Feline Anesthesia and Pain Management

Contents

Cover

Title Page

Copyright

Dedication

Foreword

Contributors

Chapter 1: Handling, Restraint, and Preanesthetic Assessment

Introduction

Handling and Restraint

Preanesthetic Assessment

Risk Factors, Morbidity, and Mortality

Further Reading

Chapter 2: Anatomy, Physiology, and Pharmacology

Introduction

Cardiovascular System

Respiratory System

Nervous System

Urinary System

Hepatic System

Endocrine System

Gastrointestinal System

Further Reading

Chapter 3: Sedation and Premedication

Introduction

Drugs used for Sedation in Cats

Acepromazine

Benzodiazepines

Agonists of α2-Adrenergic Receptors

Anticholinergics

Opioids

Ketamine and Alfaxalone

Trazodone

Other Drugs

Further Reading

Chapter 4: Injectable Anesthetics and Induction of Anesthesia

Introduction

General Considerations for Induction of Anesthesia

Drugs used for Induction of Anesthesia

Propofol

Alfaxalone

Dissociative Anesthetics (Ketamine and Tiletamine)

Barbiturates

Etomidate

Fentanyl plus Midazolam

Induction with Volatile Anesthetics

Total Intravenous Anesthesia (TIVA)

Infusion Devices

Injectable-only Protocols

Further Reading

Chapter 5: Local Anesthetics and Loco-regional Techniques

Introduction

Physicochemical and Pharmacodynamic Properties of Local Anesthetics

Axons and Nerve Fibers

Pharmacokinetics

Factors Influencing Onset and Duration of Action

Metabolism

Adjuvants

Local Anesthetics

Techniques for Nerve Location

Local Anesthetic Techniques

Further Reading

Chapter 6: Inhalation and Balanced Anesthesia

Volatile Anesthetics

Halothane

Isoflurane

Sevoflurane

Desflurane

Balanced Anesthetic Techniques

Opioids

Ketamine

Nitrous Oxide

Lidocaine

Dexmedetomidine

Gabapentin

Balanced Anesthesia Summary

Breathing Systems

Further Reading

Chapter 7: Monitoring

Introduction

Clinical Monitoring using Physical Senses (Hands On)

Cardiovascular System

Respiratory System

Further Reading

Chapter 8: Fluid Therapy

Introduction

Feline Physiology and Pathology with regard to Fluid Therapy

Fluids

Preoperative Preparation

Intraoperative Fluids

Postoperative Care

Further Reading

Chapter 9: Anesthetic Management of Special Conditions

Introduction

Urethral Obstruction and Uroabdomen

Chronic Kidney Disease (CKD)

Hyperthyroidism

Hypertrophic Cardiomyopathy (HCM)

Neuroanesthesia

Diaphragmatic Rupture

Gastrointestinal Emergencies

Idiopathic Hepatic Lipidosis

Diabetes Mellitus

Other Conditions

Further Reading

Chapter 10: Anesthetic Complications

Introduction

Airway Management

Respiratory Insufficiency

Circulation

Trauma

Recovery

Body Temperature

Cardiopulmonary Resuscitation (CPR)

Further Reading

Chapter 11: Mechanisms of Pain

Introduction

Mechanisms of Modulation in Tissues

Mechanisms of Modulation in Peripheral Nerves

Mechanisms of Modulation in The Spinal Cord

Mechanisms of Modulation in the Brain

The Role of Glial Cells (Glia, Neuroglia) and the Immune System

Mechanisms of Cancer Pain

Diabetic Neuropathy

Pruritus (Itch)

Further Reading

Chapter 12: Assessment and Recognition of Acute Pain

Introduction

Pain-assessment Tools

Behavior-based Indicators of Pain (Box 12.3)

