A TEXTBOOK OF VETERINARY SPECIAL PATHOLOGY
Part I Pathology of Aquatic Animal Species 1 Introduction to the Manifestation of Disease and Major Pathogens 1 1 Aquatic Invertebrates 3 Porifera (Sponges) 4 Overview 4 Clinical Signs 4 Coelenterates 4 Taxonomic Overview 4 Key Points 4 Clinical Signs 7 Clinical Signs: Corals (Anthozoans) 7 Diseases of Coral in Cultivation and Aquaria 7 Diseases of Small Polyp Stony Coral 7 Acropora-Eating Flatworm 7 Parasitic Copepods/Amphipods 10 Ciliates 11 Montipora-Eating Nudibranch 11 Diseases of Large Polyp Stony Corals 13 Euphyilla Flatworms 13 Dendrophilia-Eating Nudibranch 14 Diseases of Zoanthids 15 Zoanthid-Eating Nudibranch 15 Zoanthid Sea Spider 15 Other Parasites 15 Red Planaria (Convolutriloba retrogemma) (Figure 117) 15 Contents Vermetidae Infestation 17 Class Hydrozoa 18 Introduction 18 Infectious Diseases 18 Mollusks (Bivalves) 19 Anatomy and Clinical Features 19 Clinical Differentials 21 Specific Diseases 22 Other Pathologies 26 Zoonoses 26 Abalone 27 Culture Methods 27 Breeding 27 Anesthetics 27 Environmental Requirements 27 Infectious and Parasitic Diseases 29 Helminths 30 Non-Infectious Diseases 31 Miscellaneous Findings 31 Sampling for Laboratory Testing 31 Cephalopods 32 Gastropods 32 Crustacea 32 Overview 32 Biology 33 Aquaculture and Economic Significance 35 Aquaria 37 Disease and Diagnostics 37 Clinical Signs 39 Specific Diseases 40 Notifiable Diseases 40 Freshwater Infections 57 Non-Notifiable Diseases 59 Zoonoses 61 References 62 Appendix 11 74 2 Teleost Fish 81 Parasitic Diseases 81 Ectoparasites 81 Flukes (Monogenean Parasites) 81 Digenean Black Spot Disease 83 Turbellarian Black Spot Disease (Tang Disease, Black Itch) 85 Piscicolosis 87 Fish Henneguya (Henneguyosis) 87 Parasitic Crustacean Infestations 89 Endoparasites 93 Fish Eustrongylides (Eustrongylidosis) 93 Fish Anisakis (Anisakidosis) 95 Fish Tapeworm Infection (Diphyllobothriasis) 96 Fish Triaenophorus (Triaenophorosis) 97 Intestinal Ligulosis 99 References 100 Appendix 21 103 Appendix 22 107 Appendix 23 111 3 Amphibians 115 Ranavirosis 115 Overview 115 Etiology 115 Host Range and Transmission 115 Signs and Diagnosis 115 Differential Diagnosis 116 Prevention, Treatment, and Control 116 Bacterial Dermatosepticemia (Red Leg Syndrome) 116 Overview 116 Etiology 117 Host Range and Transmission 117 Signs and Diagnosis 117 Differential Diagnosis 117 Prevention, Treatment, and Control 117 Ammonia Toxicity 117 Overview 117 Etiology 118 Host Range 118 Signs and Diagnosis 118 Differential Diagnosis 118 Prevention, Treatment, and Control 118 Gas Bubble Disease 118 Overview and Etiology 118 Host Range 118 Signs and Diagnosis 119 Differential Diagnosis 119 Prevention, Treatment, and Control 119 Frog Chytridiomycosis 119 Overview 119 Etiology 120 Host Range and Transmission 120 Signs and Diagnosis 120 Differential Diagnosis 120 Prevention, Treatment, and Control 120 Salamander Chytridiomycosis 120 Overview 120 Etiology 121 Host Range and Transmission 121 Signs and Diagnosis 121 Differential Diagnosis 121 Prevention, Treatment, and Control 121 Renal Calculi (Oxalate Toxicity or Nephrocalcinosis) 122 Overview 122 Etiology 122 Host Range 122 Signs and Diagnosis 122 Differential Diagnosis 122 Prevention, Treatment, and Control 122 Mycobacteriosis 122 Overview 122 Etiology 123 Host Range and Transmission 123 Signs and Diagnosis 123 Differential Diagnosis 124 Prevention, Treatment, and Control 124 Pulmonary Nematodiasis 124 Overview 124 Etiology 124 Host Range and Transmission 124 Signs and Diagnosis 124 Differential Diagnosis 125 Prevention, Treatment, and Control 125 Hypovitaminosis A (Short-Tongue Syndrome) 125 Overview 125 Etiology 125 Host Range 125 Signs and Diagnosis 125 Differential Diagnosis 125 Prevention, Treatment, and Control 126 Corneal Lipidosis 126 