Contents
Contributors
Contributors
Preface
Chapter1Patientevaluationandriskmanagement
Introduction
Preanestheticevaluation
Patientpreparation
Selectionofananestheticandanalgesicdrugs
Risk
Recordkeeping
Chapter2Anestheticphysiologyandpharmacology
Cardiovascularanatomyandphysiology
Respiratorysystemphysiology
Nervoussystemanatomyandphysiology
Sedativeandanticholinergicpharmacology
Injectableanestheticagents
Inhalationanesthetics
Musclerelaxantsandneuromuscularblockade
Chapter3Painphysiology,pharmacology,andmanagement
Introduction
Definitionofpain
Neuroanatomyofnociceptivepathways
Painmodulation
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Neuropathicpain
Measuringpaininveterinarypatients
Managementofpain

AcupunctureandtraditionalChinesemedicine
Rehabilitationtherapy
Chapter4Chronicpainmanagement
Generalconsiderations
Theimportanceofalleviatingpain
Assessmentofchronicpain
Principlesofalleviationofchronicpain
NSAIDs
Otheranalgesics
Otherchronicpain-relievingmodalities
Chapter5Anesthesiaequipment
Introduction
Safetyanddesign
Endotrachealtubesandlaryngoscopes
Medicalgassupply
Themodernanestheticmachine
Breathingsystems
Wastegasscavengesystem
Anesthesiaventilators
Properventilatorsetupandmonitoring
References
Chapter6Patientmonitoring
Introduction
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MonitoringCNSfunction
Physiologicalconsequencesoftheanesthesia
MonitoringDO2
Monitoringcirculation,oxygenation,andventilation

Monitoringoxygenation
Monitoringventilation
Monitoringthermoregulation
Monitoringotherparameters
Managingcommonanestheticcomplications
Chapter7Acid–basebalanceandfluidtherapy
Introduction
Regulationofacid–basebalance
Thetraditionalapproachtoacid–baseanalysis
Alternativeapproachestoacid–baseanalysis
Thebaseexcessapproachtoacid–baseanalysis
Theaniongapapproachtoacid–baseanalysis
Thestrongionapproachtoacid–baseanalysis
Regulationoffluidbalance
Considerationsforperianestheticfluidtherapy
Typesoffluids
Chapter8Anesthesiamanagementofdogsandcats
Introduction
Drugprotocolselection
Balancedanesthesia
Chapter9Anesthesiaandimmobilizationofsmallmammals
Introduction
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Laboratorymammalanesthesia
Chapter10Localanestheticsandregionalanalgesictechniques
Introduction
Electrophysiology
Mechanismsofaction

Chemicalstructure
Differentialnerveblockade
Factorsinfluencingefficacy
Drugdisposition
Localanesthetictoxicity
Tachyphylaxis
Localandregionalanalgesictechniques:dogs
Localandregionalanalgesictechniques:cats
Conclusion
Chapter11Anesthesiaforpatientswithcardiovasculardisease
Introduction
Cardiovascularphysiology
Pharmacologyofanestheticdrugs
Anesthesiaoverview
Anesthesiaforpatientswithspecificcardiovasculardisease
References
Chapter12Anesthesiaforpatientswithrespiratorydisease
and/orairwaycompromise
Introduction
Physiologyoftherespiratorysystem
Pharmacologyofanestheticdrugs
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Anesthesiaforpatientswithspecificrespiratorydiseaseor
airwaycompromise
References
Chapter13Anesthesiaforpatientswithneurologicaldisease
Introduction
Physiology

Pharmacology
Anestheticmanagementofspecificneurologicalproblems
References
Chapter14Anesthesiaforsmallanimalpatientswithrenal
disease
Introduction
Renalphysiology
Renalpathophysiology
Anestheticeffectsonrenalfunction
Effectsofrenaldiseaseonanesthesia
Anestheticmanagementofpatientswithrenaldisease
Adjunctivetreatmentsforpatientswithrenaldisease
Managementofpatientswithpost-renaldisease
References
Chapter15Anesthesiaforpatientswithliverdisease
Anatomyandphysiology
Drugsandtheliver
Anesthesiaforspecificprocedures
References

