Fundamentals of Small Animal Surgery E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 460

Veröffentlichungsjahr: 2011

Beschreibung

Fundamentals of Small Animal Surgery offers a thorough introduction to the surgical principles essential to good veterinary practice. With many high-quality pencil drawings and clinical photographs to complement the detailed descriptions, the book is a useful resource for building basic surgery skills. Fundamentals of Small Animal Surgery is designed to provide a grounding in the foundations of veterinary surgical practice and an understanding of the practical application of surgical techniques. Covering topics ranging from assessment and surgical pack preparation to aseptic technique and postoperative pain management, the book is a valuable reference for surgical procedure training in veterinary or veterinary technician schools, and serves as a refresher for veterinarians and technicians in practice.

Leseprobe

Contents

Contributors

Preface

Acknowledgments

Chapter 1: Preoperative Patient Assessment

History

Physical Examination

Laboratory Data

Diagnostic Imaging

Assessment of Anesthetic and Surgical Risk

Chapter 2: Basic Small Animal Anesthesia

Drugs Used in Small Animal Anesthesia

Step-by-Step Approach to Anesthetizing the Small Animal Patient

Chapter 3: Asepsis in Small Animal Surgery

Chapter 4: Antibiotic use in Small Animal Surgery

Chapter 5: Basic Surgical Instruments

Chapter 6: Pack Preparation for Sterilization

Chapter 7: Operating Room Protocol

Chapter 8: Surgical Attire

Chapter 9: Scrubbing, Gowning, and Gloving

Chapter 10: Surgical Preparation and Animal Positioning

Chapter 11: Surgical Draping

Chapter 12: Instrument Handling

Chapter 13: Surgical Knot Tying

Chapter 14: Suture Materials and Basic Suture Patterns

Absorbable Suture Materials

Nonabsorbable Suture Materials

Basic Suture Patterns

Chapter 15: Basic Wound Healing and Wound Closure

Inflammation and Debridement Phase

Repair (Proliferative) Phase

Maturation Phase

Wound Closure

Management of Acute Traumatic Wounds and Deciding when and How to Close Them

Additional Resources

Chapter 16: Surgical Hemostasis

Hemostasis

Control of Surgical Hemorrhage

Direct Pressure and Hemostatic Forceps

Electrosurgery

Radiosurgery

Feedback-Monitored Bipolar Forceps

Ultrasonically Activated Scalpel

Surgical Lasers

Vessel Ligation

Hemostatic Agents

Acknowledgment

Chapter 17: Surgical Tubes and Drains

Intranasal Tubes

Thoracostomy Tubes

Tracheostomy Tubes

Cystostomy Tubes

Esophagostomy Tubes

Gastrostomy Tubes

Jejunostomy Tubes

Wound Drains

Chapter 18: Canine Ovariohysterectomy

Chapter 19: Postoperative Pain Management

Pathophysiology of Acute Pain

Local Anesthetics

Opioids

Nonsteroidal Anti-Inflammatory Drugs

N-Methyl-D-Aspartate Receptor Antagonists

Alpha-Two Agonists

Constant Rate Infusion

Conclusions

Chapter 20: Patient Aftercare and Followup

Immediately Postoperative Care

Nutritional Support

Physical Activity

Followup

Index

This edition first published 2011 © 2011 by Blackwell Publishing Ltd.

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Library of Congress Cataloging-in-Publication Data

Mann, Fred Anthony.

Fundamentals of small animal surgery / Fred Anthony Mann, Gheorghe M. Constantinescu, Hun-Young Yoon.

p. ; cm.

Includes bibliographical references and index.

Summary: “Fundamentals of Small Animal Surgery offers a thorough introduction to the surgical principles essential to good veterinary practice. With many high–quality line drawings and clinical photographs to complement the detailed descriptions, the book is a useful resource for building basic surgery skills. Covering topics ranging from assessment and surgical pack preparation to aseptic techniques and postoperative pain management, the book is a valuable reference for surgical procedure training in veterinary or veterinary technician schools, and serves as a refresher for veterinarians and technicians in practice.” –Provided by publisher.

ISBN 978-0-7817-6118-5 (pbk. : alk. paper) 1. Veterinary surgery. 2. Pet medicine. I. Constantinescu, Gheorghe M., 1932- II. Yoon, Hun-Young. III. Title.

[DNLM: 1. Animal Diseases-surgery. 2. Animals, Domestic–surgery. 3. Surgical Procedures, Operative–veterinary. SF911]

SF981.M257 2011

636.089’7–dc22

2010042173

A catalogue record for this book is available from the British Library.

Dedications

We, the authors, dedicate this textbook to all of the students who we have had the pleasure of training in the art and science of small animal surgery and to all of those companion animals who have benefitted from their surgical skills. The authors also state the following individual dedications.

I dedicate this textbook to my loving wife, Dr. Colette Wagner-Mann, my son, Lucas Mann, and my daughter, Danielle Mann. I thank them for their love, understanding, and patience as I have dedicated enormous amounts of time to veterinary student education, including the production of this textbook.

My contribution to this book as an anatomist and medical illustrator started long ago and was encouraged by my wife, Dr. Ileana Constantinescu, whom I thank warmly for her unlimited support, understanding, and sacrifice. I dedicate this book to her, to my son Dr. Razvan Constantinescu and daughter Adina Klima, and their families.

I would like to thank my wonderful family, my wife, Kyunghwa Kim, and my son, Dongbin Yoon, for their support and encouragement during production of this textbook.

Contributors

Gheorghe M. Constantinescu, DVM, PhD, mult Drhc

Professor of Veterinary Anatomy and Medical Illustrator

Department of Biomedical Sciences College of Veterinary Medicine

University of Missouri Columbia, Missouri

John R. Dodam, DVM, MS, PhD, Diplomate ACVA

Associate Professor Chairman

Department of Veterinary Medicine and Surgery

Veterinary Medical Teaching Hospital College of Veterinary Medicine University of Missouri Columbia, Missouri

Fred Anthony Mann, DVM, MS, Diplomate ACVS, Diplomate ACVECC

Director of Small Animal Emergency and Critical Care Services

Small Animal Soft Tissue Surgery Service Chief Professor

Department of Veterinary Medicine and Surgery

Veterinary Medical Teaching Hospital College of Veterinary Medicine

University of Missouri Columbia, Missouri

John P. Punke, DVM

Small Animal Surgery Resident Department of Veterinary Medicine and Surgery

Veterinary Medical Teaching Hospital College of Veterinary Medicine

University of Missouri Columbia, Missouri

Carlos H. de M. Souza, DVM, MS, Diplomate ACVIM (Oncology)

