Equine Clinical Nutrition

Contributors xvi

Preface xix

Section I The Horse 1

Animal Assessment 3

1 Feeding Horses: Back to Evolution 5
Rebecca L. Remillard

1.1 Introduction 5

1.2 The Evolution of Equus 6

1.2.1 Environmental Changes 6

1.2.2 Musculoskeletal System Changes in Response to Predation on the Open Plains 7

1.2.3 Alimentary System Changes in Response to a Changing Food Supply 8

1.3 Equine Nutrient Requirements vs. Recommendations 10

References 13

2 Nutritional Assessment of the Horse 15
Shannon Pratt Phillips and Meri Stratton- Phelps

2.1 Introduction 15

2.2 Obtaining a History 16

2.3 Physical Examination 16

2.3.1 Determining Body Weight 17

2.3.2 Estimating Body Composition 19

2.3.3 Body Condition Scoring 21

2.4 Changes in Body Weight 22

2.4.1 Etiology of Weight Loss 24

2.4.2 Weight Gain in Adult Horses 26

2.5 Laboratory Tests 26

2.5.1 Weight Loss or Low Body Condition Score 26

2.5.2 Weight Gain or High Body Condition Score 27

2.5.3 Mineral and Vitamin Imbalances 27

References 30

3 The Horse: Host 33
Veronique Julliand, Sarah L. Ralston, and Rebecca L. Remillard

3.1 Introduction 33

3.2 Oral Cavity 34

3.3 Stomach 38

3.4 Small Intestine, Pancreas, and Liver 40

3.5 Cecum and Large Colon 43

3.6 Small Colon, Rectum, and Defecation 46

References 47

4 The Horse: Microbiome 51
Veronique Julliand and J. Scott Weese

4.1 Introduction 51

4.2 Microbiota in Adult Healthy Horses 52

4.3 Microbiota in Healthy Foals and Young Horses 54

4.4 The Role of the Microbiota 55

4.4.1 Nourishment 55

4.4.2 Disease 57

4.5 Exogenous Impacts on and Manipulation of the Microbiome 58

4.5.1 Diet 58

4.5.2 Probiotics 59

4.5.3 Prebiotics 60

4.5.4 Drugs 60

4.5.5 Other Factors 61

4.5.6 Fecal Microbial Transplantation 61

4.6 Assessment of the Microbiota and Microbiome 61

4.6.1 Sampling Sites and Types 62

4.6.2 Sample Handling 62

4.6.3 Testing Methods 62

4.7 Summary 63

References 63

Section II The Diet 69

Nutrient Metabolism 71

5 Water 73
Jonathan M. Naylor

5.1 Water as a Nutrient 73

5.2 Body Water Content 74

5.3 Water Requirement 74

5.4 Water Deficiency 76

5.5 Watering Devices 77

5.6 Sources of Water 78

5.7 Water Quality 79

5.8 Water as Habitat for Disease Vectors and Insects 82

References 83

6 Energy 86
Richard Godbee and Robert Coleman

6.1 The Concept of Energy 86

6.2 Dietary Energy 89

6.2.1 Dietary Carbohydrates 89

6.2.2 Dietary Fats 91

6.3 Horse Energy Requirements 93

6.3.1 Cold Weather Care 95

6.3.2 Hot Weather Care 96

References 97

7 Protein 100
Patricia Graham- Thiers

7.1 Function and Composition 100

7.2 Dietary Protein 101

7.2.1 Protein Digestion 101

7.2.2 Protein Quality 102

7.2.3 Ideal Protein 104

7.2.4 Protein Supplements 104

7.2.5 Non- Protein Nitrogen Sources 105

7.2.6 Protein Imbalance 105

7.3 Horse Protein Requirements by Life Stage 106

7.3.1 Maintenance 106

7.3.2 Growth 108

7.3.3 Gestation 108

7.3.4 Lactation 108

7.3.5 Work 109

References 110

8 Minerals 113