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Chapter16Anesthesiaforpatientswithgastrointestinaldisease
Conditionsassociatedwiththeoralcavityandpharynx
Conditionsassociatedwiththegastrointestinaltract
Obesity
References
Chapter17Anesthesiaforpatientswithendocrinedisorders
Disordersoftheadrenalgland

Disordersofthepancreas
Disordersoftheparathyroid
Disordersofthethyroid
References
Chapter18Anestheticconsiderationsforspecialprocedures
Ocularpatients
Cesareansectionpatients
Traumaandcriticallyillpatients
Neonatalandgeriatricpatients
Dentalpatients
Orthopedicpatients
Selecteddiagnosticandtherapeuticprocedures
Chapter19Anestheticemergenciesandaccidents
Introduction
Anestheticrisk
Species-relatedrisk
High-riskpatients
Cardiovascularemergencies
Allergicreactions
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Cardiacarrest
Perivascularinjection
Respiratoryinsufficiency
Equipmentmalfunction
Delayedrecovery
Gastroesophagealrefluxandregurgitation
Hypothermia
Hyperthermia

Injuries
Epiduralanalgesiaandregionalnerveblock
Electrolyteabnormalities
Index

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Thiseditionfirstpublished2011©2011byJohnWiley&Sons,Inc.
FirstEdition©1999byLippincott,Williams,andWilkins
Wiley-BlackwellisanimprintofJohnWiley&Sons,formedbythemergerofWiley’sglobal
Scientific,TechnicalandMedicalbusinesswithBlackwellPublishing.
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areISBN-13:978-0-8138-1236-6/2011.
Designationsusedbycompaniestodistinguishtheirproductsareoftenclaimedastrademarks.

Allbrandnamesandproductnamesusedinthisbookaretradenames,servicemarks,
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associatedwithanyproductorvendormentionedinthisbook.Thispublicationisdesignedto
provideaccurateandauthoritativeinformationinregardtothesubjectmattercovered.Itis
soldontheunderstandingthatthepublisherisnotengagedinrenderingprofessionalservices.
Ifprofessionaladviceorotherexpertassistanceisrequired,theservicesofacompetent
professionalshouldbesought.
LibraryofCongressCataloging-in-PublicationData
Essentialsofsmallanimalanesthesiaandanalgesia.–2nded./editors,KurtA.Grimm,
WilliamJ.Tranquilli,LeighA.Lamont.
p.;cm.
“CompaniontotherecentlypublishedLumbandJones’VeterinaryAnesthesiaandAnalgesia,
4thedition”–Pref.
Includesbibliographicalreferencesandindex.
ISBN-13:978-0-8138-1236-6(pbk.:alk.paper)
ISBN-10:0-8138-1236-4

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1.Veterinaryanesthesia–Handbooks,manuals,etc.2.Analgesia–Handbooks,manuals,etc.3.
Pets–Surgery–Handbooks,manuals,etc.I.Grimm,KurtA.II.Tranquilli,WilliamJ.III.
Lamont,LeighA.IV.Lumb&Jones’veterinaryanesthesiaandanalgesia.
[DNLM:1.Analgesia–veterinary.2.Anesthesia–veterinary.SF914]
SF914.E772011
636.089’7–dc23
2011017805

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Contributors
Thefollowingauthorscontributednewmaterialtothisbook:
JenniferG.Adams,DVM,ACVIM(LA),
ACVA1341BufordCareyRoad
Hull,Georgia30646
StuartClark-Price,DVM,MS,DACVIM-LA,DACVA
UniversityofIllinoisVeterinaryTeachingHospital
Urbana,IL61802
FernandoGarcia,DVM,MS,DACVA
DepartmentofSmallAnimalClinicalSciences
CollegeofVeterinaryMedicine
MichiganStateUniversity
EastLansing,MI48824-1314
StephenA.Greene,DVM,MS,DACVA
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
WashingtonStateUniversity
Pullman,WA99164-6610
TamaraL.Grubb,DVM,MS,DACVA
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
WashingtonStateUniversity
Pullman,WA99164
CraigMosley,DVM,MSc,DACVA
CanadaWestVeterinarySpecialistsandCriticalCareHospital
Vancouver,CanadaV5M4Y3