Assistant Professor of Small Animal Surgery Department of Veterinary Medicine and Surgery

Veterinary Medical Teaching Hospital College of Veterinary Medicine

University of Missouri Columbia, Missouri

Elizabeth A. Swanson, DVM

Small Animal Surgery Resident

Department of Veterinary Clinical Sciences Veterinary Teaching Hospital School of Veterinary Medicine Purdue University West Lafayette, Indiana

Hun-Young Yoon, DVM, MS, PhD

Research Professor

College of Veterinary Medicine

Veterinary Science Research Institute

Konkuk University

Seoul, South Korea

Preface

Today, owners of dogs and cats typically consider their pets to be members of the family. As such, the pet-owning public expects access to the same level of medical and surgical care that is available to human beings. Further, the general public expects veterinarians to have a certain level of surgical competence immediately upon graduation from veterinary school. To that end, veterinary educators are charged with preparing veterinary students to be competent surgeons. Competent surgery begins with a thorough knowledge of surgical principles and proficiency in basic surgical techniques. This textbook is intended to facilitate the initial stages of surgical training and to serve as a refresher to those in the profession who may have had little surgical experience since veterinary or veterinary technician schooling. It is the authors’ hope that those studying to be veterinarians and veterinary technicians will find this textbook to be a helpful complement to their instruction and that graduate veterinarians and veterinary technicians will find this textbook to be valuable in postgraduate in-service training for veterinary staff.

Acknowledgments

We thank the following individuals for assistance with photography, artwork, and portions of some chapters:

Mr. Howard Wilson

Senior Multimedia Specialist

College of Veterinary Medicine

University of Missouri

Columbia, Missouri

[Photographic and artistic assistance]

Mr. Donald L. Connor

Senior Multimedia Specialist

College of Veterinary Medicine

University of Missouri

Columbia, Missouri

[Artistic assistance]

Linda M. Berent, DVM, PhD, Diplomate

ACVP (Clinical and Anatomic Pathology)

Clinical Assistant Professor

Department of Veterinary Pathobiology

College of Veterinary Medicine

University of Missouri

Columbia, Missouri

[Assistance in assuring accuracy in the first section of Chapter 16]

Eric A. Rowe, DVM

Small Animal Surgery Resident

Department of Clinical Sciences

Veterinary Teaching Hospital

College of Veterinary Medicine

North Carolina State University

Raleigh, North Carolina

[Assistance with portions of Chapters 3, 7,

and 17 while employed as a Small Animal

Soft Tissue Research/Teaching Intern at the

University of Missouri, Columbia, Missouri]

Last, but not least, we extend our thanks and appreciation to Nancy Turner, Development Editor for Health Sciences, Wiley-Blackwell, Ames, Iowa, for her patience with the authors, assistance in attention to details, guidance through the publication process, and dedication to making this work the best it can be. We also thank the staff of Wiley-Blackwell for making this book a reality.

Chapter 1

Preoperative Patient Assessment

Elizabeth A. Swanson and Fred Anthony Mann

In general practice, the veterinarian often already knows the patient being presented for surgery. Even so, the veterinarian should take this opportunity to instill a sense of confidence and firmly establish a solid veterinarian-client–patient relationship. To that end, a complete history and physical examination are paramount in the surgeon’s toolbox of information about the patient. The history and physical examination will determine whether a patient is a good candidate for surgery, will determine what further tests are necessary prior to anesthesia, and will allow the veterinarian to give the owner an accurate assessment of what to expect. The information gained also helps to guide decision-making regarding anesthetic protocol, type of procedure to be performed, pain management, and postoperative care. In short, nothing can replace a thorough history and physical examination in establishing a base of information about the patient that can be used for perioperative decision making.

History

Even when the patient is known to the surgeon, a current and detailed patient history should be obtained from the owner at the time of presentation. The presenting complaint is ascertained and details recorded on the duration of the problem, what clinical signs have been observed, and whether the owner feels the problem is better, worse, or the same as when it was first noticed. Such historical information may not be pertinent for a healthy dog or cat being presented for elective ovariohysterectomy or orchiectomy; however, it is necessary to make certain that there have been no changes in the patient’s health status prior to surgery. In addition, for dogs and cats presenting for ovariohysterectomy, it is important to always ask about when the animal was last in heat and if there is a possibility that the animal is pregnant.

Other information gathered when taking the history includes environment, diet, patient lifestyle, any current or previous medical conditions, previous surgeries, current medications (including over-the-counter medications, supplements, and heartworm and flea/tick preven-tatives), and adverse reactions to medication. Appetite, drinking, urination, defecation, and occurrences of coughing, sneezing, vomiting and/or diarrhea are also noted.

Medical information may lead the veterinarian to identify previously undiagnosed disorders, such as hyperthyroidism in a geriatric cat presented for dental prophylaxis with increased appetite and concurrent weight loss. Patient lifestyle can play a huge role in determining which procedure should be performed. For example, external fixation of a tibial fracture in a free-roaming farm dog may not be the best option for healing and management of that fracture.

In the case of an emergency, basic information should include signalment, the presenting complaint, major concurrent medical conditions, current medications, and drug sensitivities. The remainder of the history may be obtained at the first available opportunity.

Physical Examination

The physical examination may commence once the history has been taken. A more experienced practitioner will be able to begin the physical examination while still taking the history, a practice that can be most beneficial for triag-ing emergency cases. The importance of a good physical examination cannot be overly stressed. A thorough physical examination can identify both major and subtle changes in a patient’s condition that may affect what is done for that patient. The finding of a swollen vulva in an intact female dog presented for ovariohysterec-tomy may lead the veterinarian to discuss with the owner the increased risk of hemorrhage and, potentially, the recommendation to postpone the surgery.

A consistent, systematic approach is recommended for physical examination. Important developments may be missed when the examiner makes the mistake of focusing only on the presenting problem. A full examination consists of close inspection of the head and neck (eyes, ears, nose, oral cavity), lymph nodes, cardiovascular system, respiratory system, digestive tract, urogenital system, integument, musculoskeletal system, and neural system. The precise order of the examination is not dictated, but to ensure that no system is missed, the examiner should establish an order and remain consistent from one patient to the next.

Laboratory Data

Findings during the history and physical examination will help determine which laboratory data are necessary. For a young, healthy animal less than five years of age that is presented for elective surgery, a laboratory baseline of packed cell volume (PCV), total protein (TP), blood urea nitrogen (BUN) or creatinine, blood glucose, and urine specific gravity will typically suffice. Full laboratory work-up, including complete blood cell count (CBC), serum chemistries, electrolytes, and urinalysis, are in order for patients older than five years and any sick or debilitated patient. A recent heart-worm test should be required for patients who have lived or traveled in endemic areas. All cats should be tested for feline leukemia and feline immunodeficiency virus if they have not previously been tested. Cats that have access to the outside or that come in regular contact with an outdoor cat should be tested annually. Additional tests may be run in patients with specific medical conditions.

