Veterinary Assistant Tasks in Large Animal Practice PDF

DR. WILLIAM JOHNSTON Veterinary Assistant Tasks in Large Animal Practice DR. WILLIAM JOHNSTON ISBN 978-2-923623-35-1 Copyright © 2016 Darnley Publishing Group All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means: electronic or me...

DR. WILLIAM JOHNSTON Veterinary Assistant Tasks in Large Animal Practice DR. WILLIAM JOHNSTON ISBN 978-2-923623-35-1 Copyright © 2016 Darnley Publishing Group All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means: electronic or mechanical, including photocopying, recording or by any information storage or retrieval system, without permission in writing from the Publisher. Printed in Canada Catalog Number: TCEC5  Author: William Johnston, D.V.M. Instructional Designer and Reviewer: Claude P. Major, Ph.D. Technical Writer: Krista E. Garver Project Manager: Francine Hébert, M.Ed. Design and Layout: Michael Gonzalez Jason Carrière  Table of Contents Introduction Introduction 1 Part 1: Large Animal Practice Chapter 1 Chapter 1 Horses 5 Highlights of the Chapter..........................................................................5 Introduction..............................................................................................5 Anatomy and Physiology..........................................................................7 Routine Care............................................................................................11 Housing..............................................................................................................11 Nutrition..............................................................................................................11 Grooming............................................................................................................14 Common Illnesses and Their Treatment....................................................18 Colic....................................................................................................................18 Colitis..................................................................................................................19 Equine Herpesvirus..............................................................................................19 Equine Viral Encephalitis......................................................................................20 Laminitis and Founder..........................................................................................20 Influenza..............................................................................................................21 Potomac Horse Fever..........................................................................................22 Rabies..................................................................................................................22 Strangles..............................................................................................................23 Preventive Healthcare..............................................................................23 Vaccinations........................................................................................................23 Deworming..........................................................................................................25 Foot Care..............................................................................................................26 Dental Care..........................................................................................................26 Nursing Care............................................................................................27 Administering Oral Medication..............................................................................27 Treating Limb Injuries............................................................................................28 Wound Cleaning..............................................................................................28 Bandaging............................................................................................................29 Applying a Basic Bandage................................................................................30 iv Veterinary Assistant Tasks in Large Animal Practice Table of Contents Applying a Sweat Wrap....................................................................................31 Applying a Full Bandage....................................................................................32 Applying a Foot Bandage..................................................................................33 Preparation for Surgery............................................................................34 Standing Surgery..................................................................................................34 Postoperative Care..........................................................................................35 Surgery under General Anesthesia........................................................................35 Postoperative Care..........................................................................................36 Emergency Care......................................................................................38 Colic....................................................................................................................38 Wounds................................................................................................................38 Lameness............................................................................................................39 Eye Injuries..........................................................................................................40 Foal Care..................................................................................................40 Summary................................................................................................43 Key Terms................................................................................................45 What Do You Remember?........................................................................47 Chapter 2 Chapter 2 Cattle 51 Highlights of the Chapter..........................................................................51 Introduction..............................................................................................51 Anatomy and Physiology..........................................................................55 Routine Care............................................................................................57 Housing................................................................................................................57 Nutrition..............................................................................................................59 Minerals..............................................................................................................59 Vitamins..............................................................................................................59 Feedstuffs............................................................................................................60 Hoof Trimming......................................................................................................62 Common Illnesses and Their Treatment....................................................64 Anthrax................................................................................................................64 Bovine Respiratory Disease Syndrome (BRDS)....................................................64 Bovine Spongiform Encephalopathy (BSE)............................................................65 Table of Contents v  Table of Contents Brucellosis..........................................................................................................66 Campylobacteriosis..............................................................................................66 Chronic Diarrhea..................................................................................................67 Clostridial Diseases..............................................................................................67 Lameness............................................................................................................68 Leptospirosis........................................................................................................69 Mastitis................................................................................................................69 Traumatic Reticuloperitonitis (TRP)......................................................................70 Preventive Healthcare..............................................................................71 Administering Oral Medication..................................................................72 Preparation for Surgery............................................................................73 Standing