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Contributors
This book was distilled and revised from material contributed to Lumb and Jones’
VeterinaryAnesthesiaandAnalgesia,FourthEditionbythefollowingauthors:*
RichardM.Bednarski,DVM,MS,DACVA
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
OhioStateUniversity
Columbus,OH43210
KeithR.Branson,DVM,MS,DACVA
DepartmentofMedicineandSurgery
CollegeofVeterinaryMedicine
UniversityofMissouri
Columbia,MO65211
DavidB.Brunson,DVM,MS,DACVA
DepartmentofSurgicalSciences
SchoolofVeterinaryMedicine
UniversityofWisconsin
Madison,WI53711
RachaelE.Carpenter,DVM
DepartmentofVeterinaryClinicalMedicine
CollegeofVeterinaryMedicine
UniversityofIllinois
Urbana,IL61802
GwendolynL.Carroll,DVM,MS,DACVA
DepartmentofSmallAnimalClinicalSciences
CollegeofVeterinaryMedicineandBiomedicalSciences
TexasA&MUniversity
CollegeStation,TX77843–4474
JanyceL.Cornick-Seahorn,DVM,MS,DACVA,DACVIM

EquineVeterinarySpecialists
Georgetown,KY40324
HelioS.A.deMorais,DVM,PhD,DACVIM
DepartmentofMedicalSciences
SchoolofVeterinaryMedicine
UniversityofWisconsin
Madison,WI53706
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DianneDunning,DVM,MS,DACVS
CollegeofVeterinaryMedicine
NorthCarolinaStateUniversity
Raleigh,NC27606
A.ThomasEvans,DVM,MS,DACVA
VeterinaryClinicalCenter
MichiganStateUniversity
EastLansing,MI48824
AnnaD.Fails,DVM,PhD,DACVIM
DepartmentofBiomedicalSciences
CollegeofVeterinaryMedicineandBiomedicalSciences
ColoradoStateUniversity
FortCollins,CO80523
PaulA.Flecknell,VetMB,PhD,DECLAM,DECVA
ComparativeBiologyCentre
NewcastleUniversity
NewcastleuponTyne,UKNE24HH
JamesS.Gaynor,DVM,MS,DACVA
AnimalAnesthesiaandPainManagementCenter
ColoradoSprings,CO80918

ElizabethA.Giuliano,DVM,MS,DACVO
DepartmentofMedicineandSurgery
CollegeofVeterinaryMedicine
UniversityofMissouri-Columbia
Columbia,MO65211
MariaGlowaski,DVM,DACVA
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
OhioStateUniversity
Columbus,OH43210–1089
StephenA.Greene,DVM,MS,DACVA
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
WashingtonStateUniversity
Pullman,WA99164–6610
JenniferB.Grimm,DVM,MS,DACVR
VeterinarySpecialistServices,PC
Conifer,CO80433–0504
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KurtA.Grimm,DVM,PhD,DACVA,DACVP
VeterinarySpecialistServices,PC
Conifer,CO80433–0504
MarjorieE.Gross,DVM,MS,DACVA
DepartmentofClinicalMedicine
CollegeofVeterinaryMedicine
OklahomaStateUniversity
Stillwater,OK74078–2005
TamaraL.Grubb,DVM,MS,DACVA

