Veterinary Forensic Pathology, Volume 1 (eBook)

Jason W. Brooks, VMD, PhD, DACVP, is a veterinary pathologist from the Department of Veterinary and Biomedical Sciences at Penn State University.  As a pioneer in the field of veterinary forensic pathology, he has forged a path toward advancement of the discipline by seeking out advanced training in forensic pathology and crime scene analysis from medical and law enforcement professionals.  He routinely assists law enforcement with animal crimes investigations and strives to develop instructional materials and programs for veterinary pathologists and the law enforcement community.  He conducts research on the estimation of the postmortem interval and the pathology of gunshot wounds and teaches graduate and undergraduate students in pathology and forensic sciences.

Preface 6
Contents 8
1: Medicolegal Investigation 9
1.1 Veterinary Forensic Medicine 9
1.2 Fundamentals of Animal Abuse 10
1.3 The Role of the Veterinarian in Animal Cruelty Investigations 11
1.4 Conducting the Investigation 12
1.4.1 Initial Investigation: Reviewing the Medical History, Witness Statements, and Scene Investigation 12
1.4.2 Forensic Photography 12
1.4.3 Forensic Necropsy 12
1.5 Report Writing 13
1.6 Expert Witness Testimony 13
1.7 Criminal Proceedings 14
1.8 The Future of Veterinary Forensic Pathology 15
References 15
2: Crime Scene Findings and the Identification, Collection, and Preservation of Evidence 17
2.1 Evidence 17
2.2 Importance of the Crime Scene Investigation 20
2.3 Processing of a Crime Scene 21
2.4 Evidence Authentication 23
2.5 Evidence Documentation 25
2.6 Evidence Present on the Body 28
References 33
3: Performing the Forensic Necropsy 34
3.1 The Forensic Necropsy 34
3.1.1 Initial Evaluation and External Examination 34
3.1.2 Internal Examination 36
3.1.3 Histopathology 38
3.2 Special Techniques 38
3.2.1 Decomposed Remains 38
3.2.2 Desiccated Carcasses 39
3.2.3 Skeletal Preparation 39
3.2.4 Alternate Light Source Exam 40
3.3 Imaging 42
3.3.1 Photography 42
3.3.2 Radiography 42
3.3.3 Computed Tomography and Magnetic Resonance Imaging 44
3.4 Evidence Handling 44
3.4.1 The Chain of Custody 44
3.4.2 Trace Evidence Collection 45
3.4.2.1 Ballistic Evidence 45
3.4.2.2 Fingerprints 45
3.4.2.3 DNA Analysis 46
3.4.2.4 Toxicology Samples 47
3.4.2.5 Forensic Entomology 47
3.4.2.6 Miscellaneous Trace Evidence 47
3.4.3 Disposition of the Carcass, Samples, and Evidence 48
References 48
4: Postmortem Changes and Estimating the Postmortem Interval 50
4.1 Introduction 50
4.2 Postmortem Changes 51
4.2.1 Algor Mortis 51
4.2.2 Livor Mortis 52
4.2.3 Rigor Mortis 53
4.2.4 Desiccation 54
4.2.5 Decomposition 54
4.2.6 Mummification 58
4.3 Estimating the Postmortem Interval 59
4.3.1 Gross Changes 59
4.3.2 Temperature Changes 61
4.3.3 Entomology 62
4.4 Ancillary Methods 64
4.4.1 Botany 64
4.4.2 Postmortem Chemistry 64
4.4.3 Ocular Tonometry 64
4.4.4 Molecular Methods 65
4.4.5 Microbial Assay 65
4.4.6 Microscopic Changes 65
4.4.7 Radionuclide-Based Methods 66
4.5 Summary 66
References 67
5: Blunt Force Trauma 71
5.1 Introduction 71
5.2 Forensic Evaluation of an Animal: Goals 72
5.3 Non-accidental Injury (NAI) and Accidental Injury (AI) 72
5.4 Reasons to Suspect Non-­accidental Injury When an Animal Is Injured [8] 73
5.4.1 Person(S) Behavior and/or Statements Raise Suspicions 73
5.4.2 Clinical Picture Is Inconsistent with the Explanation Given 73
5.5 The Case of the Midwestern Twenty Something Who Didn’t Seem Interested in the Circumstances That Resulted in Her Cat’s Broken Leg 74
5.6 The Case of the Boyfriend Who Was a Serial Animal Killer 74
5.7 Differentiating Accidental from Non-accidental Injury 76
5.8 Tissue Injury 76
5.9 Blunt Force Trauma 77
5.10 Understanding Blunt Force Tissue Injury 77
5.11 Biomechanics of Blunt Force Trauma 77
5.12 Biomechanics of Animal Tissue Injury 78
5.13 Injury and Force 78