Overview 126 Etiology 126 Host Range 126 Signs and Diagnosis 126 Differential Diagnosis 126 Prevention, Treatment, and Control 127 Renal (Lucké’s) Adenocarcinoma 127 Overview 127 Etiology 127 Host Range and Transmission 127 Signs and Diagnosis 127 Differential Diagnosis 127 Prevention, Treatment, and Control 127 Herpesvirus Skin Disease 127 Overview 127 Etiology 128 Host Range and Transmission 128 Signs and Diagnosis 128 Differential Diagnosis 128 Prevention, Treatment, and Control 129 Hemoparasites 129 Overview 129 Etiology 129 Host Range and Transmission 130 Signs and Diagnosis 130 Differential Diagnosis 130 Prevention, Treatment, and Control 130 Ascites/Lymphedema 130 Overview 130 Etiology 131 Host Range 131 Signs and Diagnosis 131 Differential Diagnosis 131 Prevention, Treatment, and Control 131 Other Fungal Diseases 131 Bibliography 131 Appendix 31 134 4 Reptiles 136 Introduction to the Manifestation of Disease and Major Pathogens of Aquatic Reptiles 136 Marine Turtles 137 Prevention and Control of Marine Turtle Diseases 138 Viral Disease 138 Fibropapillomatosis 138 Lung–Eye–Trachea Disease 140 Gray Patch Disease 140 Parasitic Disease 141 Spirorchiidiasis 141 Coccidiosis 143 Bacterial Diseases 143 Fungal Diseases 144 Overview 144 Non–Infectious Disease 145 Buoyancy Disorder/Floater’s Syndrome 145 Trauma 147 Cold Stunning 149 Freshwater Turtles 150 Diseases of Freshwater Turtles: Transmission, Prevention, Treatment, and Control 151 Bacterial Disease 151 Viral Disease 152 Ranavirus 152 Herpesvirus 153 Trionyx Sinensis Hemorrhagic Syndrome Virus 154 Nidoviruses 154 Fungal Disease 155 Parasites 155 Crocodilians 156 Prevention and Control of Crocodilian Diseases 156 Viral Disease 157 Poxviral Infections 157 Systemic Lymphoproliferative Syndrome With Encephalitis 157 Adenoviral infection 158 West Nile Viral Disease 158 Parasitic Disease 159 Cutaneous Paratrichosomiasis 159 Coccidiosis 160 Bacterial disease 160 Overview 160 Etiology 160 Host Factors and Transmission 161 Gross and Clinical Signs 161 Diagnosis and Differential Diagnosis 161 Treatment 161 Nutritional Disease 161 Overview 161 Etiology 161 Host Factors and Transmission 161 Gross and Clinical Signs 161 Diagnosis and Differential Diagnosis 162 Treatment 162 Gout 162 Overview 162 Etiology 162 Host Factors and Transmission 162 Gross and Clinical Signs 162 Diagnosis and Differential Diagnosis 162 Treatment 162 Marine Iguanas 163 Sea Snakes 163 Bibliography 163 Appendix 41 173 5 Aquatic Birds 177 Parasitic Diseases of Major Taxa 177 Ectoparasites 177 Metazoan Parasites 177 Hemoprotozoans and Intracellular Protozoans 179 Viral Diseases 180 Avian Poxvirus Disease 180 Overview and Etiology 180 Signs and Diagnosis 180 Differential Diagnoses 181 Treatment/Management 181 Duck Virus Enteritis (“Duck Plague”) 181 Overview and Etiology 181 Signs and Diagnosis 181 Differential Diagnoses 182 Treatment/Management 182 Avian Influenza 182 Overview and Etiology 182 Signs and Diagnosis 182 Differential Diagnoses 183 Treatment/Management 183 West Nile Disease 183 Overview and Etiology 183 Signs and Diagnosis 184 Differential Diagnoses 184 Treatment/Management 184 Eastern Equine Encephalitis 184 Overview and Etiology 184 Signs and Diagnosis 184 Treatment/Management 184 Newcastle Disease 184 Overview and Etiology 184 Signs and Diagnosis 185 Differential Diagnoses 185 Treatment/Management 185 Wellfleet Bay Virus Disease 185 Overview and Etiology 185 Signs and Diagnosis 185 Treatment/Management 185 Aquatic Bird Bornavirus 1 Disease 186 Overview/Etiology 186 Signs and Diagnosis 186 Treatment/Management 186 Bacterial Diseases of Major Taxa 186 Salmonellosis 186 Overview and Etiology 186 Signs and Diagnosis 186 Differential Diagnoses 186 Treatment/Management 187 Mycobacteriosis (Tuberculosis) 187 Overview/Etiology 187 Signs and