Surgery..................................................................................................74 Surgery under General Anesthesia........................................................................75 Postoperative Care................................................................................................76 Emergency Care......................................................................................76 Bloat....................................................................................................................76 Dystocia..............................................................................................................77 Retained Placenta................................................................................................78 The Downer Cow..................................................................................................79 Calf Care..................................................................................................80 Summary................................................................................................82 Key Terms................................................................................................83 What Do You Remember?........................................................................86 Chapter 3 Chapter 3 Sheep and Goats 89 Highlights of the Chapter..........................................................................89 Introduction..............................................................................................89 Anatomy and Physiology..........................................................................91 Sheep..................................................................................................................91 Goats..................................................................................................................92 Routine Care............................................................................................92 Housing................................................................................................................92 Nutrition..............................................................................................................94 vi Veterinary Assistant Tasks in Large Animal Practice Table of Contents Shearing..............................................................................................................96 Hoof Trimming......................................................................................................97 Common Illnesses and Their Treatment....................................................98 Campylobacteriosis..............................................................................................98 Enterotoxemia......................................................................................................98 Footrot................................................................................................................99 Mastitis................................................................................................................99 Soremouth..........................................................................................................100 Tetanus................................................................................................................101 Urolithiasis..........................................................................................................101 White Muscle Disease..........................................................................................102 Preventive Healthcare..............................................................................103 Vaccination..........................................................................................................103 Deworming..........................................................................................................103 Controlling External Parasites................................................................................105 Administering Oral Medication..................................................................106 Lamb and Kid Care..................................................................................108 Lambs..................................................................................................................108 Kids....................................................................................................................109 Routine Procedures in Lambs and Kids....................................................110 Dehorning............................................................................................................111 Tail Docking..........................................................................................................113 Castration............................................................................................................114 Summary................................................................................................115 Key Terms................................................................................................116 What Do You Remember?........................................................................118 Chapter 4 Chapter 4 Swine 121 Highlights of the Chapter..........................................................................121 Introduction..............................................................................................121 Anatomy and Physiology..........................................................................122 Routine Care............................................................................................123 Housing................................................................................................................123 Table of Contents vii  Table of Contents Nutrition..............................................................................................................125 Common Illnesses and Their Treatment....................................................127 Erysipelas............................................................................................................127 Leptospirosis........................................................................................................127 Porcine Parvovirus (PPV)......................................................................................128 Porcine Reproductive and Respiratory Syndrome (PRRS)......................................128 Pseudorabies (PR)................................................................................................129 Swine Influenza....................................................................................................129 Transmissible Gastroenteritis (TGE)......................................................................130 Preventive Healthcare..............................................................................130 Administering Oral Medication..................................................................131 Preparation for Surgery............................................................................133 Surgery under Local Anesthesia............................................................................133 Surgery under General Anesthesia........................................................................133 Postoperative Care................................................................................................134 Piglet Care..............................................................................................134 Routine Procedures in Piglets..................................................................137 Iron Supplementation............................................................................................137 Needle Teeth Clipping............................................................................................137 Tail Docking..........................................................................................................138 Castration............................................................................................................138 Summary................................................................................................139 Key Terms................................................................................................140 What Do You Remember?........................................................................141 Part 2: Large Animal Clinical Examinations, and Emergency and Critical Care Chapter 5 Chapter 5 Large Animal Clinical Examination 145 Highlights of the Chapter..........................................................................145 Introduction..............................................................................................145 Prework—What Must Be Done before a Clinical Exam..............................146 Techniques Used for Clinical Examinations................................................148 Taking Vital Signs and