical Movement of the Head for Forelimb Lameness 126Withers Movement 129Evaluation of Vertical Movement of the Pelvis for Hindlimb Lameness (the Vertical Pelvic Movement [VPM] Method) 129Evaluation of Pelvic Rotation for Hindlimb Lameness (The Pelvic Rotation Method [PRM]) 131Bilateral Lameness 132Observing Movement of the Limbs 134Joint Angle Measurements Associated with Lameness 134Stride Timing and Length Variables Associated with Lameness 134Hoof Trajectory Associated with Lameness 135Lameness Evaluation During Ipsilateral Gaits 135Evaluation of Lameness at the Lunge 136Evaluation of Lameness Under Saddle 136Subjective Scoring Methods 137Objective Assessment of Lameness 139Kevin G. KeeganMeasurement of Ground Reaction Forces (Kinetics) 139Measurement of Movement (Kinematics) 140Perineural and Intrasynovial Anesthesia 157Gary M. BaxterTypes of Local Anesthetics 157Skin Preparation and Restraint 157Perineural Anesthesia 157Intrasynovial Anesthesia 167Acknowledgment 1873 Diagnostic Imaging 189Radiography 189Myra Barrett and Elizabeth AcuttEquipment 189Digital Radiography Systems 191Radiation Safety 194Contrast Examinations 195Principles of Radiographic Interpretation 198Limitations of Radiography 210Normal Radiographic Anatomy 211Acknowledgments 299Ultrasound 301W. Rich ReddingIntroduction 301Ultrasound to Evaluate Tendons and Ligaments 302Patient Preparation and Scan Protocol 303Ultrasonographic Assessment of Tendon/Ligament Pathology 316Limitations of Ultrasonography 321Ultrasound to Evaluate Joint Injury 323Indications for Ultrasonography of Joints 324Equipment and Technique 324Ultrasonographic Appearance of Periarticular Structures 326Ultrasonic Appearance of the Joint 327Conclusions 331Other Indications for Ultrasonography of the Musculoskeletal System 332New Directions in the Use of Ultrasound 335Nuclear Medicine/Scintigraphy 342Kurt Selberg, Elizabeth Acutt, and Alejandro Valdés‐MartínezPrinciples of Nuclear Medicine 342Radiation Safety and Protection 343Imaging Equipment 343Method for a Scintigraphic Exam of the Musculoskeletal System 344Indications for Nuclear Scintigraphy of the Musculoskeletal System in Horses 347Normal Bone Scan 348Scintigraphic Signs of Disease 356Abnormal Conditions for Specific Anatomical Regions 361Limitations of Nuclear Medicine 373Computed Tomography 376Mathieu SprietIntroduction 376Equipment and Principles of CT 376Clinical Use of CT in Equine Orthopedic Imaging 378Contrast‐Enhanced CT 380Positron Emission Tomography 383Conclusion 383Magnetic Resonance Imaging 387Michael Schramme and Emilie Segard‐WeisseIntroduction 387General Principles and Physics of MRI 387Equipment, High‐ and Low‐Field Magnets, and RF Coils 387Sequences and Protocols for Equine MRI 389Artifacts of MRI 390Interpretation of Musculoskeletal MR Images 393Contrast MRI Techniques 396How to Read an Equine MRI Study 397Indications, Case Selection, Advantages, and Disadvantages of MRI 397Magnetic Resonance Imaging of the Foot and Pastern 397Magnetic Resonance Imaging of the Fetlock Region 409Magnetic Resonance Imaging of the Metacarpal and Metatarsal Regions 416Magnetic Resonance Imaging of the Carpal Region 420Magnetic Resonance Imaging of the Tarsal Region 421Magnetic Resonance Imaging of the Stifle Region 424Thermography 431Tracy A. TurnerThermographic Instrumentation 431Principles of Use 431Specific Applications for Lameness Diagnostics 4334 Lameness of the Distal Limb 439Navicular Region/Palmar Foot 439Randy B. Eggleston and Gary M. BaxterNavicular Syndrome/Disease 439Fractures of the Navicular (Distal Sesamoid) Bone 454Soft Tissue Injuries in the Foot (DDFT and Podotrochlear Apparatus) 456Acknowledgments 459Coffin Joint and Distal Phalanx 463Gary M. BaxterOsteoarthritis (OA) of the Distal Interphalangeal (DIP) Joint 463Fractures of the Distal Phalanx (P3, Coffin Bone) 465Subchondral