Diagnosis 187 Differential Diagnoses 187 Treatment/Management 187 Pasteurellosis 188 Overview and Etiology 188 Signs and Diagnosis 188 Differential Diagnoses 188 Treatment/Management 188 Chlamydiosis 188 Overview and Etiology 188 Signs and Diagnosis 188 Treatment/Management 188 Infection with Reimerella anatipestifer 189 Overview/Etiology 189 Signs and Diagnosis 189 Differential Diagnoses 189 Treatment/Management 189 Fungal Diseases of Major Taxa 189 Aspergillosis 189 Overview and Etiology 189 Signs and Diagnosis 189 Differential Diagnoses 190 Treatment/Management 190 Candidiasis 190 Overview and Etiology 190 Signs and Diagnosis 190 Non-Infectious Diseases of Major Taxa 190 Trauma 190 Overview and Etiology 190 Signs and Diagnosis 191 Starvation 192 Overview and Etiology 192 Signs and Diagnosis 192 Gout or Hyperuricemia 195 Overview and Etiology 195 Signs and Diagnosis 195 Ingestion of Foreign Bodies 195 Overview and Etiology 195 Signs and Diagnosis 195 Amyloidosis (Protein Misfolding Disease) 196 Overview and Etiology 196 Signs and Diagnosis 196 Exertional Myopathy 196 Overview and Etiology 196 Pododermatitis (“Bumblefoot”) 196 Overview and Etiology 196 Signs and Diagnosis 197 Spontaneous Neoplasia 197 Overview and Etiology 197 Toxicoses of Major Taxa 197 Heavy Metal Intoxications 197 Lead Toxicosis 197 Zinc Toxicosis 198 Mercury Toxicosis 199 Organophosphates and Carbamates 199 Overview and Etiology 199 Signs and Diagnosis 199 Treatment/Management 200 Per/Polyfluoroalkyl Substances 200 Biotoxins from Harmful Algal Blooms 200 Overview and Etiology 200 Signs and Diagnosis 200 Treatment/Management 201 Avian Vacuolar Myelinopathy 201 Overview and Etiology 201 Signs and Diagnosis 201 Differential Diagnoses 201 Treatment/Management 201 Botulism 201 Overview and Etiology 201 Signs and Diagnosis 202 Differential Diagnoses 202 Treatment/Management 202 Mycotoxicosis 202 Overview and Etiology 202 Signs and Diagnosis 202 Treatment/Management 202 Oiling of Aquatic Birds 202 Overview and Etiology 202 Signs and Diagnosis 203 Treatment/Management 203 Salt Toxicosis 203 Disease Epidemiology in Aquatic birds 203 References 204 Appendix 51 207 6 Aquatic Mammals 214 Parasitic Diseases of Major Taxa 214 Protista (Ciliates, Flagellates, Amoebae and Apicomplexa) 214 Etiology, Host Range and Transmission 214 Clinical and Gross Signs 216 Diagnosis 218 Differential Diagnoses 219 Treatment/Management 219 Trematoda: Digenia 220 Etiology, Host Range, and Transmission 220 Clinical and Gross Signs 220 Diagnosis 222 Differential Diagnoses 222 Treatment and Management 222 Cestoda 222 Etiology, Host Range, and Transmission 222 Clinical and Gross Signs 223 Diagnosis 224 Differential Diagnoses 224 Treatment and Management 224 Acanthocephala 224 Etiology, Host Range, and Transmission 224 Clinical and Gross Signs 225 Diagnosis 226 Differentials 226 Treatment and Management 226 Nematoda 226 Etiology, Host Range, and Transmission 226 Clinical and Gross Signs 227 Diagnosis 236 Differential Diagnoses 236 Treatment and Management 236 Arthropods 237 Etiology, Host Range, and Transmission 237 Clinical and Gross Signs 238 Diagnosis 240 Differential Diagnoses 240 Treatment and Management 240 Bacterial Diseases 240 Leptospirosis 240 Etiology, Host Range, and Transmission 240 Clinical and Gross Signs 241 Diagnosis 242 Differential Diagnoses 242 Treatment and Management 243 Brucellosis 243 Etiology, Host Range, and Transmission 243 Clinical and Gross Signs 243 Diagnosis 245 Differential Diagnoses 245 Treatment and Management 245 Coxiella burnetti 245 Etiology, Host Range, and Transmission 245 Clinical and Gross Signs 246 Diagnosis 246 Differential Diagnoses 246 Treatment and Management 246 Vibriosis 246 Etiology, Host Range, and Transmission 246 Clinical and Gross Signs 247 Diagnosis 248 Differentials 248 Treatment