Determining Height and Weight..............................150 Body Temperature................................................................................................150 Pulse....................................................................................................................152 viii Veterinary Assistant Tasks in Large Animal Practice Table of Contents Respiratory Rate..................................................................................................153 Capillary Refill Time (CRT)....................................................................................154 Height and Weight................................................................................................154 Examination of Body Systems..................................................................156 Summary................................................................................................161 Key Terms................................................................................................162 What Do You Remember?........................................................................163 Chapter 6 Chapter 6 Emergency and Critical Care 165 Highlights of the Chapter..........................................................................165 Introduction..............................................................................................165 Triage of the Emergency Care Patient........................................................168 The Recovery Position..........................................................................................168 Controlling Bleeding..............................................................................................169 Providing Breathing Assistance............................................................................170 Evaluating Cardiac and Circulatory Problems........................................................170 Assessing and Treating Injuries............................................................................171 Providing Cardiopulmonary Resuscitation................................................171 Checking for an Open Airway................................................................................172 Breathing Assistance............................................................................................173 Cardiac Compression..........................................................................................174 Treating for Shock....................................................................................176 Treating Fractures....................................................................................178 Treating Hypothermia and Hyperthermia..................................................179 Patient Monitoring and Critical Care..........................................................181 Critical Care..........................................................................................................182 Summary................................................................................................184 Key Terms................................................................................................185 What Do You Remember?........................................................................187 Answer Key..........................................................................................189 Table of Contents ix Introduction L Large animal practice involves the care of horses and livestock. Much of the work that large animal veterinarians do involves preventive healthcare to maintain the health of animal herds. These veterinarians test for and vaccinate against diseases and consult with farm and ranch owners on animal reproduction, feeding, and housing issues. They also treat and dress wounds, set fractures, perform surgery, and help animals give birth. There are many large animal clinics and hospitals across the United States, where veterinary assistants support the work of veterinarians and other members of the veterinary team. Today, it is not unusual for large animal practices to limit their practice to poultry, beef cattle, dairy cattle, swine, equine, or small ruminant (sheep and goat) medicine and surgery, though a few practices treat all species. Equine veterinarians may focus on racehorses, breeding farm management, pleasure horse practice, or a combination of the three. Part I of this book deals with large animal practice and the care of horses, cattle, swine, sheep, and goats. Because the anatomy, physiology and care of large animals vary by species, each species is addressed in a separate chapter. Part II covers the clinical examination, as well as emergency and critical care, of large animals. Please note that the procedures described in this book are meant to be general guidelines only. Policies, procedures, and practices will vary by veterinary practice and the preferences of the veterinarian. When you get hired to work as a veterinary assistant in a veterinary practice or for another animal caretaker position, you will need to become familiar with the policies and procedures followed at your workplace. Introduction 1  Chapter Breakdown Part I: Large Animal Practice Part I deals with horses and livestock species in separate chapters, as follows: Chapter 1, “Horses” Chapter 2, “Cattle” Chapter 3, “Sheep and Goats” Chapter 4, “Swine” The topics covered in each chapter include anatomy and physiology, common illnesses and their treatment, grooming, feeding, giving medication, providing nursing care, and helping to prepare large animals for surgery. Part II: Large Animal Clinical Examinations, and Emergency and Critical Care Part II has the following chapters: Chapter 5, “Clinical Examinations,” will provide you with a basic understanding of how clinical exams are performed in large animal practice settings. Although most of the work will be done by the veterinarian, it is useful for you to become familiar with the principles and steps involved so that you can assist competently and confidently. Chapter 6, “Emergency and Critical Care,” will provide you with an overview of common medical emergencies affecting large animals and how to care for critically ill animals. 2 Veterinary Assistant Tasks in Large Animal Practice Special Features This book includes the following features to help you to understand the material: Highlights of the Chapter. This section is included at the beginning of each chapter to introduce the topics to be covered. Diagrams and Illustrations. Labeled diagrams and photos are included to illustrate animal anatomy and provide examples of the equipment and tools used in large animal veterinary practice. Summary. Each chapter ends with a short summary to reinforce and help you remember key points and concepts. Key Terms. Definitions of key terms introduced in the text are included in each chapter for ready reference. If you forget what a term means, you can look it up in this section. What Do You Remember? Review questions are included in each chapter so that you can test your knowledge and understanding of the content. Introduction 3 Large Animal Practice  CHAPTER 1 Horses Highlights of the Chapter Anatomy and physiology Routine care: housing, nutrition, and grooming Common illnesses and their treatment Preventive healthcare Nursing care: administering oral medication and treating limb injuries Preparation for surgery Emergency care Foal care Introduction P People own horses for a variety of reasons, including for breeding, racing, showing, riding, and as pets or work animals. Depending on their age, breeding, training, and other factors, horses may be worth anywhere from about $3000 for a trail horse to much more for a racing or breeding animal. People also tend to become much more emotionally attached to horses than they do to other livestock, such as cattle or swine. For these reasons, horses are more likely than other livestock to be brought to a large animal practice for evaluation, longer-term care, and non-routine surgery. Horses may be cared for either at their home stables or on a large animal practice’s premises. Many horses are accustomed to being handled and moved, so transporting them to a veterinary hospital is easier and more practical than it is for other large animals. Chapter 1 Horses 5  Horses are usually transported in horse trailers that are designed for the comfort and safety of the animals. They also wear protective gear, such as leg wraps, head bumpers, and blankets. As in small animal practice, detailed medical records should be kept for horses receiving treatment. The records include information on the horse owner and patient, cost estimates and signed treatment consent forms, test results, diagnoses, and treatment plans. Horses are expensive animals to keep. Without factoring in property or veterinary care, it can cost about $1500 per year to provide a horse with the very basics. When it comes to veterinary care, more than one person is required to perform many procedures and the size of a horse