Intervention Scores

Using Response to Treatment as a Diagnostic Tool

Confounding Factors

Personality, Fear and Stress

Using Pain-assessment Tools

Continued Assessment at Home

Further Reading

Chapter 13: Treatment of Acute (Adaptive) Pain

Introduction

Challenges in Feline Pain Management

Principles of Pain Management

Nonpharmacological Therapies in Acute Pain Management

Pharmacological Therapy in Acute Pain Management

Further Reading

Chapter 14: Assessment and Recognition of Chronic (Maladaptive) Pain

Introduction

Common Causes of Chronic Pain

Clinical Signs

Implications for Quality of Life

The Concept of Analgesic Challenge

Assessing Chronic Pain in Specific Conditions

Further Reading

Chapter 15: Treatment of Chronic (Maladaptive) Pain

Introduction

Client Communication: A Crucial Component of Treatment for Chronic Painful Conditions

Challenges in the Treatment of Chronic Pain in Cats

Pharmacological Therapy

Opioids

Local Anesthetics

Nonsteroidal Anti-inflammatory Drugs (NSAIDs)

Tramadol

Gabapentin

Amitriptyline

Amantadine

Emerging Analgesic Modalities

Other Analgesics

Nonpharmacological Treatment

Physical Activity and Weight Control

Physical Therapy, Massage, Acupuncture, and Transcutaneous Electrical Nerve Stimulation (TENS)

Monitoring for Treatment Efficacy

Degenerative Joint Disease (DJD)

Further Reading

Index

End User License Agreement

List of Tables

Table 1.1

Table 1.2

Table 1.3

Table 2.1

Table 2.2

Table 2.3

Table 2.4

Table 2.5

Table 3.1

Table 3.2

Table 4.1

Table 4.2

Table 5.1

Table 5.2

Table 5.3

Table 6.1

Table 7.1

Table 8.1

Table 8.2

Table 8.3

Table 11.1

Table 11.2

Table 11.3

Table 13.1

Table 14.1

Table 14.2

Table 15.1

Table 15.2

List of Illustrations

Figure 1.1

Figure 1.2

Figure 1.3

Figure 1.4

Figure 1.5

Figure 1.6

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.5

Figure 3.1

Figure 3.2

Figure 3.3

Figure 4.1

Figure 4.2

Figure 5.1

Figure 5.2

Figure 5.3

Figure 5.4

Figure 5.5

Figure 5.6

Figure 5.7

Figure 5.8

Figure 5.9

Figure 6.1

Figure 6.2

Figure 6.3

Figure 6.4

Figure 6.5

Figure 7.1

Figure 7.2

Figure 7.3

Figure 7.4

Figure 7.5

Figure 7.6

Figure 8.1

Figure 8.2

Figure 9.1

Figure 9.2

Figure 9.3

Figure 9.4

Figure 9.5

Figure 9.6

Figure 10.1

Figure 10.2

Figure 10.3

Figure 10.4

Figure 10.5

Figure 10.6

Figure 10.7

Figure 10.8

Figure 10.9

Figure 10.10

Figure 11.1

Figure 11.2

Figure 11.3

Figure 11.4

Figure 11.5

Figure 12.1

Figure 12.2

Figure 12.3

Figure 12.4

Figure 12.5

Figure 12.6

Figure 12.7

Figure 12.8

Figure 12.9

Figure 12.10

Figure 12.11

Figure 13.1

Figure 13.2

Figure 13.3

Figure 13.4

Figure 13.5

Figure 14.1

Figure 14.2

Figure 14.3

Figure 14.4

Figure 14.5

Figure 14.6

Figure 15.1

Figure 15.2

Figure 15.3

Figure 15.4

Figure 15.5

Feline Anesthesia and Pain Management

Edited by

Paulo Steagall

Université de Montréal, Saint-Hyacinthe, Canada

Sheilah Robertson

Lap of Love Veterinary Hospice, Lutz, FL, United States

Polly Taylor

Taylor Monroe, Little Downham, Ely, United Kingdom

This edition first published 2018

© 2018 John Wiley & Sons, Inc.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.

The right of Paulo Steagall, Sheilah Robertson, and Polly M Taylor to be identified as the editors of the editorial material in this work has been asserted in accordance with law.

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Library of Congress Cataloging-in-Publication Data

Names: Steagall, Paulo V. M., author. | Robertson, Sheilah A., author. |Taylor, Polly M., author.

Title: Feline anesthesia and pain management / by Paulo V.M. Steagall, Sheilah A. Robertson, Polly Taylor.

