Turner and McIlwraith's Techniques in Large Animal Surgery E-Book

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

Seitenzahl: 835

Veröffentlichungsjahr: 2025

Beschreibung

An indispensable resource for students and practitioners in large animal surgery, updated with new practices and techniques

Turner and McIlwraith’s Techniques in Large Animal Surgery provides the critical knowledge needed to confidently approach even the most challenging surgical cases. Authored by highly experienced practitioners, this comprehensive resource offers step-by-step guidance on both routine procedures and complex surgical interventions for cattle, horses, swine, goats, llamas, and camelids. Concise chapters are organized in an efficient table-based format, allowing for rapid reference in both exam preparation and real-world clinical scenarios.

The fifth edition of this classic textbook continues to set the standard for clear and reliable guidance on large animal surgery, equipping readers with the most current knowledge in clinical veterinary practice. Carefully reviewed references and enhanced visuals are accompanied by critical updates on equine orthopedic surgery, veterinary anesthesia, dental surgery, upper respiratory surgery, and more.

Addressing everything from basic pre-surgical care to specialized reconstructive procedures, Turner and McIlwraith’s Techniques in Large Animal Surgery:

• Describes the surgical conditions and techniques commonly encountered in large animal practice
• Covers general aspects of surgery including preoperative evaluation, suturing materials and patterns, and postoperative infection
• Contains a wealth of high-quality illustrations that clarify each step in complex surgical procedures
• Features interactive multiple-choice questions for self-assessment and reinforcing key concepts
• Includes downloadable images in PowerPoint format, enabling instructors and practitioners to quickly create customized presentations

Turner and McIlwraith’s Techniques in Large Animal Surgery, Fifth Edition is a must-have for veterinary students taking introductory surgery courses such as Principles of Surgery, Clinical Sciences, and Livestock Medicine, as well as for veterinary practitioners in equine and livestock surgery looking for an up-to-date reference.

Leseprobe

Table of Contents

Cover

Table of Contents

Title Page

Copyright Page

Contributors

Preface to the Fifth Edition

Preface to the Fourth Edition

Preface to the Third Edition

Preface to the Second Edition

Preface to the First Edition

About the Companion Website

1 Presurgical Considerations

Preoperative Evaluation of the Patient

Surgical Judgment

Principles of Asepsis and Antisepsis

Surgical Classifications

Role of Antibiotics

Preoperative Planning

Preparation of the Surgical Site

Postoperative Infection

References

2 Anesthesia and Fluid Therapy

Anesthesia

Fluid Therapy

References

3 Surgical Instruments

Use of Surgical Instruments

Preparation of Instruments

General Surgical Instruments

Instruments Used Specifically in Large Animal Surgery

4 Suture Materials and Needles

Suture Materials

Needles

References

5 Knots and Ligatures

Principles of Knot Tying

Ligatures

References

6 Suture Patterns

Basic Suture Patterns

Suture Patterns Used for Closure of Hollow Organs

References

7 Principles of Wound Management and the Use of Drains

Wound Management

Methods of Closure and Healing

Use of Drains

References

8 Reconstructive Surgery of Wounds

References

9 Equine Orthopedic Surgery

Medial Patellar Desmotomy

Lateral Digital Extensor Tenotomy

Inferior (Distal) Check Ligament Desmotomy

Superior Check Ligament Desmotomy (After Bramlage)

Superficial Digital Flexor Tenotomy

Deep Digital Flexor Tenotomy

Sectioning of the Palmar (or Plantar) Annular Ligament of the Fetlock

Palmar Digital Neurectomy

Amputation of the Splint (II and IV Metacarpal and Metatarsal) Bones

Arthrotomy of the Fetlock Joint and Removal of an Apical Sesamoid Chip Fracture

References

10 Equine Urogenital Surgery

Castration

Cryptorchidectomy by the Inguinal, Parainguinal, and Flank Approach

Laparoscopic Cryptorchidectomy

Caslick Operation for Pneumovagina in the Mare

Urethroplasty by Caudal Relocation of the Transverse Fold

Cesarean Section in the Mare

Circumcision of the Penis (Reefing)

Amputation of the Penis

Aanes' Method of Repair of Third‐Degree Perineal Laceration

References

11 Surgery of the Equine Upper Respiratory Tract

Tracheostomy

Laryngotomy, Laryngeal Ventriculectomy, and Ventriculocordectomy

Partial Sternothyroideus Myotenectomy (Llewellyn Procedure)

Surgical Entry and Drainage of the Guttural Pouches

References

12 Equine Dental Surgery

Introduction to Extraction

Surgical Extraction of Incisor and Canine Teeth

Surgical Extraction of Premolar and Molar Teeth

Postoperative Management

Complications Associated with the Surgical Extraction of Teeth

References

13 Equine Gastrointestinal Surgery

Ventral Midline Laparotomy and Abdominal Exploration

Standing Flank Laparotomy

Umbilical Herniorrhaphy in the Foal

References

14 Bovine Gastrointestinal Surgery

Principles of Laparotomy

Flank Laparotomy and Abdominal Exploration

Rumenotomy

Rumenostomy (Rumenal Fistulation)

Surgical Corrections of Abomasal Displacements and Torsion

Surgical Correction of Cecal Dilatation/Volvulus

Small Intestinal Resection and Anastomosis

References

15 Bovine Urogenital Surgery

Calf Castration

Urethrostomy

Hematoma Evacuation of the Bovine Penis

Preputial Resection and Anastomosis in the Bull

Circumcision for Preputial Injury in the Bull (Ring Technique)

Surgical Techniques for Teaser Bull Preparation

Inguinal Herniorrhaphy in the Mature Bull

Unilateral Castration

Cesarean Section in the Cow

Complications and Prognosis

Retention Suturing of the Bovine Vulva (Bühner's Method)

Cervicopexy for Vaginal Prolapse (after Winkler)

Urethral Extension for Urovagina in the Cow

References

16 Bovine General Surgery

Digit Amputation

Interdigital Fibroma Resection

Sequestrectomy

Eye Enucleation

Cosmetic Dehorning

Paranasal Sinus Trephination

Rib Resection and Pericardiotomy

Repair of Teat Lacerations

Third Eyelid Resection

Tracheotomy

Umbilical Surgery

References

17 Small Ruminant Surgery

Dehorning the Mature Goat

Disbudding the Young Goat

Obstructive Urolithiasis

Mastectomy

Vasectomy

Cryptorchidectomy

Inguinal Herniorrhaphy by Unilateral Castration in Small Ruminants

Cesarean Section

Rectal Prolapse Resection in Small Ruminants

References

18 Camelid Surgery

Castration of the Llama

Cesarean Section in the Camelid

Tooth Removal in the Llama

References

19 Swine Surgery

Castration of the Piglet

Inguinal Herniorrhaphy in the Piglet

Cryptorchid Castration of Piglets

Preputial Diverticulum Ablation

Cesarean Section in the Sow

Ovariohysterectomy in the Pot‐Bellied Pig

Rectal Prolapse Ring Placement

References

Index

End User License Agreement

List of Tables

Chapter 1

Table 1.1 Surgical classifications.