necessitates special equipment as well as large doses of any medications that must be given. Because a horse is such a large financial investment, horse owners often carry medical insurance for their animals. There are three main types of equine insurance: Mortality insurance covers the value of the horse in case of death. If the horse dies, the insurance company will pay the owner the estimated worth of the animal. Surgical insurance is similar to human health insurance. With certain limitations, it covers the cost of surgery and hospitalization. Loss of use insurance reimburses the owner if the horse is unable to perform its intended use due to illness or injury. As with human health care coverage, insurance companies must often be involved in making decisions about a patient’s care. For example, permission from the insurer must be obtained for certain elective and some emergency surgeries. Therefore, a horse’s medical record should include information about the animal’s insurance, such as the insurer’s contact information and the policy number. This chapter explains some of the anatomy and physiology of horses, some of the illnesses that commonly affect them, and the preventive healthcare that helps keep them healthy. It also covers the veterinary assistant’s role and tasks related to the nursing, 6 Veterinary Assistant Tasks in Large Animal Practice preparation for surgery, emergency care, and routine care of horses. A separate section deals with the special care required by newborn foals. Anatomy and Physiology There are several aspects of a horse’s anatomy and physiology that are different from other domestic animals, and these factors need to be taken into consideration when making plans for their treatment and care. To start with, horses have a very unique digestive system. As grazing animals, horses are adapted to process small amounts of the same kind of food frequently. Although the entire digestive tract is about 100 feet (30 m) long, a horse’s stomach is small compared to the animal’s overall size, and food can pass through it in as little as 15 minutes. Thus, feeding a horse a large meal only once or a couple of times each day can lead to serious illnesses, such as colic and founder, which will be covered later in this chapter. Since the stomach contains strong acids, allowing it to become empty for too long a period can also cause the horse to develop ulcers. When providing a horse with veterinary care, it is important to remember that several small meals per day are preferable to one or two large ones. Because horses spend much of their time eating, the grinding surface of their teeth is worn down through chewing. A horse’s teeth continue to erupt throughout its lifetime, making equine dental care a very important contributor to the animal’s well-being. Horses have a very large heart and lungs. In fact, a horse’s heart weighs about 10 pounds (4.5 kg). At rest, a horse’s heart rate is about 25 beats per minute, and at maximal exertion it can reach as many as 250 beats per minute. Horses are also very sensitive to temperature. Although horses sweat more than any other domestic species, during extreme exertion their body temperature can raise to dangerous levels very quickly, especially in hot, humid weather. It is very important that you closely monitor the body temperature of any horse under your care. Chapter 1 Horses 7  Due to some unique features of their anatomy and their many uses, horses are highly prone to leg injuries and ailments: About 60 to 65% of a horse’s weight is carried on the front legs. Below the knee and hock, horses are all bones and tendons. Of course, a horse’s feet and hooves take the weight and the shock of impact. As you will read later in this chapter, proper foot care is essential for a horse’s health and performance. Horses also have unique sensory systems, which are adapted for their roles in the wild as prey animals. The horse has the largest eyes of all land animals. The eyes are positioned on the side of the head, giving the horse good monocular vision. Horses have good visual acuity and some color vision. They also have two blind spots: one directly in front of them and one directly behind. These features need to be taken into account when approaching, handling, and working around horses. Female horses, or mares, reach sexual maturity at age 2, but they are not usually bred until age 3 or 4. Male horses, or stallions, reach sexual maturity at age 3. A mare’s reproductive cycle is largely controlled by the amount of sunlight. In general, mares are more receptive to stallions during the spring and summer months than they are during the fall and winter months. More about reproduction and the care of newborn horses, called foals, will be discussed later in this chapter. 8 Veterinary Assistant Tasks in Large Animal Practice  Figure 1.1 The Body Parts of a Horse Poll Mane Shoulder Forelock Croup or Rump Withers Loin Back Dock Hindquarters Muzzle Chin groove Tail Flank Forearm Gaskin Barrel Elbow Hock Cannon Knee Fetlock Pastern Hoof Back: The area extending from the withers to the last thoracic vertebrae Barrel: The main part of the body, including the rib cage and the major internal organs Cannon bone: The area between the knee or hock and the fetlock Chin groove: The part of the head behind the lower lip and chin Croup or rump: The area of the hindquarters from the hip to the dock Dock: The point where the tail connects to the rump Elbow: The point where the barrel meets the foreleg Fetlock: Sometimes called the “ankle” of the horse, though it is not the same skeletal structure as an ankle in humans. Chapter 1 Horses 9  Flank: Where the hind legs and barrel of the horse meet, specifically the area right behind the rib cage and in front of the stifle joint. Forearm: The area of the front leg between the knee and the elbow. Forelock: The continuation of the mane, which hangs from between the ears down onto the forehead of the horse. Gaskin: The large muscle on the hind leg, just above the hock and below the stifle. Homologous to the calf of a human. Hindquarters: The large, muscular area of the hind legs, above the stifle and behind the barrel of the horse. Hock: The tarsus of the horse (hindlimb equivalent to the human ankle and heel), the large joint on the hind leg. Hoof: The foot of the horse. The hoof wall is the tough outside covering of the hoof that comes into contact with the ground. The hoof wall is, in many respects, a much larger and stronger version of the human fingernail. Knee: The large joint in the front legs, above the cannon bone (equivalent to the human wrist). Loin: The area right behind the saddle, going from the last rib of the horse to the rump. Mane: Long, coarse hair growing from the dorsal ridge of the neck. Muzzle: The chin, mouth, and nostrils of the horse’s face. Pastern: The part of the horse’s leg between the fetlock joint and the hoof. Poll: Commonly refers to the poll joint at the beginning of the horse's neck, immediately behind the ears. Shoulder: Made up of the shoulder blade and associated muscles. Runs from the withers to the point of shoulder. Tail: Consists of both the living part of the tail (which comprises the coccygeal vertebrae, muscles, and ligaments) and the long hairs which grow from the living part. Withers: The ridge between the shoulder blades. 10 Veterinary Assistant Tasks in Large Animal Practice Routine Care Housing Horses are normally housed in individual stalls and also in tie stalls in barns. Barns need to be clean, organized, and well ventilated so that air can circulate freely. Stalls should be open and at least 12 feet X 12 feet (3.7 m x 3.7 m) for an average 1000-pound (455 kg) horse, allowing the horse room to move and to lie down. There are two main types of stall floors used in horse facilities: Dirt-packed clay Concrete Dirt floors are more comfortable for horses, but they are also more difficult to clean. Stalls with dirt floors must be constructed to allow for proper drainage. Newer facilities are likely to have concrete or tarmac floors and walls, which are easier to clean. The stalls can be hosed down and scrubbed using disinfectants. To make concrete floors more comfortable for horses, rubber mats are often placed between the floor and the bedding. There are several types of bedding used in horse stalls, which provide extra comfort as well as absorb urine. The two most common types of bedding are wood shavings and straw, but sawdust, peat moss, shredded paper, and hemp may also be used. Each type of bedding has its advantages and disadvantages. For example, some types of straw and sawdust can produce dust, so they should not be used for horses with respiratory problems. Other types of straw are dust- and mold-free. Some horses will eat straw, which has little nutritional value and in large quantities can cause digestive problems. Peat moss is cushiony, highly absorbent, and not likely to be eaten. It is often used as a base under other types of bedding. Shredded paper is also very absorbent and produces