and Management 248 Pasteurellosis 248 Etiology, Host Range, and Transmission 248 Clinical and Gross Signs 248 Diagnosis 248 Differential Diagnoses 248 Treatment and Management 249 Enterobacteriaceae 249 Klebsiellosis 249 Etiology and Transmission 249 Clinical and Gross Signs 249 Diagnosis 251 Differential Diagnoses 252 Treatment and Management 252 Salmonellosis 252 Etiology, Host Factors, and Transmission 252 Clinical and Gross Signs 252 Diagnosis 252 Differentials 252 Treatment and Management 252 Melioidosis 253 Etiology, Host Factors, and Transmission 253 Clinical and Gross Signs 253 Diagnosis 253 Differential Diagnoses 253 Treatment and Management 253 Campylobacteriosis 253 Etiology, Host Factors, and Transmission 253 Clinical and Gross Signs 253 Diagnosis 254 Differentials 254 Treatment and management 254 Erysipelosis 254 Etiology, Host Factors, and Transmission 254 Clinical and Gross Signs 254 Diagnosis 254 Differentials 255 Treatment and Management 255 Nocardiosis 255 Etiology, Host Factors, and Transmission 255 Clinical and Gross Signs 255 Diagnosis 255 Differential Diagnoses 256 Treatment and Management 256 Other Pyogenic Bacteria 257 Clinical and Gross Signs 257 Diagnosis 257 Differential Diagnoses 257 Treatment and Management 258 Mycobacteriosis 258 Etiology, Host Factors, and Transmission 258 Clinical and Gross Signs 258 Diagnosis 258 Differential Diagnoses 259 Treatment and Management 259 Mollicutes 260 Etiology, Host Factors, and Transmission 260 Clinical and Gross Signs 260 Diagnosis 261 Differential Diagnoses 261 Treatment and Management 261 Fungal Diseases (Dermatophytosis and Systemic Mycosis) 261 Etiology, Host Factors, and Transmission 261 Dermatophytosis 262 Clinical and Gross Signs 262 Diagnosis 262 Differential Diagnoses 262 Treatment and Management 262 Systemic Mycosis 263 Clinical and Gross Signs 263 Diagnosis 266 Differential Diagnoses 266 Treatment and Management 267 Viral Diseases 267 RNA Viruses 267 Morbillivirus infection 267 Influenza 269 Coronaviruses 270 Caliciviruses 271 DNA Viruses 272 Herpesviruses 272 Papillomaviruses 273 Poxviruses 275 Adenoviruses 277 Non-Infectious Disease 277 Neoplasia 277 Etiology, Host Factors, and Transmission 277 Clinical and Gross Signs 278 Diagnosis 285 Differential Diagnoses 285 Treatment and Management 285 Toxins 285 Harmful Algal Blooms 285 Etiology, Host Factors, and Transmission 285 Clinical and Gross Signs 286 Diagnosis 292 Differentials 292 Treatment and Management 292 Persistent Organic Pollutants 292 Etiology, Host Factors, and Transmission 292 Clinical and Gross Signs 293 Diagnosis 293 Differentials 293 Treatment and Management 293 Heavy Metals 293 Etiology, Host Factors, and Transmission 293 Clinical and Gross Signs 294 Diagnosis 294 Differential Diagnoses 294 Treatment and Management 294 Congenital or Genetic Diseases 294 Etiology, Host Factors, and Transmission 294 Clinical and Gross Signs 294 Diagnosis 296 Differential Diagnoses 296 Treatment and Management 296 Age-Related or Degenerative Pathology 296 Etiology, Host Factors, and Transmission 296 Clinical and Gross Signs 299 Diagnosis 301 Differential Diagnoses 301 Treatment and Management 301 Nutritional and Metabolic Diseases 301 Etiology, Clinical and Gross Signs, Diagnosis 301 Treatment and Management 304 Miscellaneous Diseases 305 Amyloidosis 305 Etiology, Clinical and Gross Signs, Diagnosis 305 Treatment and Management 305 Gastrointestinal Ulceration 305 Etiology, Clinical and Gross Signs, Diagnosis 305 Treatment and Management 306 Cardiomyopathy 306 Etiology, Clinical and Gross Signs, Diagnosis 306 Dermatitis in Northern Elephant Seals 307 Etiology, Clinical and Gross Signs, Diagnosis 307 Treatment and Management 309 Alopecia in Pinnipeds and Polar Bears 309 Etiology, Clinical and Gross Signs, Diagnosis 309 Treatment and