Description: Hoboken, NJ : Wiley, 2018. | Includes bibliographical references and index. |

Identifiers: LCCN 2017026911 (print) | LCCN 2017027877 (ebook) | ISBN9781119167846 (pdf) | ISBN 9781119167877 (epub) | ISBN 9781119167808 (pbk.)

Subjects: | MESH: Cat Diseases–drug therapy | Pain Management–veterinary |Anesthesia–veterinary

Classification: LCC SF985 (ebook) | LCC SF985 .S74 2018 (print) | NLM SF 985| DDC 636.8/089796–dc23

LC record available at https://lccn.loc.gov/2017026911

Cover images: Courtesy of the editors

Cover design by Wiley

Dedication

Paulo Steagall

To my mother Ilza who has always supported my dreams. To my partner in crime Beatriz Monteiro who accepted me to ride along in this journey. To my father who taught me the love for cats. To Polly Taylor and Sheilah Robertson for believing. This book is for all cats and for people who dedicate their lives to protect and help them. Cats gave me a reason to become a veterinarian, and a job for the rest of my life.

Sheilah Robertson

To my parents who always believed in education and supporting my career choice. To Paulo Steagall and Polly Taylor for their friendship, unwavering patience, and dedication to detail during the writing and editing process. To all the cats that have owned me and all my feline patients, thank you for everything you have taught me.

Polly Taylor

Thanks to Leslie Hall and Peter Lees who each in their own way encouraged me in the pursuit of all things feline – for cats in their own right, not as little dogs. To all cats, wonderful creatures, especially those who have owned me over the years, and particularly to Jasper, the current incumbent, who typed enthusiastically, if unhelpfully, some variations on the text herein. And most of all to Paulo and Sheilah for making it all happen, and to my family for their extreme patience and well-timed glasses of wine.

We would like to thank all collaborators for donating their time and expertise for this book.

Foreword

It gives me enormous pleasure, and it is a great privilege, to be able to write a preface for the first edition of this new book, edited and coauthored by Drs. Paulo Steagall, Sheilah Robertson, and Polly Taylor. If you are reading this having just purchased the book, the first thing to say is congratulations! You have made a sound investment!

For many decades there has been a trend for growth in cat ownership, and in many countries throughout the world the pet cat population now exceeds that of dogs. Despite their rising popularity, cats are still often a second class veterinary patient. Cats are taken to the veterinarian less frequently than dogs, and, regrettably, veterinary publications on dogs still far outweigh those on cats. Things are changing though – many practitioners appreciate the real value in focusing on the differing (and sometimes unique) needs of cats, and there is a growing emphasis on a better understanding of cats as veterinary patients.

The welfare of patients under our care is, of course, the primary concern of every veterinarian. It is also true that, in terms of animal welfare, nothing is more important than pain relief, which is why I am so pleased to see the publication of this new book. It is nearly 25 years since the last veterinary book to focus on feline anesthesia was published (Anaesthesia of the Cat, edited by Hall and Taylor, published in 1994). As so much has changed in our knowledge in the past 25 years, this new publication is both timely and a very welcome addition to the literature.

This book takes a very practical approach to feline anesthesia and analgesia. It is designed to be a practical clinical tool, providing state-of-the-art information in accessible format enabling improved management of cats under our care. This book is equally relevant to veterinary practitioners, students, nurses and technicians, and with its emphasis on the management of both acute and chronic pain it will serve as an invaluable resource in any clinic.

The concise and clear layout of this book makes accessing information particularly easy for the busy practitioner. The text is concise, practical, relevant, and addresses exactly the sorts of questions and issues that occur in day-to-day veterinary practice. Chapters are well illustrated and authored by an outstanding collection of international experts in feline anesthesia and analgesia.

It is perhaps unusual to look at a book's table of contents and to look forward to reading every single chapter in the publication. I can honestly say that is the case with this book though. Much thought has gone into its structure, the subjects covered, and the way they are addressed. I hope and believe that this book will be very widely read and used. For anyone purchasing the book, it is destined to be something that is used on a daily basis in the clinic, and will not be a book that simply collects dust on the shelf!

