Parasitology Procedures for Veterinary Technicians

Preface 

1 Introduction to Large Animal Parasitology Procedures for Veterinary Technicians 1

Gastrointestinal Parasitism Can be Categorized into Four Distinct Periods of Development 22

Early Larvae Development and Translation Period 22

The Ingestion and Infective Prepatent Period 30

The Inhibition or Arrested Development Phase 31

The Patent Period 35

References 57

2 The Modified Wisconsin Sugar Flotation Method 59

Standard Operating Procedure for the “Modified Wisconsin Sugar Flotation Technique” 82

Interpretation of Fecal Worm Egg Counts in Sheep, Goats, and Camelids Using the Modified Wisconsin Sugar Flotation Technique 88

Quick Assessment for Sheep, Goats, and Camelids Based on Fecal Worm Egg Counts 97

References 106

3 Parasites in Beef Cattle 107

Strategic Deworming Entails More than Simply Applying a Dewormer 115

The Economics of an Aggressive Deworming Program 115

Interpretation of Fecal Worm Egg Counts in Cattle Using “The Modified Wisconsin Sugar Flotation Technique” 133

Fecal Egg Count Reduction Test (FECRT) 137

Product Profile of Fenbendazole (Safe-Guard^®/Panacur^® – Merck Animal Health) 137

Treatment Timing 142

Gastrointestinal and Lungworm Parasites Found in Beef Cattle 142

Stomach (Abomasal) Worms 142

Intestinal Nematode Parasites 142

Intestinal Cestode Parasites (Cattle Tapeworms) 158

Cattle Lungworm (Dictyocaulus viviparous) 158

Trematodes Parasites (Liver Flukes) 161

Protozoan Parasites of Cattle 162

References 167

4 Parasites in Dairy Cattle 171

Detection is Foremost in the Economic Analysis 171

Gastrointestinal and Lung Parasite Infections Found in Dairy Cattle (See Figure 4.8) 175

Stomach Worms 175

Intestinal Nematode Parasites 177

Intestinal Cestode Parasites (Cattle Tapeworms) 183

Cattle Lungworm (Dictyocaulus Viviparous) 185

Trematodes Parasites (Liver Flukes) 185

Protozoan Parasites of Cattle 185

Risk Factors and Production Losses Caused by Gastrointestinal Parasitism 188

How Many Parasites are Needed to Cause Clinical Disease? 188

Level of Efficiency Can Affect Production Losses 189

Variation in Parasites Numbers and Levels of Contamination Rates Exists 190

Age and Management Variations Affect Parasite Buildup in Animals 191

Understanding How Gastrointestinal Parasites Affect Lactating Dairy Cows 191

Monitoring Dairy Herds for Gastrointestinal Parasite Infections 192

Every Herd is Different when it Comes to Internal Parasitic Infections 192

The Following are Guidelines to Determine Parasite Exposure of a Dairy Herd Based on Animal Management 192

Obtaining a Comprehensive “Parasite Fecal Check” of the Herd Can be Important 193

Production Losses Due to Gastrointestinal Parasites 193

Seasonal Control of Gastrointestinal Parasitic Infections in Dairy Operations 193

Conclusion 197

References 198

5 Parasites in Equine 199

Gastrointestinal Nematode Parasites Affect Horses in Many Ways 200

Parasites Develop Differently in Horses than in Cattle 202

Parasite Resistance to Dewormers has Become a Major Problem 206

The Seasonal Transmission of Parasites in the Horse 208

Seasonal Control of Parasites in Horses Can be Achieved by Reducing Parasite Contamination from the Environment 211

General Recommendations for Strategic Timed Deworming for the Season Control of Gastrointestinal Parasites in Horses 212

A Two-Year Study Demonstrating the Value of Strategic Deworming to Reduce Environment Contamination was Conducted in Nevada 213

Equine Dewormers 217

Fecal Monitoring is the Best Way to Determine Whether Treatment is Effective 218

The Major Gastrointestinal Nematode Parasites of Horses are 219

Other Notable Internal Parasites of the Horse 219

Review of Internal Nematode Parasite of Horses 219

Other Parasites 228

Guide for Interpretation of Fecal Worm Egg Counts in Horses Using “The Modified Wisconsin Sugar Flotation Technique” 231

Quick Assessment for Equine Based on Fecal Worm Egg Counts 231

Inhibited Small Strongyles Cause Problems with Worm Egg Count Interpretations 231

References 232

6 Parasites of Swine 235

Large Roundworms (Ascaris suum) 241

Background 241

Diagnosis in Lungs 243

Diagnosis in Liver 245

Diagnosis in the Feces 245

Whipworms (Trichuris suis) 247

Background 247

Diagnosis in the Cecum 247

Diagnosis in the Feces 250

Threadworms (Strongyloides ramsoni) 252

Background 252

Diagnosis in the Feces 252

Treatment Guidelines 253

Nodular Worms (Oesophagostomum dentatum) 253

Background 253

Diagnosis in the Large Intestine 254

Diagnosis in the Feces 255

Treatment Guidelines 257

The Development and Buildup of Parasitism within a Swine Operation Depends on Many Factors 257