Advanced laboratory tests may be indicated in certain conditions. Breeds that have a high incidence of von Willebrand’s Disease, such as Doberman pinschers, should have a buccal mu-cosal bleeding time (BMBT) performed as part of the preoperative work-up before any surgery, elective or otherwise, is performed, even if there is no history of abnormal bleeding tendencies. A prolonged BMBT (>5 minutes) indicates further testing, such as for von Willebrand’s factor (vWF). An elective procedure may be postponed pending further information. If surgery is required and the patient is suspected to have Type I (low concentration of vWF) von Willebrand’s disease, the animal may be pre-treated with desmopressin acetate (1-deamino-8-D-arginine vasopression, also called DDAVP) or administered cryoprecipitate. Fresh whole blood, fresh frozen plasma, or cryoprecipitate may be necessary if significant hemorrhage occurs or in dogs with Type II (low concentration of large multimers of vWF) or Type III (complete absence or only trace amounts of vWF) von Willebrand’s disease. If time allows, desmopressin can also be administered to a blood donor 30–120 minutes prior to blood collection. The BMBT is also indicated to assess the bleeding tendency of patients with suspected thrombocytopathia, such as dogs that have been treated with aspirin.

Platelet counts and coagulation panels are necessary for any patient showing signs of easy bruising, ecchymoses, or petechia pre- or post-operatively. Platelet counts and coagulation panels should also be run for patients undergoing procedures where significant hemorrhage is possible and adequate hemostasis may not be directly achieved, such as for liver biopsies obtained via laparoscopy or ultrasound-guided needle biopsy. If a coagulopathy is diagnosed, fresh frozen plasma should be administered to provide coagulation factors. Also, transfusion of fresh whole blood may be necessary to stabilize a patient with thrombocytopenia. It is important to realize that whole blood, platelet-rich plasma, and platelets do not significantly raise the platelet count.

Arterial blood gas analysis and acid–base status should be evaluated in patients with suspected hypoxia or hypoventilation, such as patients with pulmonary disease (i.e., aspiration pneumonia, pulmonary edema, thromboem-bolism), pneumothorax, pleural effusion, and in critical patients that are in shock, are septic, or are showing signs of systemic inflammatory response syndrome. The arterial partial pressure of oxygen (PaO2), the arterial partial pressure of carbon dioxide (PaCO2), pH, bicarbonate concentration ([HCCO3–]), base excess (BE), anion gap, and electrolyte concentrations can be interpreted together to evaluate respiratory function and to determine the cause of acid–base imbalance. Blood gas analysis is used to help determine what, if any, supplemental therapy is necessary and to help monitor the response to treatment.

Critical patients, especially those with effusive disease processes, such as peritonitis, protein-losing enteropathy, generalized lym-phangiectasia, and burns, may lose a large amount of protein into the effusion through leaky bloodvessels. Loss of protein, especially albumin, causes movement of intravascular fluid into the interstitium (edema) or body cavities via osmosis. The pressure exerted within the blood vessels by albumin and other colloids is called colloid oncotic pressure (COP), which can be measured from a patient’s whole blood sample. The measurement of COP is used to help direct fluid therapy, particularly the use of colloids, such as hetastarch, dextran, whole blood, and plasma.

Diagnostic Imaging

Diagnostic imaging is not routinely performed prior to elective procedures in healthy animals. Other conditions, however, benefit from data obtained through radiography, ultrasonogra-phy, and more advanced imaging modalities, including computed tomography and magnetic resonance imaging (MRI). Patients undergoing surgery as therapy for neoplasia should be staged according to the suspected tumor type, and diagnostic imaging is part of the staging process. Minimal data obtained for oncological surgery patients should include CBC, serum chemistries, urinalysis, thoracic radiographs (right and left lateral views and ventrodorsal view), right lateral and ventrodorsal abdominal radiographs, and abdominal ultrasound. Computed tomography or MRI, whichever is more appropriate for the given situation, is used to map tumors and help plan surgical margins.

The minimal database for trauma patients should include PCV/TP, BUN, blood glucose, urine specific gravity, right lateral and ventrodorsal thoracic and abdominal radiographs, and sometimes abdominal ultrasound. Diaphragmatic continuity, body wall continuity, and the presence of a urinary bladder should be assessed, in addition to looking for pneu-mothorax, pleural and peritoneal effusion, and pulmonary contusions.

While orthogonal views are always preferred when interpreting radiographs, obtaining a right lateral radiograph of a critical, bloating dog will usually suffice in diagnosing gastric dilatation-volvulus (GDV). Right and left lateral and ventrodorsal thoracic radiographs should also be taken in geriatric dogs with GDV to evaluate for evidence of neoplasia, because the presence of neoplasia may influence owner decisions. Of course, the GDV patient must be stable enough to take additional radiographs prior to surgery.

Patients with a heart murmur or known cardiac disease should have right lateral and either ventrodorsal or dorsoventral thoracic radiographs taken and, if indicated, an echocardio-gram performed prior to anesthesia. Right lateral and ventrodorsal thoracic radiographs are indicated for any vomiting or regurgitating patient to assess for aspiration pneumonia and for patients that develop an increased respiratory effort or respiratory distress during treatment.

Various forms of contrast radiography are used in the diagnosis of medical problems. Videofluoroscopy can be used to evaluate esophageal function and gastric emptying times. Oral administration of barium with sequential right lateral and ventrodorsal abdominal radiographs is used to evaluate gastrointestinal motility and to identify gastrointestinal obstruction, such as from a foreign object or tumor. Excretory urography is useful in evaluating renal function of the opposite kidney prior to nephrectomy if renal function is questionable. Evaluation of the urinary bladder and urethra for tumors, tears, and luminal filling defects is performed, using positive-contrast cys-tourethography.

Postoperative radiographs are indicated for any orthopedic procedure where metal implants are used or removed. Radiographs are also taken after cystotomy to document removal of uroliths from the urinary bladder. Proper na-sogastric and esophageal feeding tube position and percutaneous chest tube placement should be checked radiographically with orthogonal thoracic views.

