Equine Clinical Nutrition

Rebecca L. Remillard, DVM, PhD, DACVN, is the Founder and President of Veterinary Nutritional Consultations, Inc. in Hollister, North Carolina, USA.

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 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