Chapter 2

Table 2.1 Epidural anesthesia and analgesia in cattle and small ruminants....

Table 2.2 Caudal epidural analgesic agents in the horse.

Table 2.3 Epidural analgesic agents in swine.

Table 2.4 Tranquilizers and sedatives used in cattle.

Table 2.5 Tranquilizers and sedatives used in horses.

Table 2.6 Tranquilizers and sedatives used in swine.

Table 2.7 Tranquilizers and sedatives used in small ruminants.

Table 2.8 Anesthetic induction regimens in the equine patient.

Table 2.9 Anesthetic induction regimens in cattle and small ruminants.

Table 2.10 Anesthetic induction regimens in swine.

Table 2.11 Anesthetic maintenance in large animals.

Table 2.12 Assessment of degrees of clinical dehydration.

Table 2.13 Normal values used in the evaluation of fluid balance in large a...

Table 2.14 Composition of intravenous fluids (mEq/l).

Chapter 4

Table 4.1 Commonly used suture materials.

List of Illustrations

Chapter 2

Fig. 2.1. Inverted L block.

Fig. 2.2. Paravertebral block.

Fig. 2.3. Bovine epidural anesthesia.

Fig. 2.4. Equine epidural anesthesia. A. Overall view of hindquarters. B. Cl...

Fig. 2.5. Intravenous limb anesthesia. A. Forelimb, dorsal aspect. B. Hind l...

Chapter 3

Fig. 3.1. The use of nos. 10, 20, 21, and 22 blades. A. Stroke. B. Pencil gr...

Fig. 3.2. A. Pencil grip for nos. 11 and 15 blades. B. Incorrect use of a no...

Fig. 3.3. A. Applying a scalpel blade, B. and C. Removing the used scalpel b...

Fig. 3.4. Aseptic technique for handling a new blade.

Fig. 3.5. Correct way to hold scissors.

Fig. 3.6. A. Using rings to hold the needle holders. B. Palming the needle h...

Fig. 3.7. Correct way to hold thumb forceps.

Fig. 3.8. Passing hemostatic forceps.

Chapter 4

Fig. 4.1. A swaged‐on needle. The suture and needle have approximately the s...

Fig. 4.2. Various needle shapes.

Fig. 4.3. Various points and shaft designs of suture needles.

Chapter 5

Fig. 5.1. Surgical knots.

Fig. 5.2. A–F. Tying with a needle holder.

Fig. 5.3. Transfixation ligature.

Chapter 6

Fig. 6.1. Simple interrupted suture with cross section of suture bite.

Fig. 6.2. Simple continuous suture with cross section of suture bite (eyed n...

Fig. 6.3. A. Simple continuous suture with cross section of suture bite (swa...

Fig. 6.4. A. Interrupted horizontal mattress suture. B. Interrupted horizont...

Fig. 6.5. Continuous horizontal mattress suture.

Fig. 6.6. A. Vertical mattress suture. B. Vertical mattress suture as tensio...

Fig. 6.7. A–C. Near‐far‐far‐near suture.

Fig. 6.8. A and B. Subcuticular suture. C. Cross section showing parallel su...

Fig. 6.9. A. Cruciate (cross mattress) suture. B. Cross section of suture bi...

Fig. 6.10. A and B. Continuous lock stitch (Ford interlocking suture).

Fig. 6.11. A. Interrupted Lembert suture. B. Lembert suture before tightenin...

Fig. 6.12. Continuous Lembert suture.

Fig. 6.13. A. Cushing suture. B. Cross section of Cushing suture. C. Cushing...

Fig. 6.14. A. Connell suture. B. Cross section of Connell suture. C. Connell...

Fig. 6.15. A–E. Parker–Kerr oversew.

Fig. 6.16. A and B. Purse‐string suture.

Fig. 6.17. Simple interrupted suture used in bowel.

Fig. 6.18. A and B. Gambee suture. C. Gabee suture after tightening.

Fig. 6.19. A. Stent bandage with horizontal mattress suture. B. With loops a...

Fig. 6.20. A–E. Locking‐loop tendon suture.

Fig. 6.21. A–G. 3‐loop pulley suture.

Fig. 6.22. Six‐strand savage repair.

Chapter 7

Fig. 7.1. Penrose drain with one end emerging from wound. The retention sutu...

Fig. 7.2. Penrose drain used for treatment of hygroma.

Fig. 7.3. A. Using a trocar to exit a fenestrated drain. B. Syringe techniqu...

Fig. 7.4. Sump‐Penrose drain combination.

Chapter 8

Fig. 8.1. A and B. Elliptical excision undermining for repair of an elongate...

Fig. 8.2. A and B. Use of tension‐relieving incisions to facilitate wound cl...

Fig. 8.3. A and B. Sliding H‐flap.

Fig. 8.4. A and B. Rhomboid flap.

Fig. 8.5. A–C. Rotational skin flap with donor site left open and dono...

Fig. 8.6. A–C. Z‐plasty as a relaxation procedure.

Fig. 8.7. A and B. Z‐plasty to relieve ectropion of the eyelid.

Fig. 8.8. A and B. V to Y plasty to relieve ectropion of the eyelid.

Fig. 8.9. A–C. Removal of excessive scar tissue (debulking) to allow p...

Fig. 8.10. A–D. Pinch‐skin grafting.

Fig. 8.11. A–D. Punch‐skin grafting.

Fig. 8.12. Tunnel grafting.

Chapter 9

Fig. 9.1. A–D. Medial patellar desmotomy and scalpel.

Fig. 9.2. A–H. Lateral digital extensor tenotomy.

Fig. 9.3. A–E. Inferior check ligament desmotomy.

Fig. 9.4. A–E. Superior check ligament desmotomy.

Fig. 9.5. A–C. Superficial digital flexor tenotomy.

Fig. 9.6. A. Drawing showing the location of palmar/plantar annular ligament...

Fig. 9.7. A–C. Palmar digital neurectomy.