little dust. Hemp is becoming more popular, but it is not available in all areas. Nutrition As mentioned earlier, the digestive system of a horse is adapted for grazing. If grazing in a pasture is not possible, horses should be fed at least three or four times daily, rather than all at once. Hay and Chapter 1 Horses 11  grains are the basic building blocks of a horse’s diet, with hay comprising the bulk. As a general rule, horses that are a healthy body weight should be fed 1.5 to 2 pounds (0.7–0.9 kg) of hay per 100 pounds (45 kg) of body weight. You can estimate whether or not a horse is a healthy body weight by examining the animal visually and by running your hand firmly along the animal’s side and pressing lightly into the ribs. If the horse is a healthy weight, you should just be able to feel the ribs. If the ribs are easy to see and feel, the horse is underweight and requires more calories. If you cannot feel the ribs at all, the horse may be overweight. To calculate drug doses and feeding schedules for certain animals, you will need a more accurate weight measurement. You can use a weight tape to measure the horse’s girth (area around the middle) and length, and these measurements can be used to estimate the animal’s total weight (for more information, see page 154). Table 1.1 Nutritional Requirements of Horses Nutritional Sources Requirement Energy Hay, cereal grains (oats, barley, corn) Grasses, hay Fiber (Daily feed should contain 70% fiber) Alfalfa hay, cereal grains, soybean meal Protein (Daily feed should contain 8–10% protein) Grasses, hay, cereal grains, Vitamins vitamin/mineral supplement Minerals Hay, vitamin/mineral supplement To maintain good health, horses should also be given salt to provide sodium in their diets. They can be given either loose salt or salt in block form, called a salt/mineral block or “lick.” Vitamin A and the mineral selenium are essential for horses, and these are often provided through a vitamin and mineral 12 Veterinary Assistant Tasks in Large Animal Practice supplement. Horses that are fed good quality hay and grain may not require a supplement, as they receive all of their vitamins and minerals in the hay (Table 1.2 describes characteristics of high- and low-quality hay). Stored hay, however, may lack vitamin A and not all soils contain selenium. Vitamin E is also important, especially for a sick horse, as it has antioxidant properties and can help boost the immune system. If there are any concerns that an animal’s feed is not providing all of the essential nutrients, or if an animal has a weakened immune system or is prone to respiratory viruses, a well-balanced vitamin and mineral supplement should be given. Table 1.2 Characteristics of High- and Low-quality Hay High-quality Hay Low-quality Hay Bright green Yellow or brown No weeds, dust, or mold Moldy or dusty Warm and dry to the touch Hot to the touch and/or moist Seed heads closed and leaves Seed heads open and leaves intact broken For horses that are fed in their stalls, hay nets or racks should be used to suspend the food above the animal’s shoulder level. This will prevent urine and manure from contaminating the feed. As a veterinary assistant, you should keep track of what a horse eats (or doesn’t eat) and how much. A sick horse may eat only part of its ration or may refuse to eat certain types of food. This information can be an important symptom for the veterinarian. Horses should have access at all times to fresh, clean water. In general, horses require an average of 5 to 10 gallons of water each day, and more in hot weather. Water should be provided in a 5-gallon container so that it will be easy to determine how much water an animal is drinking every day. Horses in a hospital setting may drink less because of stress or illness, or Chapter 1 Horses 13  because the water tastes different than what they drink at home. During the winter months, providing warm water will help increase a horse’s water consumption and reduce the risk of the horse developing colic. Water buckets should also be located at or above the horse’s shoulder level. Keep track of how much water a horse consumes each day and note this amount in the medical record. When recording a horse’s water intake, be sure to check the ground underneath the bucket for evidence that a considerable amount of water has been splashed on the ground rather than consumed by the horse. Grooming Horses should be groomed daily, not only to maintain cleanliness but also as a way of checking for any cuts, swelling, skin infections, discharges, or changes in the horse’s behavior. Grooming enhances a horse’s well-being, and many animals enjoy it. It is also an important part of client relations. A client who finds his or her animal well-groomed following a hospital stay or other veterinary care procedure will have a favorable impression of your practice and the service that you provide. A daily grooming routine has three basic steps: Curry combing. A rubber curry comb or mitt is used to loosen the dirt from the horse’s coat. Brushing. A variety of brushes are used to remove the loosened dirt, smooth the coat, and groom the mane and tail. Hoof cleaning. A hoof pick and brush are used to clean the hooves. This step is extremely important in detecting and treating thrush, a bacterial and fungal infection commonly found on a horse’s hooves. There are several different types of bristles used for grooming brushes. Stiff-bristled brushes should be used only on the fleshy parts of the body. The head, face, and lower limbs should only be groomed using soft-bristled brushes. 14 Veterinary Assistant Tasks in Large Animal Practice Proper hoof care is essential to prevent thrush, which is caused by bacteria that are naturally found in a horse’s environment, especially in wet or unsanitary conditions. Thrush is not difficult to treat, but if left untreated it can cause lameness. The most obvious sign of thrush is a bad odor that is noticed when picking out the feet. The affected tissues will be black and will break and crumble when picked out. If you detect signs of thrush, notify the veterinarian so that the horse can be treated as soon as possible. When grooming, remember that horses are powerful kickers. Never stand directly behind a horse. Also, the horse should be securely tied with either crossties or a quick-release knot. Make sure that your box or stool is placed where it will not be knocked over and where you will not trip over it. Equipment Required: Curry comb or mitt Body brush with fairly stiff bristles Mane and tail comb (plastic causes less breakage than metal) Fine soft-bristled finishing brush Hoof pick and brush Clean towels To groom a horse: Run the curry comb in a circular motion over the fleshy, muscular parts of the horse. Use a gentle touch 1 over the boney areas of the shoulders, hips, and legs. Do not use the curry comb on the lower legs and face. Use the body brush to remove the dirt brought to the 2 surface by the curry comb. Use sweeping strokes, and follow the direction of the hair growth. Use the finishing brush to brush the horse’s head, 3 face, and lower limbs. Use a dry towel to remove any dirt still remaining on 4 the surface of the coat. Chapter 1 Horses 15  Use a moist towel to clean any discharges from the eyes or 5 nose and around the tail. Use the mane and tail comb to comb the forelock, mane, and tail hairs by separating them into small sections and combing 6 each section individually. To brush the tail, stand to one side and pull the tail gently over to you to ensure that you are out of the way if the horse should kick. To clean a horse’s hooves: Starting with the left foreleg, lift the horse’s foot and support 1 the hoof with your legs. Use the hoof pick to remove any dirt, manure, or other debris from the sole of the foot and the frog, which is a piece of soft, 2 flexible horn that extends from the heel to midway toward the toe (see Figure 1.2). To help prevent bacterial and fungal infections, take care to clean the recesses of the hoof completely. Use the hoof brush and warm water to gently clean inside the 3 hoof. Wipe the hoof with a clean towel and allow it to air dry for 10 4 minutes. 5 Gently place the foot back on the ground Repeat the process for the remaining three hooves. 1 2 3 4 While cleaning a horse’s feet, check for any injuries and signs of thrush or other problems. Take note of any cracks in the wall of the hoof. These are usually treated by a farrier. 