On a personal note, I am passionate about feline welfare – I have also known Paulo, Sheilah, and Polly for a number of years and I know how passionate they are too about improving cat welfare through better clinical application of analgesia. With this book, any veterinarian or nurse/technician will find a wealth of practical information that will directly impact their everyday clinical work, and will improve the lives of the cats that are under their care. I can offer no higher recommendation – this book will improve your ability to care for your feline patients and improve their welfare, and as such it deserves to have a place in every small animal clinic.

Dr. Andy Sparkes BVetMed PhD DipECVIM MANZCVS MRCVS

Veterinary Director, International Cat Care and International Society of Feline Medicine

www.icatcare.org

Contributors

Graeme Doodnaught

Resident in Veterinary Anesthesia and Analgesia

Department of Clinical Sciences Faculty of Veterinary Medicine Université de Montréal

3200 Rue Sicotte

Saint-Hyacinthe, QC J2S2M2

Canada

Craig B. Johnson

Professor of Veterinary Neurophysiology Institute of Veterinary, Animal and Biomedical Sciences

College of Sciences

Massey University Private Bag 11 222

Palmerston North

New Zealand

Duncan Lascelles

Professor of Small Animal Surgery and Pain Management Comparative Pain Research Laboratory

College of Veterinary Medicine

North Carolina State University

1060 William Moore Drive

Raleigh, NC 27607

United States

Beatriz Monteiro

PhD Candidate in Veterinary Pharmacology

Vanier Scholar

Department of Biomedical Sciences Faculty of Veterinary Medicine Université de Montréal

3200 Rue Sicotte

Saint-Hyacinthe, QC J2S2M2

Canada

Daniel Pang

Associate Professor of Veterinary Anesthesiology

Department of Clinical Sciences Faculty of Veterinary Medicine Université de Montréal

3200 Rue Sicotte

Saint-Hyacinthe, QC J2S2M2

Canada

Peter Pascoe

Professor of Anesthesia and Critical Patient Care

Department of Surgical and Radiological Sciences

School of Veterinary Medicine

1 Shields Ave

University of California

Davis, CA 95616

United States

Bruno Pypendop

Professor of Veterinary Anesthesiology

Department of Surgical and Radiological Sciences

School of Veterinary Medicine

University of California

One Shields Avenue

Davis, CA 95616

United States

Sheilah Robertson

Senior Medical Director

Lap of Love Veterinary Hospice

17804 US-41, Lutz, FL 33549

United States

Bradley Simon

Assistant Professor of Veterinary Anesthesiology

Department of Small Animal Clinical Sciences

College of Veterinary Medicine and Biomedical Sciences, Texas A&M University

402 Raymond Stotzer Pkwy

College Station, TX 77843-4474

United States

Francesco Staffieri

Associate Professor of Veterinary Anesthesiology

Department of Emergency and Organ Transplantation, Section of Veterinary Clinics and Animal Production University of Bari

SP per Casamassima km 3, 70010 Valenzano

Bari

Italy

Paulo Steagall

Associate Professor of Veterinary Anesthesiology

Department of Clinical Sciences Faculty of Veterinary Medicine

Université de Montréal

3200 Rue Sicotte

Saint-Hyacinthe, QC J2S2M2

Canada

Polly Taylor

Independent Consultant in Veterinary Anaesthesia Taylor Monroe

Little Downham

Nr. Ely

Cambs CB6 2TY

United Kingdom

Eric Troncy

Professor of Veterinary Pharmacology

Department of Biomedical Sciences Faculty of Veterinary Medicine

Université de Montréal

3200 Rue Sicotte

Saint-Hyacinthe, QC J2S2M2

Canada

1

Handling, Restraint, and Preanesthetic Assessment

Graeme Doodnaught and Paulo Steagall

Université de Montréal, Saint-Hyacinthe, Canada

Key Points

Behavioral considerations

Handling methods and physical restraint

Routes of drug administration

Airway management

Preanesthetic evaluation

Mortality and morbidity in feline anesthesia

Introduction

The pet cat population has grown over the last few decades, as has our understanding of disease prevention and treatment in this species. Despite population growth, fewer cats visit a veterinary clinic on a regular basis when compared with dogs. Cat owners often avoid veterinary visits as transportation of the cat to the clinic may be stressful. Handling, appropriate physical examination, knowledge of behavior, and preanesthetic assessment are essential components of feline anesthesia and analgesia.