Fig. 9.8. A–C. Amputation of the small metacarpal and metatarsal (spli...

Fig. 9.9. A–E. Arthrotomy of fetlock joint for removal of apical sesam...

Chapter 10

Fig. 10.1. A–H. Castration.

Fig. 10.2. A–S. Cryptorchidectomy.

Fig. 10.3. A–I. Caslick operation.

Fig. 10.4. A–H. Urethroplasty by caudal relocation of the transverse f...

Fig. 10.5. Cesarean section in the mare and uterine closure.

Fig. 10.6. A–D. Circumcision of the penis (reefing).

Fig. 10.7. A–G. Amputation of the penis.

Fig. 10.8. A–H. Aanes' method of repair of third‐degree perineal lacer...

Chapter 11

Fig. 11.1. A–D. Tracheostomy.

Fig. 11.2. A–H. Laryngotomy, laryngeal ventriculectomy, laser ventricu...

Fig. 11.3. A Ventral aspect of larynx showing location of sternohyoideus mus...

Fig. 11.4. A–E. Surgical entry and drainage of the guttural pouches.

Chapter 12

Fig. 12.1. Incision for mucogingival flap creation (thick white dashed line)...

Fig. 12.2. A. Reflected mucogingival flap and alveolectomy for extraction of...

Fig. 12.3. A. Ostectomy and alveolectomy to expose the roots and reserve cro...

Fig. 12.4. Placement of a right angle, small diameter punch on the remaining...

Fig. 12.5. A. Surgical extraction of a fractured mandibular third molar toot...

Chapter 13

Fig. 13.1. A–L. Ventral midline laparotomy and abdominal exploration....

Fig. 13.2. A–J. Standing flank laparotomy in the horse.

Fig. 13.3. A–H. Umbilical herniorrhaphy.

Chapter 14

Fig. 14.1. A–H. Flank laparotomy and abdominal exploration.

Fig. 14.2. A–F. Rumenotomy.

Fig. 14.3. A–D. Rumenostomy.

Fig. 14.5. A–C. Left‐flank abomasopexy.

Fig. 14.6. The fluid within the abomasum is removed using a medium‐sized sto...

Fig. 14.7. A–G. Ventral paramedian abomasopexy.

Chapter 15

Fig. 15.1. A–D. Calf castration.

Fig. 15.2. A–H. Urethrostomy.

Fig. 15.3. A–F. Hematoma evacuation of the bovine penis.

Fig. 15.4. A–E. Preputial amputation (circumcision) in the bull.

Fig. 15.5. A–E. Teaser bull preparation by penile translocation.

Fig. 15.6. A–D. Teaser bull preparation by penile fixation.

Fig. 15.7. A–D. Epididymectomy.

Fig. 15.8. A–G. Inguinal herniorrhaphy in the bull.

Fig. 15.9. A–N. Cesarean section in the cow.

Fig. 15.10. A–D. Buried purse‐string suture for vaginal and uterine pr...

Fig. 15.11. A–C. Cervicopexy for vaginal prolapse.

Chapter 16

Fig. 16.1. A–E. Digit amputation in cattle.

Fig. 16.2. A–D. Eye enucleation in cattle.

Fig. 16.3. A–C. Cosmetic dehorning in cattle.

Fig. 16.4. A–E. Pericardiotomy.

Fig. 16.5. A–D. Repair of teat laceration.

Chapter 17

Fig. 17.1. A–E. Dehorning the mature goat.

Fig. 17.2. A. Tube stent placement for rectal prolapse resection. B. Rectal ...

Chapter 18

Fig. 18.1. Dentition of the llama (Lama glama).

Fig. 18.2. A–H. Tooth removal in the llama.

Chapter 19

Fig. 19.1. A–E. Castration of the piglet.

Fig. 19.2. A–E. Inguinal herniorrhaphy in the piglet.

Fig. 19.3. A. Forceps placed into the preputial diverticulum. B. The everted...

Fig. 19.4. Cesarean section in the sow.

Guide

Cover Page

Table of Contents

Title Page

Copyright Page

Contributors

Preface to the Fifth Edition

Preface to the Fourth Edition

Preface to the Third Edition

Preface to the Second Edition

Preface to the First Edition

About the Companion Website

Begin Reading

Index

Wiley End User License Agreement

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Turner and McIlwraith’s Techniques in Large Animal Surgery

Fifth Edition

Edited by

Dean A. Hendrickson

DVM, MS, DACVS

Colorado State University

College of Veterinary Medicine

and Biomedical Sciences

Fort Collins, Colorado

A. N. (Nickie) Baird

DVM, MS, DACVS

Auburn University

College of Veterinary Medicine

Auburn, Alabama

Copyright © 2025 by John Wiley & Sons, Inc. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.

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Library of Congress Cataloging‐in‐Publication Data Applied for:Paperback ISBN: 9781394261932

Cover Design: WileyCover Images: © Monica Rodriguez/Getty Images, © John Gone/500px/Getty Images, Courtesy of Dean A. Hendrickson

Contributors

Dean A. Hendrickson, DVM, MS, DACVSEditor‐in‐ChiefCollege of Veterinary Medicine and Biomedical SciencesColorado State UniversityFort Collins, Colorado, USA

A. N. (Nickie) Baird, DVM, MS, DACVSAssociate EditorCollege of Veterinary MedicineAuburn UniversityAuburn, Alabama, USA

Khursheed Mama, DVM, DACVACollege of Veterinary Medicine and Biomedical SciencesColorado State UniversityFort Collins, Colorado, USA

Lauren K. Luedke, DVM, DACVS (Large Animal)College of Veterinary Medicine and Biomedical SciencesColorado State UniversityFort Collins, Colorado, USA

Jennifer Rawlinson, DVM, DAVDC (Equine Specialty)College of Veterinary Medicine and Biomedical SciencesColorado State UniversityFort Collins, Colorado, USA

Preface to the Fifth Edition

The first two editions of Techniques in Large Animal Surgery have been well accepted much to the credit of Drs. Turner and McIlwraith. They have been excellent texts for veterinary students and large animal practitioners. I was fortunate in that when it came time to update the information for a third edition, I was able to take on the task. It seems hard to believe that it is already time for a fifth edition.

The fifth edition of Techniques in Large Animal Surgery has been updated in response to the continued need for such a book for both veterinary students and large animal practitioners. As with the previous editions, we have gone through the entire text to make sure the information was reliable. The “tried‐and‐true” procedures have been retained, the outdated procedures have been removed, and new procedures have been added. As we thoroughly researched each of the chapters in the text, we did a major overhaul of the references.