Cystic Lesions of the Distal Phalanx (P3) 471Collateral Ligament Injuries of the Distal Phalanx 472Ossification of the Collateral Cartilages of the Distal Phalanx (Sidebone) 474Miscellaneous Conditions of the Foot 477Gary M. BaxterSole Bruises, Corns, and Subsolar Abscesses 477Septic Pedal Osteitis 479Penetrating Injuries of the Foot 481Keratoma 483Avulsion Injuries of the Hoof 485Acknowledgments 489Laminitis 490James Belknap, Andy Parks, and Katy DernOverview 490Relevant Anatomy 490Pathogenesis: Pathophysiologic Considerations 491Pathogenesis: Structural Considerations of the Equine Digit 492The Clinical Presentation: The Horse at Risk of Laminitis 494Clinical Signs: The Acute Onset of Laminitis 496Hoof Wall Resections 509Coronary Band Grooving and Resection 509The Pastern 512Ashlee E. Watts and Gary M. BaxterOsteoarthritis (OA) of the PIP Joint (High Ringbone) 512Osteochondrosis (OC) of the PIP Joint 517Luxation/Subluxation of the Proximal Interphalangeal (PIP) Joint 518Fractures of the Middle (Second) Phalanx (P2) 522Fractures of the Proximal (First) Phalanx (P1) 525Desmitis of the Distal Sesamoidean Ligaments (DSLs) 532Desmitis of Digital Annular Ligaments 535SDFT and DDFT Abnormalities 536The Fetlock 541Matt Brokken and Alicia BertoneOsteochondral Fractures and Fragmentation of the Proximal Phalanx 541Fractures of the Proximal Sesamoid Bones 543Sesamoiditis 548Axial Osteitis/Osteomyelitis of the Proximal Sesamoid Bones 549Osteoarthritis of the Metacarpophalangeal/ Metatarsophalangeal Joint 550Palmar/Plantar Osteochondral Disease 552Fetlock Subchondral Cystic Lesions (SCLs) 553Traumatic Rupture of the Suspensory Apparatus 554Luxation of the Metacarpophalangeal/ Metatarsophalangeal Joint (Fetlock Luxation) 556Constriction of or by the Fetlock Palmar/Plantar Annular Ligament 558Acknowledgments 560The Metacarpus and Metatarsus 563Kyla F. Ortved and Alicia L. BertoneBucked Shin Complex and Stress Fractures of the Dorsal Third Metacarpus 563Fractures of the Condyles of the Third Metacarpal/ Metatarsal Bones (Condylar Fractures, Longitudinal Articular Fractures) 567Fractures of the Third Metacarpal/Metatarsal (Cannon) Bone 571Metacarpal/Metatarsal Exostosis (Splints) 572Fractures of the Small Metacarpal and Metatarsal (Splint) Bones 576Enostosis‐Like Lesions 580Suspensory Ligament Desmitis 580Superficial Digital Flexor (SDF) Tendinitis (Bowed Tendon) 585Deep Digital Flexor Tendinitis 590Desmitis of the Accessory Ligament of the Deep Digital Flexor Tendon (Distal Check Ligament) 5915 Lameness of the Proximal Limb 597The Carpus 597Chris KawcakDevelopmental Abnormalities of the Carpus 598Miscellaneous Carpal Swellings 604Dorsal Carpal Swelling 605Intra‐articular Fractures 607Accessory Carpal Bone Fracture 612Carpal Luxations 613Soft Tissue Damage to the Carpus 614Osteoarthritis 615Carpometacarpal Osteoarthritis 616Osteochondrosis of the Carpus 617Osteochondroma of the Distal Radius 617Desmitis of the Accessory Ligament (Radial or Superior Check Ligament) of the Superficial Digital Flexor Tendon 619The Antebrachium, Elbow, and Humerus 623Jeremy HubertFractures of the Radius 623The Elbow 627Fractures of the Humerus 633Neoplastic Lesions of the Humerus 637Paralysis of the Radial Nerve 637Acknowledgment 638The Shoulder and Scapula 641Jeremy HubertInflammation of the Intertubercular Bursa (Bicipital Bursitis) 641Inflammation of the Infraspinatus Bursa 643Osteochondrosis (OC) of the Scapulohumeral (SH) Joint or Shoulder 644Osteoarthritis (OA) of the Scapulohumeral Joint 646Luxation of the Scapulohumeral (Shoulder) Joint 648Suprascapular Nerve Injury (Sweeny) 650Fractures of the Scapula 652Fractures of the Supraglenoid Tubercle (Tuberosity) 653Acknowledgment 655The Tarsus 657W. Rich ReddingIntroduction 657Diagnosis of Tarsal Lameness 657Articular Diseases of the Tarsus 662Cunean Tenectomy 