Ashley Fowler, Mieke Brummer- Holder, and Laurie A. Lawrence

8.1 Introduction 113

8.2 Macrominerals 114

8.2.1 Calcium 115

8.2.2 Phosphorus 121

8.2.3 Magnesium 122

8.2.4 Sodium, Potassium, and Chlorine 124

8.2.5 Sulfur 126

8.3 Microminerals 127

8.3.1 Selenium 127

8.3.2 Iodine 131

8.3.3 Copper 133

8.3.4 Zinc 135

8.3.5 Iron 136

8.4 Other Minerals of Interest 138

References 140

9 Vitamins 148
Sarah Dodd, Sarah K. Abood, and Jacqueline M. Parr

9.1 Introduction 148

9.1.1 Sources 149

9.1.2 Requirements 149

9.1.3 Deficiencies and Toxicities 151

9.1.4 Summary 153

9.2 Fat- Soluble Vitamins 154

9.2.1 Vitamin A 154

9.2.2 Vitamin d 157

9.2.3 Vitamin E 159

9.2.4 Vitamin K 161

9.3 Water- Soluble Vitamins 163

9.3.1 Thiamine (B₁) 163

9.3.2 Riboflavin (B₂) 164

9.3.3 Niacin (B₃) 165

9.3.4 Pantothenic Acid (B₅) and Pyridoxine (B₆) 165

9.3.5 Biotin (B₇) 166

9.3.6 Folate (B₉) 167

9.3.7 Cobalamin (B₁₂) 168

9.3.8 Vitamin c 168

References 169

Ration Assessment 175

10 Ration Assessment and Farm Investigations 177
Rebecca L. Remillard and Sarah L. Ralston

10.1 Introduction 177

10.2 Farm Investigation 177

10.2.1 Animal Assessment 178

10.2.2 Ration Assessment 178

10.2.3 Water 182

10.2.4 Feeding Management Assessment 182

10.3 Ration Analysis 182

10.4 Ration Formulation 186

10.5 Reassessment 187

References 188

11 Forages 190
Bridgett McIntosh

11.1 Introduction 190

11.2 Importance of Forages 190

11.3 Hay 192

11.3.1 Types of Hay 192

11.3.2 Forms of Hay 193

11.3.3 Hay Cuttings 195

11.3.4 Hay Grades and Relative Feed Value 195

11.3.5 Feeding Management of Hay 196

11.4 Pasture 200

11.4.1 Soil Testing and Fertility 201

11.4.2 Forage Selection 202

11.4.3 Nutritional Considerations in Pasture Plant Selection 203

11.4.4 Grazing Management 205

References 209

12 Toxic Plants 212
Bryan Stegelmeier and T. Zane Davis

12.1 Introduction 212

12.2 Plants that Damage Dermal and Epithelial Tissues 213

12.2.1 Skin Photosensitization 213

12.2.2 Mechanical Injuries to Facial and Oral Tissues 218

12.2.3 Inflammation of the Hoof Laminae 218

12.3 Plants that Contain Gastrointestinal Toxins 220

12.4 Plants that Contain Hepatotoxins 223

12.5 Plants Containing Neurotoxins 227

12.6 Plants that Contain Muscle Toxins 235

12.7 Plants that are Toxic to the Urogenital System 238

References 241

13 Manufactured Feeds 244
Erin Perry, Kathleen Crandell, Jeanne van der Veen, and Jesse M. Fenton

13.1 Introduction 244

13.2 Manufacturing Processes 244

13.2.1 Ingredients 245

13.2.2 Ingredient Processing 250

13.3 Palatability and Preference 254

13.4 Quality Control Measures 255

13.5 Package and Label 257

13.6 Equine Marketing Concepts 257

13.6.1 Specific Purpose 257

13.6.2 Price and Ingredients 258

13.6.3 Nutrients 258

13.6.4 Features and Benefits 258

13.7 Calculating Cost of Feeding 259

References 260

14 Dietary Supplements 264
Donna M. Raditic

14.1 Introduction 264

14.2 Regulation of Supplements 264

14.3 Marketing of Supplements 265

14.3.1 Animal Food Additive 265