In the fourth edition, Nickie Baird joined me in coauthoring the revision. His expertise in livestock animal surgery was a perfect fit for this textbook. He brings a great deal of new information to the text and has been a great partner. Dr. Khursheed Mama is still with us as the author of Chapter 2, Anesthesia and Fluid Therapy. She did an excellent job updating all of the information. Drs. Jennifer Rawlinson and Lauren Luedke have joined in this revision to update the Dental Surgery and Upper Respiratory Surgery chapters, respectively. We are very grateful for their expertise and input. It is a much‐improved text due to their participation.

We added a considerable amount of new information in the text and retained the table format to simplify information. New figures have been added, where needed, to support the updated information.

I am very grateful to Grace McCormick for illustrating the new procedures, as well as Meaghan Eickelbeck for providing a lot of the background research. Thanks as well to the folks at Wiley for their help and assistance in the production of this edition.

Dean A. Hendrickson

Fort Collins, Colorado

A. N. (Nickie) Baird

Auburn, Alabama

Preface to the Fourth Edition

The first two editions of Techniques in Large Animal Surgery have been well accepted much to the credit of Drs. Turner and McIlwraith. They have been excellent texts for veterinary students and large animal practitioners. I was fortunate in that when it came time to update the information for a third edition, I was able to take on the task, and now we have added a fourth edition.

The fourth edition of Techniques in Large Animal Surgery has been updated in response to the continued need for such a book for both veterinary students and large animal practitioners. As with the third edition, we have gone through the entire text to make sure the information was reliable. The “tried‐and‐true” procedures have been retained, the outdated procedures have been removed, and new procedures have been added. As we thoroughly researched each of the chapters in the text, we did a major overhaul of the references.

Probably the most important change in this text is the addition of two authors. Nickie Baird joined me in coauthoring the fourth edition. His expertise in livestock animal surgery was a perfect fit for this textbook. He brings a great deal of new information to the text and has been a great partner. Dr. Khursheed Mama joined us as the author of Chapter 2, Anesthesia and Fluid Therapy. She did an excellent job updating all of the information.

We added a considerable amount of new information in the text and retained the table format to simplify information. New figures have been added, where needed, to support the updated information.

I am very grateful to Grahm Hendrickson for illustrating the new procedures, as well as to Katie Hunsucker and Joy Fuhrman for providing a lot of the background research. Thanks as well to the folks at Wiley for their help and assistance in the production of this edition.

Dean A. Hendrickson

Fort Collins, Colorado

A. N. (Nickie) Baird

West Lafayette, Indiana

Preface to the Third Edition

The first two editions of Techniques in Large Animal Surgery have been well accepted, much to the credit of Drs. Turner and McIlwraith. They have been excellent texts for veterinary students and large animal practitioners. I was fortunate to be able to take on the task when it came time to update the information for a third edition. I am deeply appreciative of the opportunity to take such an excellent text and update it with new information and techniques.

The third edition of Techniques in Large Animal Surgery has been updated in response to the continued need for such a book for both veterinary students and large animal practitioners. Some techniques are time‐tested and continue to be included. Other techniques have been refined or replaced and are included in the new text.

New information has been included in essentially every chapter. We have made extensive use of tables to simplify the information. The anesthesia section includes new and updated information on sedation and anesthetic agents. The instrument section has been evaluated, adding new instruments where applicable and removing outdated or unavailable instruments. The section on suture materials has been updated to include new materials. There are new illustrations in the suture pattern section to better aid the practitioner with surgical techniques. The sections on wound management and reconstructive surgery have been increased to provide up‐to‐date information on wound care. Tables of required instrumentation have been added to all sections of the remaining surgical chapters to aid in surgical planning and preparation.

I am very grateful for our new illustrator Anne Rains; she has done an excellent job and has made my life very easy. I am indebted to Joanna Virgin who has done the lion’s share of the research to make sure this text was as up‐to‐date and accurate as possible. I could not have done this work without her. Thanks to the folks at Blackwell for their help and assistance in the production of this edition.

Dean A. Hendrickson

Fort Collins, Colorado

Preface to the Second Edition

The second edition of Techniques in Large Animal Surgery is in response to the acceptance of the first edition and the continued need for such a book for both veterinary students and large animal practitioners. In many instances, the techniques are time‐honored and require no change from 5 years ago. In other instances, however, refinements in technique as well as improved perception of indications, limitations, and complications have made changes appropriate.

A significant change is the addition of Dr. R. Bruce Hull, Professor of Veterinary Clinical Sciences, The Ohio State University, as a contributor. He has carefully analyzed the entire bovine section, and his suggested changes and additions have been incorporated into the text. In addition, two procedures, “teaser bull preparations by penile fixation” and “treatment of vaginal prolapse by fixation to the prepubic tendon,” have been added. We are most grateful in having Dr. Hull’s help and expertise. Among the introductory chapters, the section on anesthesia required the most updating, and we are grateful to our colleague Dr. David Hodgson at Colorado State University for his review and advice. Two new procedures, “superior check ligament desmotomy” and “deep digital flexor tenotomy,” were considered appropriate additions to this edition. We are grateful to Dr. Larry Bramlage, Ohio State University, for his comments and help with the first of these procedures. Many of the other changes in this edition are in response to the book reviews and comments on the first edition returned to Lea & Febiger. To these people, we appreciate your feedback.

A chapter on llama tooth removal was added because of the increased popularity of this species, especially in our own part of the country. Although we only discuss this one technique, it should not be inferred that other operations are unheard of in llamas. We have corrected angular limb deformities, repaired fractures, and performed gastrointestinal surgery, among other procedures, but tooth removal is the most common. Descriptions of these other procedures in llamas are beyond the scope of this book at this stage.

The need for more sophisticated equine techniques prompted us to produce the textbook Equine Surgery: Advanced Techniques in 1987. It is envisioned that the book will be used as a companion to this second edition, to provide a full spectrum of equine procedures, with the well‐accepted format of concise text and clear illustrations.

Again, we are thankful to Mr. Tom McCracken, Assistant Professor, Department of Anatomy and Neurobiology, Colorado State University, for his talent in capturing the techniques described in his line drawings. We are also indebted to Helen Acvedo for typing our additions and to Holly Lukens for copyediting. Finally, our thanks again to the excellent staff at Lea & Febiger for the production of this edition.