Assessment of Anesthetic and Surgical Risk

Once the full picture has been obtained, as appropriate for the patient and situation, the patient’s anesthetic and surgical risk is assessed. In 1963, the American Society of Anesthesiologists developed a simple classification system by which to determine a patient’s physical status and potential risk for complications. These same criteria have been adapted for use in veterinary medicine (Table 1.1). In general, no adjustment to the anesthetic protocol is considered unless a patient is classified as Physical Status 3 or higher. In human medicine, a sixth level has been added to include brain-dead patients whose organs are being removed for donation. The letter E is used to denote an emergent case. For example, most cases of gastric dilatation-volvulus would be designated as physical status 4-E.

Clients should be alerted to the possible complications of the procedure to be performed and the relative likelihood of adverse events. Even routine, elective procedures carry risk, and it is wrong not to inform the client. For all patients, general anesthesia poses risk of death, albeit minor in healthy animals. Common risks, such as hemorrhage, incisional dehiscence, and postoperative infection of the surgical wound, should always be discussed, in addition to any complications specific to the procedure performed. A well-informed client is in a better position to recognize and handle complications than one who is not.

Table 1.1 Physical status classification systema

Physical statusPatient conditionExamples1Normal, healthy patientElective ovariohysterectomy; elective orchiectomy2Patient with localized disease or mild systemic diseaseFractures; cranial cruciate ligament rupture; skin laceration; skin mass removal (E: Open fracture)3Patient with severe systemic diseaseRenal failure; fever; hyperadrenocorticism; dehydration; anemia (E: Gastrointestinal perforation)4Patient with severe systemic disease that is a constant threat to lifeAny condition prone to developing systemic inflammatory response; heart failure (E: Gastric dilatation-volvulus)5Moribund patient not expected to live with or without the operationSystemic inflammatory response that is progressing toward multiple organ dysfunction; trauma with decompensatory shock (E: Intestinal volvulus)6Brain-dead patient whose organs may be removed for donation purposesCurrently no veterinary examples

Use “E” after the appropriate classification to denote an emergency operation

aBased on Classification of Physical Status. ASA Relative Value Guide. 2009.

(www.asahq.org/clinical/physicalstatus.htm) of the American Society of Anesthesiologists. A copy of the full text can be obtained from ASA, 520 N. Northwest Highway, Park Ridge, Illinois 60068-2573.

References

1. Muir WW. Considerations for general anesthesia. In: Tranquilli WJ, Thurmon JC, Grimm KA, eds. Lumb & Jones Veterinary Anesthesia and Analgesia, 4th ed. Ames, Iowa: Blackwell Professional Pub lishing, 2009:17.

2. Muir WW, Hubbell JAE, Bednarski RM, Skarda RT. Patient evaluation and preparation. In: Muir WW, Hubbell JAE, Bednarski RM, Skarda RT, eds. Handbook of Veterinary Anesthesia, 4th ed. St. Louis, Missouri: Mosby Elsevier, 2007:22.

Additional Resources

Additional information about preoperative patient assessment in small animal surgery can be found in the following textbook chapters:

1. Fossum TW. Preoperative and intraoperative care of the surgical patient. In: Fossum TW, ed. Small Animal Surgery, 3rd ed. St. Louis, Missouri: Mosby Elsevier, 2007:22–31.

2. Shmon C. Assessment and preparation of the surgical patient and operating team. In: Slatter D, ed. Textbook of Small Animal Surgery, 3rd ed. Philadelphia, Pennsylvania: Saunders, 2003;162–168.

3. Brooks M. von Willebrand Disease. In: Feldman BF, ZinklJG,Jain NC, eds. Schalm’s Veterinary Hematology, 5th ed. Baltimore, Maryland: Lippincott Williams & Wilkins, 2000:509–515.

Chapter 2

Basic Small Animal Anesthesia

John R. Dodam and Fred Anthony Mann

A single chapter cannot provide a comprehensive review of small animal anesthesia. Instead, this chapter will attempt to provide a procedural framework that can be expanded and modified to fit the needs and goals of the surgeon and anesthetist. The procedural framework will be based upon an anesthetic protocol that includes preoperative assessment of the patient; premedication with sedative, analgesic, and/or anticholinergic agents; induction of unconsciousness by intravenous injection of a hypnotic, sedative, or dissociative agent; maintenance of anesthesia with an inhalant anesthetic; and recovery of the patient.

Drugs Used in Small Animal Anesthesia

The following is a summary of the classes of drugs used for premedication, induction, or maintenance of anesthesia. Please consult an appropriate resource for more detailed information concerning any of the listed agents, specific drug combinations, or for appropriate dosing recommendations.

Drugs used in anesthesia premedication are usually given by intramuscular or subcutaneous injection 20–40 minutes prior to the induction of general anesthesia. Premedication of the patient is important from a logistical standpoint because the drugs may sedate or calm the patient, decrease the level of physical restraint required, and facilitate catheter placement. Importantly, anesthesia premedication drugs may improve the quality of anesthetic induction and/or recovery and decrease the requirement for induction or maintenance anesthetics. Premedication drugs may also be used to provide preemptive analgesia. Indeed, the administration of analgesic drugs prior to a surgical insult may improve the effectiveness of postoperative interventions aimed at treating a patient’s postoperative pain. Premedication drugs may also be used to modify autonomic tone, stabilize or increase heart rate, or decrease salivary secretions.

Anticholinergics

Anticholinergic agents like atropine or gly-copyrrolate interfere with the action of acetylcholine at muscarinic receptors of the autonomic nervous system. Thus, these agents are used to increase heart rate (or prevent bradycardia) and decrease salivary and respiratory secretions. They also increase gastric pH, decrease gastrointestinal motility, and evoke bronchodilation. Although many veterinarians use these agents routinely as part of premedica-tion protocols, others prefer to use them only as needed to treat bradycardia. Both atropine and glycopyrrolate can cause tachycardia and/or ventricular dysrhythmias, but the risk is higher after intravenous injection than intramuscular or subcutaneous administration. Glycopyrrolate has a longer duration of action than atropine and does not cause central nervous system effects. Atropine has a shorter onset time than glycopyrrolate. For these reasons, glycopyrrolate is often preferred as part of an anesthesia premedication protocol, while atropine is preferred for emergency treatment of life-threatening bradycardia.

Phenothiazines

Acepromazine is a phenothiazine tranquilizer that produces mental calming without providing analgesia. It decreases histamine release, has antidysrhythmic properties, and has been reported to decrease mortality associated with anesthesia. However, acepromazine causes va-sodilatation, hypotension, hypothermia, and decreased platelet function, and may decrease seizure threshold. Acepromazine is commonly used with opioids as part of premedication protocols, and because of its long duration of action, premedication with acepromazine may help to smooth postoperative recoveries.