PfizerAnimalHealth
Uniontown,WA99179
ElizabethM.Hardie,DVM,PhD,DACVS
DepartmentofClinicalSciences
CollegeofVeterinaryMedicine
NorthCarolinaStateUniversity
Raleigh,NC27606
SteveC.Haskins,DVM,MS,DACVA,DACVECC
DepartmentofSurgicalandRadiologicalSciences
SchoolofVeterinaryMedicine
UniversityofCalifornia
Davis,CA95616
PeterW.Hellyer,DVM,MS,DACVA
CollegeofVeterinaryMedicineandBiomedicalSciences
ColoradoStateUniversity
FortCollins,CO80523
RobertD.Keegan,DVM,DACVA
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
WashingtonStateUniversity
Pullman,WA99164
CarolynL.Kerr,DVM,DVSc,PhD,DACVA
DepartmentofClinicalStudies
OntarioVeterinaryCollege
UniversityofGuelph
Guelph,CanadaN1G2W1
LeighA.Lamont,DVM,MS,DACVA
DepartmentofCompanionAnimals
AtlanticVeterinaryCollege
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UniversityofPrinceEdwardIsland
Charlottetown,CanadaC1A4P3
DuncanX.Lascelles,BVSc,PhD,DECVS,DACVS
DepartmentofClinicalSciences
CollegeofVeterinaryMedicine
NorthCarolinaStateUniversity
Raleigh,NC27606
KipA.Lemke,DVM,MS,DACVA
DepartmentofCompanionAnimals
AtlanticVeterinaryCollege
UniversityofPrinceEdwardIsland
Charlottetown,CanadaC1A4P3
Hui-ChuLin,DVM,MS,DACVA
DepartmentofClinicalSciences
CollegeofVeterinaryMedicine
AuburnUniversity
Auburn,AL36849
VictoriaM.Lukasik,DVM,DACVA
SouthwestVeterinaryAnesthesiology
SouthernArizonaVeterinarySpecialtyCenter
Tucson,AZ85705
KhursheedR.Mama,DVM,DACVA
DepartmentofClinicalSciences
CollegeofVeterinaryMedicineandBiologicalSciences
ColoradoStateUniversity
FortCollins,CO80523–1620
SandraManfraMarretta,DVM,DAVDC
DepartmentofVeterinaryClinicalMedicine

CollegeofVeterinaryMedicine
UniversityofIllinois
Urbana,IL61802
StevenL.Marks,BVSc,MS,DACVIM
DepartmentofClinicalSciences
CollegeofVeterinaryMedicine
NorthCarolinaStateUniversity
Raleigh,NC27606
DavidD.Martin,DVM,DACVA
VeterinaryOperations
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CompanionAnimalDivision
PfizerAnimalHealth
NewYork,NY
ElizabethA.Martinez,DVM,DACVA
DepartmentofSmallAnimalClinicalSciences
CollegeofVeterinaryMedicineandBiomedicalSciences
TexasA&MUniversity
CollegeStation,TX77843–4474
KarolA.Mathews,DVM,DVSc,DACVECC
DepartmentofClinicalStudies
OntarioVeterinaryCollege
UniversityofGuelph
Guelph,CanadaN1G2W1
WayneN.McDonell,DVM,PhD,DACVA
DepartmentofClinicalStudies
OntarioVeterinaryCollege
UniversityofGuelph

Guelph,CanadaN1G2W1
WilliamW.Muir,DVM,PhD,DACVA,DACVECC
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
OhioStateUniversity
Columbus,Ohio43210
MarkG.Papich,DVM,MS,DACVCD
DepartmentofMolecularBiomedicalSciences
CollegeofVeterinaryMedicine
NorthCarolinaStateUniversity
Raleigh,NC27606
GlennR.Pettifer,DVM,DVSc,DACVA
VeterinaryEmergencyClinicandReferralCentre
Toronto,CanadaM4W3C7
AleksandarPopovic,DVM,CertLAS
MerckFrosstCentreforTherapeuticResearch
Kirkland,CanadaH9H3l1
MarcR.Raffe,DVM,MS,DACVA,DACVECC
DepartmentofVeterinaryClinicalMedicine
CollegeofVeterinaryMedicine
UniversityofIllinois
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Urbana,IL61802
ClaireA.Richardson,BVM&S
ComparativeBiologyCentre
NewcastleUniversityMedicalSchool
NewcastleuponTyne,UKNE24HH
SheilahA.Robertson,BVM&S,PhD,DACVA