5.14 Qualitative Aspects of Forces 78
5.15 Types of Forces That Can Impact Tissue [20, 21] 79
5.16 What Happens to a Three-­Dimensional Object When a Force Is Applied? [20] 79
5.16.1 Strain, Shear, Stress, and Deformation 79
5.16.2 Terms Used to Describe the Effect of Forces on Objects 79
5.16.2.1 Strain 79
5.16.2.2 Shear 80
5.16.2.3 Stress 80
5.16.2.4 Deformation 80
5.17 Mechanisms of Injury from a Blunt Force Impact 80
5.18 Case of a Left-Sided Impact and a Possible Additional Right-Sided Impact 81
5.18.1 Injuries Identified at Forensic Necropsy (Figs. 5.3 and 5.4, 5.5 and 5.6, and 5.7–5.9) 81
5.19 Characteristics of the Blunt Object 83
5.20 Tissue Characteristics That Influence Type and Severity of Injury [12] 83
5.21 Tissue Response to Blunt Force Impact 85
5.22 Types of Soft Tissue Blunt Force Trauma Injuries 85
5.23 Case Study of the Dog with a Single Abdominal Contusion (Fig. 5.21–5.23) 88
5.24 Fractures [20, 21] 88
5.25 Fracture Healing [29] 89
5.26 Blood Loss (Hemorrhage) 90
5.27 Differentiating Accidental from Non-accidental Injury: Patterns and Types of Injuries (See Table 5.6) 90
5.28 Case Study: A 10-Year-Old Pomeranian: Cause of Death Unknown (Figs. 5.24 and 5.25, 5.26 and 5.27, and 5.28 and 5.29) 90
5.29 Rib Fractures 92
5.29.1 The Case of the “Battered” 16-Year-Old Chihuahua (Figs. 5.30, 5.31 and 5.32) 92
5.30 Repetitive Injuries, “Battered Animals”: Injuries at Different States of Healing 92
5.31 Number of Impacts 94
5.32 Age of Injuries 94
5.33 The Case of the Battered 5-Month-Old Puppy 94
5.34 “Failure to Treat” 96
5.35 Pain 97
5.36 When Did a Traumatic Injury Occur Relative to the Animal’s Death? Terminology 97
5.37 The Case of Delilah, a Dog Who Was Reported to Be Injured by a Cordless Drill that Fell from the Top of a Five Foot Refrigerator (Fig. 5.36 and 5.37) 97
5.37.1 Case Example (CR 4211-11) 99
References 99
6: Sharp Force Trauma 101
6.1 Description, Interpretation, and Documentation of Sharp Force Injuries 101
6.2 Incised Wounds 103
6.3 Stab Wounds 104
6.4 Chop Wounds 105
6.5 Chainsaw Injuries 105
6.6 Goring Injuries 106
6.7 Claw Marks and Bite Wounds 106
6.8 Trap Injuries 106
6.9 Bow and Arrow Injuries 107
6.10 Internal Examination 109
6.11 Aging of Wounds 109
References 111
7: Firearm Injuries 113
7.1 Introduction 113
7.2 General Considerations 113
7.3 Projectile Injury in Companion Animals in the United States 114
7.4 Wildlife Projectile Injury 115
7.5 Weapons and Projectiles 115
7.6 Non-firearm Projectiles and Other Devices 116
7.7 Ammunition 117
7.8 The Process of Firing a Gun 119
7.9 Ballistics and Wounding Capacity 120
7.10 Examination and Necropsy: General Considerations 120
7.11 Photography 121
7.12 Radiology 122
7.13 Computed Axial Tomography 123
7.14 Collecting External Evidence 123
7.15 Necropsy Findings: Wound Analysis 123
7.16 Distance 126
7.17 Examination of the  Wound Tract 127
7.18 Comparison of Gunshot and Arrow Wounds 129
7.19 Angles and Trajectories 129
7.20 The Necropsy Report 131
7.21 Projectiles as Evidence: Collection and Storage 131
7.22 Advanced Techniques in Gunpowder Analysis 131
References 132
8: Strangulation, Suffocation, and Asphyxia 134
8.1 Introduction 134
8.2 Classification and Terminology 135
8.3 Asphyxia: Traditional Misconceptions and Myths 136
8.4 Categories of Asphyxia 137
8.4.1 Strangulation 137
8.4.1.1 Lesions of Strangulation 139
8.4.1.2 Case Report: Manual Strangulation [102] 141
8.4.2 Suffocation 142
8.4.2.1 Obstructive Suffocation 142
8.4.2.2 Nonobstructive Suffocation 142
Nonobstructive Suffocation: Oxygen Depletion and Vitiated Atmosphere 142
Case Report: Death Due to Entrapment in Confined Space [3] 143
Carbon Dioxide Toxicity 143
Chemical Asphyxiants 144
Carbon Monoxide 144
Cyanide Toxicity 145
Hydrogen Sulfide 146
Lesions of Suffocation 146
8.4.3 Mechanical Asphyxia 147
8.4.4 Lesions of Mechanical Asphyxia 147
8.5 Summary 148
References 148
Index 154