Equine Clinical Pathology

Raquel M. Walton , VMD, MS, PhD, is a senior Clinical Pathologist at the Animal Medical Center in New York, New York.

Contributors xi Preface xiii 1 General Laboratory Medicine 3 Raquel M. Walton General laboratory medicine 3 Basic hematologic techniques 4 Point-of-care testing 6 Test validation and reference values 10 References 14 2 Equine Hematology 15 Raquel M. Walton Complete blood count interpretation 15 Erythrocyte indices 15 Leukogram 20 Platelets 22 Blood film evaluation 23 Erythrocytes and platelets 25 Leukocytes 30 References 33 3 Immunohematology and Hemostasis 37 Karen V. Jackson Immunohematology testing 39 Blood typing 39 Crossmatching 41 Antibody screening and jaundiced foal agglutination test 42 Immune-mediated hemolytic anemia 44 Neonatal isoerythrolysis 46 Infection-associated (Clostridial, EIA, R. equi, S. equi) 48 Drug-associated 50 Neoplasia-associated 50 Coagulation testing 51 Physiology of hemostasis 51 Coagulation testing and disorders causing abnormalities 60 References 66 4 The Liver 71 Dennis J. Meyer and Raquel M. Walton Liver enzymes 71 Hepatocellular enzymes 73 Hepatobiliary enzymes 74 Liver function tests 76 Excretory function tests 76 Tests dependent on synthetic/metabolic functions 77 Other tests 79 Hepatic diseases 80 Toxins 80 Infections 82 Hepatic lipidosis 83 Serum hepatitis (Theiler's disease) 83 Hepatocellular neoplasia 84 References 84 5 Laboratory Evaluation of the Equine Renal System 87 Andrea A. Bohn Laboratory assessment of the kidney 87 Glomerular filtration rate 89 Reabsorption and electrolyte regulation 90 Water conservation and blood volume regulation 91 Other renal functions 92 Urinalysis 92 Gross evaluation 92 Urine-specific gravity 92 Reagent test strips 94 Urine sediment exam 95 Laboratory abnormalities associated with different disease states 98 Acute renal failure 98 Chronic renal failure 98 Urinary tract rupture 99 "Early" renal disease 100 Strenuous exercise 101 References 101 6 Acid-Base and Electrolytes 103 Andrea A. Bohn Acid-base 103 Steps to evaluating acid-base status 104 Bicarbonate 104 Metabolic acidosis and alkalosis 105 Respiratory acidosis and alkalosis 106 Compensatory mechanisms 106 Base excess 107 Electrolytes 107 Sodium 107 Chloride 109 Potassium 110 Calcium 112 Magnesium 114 Phosphate 115 References 116 7 Proteins 119 Koranda Wallace Plasma proteins 119 Albumin 119 Globulin 120 Acute phase proteins 120 Protein disorders 124 Hypoalbuminemia with hypoglobulinemia 124 Hypoalbuminemia with normal or increased globulins 125 Hypoglobulinemia with normal to increased albumin 125 Hyperalbuminemia 126 Hyperalbuminemia and hyperglobulinemia 126 Hyperglobulinemia 126 Hyperfibrinogenemia 127 References 127 8 Laboratory Assessment of Lipid and Glucose Metabolism 131 Raquel M. Walton Lipids 131 Triglyceride metabolism 132 Laboratory characterization of lipid metabolism 133 Equine hyperlipidemias 136 Glucose 138 Glucose metabolism 139 Insulin resistance 140 Laboratory characterization of glucose metabolism 140 Diseases associated with glucose metabolic defects 145 References 149 9 Skeletal Muscle 153 Allison Billings Laboratory evaluation of equine muscle disorders 153 General causes of increased serum enzymes 153 Serum enzymes detecting muscle injury 154 Additional factors affecting CK and AST enzyme activity 158 Other markers detecting muscle injury 159 Equine muscle diseases 161 Immune-mediated myopathies 161 Infectious myopathies 163 Traumatic myopathies 165 Inherited or congenital myopathies 166 Toxic myopathies 169 Nutritional myopathies 171 Myopathies of unknown cause 171 Other myopathies 173 References 173 10 Endocrine Evaluation 181 Jill Beech Testing for pituitary pars intermedia dysfunction (PPID) 181 Cortisol concentrations 182 Adrenocorticotropin (ACTH) concentration 184 Alpha-melanocyte-stimulating hormone (alpha-MSH) concentrations 186 ACTH and alpha-MSH concentration responses following thyrotropin releasing hormone (TRH) administration 186 Insulin concentrations 187 Testing thyroid function in horses 189 Thyroid dysfunction 189 Thyroid hormones 189 Extrathyroidal effects on thyroid hormones 190 Nonthyroidal illness syndrome 192 Thyroid hormone evaluation 192 Thyroid stimulating hormone (TSH) concentration 193 Thyrotropin releasing hormone (TRH) stimulation 194 TSH stimulation test 194 T3 suppression test 195 References 195 11 Fluid Analysis 203 Raquel M. Walton Pleural and peritoneal fluid 203 Pathogenetic mechanisms of body cavity effusions 204 Body cavity fluid analysis 208 Biochemical evaluation 210 Cells and cell counts 212 Synovial fluid 218 Fluid analysis 219 Degenerative arthropathies 224 Inflammatory arthropathies 225 Eosinophilic synovitis 227 Hemarthrosis 227 References 229 12 Cytology of the Lower Respiratory Tract 233 Martina Piviani Indications 233 Collection techniques 234 Bronchoalveolar lavage 234 Tracheal wash 234 Sample processing 235 Normal findings 236 Cellular elements 236 Acellular elements 239 Contaminants 240 Interpretation of cytologic patterns 241 Neutrophilic inflammation 241 Mixed neutrophilic and histiocytic inflammation 245 Eosinophilic and mastocytic inflammation 245 Hemosiderosis 246 Cellular atypia 248 References 249 13 Cerebrospinal Fluid 253 Andrea Siegel Formation, circulation, absorption, and function 253 Collection 254 Laboratory analysis 254 Gross appearance 255 Protein concentration 256 Antibody titers 258 Cell counts 258 Glucose 260 Enzymes 260 Lactic acid 260 Polymerase chain reaction 261 Phenotyping 261 Cytological examination 261 Normal findings 262 Abnormal findings 263 CSF in specific diseases 264 Viral infections 264 Bacterial infections 265 Fungal infections 265 Parasitic infections 266 Other diseases 266 References 266 Index 271