DepartmentofSmallAnimalClinicalSciences
CollegeofVeterinaryMedicine
UniversityofFlorida
Gainesville,FL32610
DavidC.Seeler,DVM,MSc,DACVA
DepartmentofCompanionAnimals
AtlanticVeterinaryCollege
UniversityofPrinceEdwardIsland
Charlottetown,Canada,C1A4P3
RomanT.Skarda,(deceased)DMV,PhD,DACVA,DECVA
DepartmentofVeterinaryClinicalSciences
CollegeofVeterinaryMedicine
OhioStateUniversity
Columbus,OH43210–1089
EugeneP.Steffey,VMD,PhD,DACVA,DECVA
DepartmentofSurgicalandRadiologicalSciences
SchoolofVeterinaryMedicine
UniversityofCalifornia
Davis,CA95616
WilliamJ.Tranquilli,DVM,MS,DACVA
DepartmentofVeterinaryClinicalMedicine
CollegeofVeterinaryMedicine
UniversityofIllinois
Urbana,IL61802
DeborahV.Wilson,BVSc,MS,DACVA
DepartmentofLargeAnimalClinicalSciences
CollegeofVeterinaryMedicine
MichiganStateUniversity
EastLansing,MI48824
* Note: Many author affiliations have changed since the fourth edition of Lumb & Jones’


VeterinaryAnesthesiaandAnalgesiawaspublished.

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Preface
TheEssentialsofSmallAnimalVeterinaryAnesthesiaandAnalgesia,SecondEditionisthe
companiontotherecentlypublishedLumbandJones’VeterinaryAnesthesiaandAnalgesia,
FourthEdition.Itsmajorpurposeistoprovideveterinarycareprovidersandstudentswiththe
essentialsofanestheticandanalgesicpharmacology,physiology,andclinicalcasemanagement
for small animal patients. The editors have included clinically focused small animal content
from chapters covering physiology, pharmacology, patient assessment, and monitoring
originally published in Lumb and Jones’ Veterinary Anesthesia and Analgesia, Fourth
Edition. Readers may find it helpful to refer back to those chapters if they wish to delve
deeper into subject matter or references not included in this Essentials book. Additionally,
several authors contributed new chapters on the equipment and management of patients with
specific conditions specifically for this book. Those chapters have detailed references
includedandprovidedifferentperspectivesonclinicalcasemanagement.
The editors wish to express our gratitude to all the authors who provided content for the
originalchaptersinLumbandJonesVeterinaryAnesthesiaandAnalgesia,FourthEdition,as
well as the new authors making contributions to this book. Dr. Steven Greene deserves a
special thank you for assisting us with the coordination and editing of the chapters on
managementofpatientswithspecificconditions.Wewouldalsoliketothanktheprofessionals
atWiley-BlackwellandspecificallyEricaJudisch,NancyTurner,andSusanEngelkenfortheir
assistancewiththisproject.Finally,wecanneverthankourfamiliesenoughfortheirpatience,
understanding,andlovewhenourworktakesusawayfromthem.
KurtA.Grimm
LeighA.Lamont
WilliamJ.Tranquilli


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Chapter1
Patientevaluationandriskmanagement
WilliamW.Muir,SteveC.Haskins,andMarkG.Papich

Introduction
Thepurposeofanesthesiaistoprovidereversibleunconsciousness,amnesia,analgesia,and
immobility for invasive procedures. The administration of anesthetic drugs and the
unconscious, recumbent, and immobile state, however, compromise patient homeostasis.
Anestheticcrisesareunpredictableandtendtoberapidinonsetanddevastatinginnature.The
purpose of monitoring is to achieve the goals while maximizing the safety of the anesthetic
experience.