14.3.2 Dosage Forms 266

14.4 Evidence- Based Medicine 267

14.5 Musculoskeletal Diseases 268

14.6 Gastrointestinal Diseases 270

14.7 Behavior 272

14.8 Respiratory Diseases 272

14.9 Metabolic/Endocrine Diseases 273

References 274

15 USA Feed Regulations and Safety 279
David A. Dzanis

15.1 Introduction 279

15.2 USA Regulatory Oversight 280

15.2.1 Food and Drug Administration Authority 280

15.2.2 State Authority 280

15.3 Basic Label Requirements 281

15.4 Labeling Claims 285

15.5 Special Products 287

15.5.1 Supplements 287

15.5.2 Medicated Feeds/Veterinary- Directed Feeds 287

15.6 Feed Safety 290

15.7 Enforcement 291

15.8 Reporting Problems with Horse Feed Products 292

15.9 Summary 293

References 293

Section III Feeding Management 295

Healthy Horses 297

16 Feeding and Drinking Behaviors 299
Katherine A. Houpt and Rebecca L. Remillard

16.1 Introduction 299

16.2 Feeding Behaviors 299        

16.2.1 Time Management 300

16.2.2 Pastured Horse Feeding Behaviors 301

16.2.3 Stabled Horse Feeding Behaviors 302

16.2.4 Food and Water Intake 303

16.2.5 Pica 303

16.3 Drinking Behavior 303

References 304

17 Feeding Adult and Senior Horses 307
Géraldine Blanchard and Nettie R. Liburt

17.1 Introduction 307

17.2 Animal Assessment 308

17.3 Ration Assessment 312

17.4 Feeding Management 317

17.4.1 Maintenance of Weight and Condition 318

17.4.1.1 Bcs >6/ 9 318

17.4.1.2 Bcs <4/ 9 319

References 320

18 Feeding Athletes and Working Horses 323
Shannon Pratt- Phillips and Jenna Kutzner Mulligan

18.1 Introduction 323

18.2 Animal Assessment 324

18.3 Ration Assessment 329

18.4 Feeding Management 333

18.4.1 Growing Athlete 335

18.4.2 Mature Athlete 335

18.4.3 Feeding Management Based on Workload 336

18.4.4 Feed and Water During Transport 338

18.4.5 Feeding Management for Specific Conditions 340

References 347

19 Feeding Stallions 354
Stewart K. Morgan and Megan Shepherd

19.1 Introduction 354

19.2 Animal Assessment 354

19.3 Ration Assessment 356

19.4 Feeding Management 359

References 361

20 Feeding Broodmares 364
Stewart K. Morgan and Megan Shepherd

20.1 Introduction 364

20.2 Animal Assessment 365

20.3 Ration Assessment 368

20.4 Feeding Management 372

20.4.1 Gestation 373

20.4.2 Lactation 374

20.4.3 BCS for Reproductive Efficiency 374

References 376

21 Feeding Growing Horses 381
Stewart K. Morgan and Megan Shepherd

21.1 Introduction 381

21.2 Animal Assessment 381

21.3 Ration Assessment 383

21.4 Feeding Management 388

21.4.1 Neonate 388

21.4.2 Suckling Foal 389

21.4.3 Weanling 391

21.4.4 Yearling 392

21.4.5 Two- to Five- Year- Olds 392

References 393

Clinical Nutrition 399

22 Pain and Discomfort Behaviors 401
Katherine A. Houpt

22.1 Introduction 401

22.2 Assessments of Discomfort, Pain, Depression, and Distress 401

22.2.1 Physical Assessments 401

22.2.2 Behavioral Assessments 402

22.3 Freedom from Thirst, Hunger, and Malnutrition 403

22.4 Freedom from Thermal and Physical Discomfort 405