Box 1.1: Cat-friendly Techniques in Clinical Practice

Safe handling and cat-friendly practices minimize stress, fear, anxiety, and potential personnel injuries related to aggression. They are key components of veterinary care for the anesthetist and staff members.

A cat-friendly practice will provide an environment that reduces the stress of veterinary consultation and hospitalization. More information can be found at http://icatcare.org (June 24, 2017). These practices involve:

A calm, safe, and quiet clinic with cat-designated areas or cat-only appointment times

Gentle and efficient physical examination and treatment

Client education on transporting the cat to and from the clinic

Client communication about feline anesthesia and analgesia

Handling and Restraint

Each cat is unique and can exhibit a wide range of behaviors. Experienced handlers will often adapt their approach and handling technique to suit each patient. While there is no substitute for experience, some principles exist to aid in the restraint of most cats. The mantras go slow to go fast and less is more are commonplace. Good feline handling revolves around the premise of de-escalation, where the handler avoids potential actions that may elevate a patient's stress. De-escalation minimizes noxious visual, auditory, and olfactory stimuli that could lead to avoidance or aggressive behavior. It should be noted that the major cause of defensive or aggressive behavior is fear. Cats have limited appeasement behaviors, making it difficult to calm them once they are distressed. Thus, avoiding these behavioral triggers is critical to success.

To facilitate handling throughout life, kittens should be encouraged to interact with people, animals, and new environments between 2 and 7 weeks of age. With all ages of cats, positive reinforcement techniques (e.g. rewarding with food, play, brushing) along with behavioral therapy in difficult individuals, help to reduce the stress and anxiety associated with veterinary visits.

Most cats in a calm environment will readily explore their surroundings. Anxious or fearful individuals will tend to remain within their carriers. The cat should be handled with patience and a positive attitude throughout the physical examination. Minimal restraint is required to perform a full physical examination in most cats. Gentle touch and petting around the head and neck are generally well tolerated, and allow for minor manipulations without the need for physical restraint (Figure 1.1a, b, c). Timid or fearful individuals who choose to remain in the carrier should be allowed to do so. The top of a carrier may be removed and an examination can be performed with the cat still inside (Box 1.2).

Box 1.2: Safe Handling in Feline Practice

Consider using top-opening carriers and baskets for transporting cats into the clinic. This allows for easy handling and provides a safe and secure environment.

Figure 1.1 A cat-friendly approach in a hospital setting. (a) This cat explores the examination room and its surroundings. (b) The handler gently pets the cat to control its movement without using forcible restraint. (c) Placing the hands under the chin allows for better control of the head and neck.

It is understandable that most medical procedures in cats require some level of restraint. This makes treatments and procedures safer for both cat and handler. While immobilization is often required, the approach should still be gentle. Figure 1.2 shows common methods of control.

Figure 1.2 Restraint for common procedures in cats. (a) Most cats will tolerate gentle extension of the neck to expose the jugular veins for blood sampling. In this image the jugular vein is occluded with the cat in lateral recumbency. (b) Restraint of the forelimb for cephalic blood sampling or IV catheterization. The handler is preventing the cat from backward movement by applying gentle pressure over the cat's hind limbs. Using the same arm, the handler is extending the right limb forward with three fingers behind the elbow to prevent retraction of the limb, and rotating and raising the cephalic vein with their first and second digits. (c) Restraint of the hind limb for medial saphenous blood sampling or IV catheterization. The cat is restrained in lateral recumbency with the dependent limb intended for venous sampling. The handler uses one hand to restrain the contralateral (upper) hind limb and apply medio-lateral pressure over the vein proximal to the sampling site. Once the vessel is visualized, the clinician directs the needle in a distal to proximal direction while maintaining control of the lower limb with the opposite hand. (d) This cat is allowed to stand freely on the treatment table and is only restrained by gentle control of the head and neck. This allows free access to the epaxial muscles for intramuscular injection.