A. Simon Turner

C. Wayne McIlwraith

Fort Collins, Colorado

Preface to the First Edition

This book presents some fundamental techniques in large animal surgery to both veterinary students and large animal practitioners. It is designed to be brief, discussing only the major steps in a particular operation, and each discussion is accompanied by appropriate illustrations. Most of the techniques presented in this book can be performed without the advantages of a fully equipped large animal hospital or teaching institution.

The book assumes a basic understanding of anatomy and physiology. Those who wish to know more about a particular technique are encouraged to consult the bibliography.

We and our colleagues at the Veterinary Teaching Hospital, Colorado State University, consider the procedures discussed in this book to be time‐honored. Some practitioners may perform certain techniques in slightly different ways. We would be happy to receive input about modifications of these techniques for future editions of this book.

All of the drawings in the book are original and based on rough sketches and photographs taken at various points during actual surgery. Occasionally, dissections were performed on cadavers.

The surgical procedures described in this text represent not only our thoughts, but suggestions from many of our colleagues as well. Their help was an important contribution to the production of this book. We are indebted to Dr. Wilbur Aanes, Professor of Surgery, Colorado State University, who unselfishly shared 30 years of his personal experience in large animal surgery with us. We are proud to be able to present in Chapter 10 of this book “Aanes’ Method of Repair of Third‐Degree Perineal Laceration” in the mare, a technique that he pioneered over 15 years ago. We also wish to give credit to the following faculty members at the Veterinary Teaching Hospital, Colorado State University, who willingly gave us advice on the diagrams and manuscript of various techniques discussed in this book: Dr. Leslie Ball, Dr. Bill Bennett, Dr. Bruce Heath, Dr. Tony Knight, Dr. LaRue Johnson, Dr. Gary Rupp, Dr. Ted Stashak, Dr. Gayle Trotter, Dr. James Voss, and Dr. Mollie Wright. We also wish to express appreciation to Dr. John Baker, Purdue University, and Dr. Charles Wallace, University of Georgia, for their comments on some of our questions. Dr. McIlwraith is also grateful to Dr. John Fessler, Professor of Surgery, Purdue University, for his inspiration and training.

We are particularly grateful to Dr. Robert Kainer, Professor of Anatomy, Colorado State University, for checking the manuscript and the illustrations and advising us on nomenclature. His input impressed upon us the importance of the relationship between the dissection room and the surgery room.

The terrific amount of time and effort involved with the illustrations will be clear to the reader who cares only to leaf through the book. For these illustrations, we are indebted to Mr. Tom McCracken, Director, Office of Biomedical Media, Colorado State University. We are thankful for his expertise, as well as his cooperation and understanding. The diagrams for “Aanes’ Method of Repair of Third‐Degree Perineal Laceration” were done by Mr. John Daughtery, Medical Illustrator, Colorado State University. We must also thank Kathleen Jee, who assisted with various aspects of the artwork. We would also like to thank Mr. Al Kilminster and Mr. Charles Kerlee for taking photographs during the various surgical procedures that were used to assist with the artwork of this text.

The manuscript was typed by Mrs. Helen Mawhiney, Ms. Teresa Repphun, and Mrs. Jan Schmidt. We thank them for their patience and understanding during the many changes we made during the generation of the final manuscript.

We are grateful to the following instrument companies for allowing us to use some of the diagrams from their sales catalogs for inclusion in Chapter 3, “Surgical Instruments”: Schroer Manufacturing Co., Kansas City, MO; Intermountain Veterinary Supply, Denver, CO; Miltex Instrument Co., Lake Success, NY; J. Skyler Manufacturing Co., Inc., Long Island, NY.

The idea for this book was conceived in 1978 when one of us (AST) was approached by Mr. George Mundroff, Executive Editor, Lea & Febiger. We would like to thank him for his encouragement and guidance. We are also grateful to Mr. Kit Spahr, Jr., Veterinary Editor; Diane Ramanauskas, Copy Editor; Tom Colaiezzi, Production Manager; and Samuel A. Rondinelli, Assistant Production Manager, Lea & Febiger, for their assistance, as well as to others at the Publisher who assisted in the production of this book.

A. Simon Turner

C. Wayne McIlwraith

Fort Collins, Colorado

About the Companion Website

The following companion website accompanies this book:

www.wiley.com/go/hendrickson/largeanimal_surgerytechniques 

The website includes

PowerPoints of all figures from the book for downloading

1Presurgical Considerations

Dean A. Hendrickson, DVM, MS, DACVS

OBJECTIVES

Discuss some of the presurgical considerations that can affect the success of a procedure, including the physiological state and condition of the patient; the predisposing factors for infection; and the limitations of the surgeon, facilities, and equipment.

Describe the methods of asepsis and antisepsis.

Describe the classification of different procedures with regard to risk of infection and degree of contamination.

Discuss the judicious use of antibiotics and their applications in prophylaxis and postoperative infection.

Describe proper techniques for surgical site preparation.

Preoperative Evaluation of the Patient

Before a surgical procedure, a physical examination is generally indicated. This applies to both emergency and elective surgeries. The following are laboratory tests that are generally indicated for horses based on animal age and systemic status at our clinic:

For horses younger than 4 years old and healthy:

Packed cell volume

Total protein

Appropriate for horses > 4 years old or those that are systemically ill:

Complete blood count

Chemistry

Exactly where to draw the line on laboratory tests is largely a matter of judgment on the part of the surgeon. Obviously, if the surgery consists of castration of several litters of piglets, then for purely economic reasons laboratory tests prior to surgery may not be performed. In many cases, however, additional tests will be necessary. The following are examples of other optional tests and their indications:

Electrolyte measurement for right‐sided abomasal diseases of the dairy cow

Urinalysis in the dairy cow to evaluate the presence of ketosis

Measurement of and creatinine if urinary problems are suspected

Analysis of peritoneal fluid prior to laparotomy for horses with colic

Full chemistry panels when there are age or systemic considerations

If any laboratory parameters are abnormal, the underlying causes should be investigated and efforts made to correct them. In “elective” surgery, this is possible, but it may not be possible in an emergency. The owner should be made aware of any problems prior to subjecting the animal to surgery. Risks are always present in normal elective surgery, and these should be explained to the owner. It is always better to have an early, frank discussion with the owner about the possible risks associated with the surgery than to have the discussion after the risk has been realized.

Fluid replacement should be performed if necessary. In the elective case, the surgical procedure should be postponed if the animal’s physical condition or laboratory parameters are abnormal. In some animals, internal and external parasitism may have to be rectified to achieve this goal.