Management 311 Freshwater Skin Disease 311 Etiology, Host Factors, and Transmission 311 Clinical and Gross Signs 312 Diagnosis 312 Differentials 312 Treatment and Management 312 Ultraviolet Irradiation (Sunburn) 312 Etiology, Host Factors, and Transmission 312 Clinical and Gross Signs 312 Diagnosis 312 Differential Diagnoses 314 Treatment and Management 314 Angiomatosis 314 Etiology, Host Factors, and Transmission 314 Clinical and Gross Signs 314 Diagnosis 314 Differentials 315 Treatment and Management 315 Trauma 315 Predation and Interspecific Aggression 315 Human Interaction 318 Acknowledgments 321 Bibliography 321 Appendix 61 347 Part II Epidemiology and Animal Health Economics 351 Introduction 351 7 Epidemiology Keyword Refresher 353 Biosecurity 353 Design Prevalence 353 Epidemiology 354 Epidemiological Unit 354 Incidence 354 Likelihood ratios 354 Monitoring 355 Odds Ratio 355 Predictive values 356 Prevalence 356 Probability (Frequentist) 357 Probability (Bayesian) 357 Probability Notation 357 Independent Probabilities 357 Conditional Probabilities 357 Relative Risk 358 Sensitivity 358 Specificity 358 Surveillance 358 Probabilities and Probability Distributions 358 Independent Probabilities 358 Conditional Probabilities 359 Mutually Exclusive Probabilities 359 Independent Events That can Occur Simultaneously 360 Probability Distributions 360 Distributions Used to Model a Binomial Process 361 Binomial Distribution 361 Syntax for Excel 362 Beta Distribution 362 Example 362 Syntax for Excel 362 Negative Binomial Distribution 363 Example 363 Syntax for Excel 364 Distributions Used to Model a Poisson Process 364 Poisson Distribution 364 Gamma Distribution (a) 365 Gamma Distribution (b) 366 Exponential Distribution 366 Hypergeometric Distribution 367 Lognormal Distribution 368 Normal Distribution 369 Pert Distribution 369 Using and Assessing Data Sources 370 Descriptive Epidemiology 373 Analytic Epidemiology 374 Cross-sectional studies 374 Cohort Studies 374 Case–Control Studies 374 Ecologic Studies 374 Randomized Controlled Trials 374 Expert Opinion 374 Further Reading 375 8 Diagnostics: Sampling and Diagnostic Testing 376 Test Characteristics 376 Tests in Combination 378 To Obtain an Estimation of Disease Prevalence 379 Example 380 References 380 9 Biosecurity: The Use of Risk Assessment, Surveillance, Outbreak Investigation, Modelling Disease Outbreaks 382 Chris Walster and Leo Foyle Risk Assessment 382 Disease Risk Analysis: Evaluating an Operation’s Risk from Disease Hazard 382 Identifying an Aquaculture Operations Critical Control Points 384 Disease Risk Management/Mitigation Options 384 Disease Epidemiology and Surveillance Information 385 Determining Disease Status and Freedom – Qualitative Compared With Quantitative Approaches 386 Disease Diagnostics and Monitoring 386 Auditing and Certifying Biosecurity Status 387 The Risk of Introducing Infection 389 Demonstrating Freedom from Disease 390 Basic Sampling for Presence or Absence of Disease 393 Risk-Based Sampling for Presence or Absence of Disease 394 Scenario Tree Modelling 394 Surveillance 395 Principles of Outbreak Investigation 396 Disease Contingency Plans 396 Disease Dynamics, Prevention and Control 397 Threshold for Disease Transmission 397 How Fast Does an Outbreak Take-Off? 398 Observed or Effective Reproduction Ratio 398 Modeling Disease Dynamics 399 Selecting the Model Structure 399 Difference Equation Models 399 Model Parameters 400 References 402 Further Reading 402 10 Animal Health Economics 404 Economics and Biosecurity 404 Opportunity Costs 405 Rational Choices 405 Marginal Costs and Benefits 406 Production Functions 406 Economic Analysis of the Epidemiological Unit Biosecurity Plan 409 Partial Budgeting 411 Decision Tree Analysis 411 Cost–Benefit Analysis 412 References 414 Further Reading 414