Scruffing

Scruffing is a controversial method of restraint. Many clinics have a no-scruffing policy. Scruffing should be regarded as a last resort for physical restraint to avoid injuries and accidents. For these exceptional cases, the cat is gently grasped by the skin over the dorsum of the neck and scapulae, and minimal (firm) pressure is maintained. The method should certainly not be used if there is already pain or discomfort present. It is important to highlight that scruffing may lead to fear-based aggression and further escalation of stress. The American Association of Feline Practitioners (AAFP) and the International Society of Feline Medicine (ISFM) state that the technique should be used sparingly. A cat should never have its full weight suspended from the scruff.

The Fearful Cat

Fear is the most common cause of aggression in hospitalized cats. De-escalation techniques do not always work in fearful individuals. These cats exhibit strong avoidance or aggressive behavior making handling difficult. In this situation, chemical restraint should be considered before any manipulation (Chapter 3). To assist in the physical restraint of these patients, use of appropriate handling equipment is recommended (description of techniques to follow). In these cases, the equipment for IV catheter placement, and for anesthetic induction, maintenance, and monitoring should be ready.

Box 1.3: The Handling Equipment

Handling equipment should be:

Safe for the cat and handler

In good working order with frequent check ups

Easy to use and to clean

Suitable for the intended task

Some techniques used for appropriate restraint of the fearful and/or aggressive cat are listed below:

Towels or blankets are commonly used for restraining fearful cats. They are often successful in protecting the handler from injury. By covering the patient, they give the cat a place to hide, minimizing visual and auditory stimulation. The handler maintains good dexterity and can assist with the procedure

Synthetic feline facial pheromones mimic natural pheromones that are secreted by cats via facial rubbing when they are comfortable and when they mark their territories. These products have been shown to decrease stress and facilitate handling of some cats

Masks or hoods may assist with physical restraint of some cats by limiting visual stimulation. A well-fitted mask will also protect the handler from bites. They are variably tolerated and require judicious use

Bags for restraint protect individuals from aggressive cats. Openings in these bags allow access to the limbs and head

Feral cats may require the use of squeeze cages, humane traps or nets for drug administration. Their application is limited to capture and restraint of cats for injection. Nets are used in exceptional conditions such as when a cat escapes or where there are extremely limited facilities. Such equipment can easily cause trauma if not used properly

Anesthetic induction chambers may be used to anesthetize cats. This requires minimal restraint but placing the cat inside the chamber can be a challenge. While the absence of restraint is arguably better for the cat, there is potential for environmental contamination and exposure of personnel with volatile anesthetics. A fearful cat can be briefly restrained using a towel or cat bag for mask induction using volatile anesthetic agents. Techniques for induction of general anesthesia are discussed in Chapters 4 and 6

Leather handling gauntlets or gloves can protect the handler from an aggressive cat but they limit dexterity. They should be used only as a last resource for restraint. Leather is also difficult to clean and repeated disinfection is required

Blood Sampling

Restraint for blood sampling can be performed in many ways. The jugular vein is a common site as it is easily identified and allows rapid withdrawal of large volumes of blood compared with distal veins (Figure 1.2a). The handler extends the head and neck with the cat in a sternal or lateral position. The clinician approaches the vein with the needle directed either in a cranio-caudal (Figure 1.2a) or caudo-cranial direction. The use of a 23-G 1.6 cm (5/8th inch) needle and a small volume syringe (1–3 mL) is recommended.

Peripheral blood sampling, for example from the cephalic vein (Figure 1.2b), may be used for low-volume sample collection, or where jugular sampling is contraindicated (e.g. coagulopathies, increased intracranial or intraocular pressure). Another common site for sampling is the medial saphenous vein (Figure 1.2c). To limit repeated venipuncture, the blood that is collected in the hub of a catheter's stylet can be used for a basic blood panel during the preoperative period (Table 1.1).

Table 1.1 Values for basic blood panel in cats.

Drug Administration

A number of routes of administration are available for drug delivery, and the choice will depend on both drug selection and intended purpose.