Benzodiazepines

Benzodiazepine drugs (e.g., diazepam, mida-zolam, and zolazepam) are tranquilizers frequently paired with dissociative agents (e.g., ketamine and tiletamine) to induce anesthesia. Benzodiazepines are not typically given alone for preoperative sedation because they are relatively ineffective unless an animal is depressed, very young, or very old. Paradoxically, benzodiazepines can cause excitement in some animals when given alone. Moreover, diazepam is not absorbed predictably after intramuscular injection. When combined with induction agents, benzodiazepines decrease the required doses of those agents, provide for muscle relaxation, and have minor effects on the cardiovascular system. Benzodiazepines are also frequently used for their anticonvulsant properties. The actions of benzodiazepine drugs are reversible with administration of flumazenil, a specific antagonist.

Alpha-Two Agonists

Alpha-two agonists (e.g., xylazine and dexmede-tomidine) decrease the release of norepine-phrine in the central nervous system. This effect causes reliable sedation, analgesia, and muscle relaxation, and greatly decreases the requirements for other anesthetic agents. Alpha-two agonists cause cardiovascular changes that are characterized by bradycardia, bipha-sic blood pressure changes (hypertension followed by hypotension), and a significant decrease in cardiac output. These drugs also cause hyperglycemia, diuresis, and decreased gastrointestinal motility. Emesis is common when low doses of these drugs are given by the intramuscular or subcutaneous route. Xylazine is shorter-acting than dexmedetomidine and is more likely to be associated with cardiac dysrhythmias. The effects of alpha-two agonists can be reversed by specific antagonists. The effects of xylazine are typically reversed in small animal patients with yohimbine, while dexmedetomidine effects are reversed with atipamezole. Alpha-two agonists are frequently given in combination with opioid drugs to decrease the dose administered and to limit the car-diopulmonary effects of the alpha-two agonists. Anticholinergic drugs may be given to limit alpha-two agonist-induced bradycardia, although the routine use of glycopyrrolate with dexmedetomidine is somewhat controversial.

Opioids

Opioids are commonly used for their analgesic activity and anesthetic sparing effects. In general, they cause mild to moderate sedation, but may be associated with excitation in some animals (especially in cats). Excitatory opioid effects are effectively eliminated when the agents are administered concurrently with tranquiliz-ers or sedatives like acepromazine or xylazine. In general, full agonists (e.g., morphine, oxy-morphone, hydromorphone, and fentanyl) are considered to be more efficacious than partial agonists or agonist/antagonists (butorphanol, buprenorphine, and nalbuphine). Side effects may also be more likely with the full agonist opioids. Respiratory depression, bradycardia, vomiting, decreased gastrointestinal propulsive motility, and urine retention are all potential side effects. Morphine may also evoke histamine release. Morphine, oxymorphone, and hydromorphone are commonly used as part of premedication protocols. Fentanyl may be given intramuscularly as part of a premedication protocol. However, fentanyl has a very short duration of action (less than an hour) and is frequently administered as a constant rate infusion when more prolonged analgesia is required. Partial agonists and agonist/antagonist drugs are generally used to treat mild to moderate pain. Butorphanol is frequently used to pre-medicate small animal patients. However, butorphanol ‘s duration of action is short in the dog. Buprenorphine, because of its relatively long duration of action, is frequently used to provide postoperative pain relief in dogs and cats.

The effects of opioids are reversible. Nalox-one is the most commonly used full antagonist used in small animal anesthesia today. Nalbuphine and butorphanol can also be used to reverse the effects of mu agonists (e.g., morphine and hydromorphone). The advantage of using nalbuphine and butorphanol is that, unlike naloxone, they will provide mild to moderate analgesia through their agonistic effects at the opioid kappa receptor.

Tramadol is an atypical opioid that is currently available in an oral formulation. Tramadol has effects on the opioid mu receptor and also works through other pathways in the central nervous system. Because an injectable formulation is not currently available in the United States, tramadol’s use in the preoper-ative period is limited.

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

Nonsteroidal anti-inflammatory drugs decrease pain and inflammation by interfering with the production of prostaglandins and, in a few cases, leukotrienes. Newer agents like carpro-fen, deracoxib, meloxicam, and tepoxalin are markedly less toxic than older NSAIDs like aspirin, indomethacin, and phenylbutazone. Renal failure and gastrointestinal ulceration are the most significant toxic effects of NSAIDs, and anesthesia-induced hypotension can contribute to NSAID toxicity. Some NSAIDs also inhibit platelet function. Because of these potential side effects, and because NSAIDs do not alter anesthetic requirements, many veterinarians confine the use of NSAIDs to the postoperative period.

Dissociative Agents

Dissociative drugs like ketamine and tiletamine are N-methyl-D-aspartate receptor antagonists that may be administered intravenously or intramuscularly as part of premedication protocols or for the induction of anesthesia. Dissociative agents are not well suited to be given as a sole agent for premedication or induction of anesthesia because they provide poor muscle relaxation and are associated with patient movement. Ketamine is frequently given intravenously and concurrently with midazolam or diazepam to induce anesthesia, and tiletamine is available as a commercial preparation with zo-lazepam (Telazol, Fort Dodge Animal Health, Fort Dodge, IA) for intravenous or intramuscular administration in small animals. Dissociative agents provide effective somatic analgesia, but are poor visceral analgesics. Unlike most anesthetic drugs, dissociative agents generally maintain or increase blood pressure, heart rate, and cardiac output. They may also cause cerebral vasodilatation, an increase in cerebral metabolic rate, and an increase in cerebral blood flow.

Hypnotic Agents

Thiopental and propofol are two commonly used hypnotic/sedative drugs in small animal veterinary anesthesia. Both are used to induce unconsciousness by intravenous injection prior to inhalant anesthesia. Due to rapid clearance, propofol has a shorter duration of action than thiopental and may be used to maintain anesthesia by intermittent intravenous injection or constant rate infusion. Propofol causes as much, or greater, cardiovascular depression than thiopental, but is much less likely to be associated with cardiac dysrhythmias. Unlike thiopental, propofol does not cause perivascu-lar damage and is not a controlled substance. Both drugs are respiratory depressants, but propofol is more likely to cause cyanosis and desaturation of hemoglobin. Whenever either drug is used, the practitioner should be prepared to orotracheally intubate the animal and provide for the administration of oxygen and ventilation. Propofol administration may be associated with pain and movement. Thiopental may be associated with transient excitatory behavior after injection. These drug effects can be minimized or eliminated by administration of a sedative, tranquilizer, or analgesic drug prior to induction of anesthesia. Moreover, the excitatory effects of thiopental can be minimized if approximately half of the calculated bolus is administered rapidly (the remaining drug should be given incrementally and to effect). Propofol administration is not typically associated with excitatory behavior, and side-effects like hypotension and apnea can be decreased by giving the drug slowly and to effect. Repeated daily administration of propofol may cause oxidative damage to feline red blood cells, but a single intravenous induction dose has not been shown to be problematic. Current preparations of propofol have a limited shelf life because the formulation promotes the growth of bacteria or yeast, and the contents of a bottle should be used within 6 hours of opening. Thiopental is associated with prolonged recoveries in sighthounds after a single induction dose, and in all animals after repeated administration for anesthesia maintenance.