Materials and Methods for Fecal Sampling 258

Specific Sample Instructions 258

Fecal Worm Egg Count Interpretation and Whole Herd Deworming Guidelines 259

Treatment to Control Parasitism and Reduce Parasite Future Contamination in a Facility 260

Developing Parasite Data for Swine Clients 261

References 261

7 Parasites in Small Ruminants 263

Strategic Deworming for Small Ruminants 278

Phase I: “0–3–6–9” Spring Dewormings 278

Phase II – Fall Cleanup Deworming 280

Summary 280

Fecal Monitoring is the Best Way to Determine Whether Treatment is Effective 280

Interpretation of Fecal Worm Egg Counts in Small Ruminants Using the Modified Wisconsin Sugar Flotation Technique 284

Quick Assessment for Sheep, Goats, and Camelids Based on Fecal Worm Egg Counts 284

Gastrointestinal and Lung Parasite Infections Found in Small Ruminants 285

Stomach Worms 286

Intestinal Nematode Parasites 288

Intestinal Cestode (Tapeworm) Parasites (Moniezia expansa and Moniezia benedeni) 300

Trematodes Parasites (Liver Flukes) 300

Protozoan Parasites of Small Ruminants 304

References 307

8 Parasites of Hoofed Wildlife 309

Gastrointestinal Nematode Parasites are Important to Wildlife 313

Parasite Life Cycles 313

Transmission of Parasites 313

Control of Parasites in the Wild 314

Dewormer for Hoofed Wildlife 314

Description and Dosage Rate 317

Estimating Herd Size and Required Dose 317

Strategic Wildlife Deworming Program 317

The Modified Wisconsin Sugar Fecal Exam (see Figure 8.11) Plus a Submission Form (See Figure 8.12) and a Picture of the Most Common Eggs Found with Hoofed Wildlife Fecal Samples (See Figure 8.13) 318

Interpretation of Fecal Worm Egg Counts in Hoofed Wildlife Using the Modified Wisconsin Sugar Flotation Technique 318

Quick Assessment for Hoofed Wildlife Based on Fecal Worm Egg Counts 320

Gastrointestinal and Lung Parasite Infections Found in Small Ruminants and Hoofed Wildlife 321

Stomach Worms 321

Intestinal Parasites 324

References 333

Index 335

Comprehensive illustrated reference on parasitic nematodes, cestodes, coccidian oocysts and trematode egg recoveries, identification, and enumeration with treatment strategies for seven separate categories of animal patients

Parasitology Procedures for Veterinary Technicians illustrates, in detail, the most sensitive diagnostic procedure for internal parasites of domestic animals using the Modified Wisconsin Sugar Flotation Method. With step-by-step pictures and bullet-point instructions, this text discusses sample collection and storage techniques, as well as the strengths and weaknesses inherent to other commonly used tests. Potential sources for infection, the seasonality of the infection, possible environmental recontamination, and control strategies are all covered in detail, with suggestions to prevent reoccurrences.

Parasites of the canine, feline, equine, large and small ruminants (including alpaca), swine, poultry and hoofed wildlife patients are included, with full color images for quick identification, an assessment of life cycle stage, and discussion of zoonotic potential. Each species section is heavily illustrated with comparative images to aid the technician in quickly identifying the parasite and life cycle stage.

In Parasitology Procedures for Veterinary Technicians, readers can find information on:

• The definition and economic importance of parasitisms, details on the epidemiology of parasitic enteritis, including basics of protozoology, helminthology, and overall applied veterinary parasitology
• Sample collection and shipment of specimens, including collection, storage, examinations, and interpretations
• Fecal examination using the Modified Wisconsin Sugar Flotation method, compared with gross examination, smear, sedimentation, and other flotation techniques, plus a fluke egg recovery technique and the Baermann technique for lungworm larvae recovery
• Internal parasite diagnosis and worm egg recoveries, descriptions and pictures of nematode parasite eggs (as well as coccidia oocysts), plus tapeworm eggs and fluke egg descriptions and photos for a variety of host animals

Illustrating commonly used diagnostic tests in veterinary parasitology, with step-by-step instructions for accuracy, Parasitology Procedures for Veterinary Technicians is an essential reference for veterinary technicians and veterinary technician students dealing with domestic animals, including dogs, cats, horses, ruminants, swine, poultry, and hoofed wildlife.

Donald H. Bliss, PhD (Veterinary Parasitologist), owns and operates a parasite diagnostic laboratory (MidAmerica Ag Research) in Verona, Wisconsin, USA.

Dwight Bowman, PhD, is Professor of Parasitology at Cornell University’s College of Veterinary Medicine in Ithaca, New York, USA.