672Fractures and Luxations of the Tarsus 680Soft Tissue Injuries of the Tarsus 687Periarticular Tarsal Cellulitis 697Tibia and Crus 701W. Rich ReddingIntroduction 701Diagnostic Analgesia of the Crus 701Imaging the Tibia/Crus 701Clinical Conditions 701Enostosis‐Like Lesions 702Fractures of the Tibia 703Incomplete Fractures 704Proximal Physeal Fractures 705Diaphyseal Fractures 706Tibial Tuberosity Fractures 706Gastrocnemius Disruption in Foals and Adults 707The Stifle: Femoropatellar Region 709Gary M. Baxter and Ken E. SullinsIntroduction 709Femoropatellar Joint 711Upward Fixation of the Patella (UFP) 717Desmitis of the Patellar Ligaments 719Patellar Luxation/Subluxation 721Synovial Osteochondroma in the Hindlimb 722The Stifle: Femorotibial Joint Region 725Chris KawcakSubchondral Cystic Lesions (SCLs) of the Stifle 726Fractures 729Femoral Condyle Lesions 731Collateral Ligament Injury 734Cruciate Ligament Disease 734Meniscal Injuries 735Synovitis/Capsulitis/OA 737Femur and Coxofemoral Region 740Nicolas S. Ernst and Troy N. TrumbleThe Femur 740Diaphyseal and Metaphyseal Femoral Fractures 740Fractures of the Third Trochanter 744Fibrotic and Ossifying Myopathy 744Femoral Nerve Paralysis (Crural Paralysis) 748Calcinosis Circumscripta 749Trochanteric Bursitis (Trochanteric Lameness, Whirlbone Lameness) 750Ruptured Quadriceps Muscle 750The Coxofemoral Joint 750Osteochondrosis or Osteochondritis Dissecans (OCD)/ HIP Dysplasia of the Coxofemoral Joint 752Infectious Arthritis/Physitis of the Coxofemoral Joint 752Partial Tear/Rupture of the Ligament of the Head of the Femur (Round Ligament) 753Coxofemoral Subluxation and Luxation (Dislocation of the Hip Joint) 754Osteoarthritis (OA) of the Coxofemoral Joint 757Capital Physeal Fractures of the Femoral Head 758Intra‐articular Acetabular Fractures 758Acknowledgment 7596 Lameness Associated with the Axial Skeleton 763The Axial Skeleton 763Rob Van WessumAnatomy and Biomechanics of the Vertebral Column 763Primary vs. Secondary Back Pain 767The Pelvis 770Rob Van WessumFractures of the Pelvis 770Specific Types of Pelvic Fractures 771Thrombosis of the Caudal Aorta or the Iliac Arteries 775Sacroiliac Region 777Rob Van WessumEtiology 778Clinical Signs 778Diagnosis 779Treatment 782Prognosis 783Thoracolumbar Spine/Back 784Rob Van WessumOverriding/Impingement of Dorsal Spinous Processes 784Supraspinous Ligament Injuries 785Fractures of the Spinous Processes 786Vertebral Fractures 787Facet Joint Arthritis and Vertebral Facet Joint Syndrome 788Discospondylitis 792Spondylosis 793Scoliosis, Kyphosis, and Lordosis 794The Neck and Poll 796Rob Van WessumNuchal Ligament 796Cervical Facet Joints 797Radiculopathy 798Discospondylitis 798Cervical Fractures 7987 Principles of Musculoskeletal Disease 801Joint Injuries and Disease and Osteoarthritis 801C. Wayne McIlwraithAnatomy and Physiology of Joints 801Pathobiology of Joints and Their Reaction to Insult and Injury 808Primary Disease of Subchondral Bone 816Bone Injuries and Disease 820Chris Kawcak and Gary M. BaxterThe Immature Skeleton 820Local Diseases of Bone 825Systemic Diseases of Bone 841Tendon and Ligament Injuries and Disease 849Laurie R. GoodrichAnatomy 849Functions of Tendons and Ligaments 851Biomechanical Properties 852Types of Tendon and Ligament Injuries 852Effect of Aging and Exercise on Tendon Injury 853Mechanisms of Tendon Degeneration 854Response of Tendons and Ligaments to Injury: Phases of Healing 854Monitoring Tendon Injury 856Biomarkers for Tendon Disease 857Common Clinical Conditions of Tendons and Ligaments 857Muscle Injuries and Disease 860Stephanie J. ValbergClassification of Muscle Disorders 860Diagnosis of Specific Muscle Disorders 860Muscle Soreness 862Exertional Rhabdomyolysis 8658 Principles of Therapy for Lameness 875Systemic/Parenteral 875Drew W. Koch and Laurie R. GoodrichParenteral