22.5 Freedom from Pain, Injury, and Disease 405

22.6 Freedom from Fear and Distress 407

22.7 Freedom to Express Normal Behaviors 409

References 409

23 Weight Management 411
Shannon P. Phillips and Rebecca L. Remillard

23.1 The Healthy Weight as a Concept 411

23.2 Feeding for Weight Loss 414

23.2.1 Animal Assessment 414

23.2.2 Ration Assessment 416

23.2.3 Feeding Management 417

23.3 Feeding for Weight Gain 421

23.3.1 Animal Assessment 421

23.3.2 Ration Assessment 422

23.3.3 Feeding Management 423

References 425

24 Refeeding and Assisted Feeding of Horses 429
Meri Stratton- Phelps and Rebecca L. Remillard

24.1 Introduction 429

24.2 Feed Reintroduction to Chronically Starved Horses 432

24.2.1 Animal Assessment 432

24.2.2 Ration Assessment 434

24.2.3 Feeding Management 436

24.3 Assisted Feeding 438

24.3.1 Animal Assessment 438

24.3.2 Ration Assessment 439

24.3.3 Feeding Management 443

24.3.3.1 Adult Horses 443

24.3.3.2 Foals 448

References 452

25 Musculoskeletal System Disorders 455
Sarah Dodd and Géraldine Blanchard

25.1 Muscle Disorders 455

25.1.1 Animal Assessment 455

25.1.2 Ration Assessment 457

25.1.3 Feeding Management 457

25.2 Developmental Orthopedic Disease 457

25.2.1 Animal Assessment 458

25.2.2 Ration Assessment 458

25.2.3 Feeding Management 460

25.2.4 Summary 461

25.3 Osteoarthritis 461

25.3.1 Animal Assessment 461

25.3.2 Ration Assessment 461

25.3.3 Feeding Management 462

25.4 Laminitis 462

25.4.1 Animal Assessment 462

25.4.2 Ration Assessment 462

25.4.3 Feeding Management 463

References 464

26 Digestive System Disorders 468
Nicolás C. Galinelli, Andy E. Durham, and Rebecca L. Remillard

26.1 Introduction 468

26.2 Oral Disorders 468

26.3 Esophageal Obstruction 469

26.4 Stomach 470

26.4.1 Ulcers 470

26.4.2 Impaction 472

26.5 Intestines 473

26.5.1 Colic 473

26.5.2 Diarrhea 476

References 479

27 Endocrine System Disorders 483
Nicholas Frank, Elizabeth M. Tadros, and Rebecca L. Remillard

27.1 Insulin Dysregulation 483

27.1.1 Introduction 483

27.1.2 Animal Assessment 487

27.1.3 Ration Assessment 489

27.1.4 Feeding Management 490

27.2 Pituitary Pars Intermedia Dysfunction 490

27.2.1 Animal Assessment 491

27.2.2 Ration Assessment 492

27.2.3 Feeding Management 493

27.3 Hyperlipemia 493

27.3.1 Introduction 493

27.3.2 Animal Assessment 494

27.3.3 Ration Assessment 495

27.3.4 Feeding Management 495

References 497

28 Metabolic Syndrome 501
Patricia Harris and Simon R. Bailey

28.1 Defining Equine Metabolic Syndrome (EMS) 501

28.2 Animal Assessment 502

28.2.1 Obesity 502

28.2.2 Insulin Dysregulation 503

28.3 Ration Assessment 503

28.3.1 Grain Concentrates 503

28.3.2 Forages 503

28.3.3 Complementary Feeds 504

28.4 Feeding Management 504

References 507

Appendix 510

A: Case in Point Answers and Outcomes 510

B: Nutrition Resources 524

C: Nutrition Competencies of Equine Veterinarians 524

D: Feed Glossary 525

E: Average body weight and heights of horses 533

F: Abbreviations 534

Index 536