Medical records should be kept at all times. Obviously, this can be difficult in such cases as castration of several litters of piglets. However, record keeping should become an essential part of the procedure for horses and cattle in a hospital, and herd records should be kept in all other situations. Finally, if the animal is insured, the insurance company must be notified of any surgical procedure; otherwise, the policy may be void.

Surgical Judgment

Surgical judgment cannot be learned overnight by reading a surgery textbook, nor is it necessarily attained by years of experience. The surgeon who continually makes the same mistake will probably never possess good surgical judgment. Not only should the surgeon learn from his own mistakes, but he also should learn from the mistakes of others, including those documented in the surgical literature. As part of surgical judgment, the surgeon must ask the following questions:

Is the surgery necessary?

What would happen if the surgery were not performed?

Is the procedure within the capabilities of the surgeon, the facilities, and the technical help?

If the surgeon finds that the procedure is too advanced for his or her capabilities and/or facilities, the surgery should be referred. Some veterinarians have a fear that this will mean the loss of the client’s business in the future, but this is rarely the case. If the surgeon explains why the case should be referred elsewhere, most clients will be grateful for such frankness and honesty. It is inexcusable to operate on a patient and then have complications arise due to inadequate training and facilities, when the surgery could easily have been referred to a well‐equipped, well‐staffed hospital with specially qualified personnel. Clearly, this rule has exceptions—mainly the emergency patient, which may fare better by undergoing immediate surgery than being subjected to a long trailer ride to another facility.

Many of the procedures described in this book can be done “on the farm.” Some, such as arthrotomy for removal of chip fractures of the carpal and sesamoid bones in horses, should be done in a dust‐free operating theater. If clients want these latter procedures to be done “in the field,” they should understand the disastrous consequences of postsurgical infection. The surgeon must be the final judge of whether his facilities or experience are suitable.

Principles of Asepsis and Antisepsis

There are four main determinants for a surgical site infection (SSI): host defense, physiologic derangement, bacterial contamination risk at surgery, and prolonged surgical time.1 Other factors that impact infection of deep structures and organs include hypoalbuminemia and a prior operation.2 Perioperative blood loss also contributes to SSI.3 Control methods include aseptic surgical practices as well as identification of the high‐risk patient, correction of systemic imbalances prior to surgery, and the proper use of prophylactic antibiotics.

We are sometimes reminded by fellow veterinarians in the field that we must teach undergraduates how to do surgery in the real world. By this, they mean that we must ignore aseptic draping and gloving and lower the standard to a “practical” level. This is fallacious in our opinion. Although we recognize that while the ideal may be unattainable in private practice, one should always strive for the highest possible standard; otherwise, the final standard of practice may be so low that the well‐being of the patient is at risk, not to mention the reputation of the veterinarian as a surgeon. For this reason, we believe that it behooves us as instructors of undergraduates to teach the best possible methods with regard to asepsis as well as techniques.

The extent to which the practice of asepsis or even antisepsis is carried out depends on the classification of the operation, as shown in Table 1.1. This classification may also help the veterinarian decide whether antibiotics are indicated or whether postoperative infection can be anticipated.

Table 1.1 Surgical classifications.

Classification

Description

Examples

Clean

Gastrointestinal, urinary, or respiratory tract is not entered.

Arthrotomy for the removal of a chip fracture of a carpal bone of a horse

Clean‐contaminated

Gastrointestinal, respiratory, or urinary tract is entered. There is no spillage of contaminated contents.

Abomasopexy for displaced abomasum in the dairy cow

Contaminated‐dirty

Gross spillage of contaminated body contents or acute inflammation occurs.

Wounds abscesses devitalized bowel

Surgical Classifications

Once the surgeon has categorized the surgical procedure, appropriate precautions to avoid postoperative infection can be determined. In all cases, however, the surgical site is prepared properly, including clipping and aseptic scrubbing.

Whatever category of surgery is performed, clean clothing should be worn. The wearing of surgical gloves is a good policy even if only to protect the operator from infectious organisms that may be present at the surgical site. Surgical gowns, gloves, and caps are recommended for clean surgical procedures, although such attire has obvious practical limitations for the large animal surgeon operating in the field. The purpose of this book is to present guidelines rather than to lay down hard‐and‐fast rules. For example, the decision between wearing caps, gowns, and gloves and wearing just gloves can be made only by the surgeon. Good surgical judgment is required. In general, it is better to be more careful than what may appear necessary in order to be better prepared when problems arise.

Role of Antibiotics

Antibiotics should never be used to cover flaws in surgical technique. The young surgeon is often tempted, sometimes under pressure from the client, to use antibiotics prophylactically. However, the disadvantages of antimicrobial therapy often outweigh its benefits. Extended periods of antimicrobial therapy can select for resistant organisms and adversely affect the gastrointestinal tract by eliminating many of the normal enteric organisms and allowing outgrowths of pathogenic bacteria, such as Clostridia spp., which can result in colitis and diarrhea.4 When selecting an antibiotic regimen, the surgeon should consider the following aspects:

Does the diagnosis warrant antibiotics?

Which organisms are most likely to be involved, and what is their in‐vitro antimicrobial susceptibility?

What is the location or likely location of the infection?

How accessible is the location of the infection to the drug?

What possible adverse reactions and toxicities to the drug could occur?

What dosage and duration of treatment are necessary to obtain sufficient concentrations of the drug?

Again, some judgment is required, but suffice it to say, antibiotics should never be substituted for “surgical conscience.” Surgical conscience consists of the following: dissection along tissue planes, gentleness in handling tissues, adequate hemostasis, selection of the best surgical approach, correct choice of suture material (both size and type), closure of dead space, and short operating time.

If the surgeon decides that antibiotics are indicated, special attention should be given to selecting the type of antimicrobial drug, the dosage, and the duration of use. Ample scientific literature indicates that for maximum benefit, antimicrobials should be administered prophylactically prior to surgery and, at the latest, during surgery. Beyond 4 hours postsurgically, the administration of prophylactic antibiotics has little to no effect on the incidence of postoperative infection.1 The duration of treatment should not exceed 24 hours because most research indicates that antimicrobial use after this period of time does not confer further benefits. If a longer duration of antimicrobial coverage is necessary, the full duration of the specific antimicrobial drug selected should be given. This varies depending on the drug; however, in most cases, the duration is at least 3 and up to 5 days. If the surgeon is operating on a food animal, there are regulations for withdrawal times from different antimicrobial drugs prior to slaughter that must be taken into account.

If topical antibiotics are used during surgery, they should be nonirritating to the tissues; otherwise, tissue necrosis from cellular damage will outweigh any advantageous effects of the antibiotics. It is also beneficial when using topical antibiotics to use antibiotics that are not generally used systemically.