NSAIDs 875Polysulfated Glycosaminoglycans (PSGAGs) and Pentosan Polysulfate (PPS) 875Hyaluronan 876Bisphosphonates 877Tetracyclines 877Estrogen 878Methocarbamol (Robaxin) 878Gabapentin 878Topical/Local 881Drew W. Koch and Laurie R. GoodrichTopical NSAIDs 881Topical First Aid (Cold Therapy and Bandaging) 881Dimethyl Sulfoxide 882Extracorporeal Shockwave Therapy 882Regional Perfusion 882Therapeutic Ultrasound, Lasers, and Electromagnetics 883Counterirritation 883Intrasynovial 886Lauren E. Smanik and Laurie R. GoodrichCorticosteroids 886Hyaluronan 888Corticosteroid and HA Combinations 889IA Polysulfated Glycosaminoglycans 889Polyglycan® 890Autologous Conditioned Serum 890Platelet‐Rich Plasma 890Autologous Protein Solution 891Bone Marrow‐ or Fat‐Derived Mesenchymal Stem Cell Therapy 891Polyacrylamide Hydrogel 891Miscellaneous 892Intrasynovial Therapy: Practical Considerations 892Intralesional 896Sara K.T. Steward and Laurie R. GoodrichIntroduction 896Hyaluronan and Polysulfated Glycosaminoglycans 896Autologous Cell Therapies: Mesenchymal Stem Cell Therapy, Autologous Bone Marrow Aspirate, Tendon‐ Derived Progenitor Cells 896Blood‐Derived Biologics: Platelet‐Rich Plasma, Autologous Conditioned Serum, Autologous Protein Solution, and Bone Marrow Aspirate 897Corticosteroids 898Miscellaneous 898Oral/Nutritional 900Nicolas S. Ernst and Troy N. TrumbleNonsteroidal Anti‐Inflammatory Drugs 900Nutraceuticals 903Therapeutic Trimming and Shoeing 911Andrew H. ParksIntroduction 911Examination of the Limb for Therapeutic Shoeing 911The Trim 912Shoeing 912Protection and Support 917Clinical Applications of Principles 918Summary 920Acupuncture Treatment of Limb Lameness and Back Pain 921Kevin K. HausslerIntroduction 921Techniques of Stimulation 921General Indications for Treatment 922Lameness 922Chronic Back Pain 923Adverse Effects 924Manual Therapy Techniques 925Kevin K. HausslerIntroduction 925Therapeutic Touch 925Massage Therapy 925Passive Stretching Exercises 925Mobilization 926Joint Mobilization and Manipulation 926Contraindications 927Rehabilitation/Physical Therapy 929Melissa King, Katherine Ellis, and Narelle C. StubbsIntroduction 929Clinical and Client Demand for Rehabilitation/PT 929Manual Therapy 930Proprioceptive Facilitation/Neuromotor Control Techniques 934Physical Modalities 936Conclusion 9439 Occupational‐Related Lameness Conditions 949The Thoroughbred Racehorse 949Ryan CarpenterRisk Factors for Injury 949Diagnosis of Lameness 950Common Conditions 951The Standardbred Racehorse 964Kimberly Johnston and Frank A. NickelsDescription of the Sport 964Lameness Exam 965Specific Lameness Conditions 966The Racing Quarter Horse 972Nancy L. Goodman and Larry R. OverlyIntroduction 972Conformation Relating to Lameness 972Training the Racing Quarter Horse 973Shoeing 973Lameness Related to Track Surface 973Lameness Examination 973Specific Lameness Conditions 975The Western Performance Horse 980Robin M. DabareinerIntroduction 980Team Roping Horses 980Tie‐Down and Breakaway Roping 981Barrel Racing 982XII Table of Contents Reining Horses 982zCutting Horses 983Jumping, Eventing, and Dressage Horses 986Omar MaherIntroduction and Horses Used for the Disciplines 986Structure of Training and Competition 987Training Surfaces and Shoeing 989Lameness Diagnosis 990Common Lameness Problems 991Acknowledgment 996The Endurance Horse 998Todd C. HolbrookThe Sport 998Athletes and Exercise Conditions 998Veterinary Control 998The Lameness Examination 1000Common Causes of Lameness 1002The Western Pleasure Horse 1006Sherry A. Johnson and David D. FrisbieUnderstanding the Sport 1006Western Pleasure Terminology 1007Training and Showing 1007Commonly Encountered Musculoskeletal Issues in the Western Pleasure Athlete 1008Foot Pain 1008Fetlock Osteoarthritis 1010Proximal Suspensory Desmopathy 1010Distal Tarsal Disease 1012Rehabilitation and Management of the Western Pleasure Athlete 1013Conclusion 1013Gaited Horses 1015David A. Wilson and Kevin G. KeeganEvaluating Gaited Horses for Lameness 1015What Is a Gaited Horse? 