Intravenous (IV) administration is the most efficacious and reliable method of drug delivery. It is commonly used for anesthetic induction, or for analgesic drugs when a catheter is in place

The intramuscular (IM) route is commonly used for premedication. Any skeletal muscle may be used but large-bellied and superficial muscles are preferred. The epaxial and muscles of the cranial and caudal thigh are often chosen (Figure 1.2d); if using the hind limb, the cranial thigh is more reliable. When using the caudal thigh, it is easy to miss muscle tissue and inject into fascial planes. The location of major blood vessels and nerves is important when selecting an injection site. For example, the sciatic nerve runs beneath the biceps femoris in the caudo-lateral thigh, and may be inadvertently injured. Aspiration should precede injection to avoid unintended intravascular injection

The subcutaneous (SC) route is used for perioperative administration of drugs such as nonsteroidal inflammatory drugs. This route can also accommodate large volumes of crystalloid fluids when intravenous fluid therapy is not possible. Most conscious cats will tolerate injection between the shoulder blades

Buccal or oral transmucosal (OTM) administration is not commonly used in hospital settings, as other routes are usually an option. However, it can be used as a less invasive route of administration during long-term hospitalization or home care. It is accomplished by inserting the syringe tip into the cat's mouth and gently squeezing the syringe contents into the cheek pouch; swallowing must be avoided to allow transmucosal absorption and prevent first-pass hepatic metabolism

IV Catheterization

A wide array of IV catheter types exists in veterinary practice. These are commonly inserted into the cephalic or medial saphenous veins. Catheterization of these vessels is often performed following premedication (Chapter 3). Intravenous catheterization allows easy drug titration during anesthetic induction, administration of fluids, emergency intervention, and minimizes the need for multiple SC or IM injections in the perioperative period. Use of topical local anesthetic creams can facilitate placement of catheters (Box 1.4). The ideal catheter material is inert, long-lasting, and atraumatic. Catheters should be placed using a sterile technique.

Silicone catheters are good choices for long-term cannulation. In cats requiring extended hospitalization, central venous catheters (18- or 21-G) are placed using the modified Seldinger method, peel-away introducers, or cut-down techniques. Aseptic technique is mandatory for the placement of long term catheters.

Box 1.4: Intravenous Catheterization in Clinical Practice Using Local Anesthetic Creams

Smaller gauge (≤ 22-G) catheters are commonly used for the cephalic and medial saphenous veins in cats. Application of topical anesthetics (e.g. EMLA; eutectic mixture of local anesthetics, a combination of lidocaine 2.5% and prilocaine 2.5%) at least 30 minutes before catheterization desensitizes the skin, thereby reducing the stress of the whole procedure. This technique can also be used for jugular venipuncture enabling minimal restraint. The cream is applied and covered with an impermeable and nonabsorbent dressing. The use of gloves is recommended, as the cream will anesthetize human skin. IV catheters should be examined daily for signs of infection and skin irritation, and to confirm patency. Taping should not be overtight otherwise distal limb edema may occur.

Intubation and Airway Management

Induction of anesthesia is commonly followed by maintenance with a volatile anesthetic and oxygen. Endotracheal intubation protects the airway, minimizing the risk of aspiration if regurgitation occurs; it also enables delivery of oxygen and anesthetic, and facilitates ventilation. Figure 1.3 shows appropriate positioning for intubation in a cat.

Figure 1.3 Restraint for intubation: with the cat in sternal recumbency, the handler gently extends the neck and head. Either the handler or the individual performing the intubation opens the mouth by exteriorizing the tongue. In this position the larynx is easily visualized with a laryngoscope enabling application of local anesthetic followed by intubation. The laryngoscope (or other instrument) should be used to exteriorize the tongue as intraoral manipulation of cats in a light plane of anesthesia may lead to a reflex bite.

The challenges and complications (i.e. laryngospasm, laryngeal trauma, tracheal rupture or necrosis and airway obstruction) of intubation in cats (Box 1.5) are discussed in Chapters 2 and 10. Most adult cats can be intubated with a 3.5–5 mm internal diameter endotracheal tube (ETT). Cuff inflation should not require more than 1.5 mL of air using a small syringe. Small increments of air (0.5 mLs) should be injected at a time into the pilot balloon until a seal is achieved when the pressure in the breathing circuit is 16–18 cmH2O. Pressure within the high-volume low-pressure cuff can be monitored using