All equine surgical patients should have tetanus prophylaxis. If the immunization program is doubtful, the horse can receive 1500–3000 units of tetanus antitoxin. Horses on a permanent immunization program that have not had tetanus toxoid within the previous 6 months should receive a booster injection.

Tetanus prophylaxis is generally not provided for food animals, but an immunization program may be considered, especially if a specific predisposition is thought to exist.

Preoperative Planning

The surgeon should be thoroughly familiar with the regional anatomy. In this book, we illustrate what we consider to be the important structures in each technique. If more detail is required, a suitable anatomy text should be consulted. Not only should the procedure be planned prior to the surgery, but the surgeon also should visit the dissection room and review the local anatomy of cadavers prior to attempting surgery on a client’s animal. We are fortunate in veterinary surgery to have greater access to cadavers than our counterparts in human surgery.

Preparation of the Surgical Site

For the large animal surgeon, preparation of the surgical site can present major problems, especially in the winter and spring when farms can be muddy. Preparation for surgery may have to begin with the removal of dirt and manure. Some animals that have been recumbent in mud and filth for various reasons may have to be hosed off. Hair should then be removed, not just from the surgical site, but from an adequate area surrounding the surgical site.

The clipping should be done in a neat square or rectangular shape with straight edges. Surprisingly, this, along with the neatness of the final suture pattern in the skin, is how the client judges the skill of the surgeon. Clipping may be done initially with a no. 10 clipper blade, and then the finer no. 40 blade may be used. The incision site can be shaved with a straight razor in horses and cattle, but debate exists regarding the benefits or problems associated with this procedure. In sheep and goats, in which the skin is supple and pliable, it is difficult to shave the edges.

Preparation of the surgical site, such as the ventral midline of a horse about to undergo an exploratory laparotomy, may have to be performed when the animal is anesthetized. If surgery is to be done with the animal standing, an initial surgical scrub, followed by the appropriate local anesthetic technique and a final scrub, is the standard procedure.

For cattle or pigs, the skin of the surgical site can be prepared for surgery with the aid of a stiff brush. For horses, gauze sponges are recommended. Sheep may require defatting of the skin with alcohol prior to the actual skin scrub. The antiseptic scrub solution used is generally a matter of personal preference. Either povidone‐iodine scrub (Betadine Scrub) alternated with a 70% alcohol rinse, or Chlorhexidine alternated with water, can be used. Finally, the skin can be sprayed with povidone‐iodine solution (Betadine Solution) and allowed to dry.

Scrubbing of the proposed surgical site is done immediately prior to the operation. Scrubbing should commence at the proposed site of the incision and progress toward the periphery; one must be sure not to come back onto a previously scrubbed area. Some equine surgeons clip and shave the surgical site the night before the surgery, perform an aseptic preparation as previously described, and wrap the limb in a sterile bandage until the next day. A shaving nick made the day before surgery may be a pustule on the day of surgery, however, so this is generally not recommended for anything proximal to the pastern region.

When aseptic surgery is to be performed, an efficient draping system is mandatory. Generally, the time taken to drape the animal properly is well spent. The draping of cattle in the standing position can be difficult, especially if the animal decides to move or becomes restless. It can be difficult to secure drapes with towel clamps in the conscious animal because only the operative site is anesthetized. However, if the surgeon applies slow pressure when closing the towel clamps, most animals will tolerate their application, even if the local site is not desensitized. If draping is not done, the surgeon must minimize contact with parts of the animal that have not been scrubbed. The tail must be tied to prevent it from flicking into the surgical field.

Several operations described in this book require the strictest of aseptic techniques; sterile, antimicrobial, adhesive, incise drapes are indicated. Characteristics of sterile plastic adhesive drapes include their ability to adhere, their antimicrobial activity, and their clarity when applied to the skin. Probably the most desirable feature is the one first mentioned. With excessive traction or manipulation, some brands of drapes quickly separate from the skin surfaces, and this separation instantly defeats their purpose.

Rubberized drapes are helpful when large amounts of fluids (such as peritoneal and amniotic fluid) are encountered during the procedure. Rubberized drapes are also useful to isolate the bowel or any other organ that is potentially contaminated, to prevent contamination of drapes. Newer fluid‐impermeable paper drapes that are disposable make the surgeon's job even easier.

Postoperative Infection

Prevention of postoperative infection should be the goal of the surgeon, but infection may occur despite all measures taken to prevent it. If infection occurs, the surgeon must decide whether antibiotic treatment is indicated, or whether the animal is strong enough to fight it using its own defense mechanisms. Some surgical wounds require drainage at their most ventral part, whereas others require more aggressive treatment. If, in the judgment of the surgeon, the infection appears to be serious, a Gram stain, culture, and sensitivity testing of the offending microorganism(s) will be indicated. A Gram stain may give the surgeon a better idea of what type of organism is involved and may in turn narrow the selection of antibiotics. Sometimes in‐vitro sensitivities have to be ignored because the antibiotic of choice would be prohibitively expensive. This is especially true for adult cattle and horses. A broad‐spectrum antibiotic should be given, if possible, as soon as practical.

References

1

Barie, P.S. Modern surgical antibiotic prophylaxis and therapy—less is more.

Surg. Infect.

,

1

:23–29, 2000.

2

Haridas, M., and Malangoni, M.A. Predictive factors for surgical site infection in general surgery.

Surgery

,

144

:496–503, 2008.

3

Sorensen, L.T., Hemmingsen, U., Kallehave, F., et al. Risk factors for tissue and wound complications in gastrointestinal surgery.

Ann. Surg.

,

241

:654–658, 2005.

4

Papich, M.G. Antimicrobial therapy for gastrointestinal disease.

Vet. Clin. North Am. Equine Pract.

,

19

:645–663, 2003.

2Anesthesia and Fluid Therapy

Khursheed Mama DVM, DACVAA

OBJECTIVES

Describe routine regional anesthetic techniques in large animals.

Discuss selected species differences in reference to anesthetic techniques.

Describe the indications for, advantages of, and disadvantages of general anesthesia in large animal species.

Provide a basic discussion of the fundamentals of fluid therapy including methods for ascertaining fluid deficits, acid–base imbalances, and electrolyte abnormalities.

Discuss specific fluid therapies in patients undergoing elective surgery and in compromised patients, either with or without preliminary data.