16 Veterinary Assistant Tasks in Large Animal Practice  Figure 1.2 Diagram of a Horse’s Hoof Coronary Band Horny Wall of Hoof Heel Toe Frog Sole Wall White Line To treat a horse for thrush: 1 Clean and dry the hoof. Use a cotton swab or gauze pad soaked in thrush medication to 2 swab all areas of the frog and any other affected areas. The swab will become darker as you work, which is a sign that 3 it is picking up dead tissue. Repeat the process, using fresh swabs, until the swab comes out 4 of the hoof clean. Allow the hoof to air dry for 10 minutes before walking the 5 horse back to its stall. This will avoid tracking dirt into the hoof before the medication dries. After a horse has been released from a veterinary hospital, that patient’s stall, grooming tools, feed and water buckets, and any medical equipment that was used should be thoroughly cleaned and disinfected. All organic waste and bedding should be removed and discarded before the stall is cleaned. If the stall floor and walls are concrete, you can use a hose to remove any dirt, debris, or organic material before a bleach or ammonia solution is applied to clean and disinfect the area. Disinfectant solution should be applied to all stall surfaces using brushes, mops, or brooms. Be sure to read the manufacturer’s instructions for the disinfectant that you are using. Most diluted disinfectants should be allowed to dry on treated surfaces. Chapter 1 Horses 17  Common Illnesses and Their Treatment Colic Overview: Colic is a general term for abdominal pain. In horses, it is caused by a variety of gastrointestinal conditions, including parasite infections, impacted food or sand in the colon, tumors and ulcers, gas, and part of the digestive tract twisting upon itself. Colic affects about 10% of horses, and it is the leading cause of premature death. Because there are so many possible causes of the condition, it is often difficult to tell the difference between colic that is relatively mild (e.g., caused by gas) and colic that may be life-threatening and requires emergency treatment (e.g., twisted gut). Therefore, it is important that you are able to recognize the signs of colic so that you can notify the veterinarian immediately. Symptoms: Biting and kicking at the abdomen, repeated lying down and rising, rolling, pacing, standing stretched out, frequent attempts to urinate, repeated curling of the upper lip, increased pulse, dark mucous membranes, loss of appetite, decreased fecal output, pawing the ground Diagnosis: The behavioral signs of colic are relatively easy to recognize; the trick is figuring out what is causing the pain. The veterinarian will visually examine the horse and listen to the abdomen using a stethoscope. Further diagnosis will depend on the suspected cause of the problem. Other tools include fecal flotation tests, radiographs, and in extreme cases exploratory surgery. Treatment: Treatment for colic depends on the condition that is causing it, but may include walking, analgesic or pain-relieving medication, a special diet, or surgery. The best way to deal with colic in a horse is to take measures to prevent it: Maintain a regular feeding schedule and restrict access to carbohydrates. Use an elevated feeding surface to prevent horses from ingesting dirt and sand. 18 Veterinary Assistant Tasks in Large Animal Practice  Do not feed the horse hay or grain that is moldy. Maintain a regular exercise routine. Make any exercise or dietary changes slowly. Provide regular dental care and deworming. Provide fresh, clean water at all times. Colitis Overview: Colitis, or inflammation of the colon, is a serious condition that can be caused by bacteria, viruses, or parasites. Colitis is potentially life-threatening due to fluid loss, shock, buildup of toxins in the blood, and electrolyte loss. It should be treated immediately. Symptoms: Diarrhea, fever, straining to defecate, abdominal pain. Any horse with diarrhea should be considered contagious and kept under quarantine. Diagnosis: Physical exam, blood and fecal testing Treatment: Antibiotics, analgesics, anti-inflammatories, oral and intravenous fluid therapy Equine Herpesvirus (also called equine viral rhinopneumonitis) Overview: Equine herpesvirus is a common, highly contagious disease that causes respiratory disease, neurologic disease, and abortion. Horses with the respiratory form of the disease may remain ill for 4 to 5 days. The neurological form of the disease is rare in horses; the recovery period can be 2 to 3 months, and the animals may never completely return to normal neurologic functioning. A vaccine is available to protect against the respiratory form of the disease, and vaccination is recommended for performance horses and brood mares. There is no vaccine available for the neurologic form of the disease. Symptoms: Respiratory: flu-like symptoms, depression; Neurologic: lack of coordination, fever, bladder dysfunction Chapter 1 Horses 19  Diagnosis: Blood testing, nose and throat swab Treatment: There is no cure for equine herpesvirus. Treatment includes fluid therapy and anti-inflammatory medication. Equine Viral Encephalitis Overview: Equine viral encephalitis is a disease that causes inflammation of the brain, leading to neurologic dysfunction and, often, death. It is transmitted by mosquitoes. There are three main types of equine viral encephalitis: Eastern, Western, and West Nile. Horses that contract Eastern equine encephalitis have a more than 75% mortality rate. Horses with Western and West Nile encephalitis have a better chance of survival, with mortality rates of 10% and 3 to 15%, respectively. The disease can be prevented through vaccination. It is recommended that horses are vaccinated 1 month prior to mosquito season. In areas where mosquitoes are prevalent year-round, such as the southern United States, horses should be vaccinated two to three times per year. Symptoms: Fever, depression, behavior changes, lack of coordination, paralysis, dementia Diagnosis: Blood test, spinal fluid test Treatment: There is no cure for equine viral encephalitis. Treatment includes supportive care to provide proper nutrition, hydration, and a clean, dry environment. Laminitis and Founder Overview: Laminitis is an acutely painful inflammation of the laminae—the soft tissues in a horse’s foot. The laminae connect the coffin bone to the hoof wall. As these tissues weaken, the coffin bone may become detached from the hoof wall, a condition known as founder. In extreme cases, the Laminitis coffin bone may rotate and penetrate the sole of the horse’s foot. 20 Veterinary Assistant Tasks in Large Animal Practice Laminitis and founder occur most often in the front Figure 1.3 Founder Stance feet, although they can affect the hind feet as well. Laminitis and founder are easier to prevent than they are to treat. Horses that are overweight, are fed too much grain, or do not receive proper hoof care have the greatest risk of developing the conditions. The best way to prevent laminitis and founder is by following proper feeding and hoof maintenance regimes. Symptoms: General symptoms of laminitis and founder include signs that the animal is in pain, such as sweating, walking tenderly, trembling, and flaring the nostrils. If only the front feet are affected, the horse will exhibit the “founder stance,” with its hind legs under its body supporting as much weight as possible and the forelegs forward with weight only on the heel. The horse will be reluctant to walk and will turn by pivoting on the hind legs. If all four feet are affected, the animal will lie on the ground whenever possible. If forced to rise, the animal will place all four feet close together under the center of its body. Diagnosis: Physical examination, radiographs Treatment: Anti-inflammatory and analgesic drugs, corrective trimming or shoeing, resecting or grooving the hoof wall Influenza Overview: Equine influenza (“horse flu”) is a highly contagious viral respiratory condition, which predisposes horses to contracting bacterial pneumonia. Horses between ages 1 and 5 are at the greatest risk. Animals generally remain ill for 3 to 4 days, but can spread the virus to other animals for up to 10 days. It takes 2 to 3 weeks for a horse to fully recover from influenza. There is a vaccine available to prevent the disease. Symptoms: Fever, cough, nasal discharge, reluctance to eat or drink, depression Chapter 1 Horses 21  Diagnosis: Physical examination, blood tests Treatment: Rest, antibiotics (if secondary infection is present) Potomac Horse Fever Overview: Potomac horse fever (PHF) is a bacterial infection that causes severe diarrhea and colic. Acute laminitis and founder develop in 20 to 40% of cases, and death occurs in about 30%. It is believed that horses acquire PHF by accidentally eating mayflies that carry the disease. There is a vaccine available, but it does not protect against all forms of the disease. Symptoms: Fever, depression, diarrhea, colic, decreased manure production, abortion in pregnant mares Diagnosis: Physical examination, blood and fecal tests Treatment: Antibiotics, intravenous fluids and electrolytes Rabies Overview: Rabies in horses is the same as rabies in small animals and people. After neurological signs appear, the disease is fatal in 3 to 10 days. Horses usually acquire rabies from being bitten by a rabid skunk, fox, raccoon, or bat. It is recommended that horses receive annual rabies vaccinations. When dealing with a rabies suspect, wear gloves, protective eyewear, and disposable outerwear and wash your hands thoroughly. Avoid contact with the animal’s saliva. Also, be aware that a horse with rabies