Step-by-Step Approach to Anesthetizing the Small Animal Patient

The following outline details premedication, intravenous induction of anesthesia, and maintenance of anesthesia with an inhalant anesthetic. As one would expect, this outline should not be used as a substitute for methodical thought and practical adjustments for each individual patient, but it can serve as a checklist and training guide for performing small animal anesthesia.

1. A thorough history should be taken and physical examination performed prior to anesthetizing a canine or feline patient. Laboratory evaluations of hematocrit, plasma protein, serum urea nitrogen or creatinine, and urine specific gravity are also part of a routine preoperative workup. Additional diagnostic tests may be necessary depending upon the condition of the patient and the procedure to be performed. Owners should be informed of the risks associated with anesthesia and should provide written permission to perform anesthesia. Owners should also be asked to express their wishes with regard to emergency management, should a catastrophic event occur during the animal’s hospital stay.

2. The specific anesthetic protocol should be chosen based upon the history, physical ex amination, laboratory evaluation, and the procedure to be performed. The anesthetic protocol should also outline the strategy that will be used to control postoperative pain. A discussion of anesthesia for concurrent diseases or for specific diagnostic or therapeutic procedures is beyond the scope of this chapter.

a. Consider the feasibility of local and/or regional analgesia techniques as a supplement to the general anesthetic protocol.

3. Calculate doses of drugs that will be used for premedication and induction of anes thesia. Label syringes for all drugs that will be used for premedication and induction. Make sure that all controlled substances are properly accounted

4. Administer preanesthetic drugs (sedativesand analgesic drugs). An animal should be returned to its cage after premedication, and 20–30 minutes should be allowed before moving the animal for catheterization and induction. While waiting for the pre-medications to exert their effects, the animal should be observed to ensure its well-being, but should not be disturbed. Indeed, excessive stimulation may diminish the effectiveness of sedative drugs.

a. Intramuscular sites for premedication are the quadriceps muscle (preferred), lumbar musculature, and semimembra-nosus/semitendinosus muscles.

5. Assemble supplies and equipment that will be used for anesthesia.

a. Select the most appropriate endotracheal tube for the patient.

b. Check the integrity of the endotracheal tube and cuff.

i. Endotracheal tubes are used to maintain a patent airway, allow for controlled ventilation, protect the airway from contamination with foreign material, and to prevent exposure of personnel to waste anesthetic gas.

ii. Examine the endotracheal tube for defects.

iii. The endotracheal tube cuff system is checked using the following procedure:

1. Attach an air-filled syringe to the inflating valve and fill the cuff with air until distended.

2. Remove the syringe from the in flating valve.

3. Allow the cuff to remain inflated for 5–15 minutes.

4. Observe the cuff for deflation.

a. If deflation occurs, the tube should be removed from service.

5. If the cuff has remained inflated, withdraw all air from the cuff via the inflating valve using a syringe.

iv. Keep the tube on a clean surface prior to use.

v. The outside surface of the patient end of the endotracheal tube may be lubricated with a modest amount of water-soluble lubricating jelly prior to insertion into the airway.

c. Check the integrity of the anesthetic circuit.

i. Assemble the anesthetic circuit (y-piece and reservoir bag); attach the oxygen and evacuation sources, and perform a pressure check of the system.

ii. The patient circuit should be able to hold pressure (30 cm H2O) for 15 seconds.

iii. Inspection and assessment of a non-rebreathing circuit depends upon the type of circuit being used. In general, a nonrebreathing circuit is used for patients less than 8-kg body weight. A circle system is used when the patient is greater than or equal to 8-kg body weight.

d. Check the level of inhalant anesthetic in the vaporizer. Fill as necessary.

e. Calculate the fresh gas flows for the anesthetic circuit.

i. To operate the system in a semi-closed fashion, the following guidelines should be applied:

1. Generally, oxygen flow rates of 22–44 mL/kg/min are considered to be acceptable maintenance flow rates for a semi-closed circle system. Alternatively, maintenance flow may be calculated based upon estimated oxygen consumption multiplied by three (i.e., 5–10 mL oxygen flow/kg/min × 3). Lower oxygen flow rates are used when a circle circuit is operated in a “closed” fashion.

2. Fresh gas flow is expected to be higher during anesthetic induction and recovery. In general, a fresh gas flow rate of 1–2 L/min is considered acceptable during induction, and 500 mL/min to 1 L/min is ac ceptable for the maintenance period of anesthesia when using a circle system.

3. The appropriate oxygen flow for a nonrebreathing system depends upon the system being used. In most cases, a flow that is calculated as 300 x body weight (kg) and expressed in ml/kg/min is appropriate for small patients on a Mapleson F nonrebreathing system.

6. Crystalloid intravenous replacement fluids (i.e., lactated Ringer’s solution) are commonly used during general anesthesia.

a. Fluid rate and types may be altered depending upon the patient, the procedure being performed, and the duration of the procedure.

b. Calculate fluid administration rate prior to anesthesia. A rate of 10 mL/kg/h is calculated and administered for the first hour of anesthesia, 5 mL/kg/h there after.

c. Fluids may be administered by an electronically controlled fluid pump or by gravity flow. When calculating fluid rates using gravity flow, the size of the drip set is necessary to determine the administration rate (in drops/minute). Common sizes for drips sets are: 10, 15, and 60 drops/mL.

d. Insert a fluid administration set into the intravenous fluid bag and prime the tubing.

7. Once supplies and equipment are collected and prepared for use, the sedated animal should be placed on a table and restrained for catheter placement.

a. The animal should be restrained in a manner that minimizes stress for the animal and prevents injury to the handler or to the anesthetist.

8. The intravenous catheter site should be clipped and surgically prepared.

a. The cephalic/accessory cephalic and lateral saphenous veins are commonsites of catheter placement in the dog.

b. The cephalic/accessory cephalic and medial saphenous veins are common sites for catheter placement in the cat.

9. An over-the-needle catheter is inserted into the vein, and a T-port is connected to the catheter.

a. Alternately, the fluid administration set may be attached directly to the intravenous catheter.