1015Classification of Gaits 1015Specific Gaits in “Gaited Horses” 1018Lameness in the Gaited Horse 1020The Draft Horse 1026Jan F. HawkinsIntroduction 1026Anamnesis 1026Lameness Examination 1026Common Causes of Lameness 1026Diseases of Young Draft Horses 103010 Lameness in the Young Horse 1033The Physis/Physeal Fractures/ Physitis 1033Dane M. Tatarniuk, Troy N. Trumble, and Gary M. BaxterThe Physis 1033Classification and Treatment of Physeal Injuries/ Fractures 1037Developmental Orthopedic Diseases 1041Epiphysitis/Physitis/Physeal Dysplasia 1042Etiology 1042Clinical Signs 1043Diagnosis 1043Treatment 1046Prognosis 1046Angular Limb Deformities (ALDs) and Cuboidal Bone Malformations 1048Nicolas S. Ernst, Troy N. Trumble, and Gary M. BaxterAngular Limb Deformities (ALDs) 1048Etiology 1048Clinical Signs 1048Diagnosis 1049Treatment 1051Prognosis 1055Cuboidal Bone Malformation/Incomplete Ossification 1055Etiology 1055Clinical Signs 1055Diagnosis 1056Treatment 1056Prognosis 1058Flexural Deformities 1059Nicolas S. Ernst, Troy N. Trumble, and Gary M. BaxterCongenital Flexural Deformities 1059Acquired Flexural Deformities 1062Osteochondrosis 1071C. Wayne McIlwraithIntroduction 1071Osteochondritis Dissecans (OCD) 1071Subchondral Cystic Lesions 1078Lameness in Foals 1081Robert J. HuntDiagnosis 1081Noninfectious Causes of Lameness 1082Infectious Causes of Lameness 108911 Foot Care and Farriery 1091Basic Foot Care 1091Stephen E. O’GradyIntroduction 1091Evaluation of the Foot 1091Principles of Trimming and Shoeing 1095Stephen E. O’GradyGuidelines for Trimming 1095Trimming the Foot 1098Trimming the Barefoot Horse 1100The Horseshoe 1102Placement and Application of the Shoe 1108Non‐nail Alternatives in Farriery 1109Acknowledgment 1111Farriery for Common Hoof Problems 1112Stephen E. O’GradyConditions of the Foot That Respond to Farriery 1112Clinical Conditions Affecting the Hoof 1121Miscellaneous Conditions of the Foot 1129Acknowledgment 1132Natural Balance Trimming and Shoeing 1134Gene OvnicekIntroduction 1134Distortions of the Hoof 1134Natural Balance Hoof Care Guidelines 1135Natural Balance Evaluation, Exfoliation, and Mapping Protocol 1135Natural Balance Barefoot Trimming 1139Natural Balance Shoeing 1139Summary 114212 Miscellaneous Musculoskeletal Conditions 1143Musculoskeletal Emergencies 1143Kathryn A. SeabaughIntroduction 1143Fracture Management 1143Musculoskeletal Wound Management 1148Tendon and Ligament Lacerations 1149Musculoskeletal Infections 1153Specific Treatment Strategies for Musculoskeletal Infections 1158The Poorly Performing Horse 1161Elizabeth J. DavidsonIntroduction 1161Signalment and History 1161Clinical Examination 1163Diagnostics 1164Treatment 1165Evaluation of Proper Saddle Fit 1166Kevin K. HausslerIntroduction 1166Clinical Signs of Poor Saddle Fit 1166Saddle Examination 1166Static Examination of Saddle Fit 1166Static Examination of Saddle Pads 1168Dynamic Examination of Saddle Fit 1168Prepurchase Examination 1170Randy EgglestonStructure of the Prepurchase Examination 1171Summary 1174Stance and Gait Anomalies Caused by Neurological Disease 1177Lutz S. GoehringNeurological Gait and (Neuroanatomical) Lesion Location 1177Findings from a Neurological Exam That Can Help in Localizing a Lesion 1178Pitfalls of Neurological Examination 1179Select Neurological Syndromes Affecting the Gait 1180Index 1183

“The illustrations and graphics are exceptional, and the photographs are well and appropriately labeled for the subject at hand. In my opinion, this book will be a valuable addition to the library of anyone with an interest in the function and care of horses.” JAVMA | JUN 15, 2021 | VOL 258 | NO. 12