can have erratic behavior and may be aggressive. Symptoms: Fever, lack of coordination and balance, hypersensitivity to touch, lameness, blindness, seizures, and behavioral changes Diagnosis: Testing brain tissue after death. If a horse is suspected of rabies, a list of all individuals who had contact with the animal must be kept and these individuals must be notified of the 22 Veterinary Assistant Tasks in Large Animal Practice results of the test. Rabies test results are usually available in 24 to 48 hours. If the tissue tests positive, anyone who had contact with the animal should receive a post-exposure rabies vaccination. Treatment: There is no cure for rabies. Euthanasia is indicated in any animals suspected of being rabid. Strangles Overview: Strangles is a common, highly contagious, bacterial respiratory disease. It causes the lymph nodes to swell, become abscessed, and burst. Horses younger than age 5 have the greatest risk of contracting strangles. If left untreated, complications from the disease may be fatal. Horses with strangles remain contagious for about 6 weeks after recovery, so any animal diagnosed with strangles should be kept under strict quarantine. A vaccine is available, but it does not guarantee immunity. Symptoms: Fever, depression, poor appetite, swelling and abscesses in the lymph nodes and under the jaw Diagnosis: Physical examination, throat culture Treatment: Draining the abscesses, antibiotics Preventive Healthcare Vaccinations A variety of vaccines are given to horses to prevent them from getting infectious disease and to prevent disease from spreading within a herd. All horses must be vaccinated against tetanus and Eastern, Western, and West Nile encephalitis. Many veterinarians also recommend that horses be vaccinated against influenza, rhinopneumonitis, and rabies. Other vaccines may be recommended, depending on a horse’s geographic location, age, and reproductive status. Table 1.3 lists the vaccines commonly given to horses and their frequency. Chapter 1 Horses 23 Table 1.3 Vaccines for Horses Vaccine Protects Against Frequency Bacterial infection Annually in high-risk areas Botulism causing muscle only weakness and paralysis Annually or twice annually Insect-borne viruses in areas where mosquitoes Eastern, Western, that cause are prevalent and/or the and West Nile inflammation of the disease is common encephalitis brain and attack the Horses should be vaccinated nervous system before the mosquito season begins in spring Equine herpesvirus Respiratory disease Quarterly Intranasal vaccine: Every 6 months Influenza Respiratory disease Intramuscular vaccine: Quarterly Bacterial disease Annually or twice annually Potomac horse fever causing diarrhea in high-risk areas Rabies Fatal viral disease Annually Annually Because of the risk of Strangles Respiratory disease serious side effects, many veterinarians recommend the vaccine only in high-risk cases Annually Bacteria that enter the Should be readministered body through wounds if the horse suffers a Tetanus and cause paralysis wound and has not been vaccinated during the preceding 6 months 24 Veterinary Assistant Tasks in Large Animal Practice Deworming Effective internal parasite control is essential for young horses’ growth and development, and it decreases the rate of colic and other disorders in all horses. Two strategies are used for parasite control in horses: daily deworming and interval deworming. The best strategy for a particular horse relies on a variety of factors, such as its age, whether or not it is new to the herd, and its deworming history. With daily deworming, a medication called pyrantel tartrate is added to a horse’s feed. The drug kills parasite larvae in the intestines, preventing them from migrating and causing further damage to the digestive system. Daily dewormer is effective against most major parasites. There are a few disadvantages to using a daily deworming system: The parasites may develop drug resistance because of constant exposure at low levels. Many horses will not eat feed that has dewormer added to it, or they may not eat a full dose of the drug. It is more expensive than interval deworming. With interval deworming, the horse is given a dose of a drug every 8 to 12 weeks. There are several different medicines that are used for interval deworming, and many veterinarians recommend rotating the product to prevent the parasites developing drug resistance. One disadvantage to interval deworming is that larvae may not be killed until a few weeks after they hatch. At a minimum, all horses should be on an interval program. In the northern United States, horses should be dewormed every 8 to 12 weeks from March to November. In the southern United States, where the climate is more agreeable to many parasites, horses should be dewormed year-round. Foals should start a deworming program at 8 weeks of age. Chapter 1 Horses 25  Foot Care As mentioned earlier in this chapter, regular foot care is essential to a horse’s health. The feet should be cleaned as part of a daily grooming routine and to remove packed dirt and mud from the sole and crevices around the frog. Even though the feet are likely to become packed again with dirt and mud, it will be fresh dirt, which carries a smaller risk of causing an infection, such as thrush. In addition to regular cleaning, thrush medication should be applied twice weekly to the soles and area surrounding the frog. A 50% bleach solution can also be used to prevent the infection from developing. Many horses wear horseshoes, which are U-shaped shoes usually made of metal and nailed or glued to a horse’s foot by a farrier. Horseshoes protect the feet of working animals, provide better traction, and can improve a horse’s gait. They are particularly beneficial for horses that are ridden on very hard or very soft terrain. There are also special correctional shoes available for horses with certain foot conditions. In general, a horse’s feet should be trimmed and reshod every 6 to 8 weeks. They may need to be trimmed more or less often depending on the animal’s exercise requirements, the time of year, and whether or not the horse is affected with laminitis. The purpose of trimming and shoeing is to maintain proper balance of the feet and the strength and integrity of the hoof wall. As a veterinary assistant, you should be able to evaluate a horse’s feet and gait to ensure that the shoes are fitted properly and are providing maximum benefit for the horse. Dental Care Because horses are grazing animals, their teeth continue to grow, or erupt, throughout their lifetimes. The constant grinding of roughage causes heavy wear on the teeth, and teeth that are not properly aligned can develop sharp, protruding surfaces. Signs that a horse’s teeth have become sharp and uncomfortable include dropping food while eating, weight loss, and chomping at the bit. To keep a horse’s teeth balanced and from becoming too sharp, they may be ground, filed, and cut. This is called dental balancing, and it should be done at least once annually. It has only been in the last several years that equine dentistry has become part of a horse’s regular care. It is now recommended that horses have a dental examination at least twice per year. 26 Veterinary Assistant Tasks in Large Animal Practice Nursing Care Administering Oral Medication The most reliable method of giving oral medication to a horse is using an oral dosing syringe. This type of syringe has a catheter tip with a thin, flexible tube for directing the medication into the mouth. Medications for horses come in tablets, powders, or pastes. For medications that come in tablet or powder form, the crushed-up tablets or powder should be mixed with water, honey, applesauce, or molasses to create a paste, which can then be administered using a dosing syringe. Horses should be medicated either before or at least 30 minutes after feeding. To give oral medication to a horse with a dosing syringe: 1 Fill the syringe with the paste containing the medication. Ask another person to help you control the horse’s head 2 movement by the holding the halter. 3 Stand next to the horse’s shoulder. Part the horse’s lips, by hooking your thumb into the corner of 4 the animal’s mouth. Insert the tip of the dosing syringe between the cheek and the 5 cheek teeth. Avoid the incisors, because the horse may use these teeth to bite and break the syringe. 6 Quickly depress the plunger. 1 2 3 4 5 6 Do not administer medication directly over the base of a horse’s tongue. The horse may be able to spit out the medication, or the paste may enter the trachea, which could cause choking. Chapter 1 Horses 27  Treating Limb Injuries A horse's legs, particularly the forelegs, are by far the most common sites for injuries. In addition to supporting 60% of the animal’s body weight, there are times during a horse’s stride when its entire weight is on one foreleg. This can result in both soft tissue injury and bone fractures. Horses also often sustain leg wounds from barbed wire, nails, fencing, glass, or metal. They run into things, step on sharp objects, or get stuck. Careful wound cleaning reduces the risk of infection and also allows you to examine the injured area. Wound Cleaning Supplies Required: Antiseptic scrub Clippers or a safety razor Syringe To clean a wound: 1 Make a solution of 1 part antiseptic to 10 parts water. Remove the hair around the wound using the clippers or safety 2 razor. 