10. The catheter and attached T-port are taped into place and triple antibiotic ointment (or other nonirritating disinfectant/ antibiotic cream/gel/ointment) should be applied to the catheter site. Sterile gauze or a sterile band-aid may be used to cover the catheter site after the catheter is secured to the limb with tape.

11. Prior to injection of an induction agent, the catheter is assessed to ensure that it is placed into the lumen of the vein. Injection of sterile normal saline solution may be used for this purpose.

12. The animal should be assessed briefly prior to induction general anesthesia. Specifically, a final check of pulse rate, pulse quality, and mucous membrane color should be performed just prior to induction of anesthesia.

a. Abnormalities in pulse rate, pulse regularity, or mucous membrane color should lead the anesthetist to investigate the cause of the abnormalities and reassess the plan of action.

13. Induction may be accomplished by administration of the selected induction agent.

14. The mouth of the animal should be held open by the assistant, and the tongue pulled forward using a gauze square.

a. The tongue should be pulled rostrally and between the mandibular canines. The anesthetist should not place his/her fingers between the animal’s teeth. In stead, the tongue should be moved outside the mouth, using the endotracheal tube or laryngoscope blade so that it may be safely grasped.

b. If used, the laryngoscope blade should be pressed against the base of the tongue. This will pull down the epiglottis and expose the larynx.

1. The laryngoscope blade may be used to gently depress the epiglottis, if necessary.

2. In cats, lidocaine may be sprayed onto the larynx to decrease sensitivity and laryngospasm during endotracheal intubation.

c. The endotracheal tube should be advanced into the mouth, through the larynx, and into the trachea.

d. The length of the tube should be checked to ensure that the tip is located just cranial to the thoracic inlet.

e. Endotracheal tubes have the potential to injure the patient. Cats are particularly prone to injury associated with endotracheal intubation. The following should be considered to prevent endotracheal tube problems:

1. Proper inflation of the cuff

a. Over inflation may damage the patient’s airway.

b. Under inflation will allow aspiration of foreign material into the airways and lungs.

c. Once the cuff is inflated, the endotracheal tube should not be twisted, inserted, or removed with out first deflating the cuff. [During dentistry procedures, temporarily detach the anesthetic tubing from the endotracheal tube before turning the animal from one side to the other, because twisting the inflated cuff can tear the trachea.]

2. Proper placement of the tube

a. Improper esophageal placement is not effective for delivering oxygen or anesthetic, does not protect the airway, and does not ensure airway patency.

b. The tip of the endotracheal tube should be located in the trachea and just cranial to the thoracic inlet.

i. A tube inserted too far caudally may isolate a single mainstem bronchus and cause significant gas exchange abnormalities.

ii. A tube that is not inserted far enough into the trachea may be easier to dislodge. In addition, in this position, the cuff may be located in the larynx and inflation may traumatize the larynx.

iii. The length of insertion necessary may be estimated prior to induction of anesthesia by holding the tube next to the animal’s head and neck.

iv. The length of insertion should be verified after placement by palpation of the tip of the tube in the trachea.

15. The animal should be placed in lateral recumbence, and the endotracheal tube should be connected to the anesthetic machine and the oxygen turned on (1–2 L/min).

16. The pulse and heart beat should be assessed.

17. The anesthetist should secure the endotracheal tube to the animal using roll gauze. The gauze should be tightly secured to the endotracheal tube with half of a square knot, and then tied over the animal’s muzzle (dogs) or behind its head (dogs and cats) using a “bow” or other knot that can be untied easily and quickly. Other devices are commercially available to secure the endotracheal tube to the patient. Some practices use lengths of intravenous tubing for this purpose in place of roll gauze.

18. Check for a leak around the endotracheal tube by closing the pressure-relief valve on the anesthesia machine and squeezing the reservoir bag to a pressure of 20–25 cm H2O. A leak can be heard in the oral cavity when positive pressure is being held in the circuit/patient.

a. Pressure should not be held in the system for more than 1-2 seconds.

b. If a leak is heard, the pressure-relief valve should be opened, and the cuff inflated with air. A volume of 1–3 mL is an appropriate volume for small animals.

c. The above steps should be repeated until a leak is no longer heard when a pressure of 20–25 cm H2O is maintained in the circuit.

d. Open the pressure-relief valve when the cuff inflation procedure is complete.

19. The vaporizer may be initially set at 2–3% if isoflurane is the inhalant anesthetic that is being administered. If sevoflurane is used, the vaporizer may initially be set at 3–5%.

a. The actual vaporizer setting should be determined after evaluating depth of anesthesia and cardiovascular performance.

b. The initial vaporizer setting will be influenced by the drugs used for premedication and induction of anesthesia.

20. The animal’s respirations, pulse rate, and depth of anesthesia should be monitored in a continuous fashion. Entries should be made onto the anesthesia record every 5 minutes.

21. The esophageal stethoscope is lubricated and advanced through the oral cavity and into the esophagus while simultaneously listening through the earpieces. Insert to the depth where cardiac sounds are most clearly heard.

22. Connect crystalloid fluids to the intravenous catheter aseptically. Begin administration at the calculated rate (see 6.b.above).

23. Lubricate the eyes with sterile ophthalmic ointment to decrease the risk for corneal ulceration.

24. The animal may now be prepared for surgery (positioning/clipping/skin preparation) .

25. Anesthetic and oxygen flow should be adjusted to maintenance levels when an

appropriate and stable plane of anesthesia has been established (5-15 minutes after induction).

a. Record observations, physiological parameters, and interventions on the anesthesia record.

b. Adjust the vaporizer setting to maintain an appropriate depth of anesthesia.

26. Physical monitoring should be combined with device-based assessment to ensure patient well being. The following are frequently used to monitor anesthetized patients:

a. Electrocardiography

b. Capnography

c. Pulse oximetry

d. Noninvasive blood pressure monitoring (oscillometric or Doppler)

e. Rectal or esophageal temperature measurement

i. Temperature support is routinely required to prevent hypothermia during anesthesia and surgery.

27. When the diagnostic or therapeutic procedure is completed, the vaporizer may be shut off and oxygen flow continued until the patient begins to swallow. Based upon the procedure performed, the premedications used, and the incorporation of local and regional analgesia techniques, it may be necessary to administer additional analgesic drugs prior to recovery.

28. The endotracheal tube cuff should be deflated completely prior to removal.

a. In some cases, partial deflation is utilized if there is suspicion that fluid or foreign material may have entered the trachea next to the endotracheal tube.

29. In general, fluid administration is discontinued when anesthetic administration is completed. The intravenous catheter is flushed with saline solution and left in place until the animal has recovered and can maintain homeostasis. In routine cases, the catheter is maintained until the animal can ambulate. Animals with excessive surgical blood loss, electrolyte disturbances, ongoing fluid losses, increased risk for seizures, abnormal cardiopulmonary function, or those exhibiting pain or dys-phoria should not have their catheter removed immediately. These animals should be reassessed and the appropriate therapy instituted.