Anesthesia

The purpose of this section is not to present an in‐depth discussion of all aspects of anesthesia. Details on the principles of anesthesia, recognition of stages of anesthesia, monitoring during anesthesia, and the pharmacology and physiology associated with anesthesia are well documented in other texts.1–3 Rather, information pertaining to routinely used anesthetic techniques for large animals is provided. The interested reader is referred to additional sources for more in‐depth information.4, 5

Local and Regional Anesthesia (Analgesia)

Regional anesthesia results from desensitization of sensory nerves to a given area. This may be performed by infiltration into the desired location or by “blocking” sensory nerve(s) innervating a region. Both techniques may be used to desensitize the surgical site. Depending on the required duration of anesthesia, local anesthetic agents including lidocaine hydrochloride (shortest onset and duration), mepivacaine hydrochloride, and bupivacaine hydrochloride (longest onset and duration) may be used. Due to cardiovascular toxicity with vascular absorption, bupivacaine use is usually limited to epidural and perineural administration; lidocaine and mepivacaine may be used by any route. Mepivacaine is often selected because of its rapid onset, intermediate duration, and reduced tissue reactivity.6 Newer long‐acting local anesthetic options include ropivacaine, levo‐bupivacaine, and a liposomal formulation of bupivacaine.

Regional anesthesia techniques are still commonly used as primary means to facilitate noxious intervention in many ruminant species. Sedation may be used as an adjunct. In horses, while these techniques may be used in sedated patients, they are also commonly used as adjuncts to general anesthesia. A description of selected regional anesthesia techniques follows.

Infiltration Analgesia

The principles of infiltration anesthesia are simple and similar for all species. Following definition of the area to be desensitized, local anesthetic is injected at an initial site with a small gauge needle and then a longer needle is inserted through the initial region of desensitization. Repeat injections are usually made through a region that has already been desensitized. When possible, the skin and subcutis should be infiltrated first and then the deeper layers, such as muscle and peritoneum. The injection of significant amounts of local anesthetic into the peritoneal cavity should be avoided as rapid vascular absorption can result in toxicity. Infiltrating injections should be made in straight lines; “fanning” should be avoided as much as possible because of the potential for tissue trauma.

Infiltration analgesia is commonly used for suturing wounds and for removing cutaneous lesions in all large animal species. It may also be used in the form of a “line block” for laparotomy, in which case the analgesic agent is infiltrated along the line of incision. Although convenient, the infiltration of the analgesic agent into the incision line causes edema in the tissues and may affect wound healing. In this respect, regional anesthetic techniques that are removed from the surgical site are generally preferred.

Techniques of Regional Analgesia

Inverted L Block 

This is the simplest technique of regional anesthesia for laparotomy and laparoscopy in large animal species. It may be used to facilitate flank or paramedian interventions. The principles of the technique are illustrated for cattle in Figure 2.1. Local anesthetic agent is administered nonspecifically in the form of an inverted L with the goal of blocking nerves entering the surgical field. The procedure is facilitated by the use of an 8–10‐cm, 16–18‐gauge needle. It is generally recommended that a dose of local anesthetic is limited to 2 mg/kg. However, up to 100 ml of 2% lidocaine has been used for adult horses and cows (4 mg/kg for 500‐kg patients). The vertical portion of the inverted L is caudal to the last rib, and the horizontal portion is just ventral to the transverse processes of the lumbar vertebrae. Ten to fifteen minutes should be allowed for the drug to take effect.

Fig. 2.1. Inverted L block.

Systemic toxicity following inadvertent intravenous administration or absorption from regional sites is reported. Experiments in sheep have shown that convulsions occur in adult sheep at a dose of lidocaine hydrochloride of 5.8 ± 1.8 mg/kg intravenously.7 Subconvulsive doses of lidocaine hydrochloride produce drowsiness. Above convulsive doses, hypotension, respiratory arrest, and circulatory collapse occur progressively. If convulsions do occur, they can be controlled with an intravenous dose of 0.5 mg/kg of diazepam (Valium). To minimize the occurrence, it is recommended that diluted local anesthetic is used for smaller‐sized animals such as sheep and goats.1, 8 Toxicity following inadvertent intravenous bupivacaine administration manifests in cardiovascular collapse.

Paravertebral Block 

While not common, the paravertebral block has been described and utilized to desensitize the flank area for standing procedures in horses.9 It is however more commonly performed in cattle, sheep, and goats.8, 10 In ruminants, the thirteenth thoracic nerve (T13), the first and second lumbar nerves (L1 and L2), and the dorsolateral branch of the third lumbar nerve (L3) supply sensory and motor innervation to the skin, fascia, muscles, and peritoneum of the flank. Regional analgesia of these nerves is the basis of the paravertebral block. For practical purposes with flank laparotomy, blocking of the dorsolateral branch of L3 is not generally considered necessary and may be contraindicated because, if one has miscounted the vertebrae, one may actually block L4, where sensory and motor nerve fibers to the hind limbs originate.

Two approaches to performing the paravertebral block have been described for cattle. The first consists of walking the needle off the transverse process, as illustrated in Figure 2.2. As the nerve is most distinct at its intervertebral foramen, walking the needle off the transverse process closer to this site allows one to block the nerve before or close to the split into individual dorsal and ventral branches. As the transverse processes slope forward, the transverse process of L1 is used as a landmark to block T13, and the transverse processes of L2 and L3 are similarly used to locate nerves L1 and L2, respectively. When the transverse process has been located, a line is drawn from its cranial edge to the dorsal midline. The site for injection is 3–5 cm from the midline (Figure 2.2) caudal to transverse processes of L1, L2, and L3. The transverse process of L1 is difficult to locate in fat animals, in which case the site is estimated relative to the distance between the processes of L2 and L3. Following subcutaneous infiltration of local anesthetic, a 1‐inch, 16‐gauge needle is inserted to act as a guide in placing a 10‐cm, 20‐gauge needle perpendicular to the transverse process is encountered. The needle is then walked off the cranial border of the transverse process and advanced 0.75 cm (will generally feel penetration of the intertransverse ligament), and approximately 10 ml of local anesthetic solution (typically 2% lidocaine or mepivacaine) is administered below the ligament. An additional 5 ml is placed dorsal to the ligament. If the drug has been administered correctly, desensitization will be effective within a few minutes. In testing the block, one must remember that the distribution of the nerves is such that T13 innervates the ventral flank area, whereas L2 innervates the more dorsal region closer to the transverse processes. A temporary lateral deviation of the spine due to muscle paralysis is observed in association with paravertebral analgesia. Vasodilation of surface vessels may also be observed.

Fig. 2.2. Paravertebral block.

An alternate technique favored by some was developed by Magda and modified by Cakala.11