3 Fill the syringe with the antiseptic solution. 4 Gently flush the wound to remove dirt and debris. For wounds of the lower leg or those that are very dirty, hose 5 the area with cold water for 5 to 10 minutes. This will clean the wound while minimizing inflammation of area. 1 2 3 4 5 28 Veterinary Assistant Tasks in Large Animal Practice Bandaging Bandages are applied to keep wounds clean, reduce swelling, and provide leg support. There are four types of bandage applied to a horse’s lower limbs: A basic bandage covers the area from just under the knee (foreleg) or hock (hind leg) to the fetlock. A basic bandage should be applied if there are wounds or swelling in this area. A sweat bandage draws out fluids and reduces swelling by creating heat over the limb. A sweat bandage should be applied if the skin under a wound becomes infected or if there is excessive swelling and inflammation. A full, or stack, bandage covers the leg from several inches above the knee or hock down to the fetlock. A full bandage is similar to a basic bandage, but is used for wounds or swelling above the knees and hocks. A foot bandage covers the entire hoof, with extra layers underneath the foot to help keep it intact. A foot bandage is used for wounds of the coronary band, hoof, and lower pastern. Figure 1.4 The Parts of a Horse’s Lower Leg Cannon Bone Fetlock Joint Proximal Sesamoid Bones Long Pastern Pastern Joint Short Pastern Coffin Joint Extensor Process Navicular Bone Pedal Bone Palmer Process Chapter 1 Horses 29  Applying a Basic Bandage Supplies Required: Sheet cotton Brown gauze Vetrap Self-adhesive elastic bandage To apply a basic bandage: Wrap the sheet cotton three times around the horse’s leg, extending from just below the knee or hock to over the fetlock 1 (the fetlock should be covered). Wrap snugly and smoothly so that there are no wrinkles beneath the final bandage. Starting at the middle of the cannon bone, wrap the brown gauze around the leg in a spiral fashion: wrap downward toward the fetlock, then upward, ending below the knee. Soft tissue injuries can occur if the gauze is applied directly to the 2 skin, so you should leave about 1 inch of sheet cotton exposed at the top and bottom of the wrap. The wrap should be snug, but not too tight—you should be able to slide two fingers underneath the sheet cotton. Follow the same procedure with the Vetrap, taking care to 3 ensure the wrap is smooth and snug. Secure the top and bottom of the bandage using the 4 self-adhesive elastic bandage. This will hold the wrap in place and help to keep the wound clean. 1 2 3 4 30 Veterinary Assistant Tasks in Large Animal Practice Applying a Sweat Wrap Supplies Required: Nitrofurazone ointment Plastic wrap Sheet cotton Brown gauze Vetrap Self-adhesive elastic bandage To apply a sweat wrap: 1 Apply a thick layer of ointment to the affected area of skin. Cover the treated skin area with a loosely applied sheet of 2 plastic wrap. 3 Wrap a basic bandage over the top of the plastic. 1 2 3 Chapter 1 Horses 31  Applying a Full Bandage A full bandage consists of two parts: A basic bandage applied to the lower leg An upper bandage that overlaps the basic bandage The same supplies used for the basic bandage are required for the full bandage. To apply a full bandage: 1 Apply a basic bandage to the lower leg. Wrap sheet cotton three times around the leg. The sheet cotton should cover an area from the middle of the lower leg to several 2 inches above the knee or hock. This will include a portion of the basic bandage. Wrap the brown gauze in a spiral fashion around the upper leg. Use a figure-8 pattern over the joint so that you avoid covering 3 the accessory carpal bone (the bone that protrudes from the back of the leg). This will help prevent pressure sores in the area. Wrap the Vetrap in the same spiral pattern, again using a 4 figure-8 over the knee. Secure the top of the bandage with the self-adhesive elastic 5 bandage. 1 2 3 4 5 32 Veterinary Assistant Tasks in Large Animal Practice Applying a Foot Bandage A foot bandage should cover the horse’s entire foot and pad the sole well enough to prevent the horse from walking through it. To prevent the bandage from getting wet, it is sealed using duct tape. Supplies Required: Sheet cotton 6-inch (15 cm) brown gauze Vetrap Duct tape Self-adhesive tape To apply a foot bandage: 1 Lift the horse’s foot off the ground. Wrap sheet cotton three times around the hoof and lower leg, 2 from just below the fetlock to 5 or 6 inches (13–15 cm) beyond the bottom of the foot. Beginning at the pastern, wrap the brown gauze in a spiral pattern around the leg and foot. As you wrap, fold the excess 3 sheet cotton over the bottom of the foot and wrap it in brown gauze. This extra sheet cotton will provide several layers of padding for the sole. Wrap the Vetrap in a spiral pattern to completely cover the 4 pastern and foot. 5 Cover the bottom of the foot with duct tape. Secure the top of the bandage with several layers of 6 self-adhesive tape. 1 2 3 4 5 6 Chapter 1 Horses 33  Preparation for Surgery In large animals, there are considerable risks involved in general anesthesia. For example, horses with colic may also be experiencing severe shock, which complicates the administration and effects of anesthesia. Patients that are very sick, debilitated, or elderly have even higher associated risks. Therefore, most surgeries on large animals are performed with the animals awake and standing. This is called standing surgery. The most common standing surgeries performed on horses include the treatment of traumatic injuries, castration of males, and female reproductive surgery. In addition to decreased risk, standing surgery is also generally less expensive than surgery under general anesthesia: it requires fewer staff members, fewer drugs, and less patient monitoring. There are, however, some disadvantages to standing surgery. The lighting in a stall is not as good as in an operating theater, it is more difficult to maintain a sterile surgical field, and there is always the possibility of the patient moving, even when under heavy sedation and physical restraint. There are many factors that contribute to the anesthesia procedures used for a particular animal. In addition, veterinarians tend to vary greatly in terms of how patients are prepared, anesthesia is administered and maintained, and patients are cared for during recovery. The following sections provide some general guidelines, but you should become familiar with the procedures used at your practice. Standing Surgery To ensure proper metabolism of any medications given, food should be withheld prior to surgery. Your veterinary practice will have its own guidelines for restricting food intake, but in general grain should be withheld for 12 hours and only small amounts of hay should be provided until 2 to 6 hours prior to the procedure. It is not usually necessary to withhold water. Standing surgeries should be performed in a clean, dry, and dust- and draft-free environment. All instruments and packs should be elevated (e.g., on a stool covered with a towel) so that they do not get contaminated with dust or debris. 34 Veterinary Assistant Tasks in Large Animal Practice Restraint of the patient will depend on several factors, including the following: Location and duration of the procedure Amount of pain involved Horse’s temperament Number of staff available to assist with the procedure Chemical restraint (sedation or tranquilization) is often used, and local anesthesia is usually given for pain control. There are several types of local anesthesia: Nerve blocks. A local anesthetic drug is administered over a nerve using a hypodermic needle. The drug diffuses over the nerve and blocks it from transmitting pain impulses. Field blocks. A field block anesthetizes the skin and soft tissues around a surgical area without blocking specific nerves. This type of anesthetic is often used for suturing wounds. Epidural anesthesia. An anesthetic is injected into the space surrounding the spinal fluid sac of the vertebrae. An epidural is usually used in procedures involving the tail, anus, rectum, and female reproductive organs. Postoperative Care If the patient was given a sedative or tranquilizer before surgery, food and water should not be given until swallowing has returned to normal. Initially, water should be given only a few sips at a time. If the horse can swallow without coughing, hay may be given within 1 to 2 hours. Full rations of grain should not be given until 24 hours following surgery, and patients should be monitored closely during this time for urine and fecal output. Surgery under Gene