30. The animal should be monitored during the postoperative period. The following parameters are particularly important to assess:

a. Respiratory and cardiovascular function

i. Pulse rate and quality

ii. Respiratory rate

iii. Hemoglobin saturation (via pulse oximetry)

b. Temperature

c. Level of pain

d. Mentation

Additional Resources

Additional information about small animal anesthe-siology, analgesia, and perioperative medicine can be found in the following textbooks:

1. Tranquilli WJ, Thurmon JC, Grimm KA, eds. Lumb & Jones Veterinary Anesthesia and Analgesia, 4th ed. Ames, Iowa: Blackwell Professional Publishing, 2009.

2. Carroll GL, ed. Small Animal Anesthesia and Analgesia. Ames, Iowa: Blackwell Professional Publishing, 2008.

3. Muir WW, Hubbel JAE, Bednarski RM, Skarda RT. Handbook of Veterinary Anesthesia, 4th ed. St. Louis, Missouri: Mosby Elsevier, 2007.

Chapter 3

Asepsis in Small Animal Surgery

Fred Anthony Mann

General principles of aseptic technique have been established to minimize the likelihood of wound contamination and subsequent wound infection. Thorough understanding of aseptic technique requires knowledge of the following five widely used terms:

Asepsis: condition in which there are no viable pathogenic microorganisms present in the tissue.Sepsis: condition in which there are pathogenic microorganisms, or byproducts of the said microorganisms, present in the tissue.Antisepsis: safe application of an agent (antiseptic) with the purpose of removing or inactivating offending microorganisms. An antiseptic is a chemical substance that can be topically applied to living tissue.Disinfection: application of a chemical substance (disinfectant) with the purpose of destroying the vegetative forms of bacteria but not the spores. A disinfectant is a chemical substance that can be applied to inanimate objects, such as certain surgical instruments or operating room furnishings.Sterilization: destruction of all microorganisms and spores on an object. Sterilization can be performed by application of heat (steam autoclave), ethylene oxide gas, vapor phase hydrogen peroxide, irradiation, and chemicals (glutaraldehyde). Sterilization is used for surgical instruments and any object that will have direct contact within or around open surgical wounds.

Prevention of bacterial contamination is of utmost importance in surgical wounds. Consequences of bacterial contamination and pursuant infection include systemic disease (peritonitis, sepsis, etc.), increased healing times, prolonged pain, delayed recovery, and altered cosmesis. Eliminating microorganisms from within or around a surgical wound would ultimately render it impossible for bacterial contamination and infection to occur. Therefore, it is important to know and be aware of the sources of bacterial contamination in the operating theater. These sources include: scrubbed and nonscrubbed personnel within the operating room, surgical equipment, operating room equipment, and the patient, the latter being the most common source of bacteria for surgical wound infections. Aseptic techniques have been designed and implemented in order to minimize the risk of contamination. If these techniques are properly followed, wound infection is unlikely unless there is a gross breach in the established surgical barriers. Surgical barriers and specific techniques of aseptic patient preparation are discussed in Chapters 9, 10, and 11.

The air in the room acts as a vehicle for introduction of bacteria into the wound. Therefore, it is important to keep air turbulence to a minimum by limiting the number of unnecessary personnel, the amount of needless action, and the amount of talking while in the operating theater. This being said, there is no such thing as a sterile surgery and there is a level of contamination that is present in all wounds. There is a preponderance of evidence supporting that 105 organisms per gram of tissue or per milliliter of fluid constitutes an infection. In most cases, an immunocompetent individual would be able to clear pathogens in lower concentrations without intervention.

An infection may develop due to impaired host defenses and characteristics of the bacterial inoculums, and as a result of various local factors, such as tissue necrosis, dead space, reduced blood supply, and presence of foreign material. One goal of the surgical team must be to preoperatively address patient characteristics listed above as well as evaluate periop-erative and intraoperative measures to ensure that contamination of the surgical wound is avoided at all costs. Perioperative measures include patient preparation, sterilization of surgical instruments, surgeon scrub, and donning of sterile barriers (on both surgeon and patient). Specifics of these perioperative measures and other practices designed to prevent surgical wound contamination are discussed in Chapters 6 through 11. The following is a list of rules commonly followed to minimize intraoperative contamination:

1. Scrubbed personnel are to stay inside and only touch objects located within the sterile field. The converse is equally true that non-scrubbed personnel are only allowed out side of the sterile field.

2. Talking and unnecessary movement must be kept to an absolute minimum.

3. Members of the surgical team should visualize the sterile field at all times. The reason is that direct visualization of sterile objects decreases the likelihood of contamination with nonsterile objects.

4. The patient table and instrument table, once donned with sterile barriers are only considered sterile at table height. The drapes and cords that hang off of the tables are out of the surgical team’s sight and must be considered contaminated.

5. The drapes used to cover the patient, patient table, and instrument table (s) should be impermeable to moisture. This will ultimately lead to prevention of strikethrough contamination. (Strikethrough contamination is defined as the translocation of bacteria from the nonsterile side to the sterile side of a surgical barrier due to the material becoming saturated with either body fluid or irrigation fluid.)

6. Gowns, once donned, are considered sterile from just below the shoulders to the waist and from gloved finger tips to 2 inches above the elbow. Because of this, hands should be kept above the level of the waist, close to the body, and clasped together when not in use.

7. Scrubbed personnel that sit during a surgical procedure should remain seated until the procedure is completed.

8. Only use properly sterilized equipment that has sterility indicators both within the pack and on the outer wrapping. If sterility of an object is not known or is questioned for any reason, consider it contaminated.

9. If a sterile instrument, contained in a sterile pouch, touches the open edge of that pouch while being opened, the instrument is considered contaminated and a new instrument must be opened. A surgical pack/pouch whose outside barrier has become damaged, wet, or compromised in any way must be considered contaminated and must not be used.

10. Pouring sterile liquid into a sterile bowl should be performed by a nonsterile person with the sterile person holding the bowl away from the sterile field. The nonsterile person should carefully pour the liquid without splashing or dripping onto the sterile field. The nonsterile fluid receptacle must not touch the sterile bowl.

These rules are mainstays of aseptic technique that when first introduced appear laborious and somewhat cumbersome; however, once practiced, most of the rules quickly become second nature.

There are several antiseptic solutions that are currently used in veterinary practice today. Examples of these include: aliphatic alcohols, iodophors, and chlorhexidine.