Preanestheticevaluation
All body systems should be examined and any abnormalities identified. The physical
examinationandmedicalhistorywilldeterminetheextenttowhichlaboratorytestsandspecial
procedures are necessary. In all but extreme emergencies, packed cell volume and plasma
protein concentration should be routinely determined. Contingent on the medical history and
physical examination, additional evaluations may include complete blood counts; urinalysis;
blood chemistries to identify the status of kidney and liver function, blood gases, and pH;
electrocardiography;clotting timeandplateletcounts;fecaland/orfilarialexaminations;and
bloodelectrolytedeterminations.Radiographicand/orultrasonographicexaminationmayalso
beindicated.
Followingexamination,thephysicalstatusofthepatientshouldbeclassifiedastoitsgeneral
state of health according to the American Society of Anesthesiologists (ASA) classification
(Table1.1).Thismentalexerciseforcestheanesthetisttoevaluatethepatient’sconditionand
provesvaluableintheproperselectionofanestheticdrugs.Classificationofoverallhealthis

anessentialpartofanyanestheticrecordsystem.Thepreliminaryphysicalexaminationshould
bedoneintheowner’spresence,ifpossible,sothataprognosiscanbegivenpersonally.This
allows the client to ask questions and enables the veterinarian to communicate the risks of
anesthesiaandallayanyfearsregardingmanagementofthepatient.
Table1.1.Classificationofphysicalstatusa
Source:MuirW.W.2007.Considerationsforgeneralanesthesia.In:LumbandJones’VeterinaryAnesthesiaand

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Analgesia,4thed.W.J.Tranquilli,J.C.Thurmon,andK.A.Grimm,eds.Ames,IA:BlackwellPublishing,p.17.
Cate gory Physicalstatus

Possible e xample softhiscate gory

I

Normalhealthypatients

Nodiscernibledisease;animalsenteredforovariohysterectomy,eartrim,caudectomy,or
castration

II

Patientswithmildsystemicdisease

Skintumor,fracturewithoutshock,uncomplicatedhernia,cryptorchidectomy,localized
infection,orcompensatedcardiacdisease

III


Patientswithseveresystemicdisease

Fever,dehydration,anemia,cachexia,ormoderatehypovolemia

IV

Patientswithseveresystemicdiseasethatisa
constantthreattolife

Uremia,toxemia,severedehydrationandhypovolemia,anemia,cardiacdecompensation,
emaciation,orhighfever

V

Moribundpatientsnotexpectedtosurvive1daywith
Extremeshockanddehydration,terminalmalignancyorinfection,orseveretrauma
orwithoutoperation

aThisclassificationisthesameasthatadoptedbytheASA.

Preanestheticpainevaluation
Thediagnosisandtreatmentofpainrequireanappreciationofitsconsequences,afundamental
understandingofthemechanismsresponsibleforitsproduction,andapracticalappreciationof
theanalgesicdrugsthatareavailable.Semiobjectiveandobjectivebehavioral,numerical,and
categoricalmethodshavebeendevelopedforthecharacterizationofpainand,amongthese,the
visualanalogscale(VAS)hasbecomepopular.Ideally,paintherapyshouldbedirectedtoward
themechanismsresponsibleforitsproduction(multimodaltherapy),withconsideration,when
possible, of initiating therapy before pain is initiated (preemptive analgesia). The American
AnimalHospitalAssociation(AAHA)hasdevelopedstandardsfortheassessment,diagnosis,

andtherapyofpainthatshouldbeadoptedbyallveterinarians(Table1.2).

Preanestheticstressevaluation
Both acute and chronic pain can produce stress. Untreated pain can initiate an extended and
potentiallydestructiveseriesofeventscharacterizedbyneuroendocrinedysregulation,fatigue,
dysphoria, myalgia, abnormal behavior, and altered physical performance. Even without a
painful stimulus, environmental factors (loud noise, restraint, or a predator) can produce a
state of anxiety or fear that sensitizes and amplifies the stress response. Distress, an
exaggerated form of stress, is present when the biologic cost of stress negatively affects the
biologic functions critical to survival. Pain, therefore, should be considered in terms of the
stressresponseandthepotentialtodevelopdistress.
Increased central sympathetic output causes increases in heart rate and arterial blood
pressure,piloerection,andpupildilatation.Thesecretionofcatecholaminesfromtheadrenal
medulla and spillover of norepinephrine released from postganglionic sympathetic nerve
terminalsaugmentthesecentraleffects.Ultimately,changesinananimal’sbehaviormaybethe
most noninvasive and promising method to monitor the severity of an animal’s pain and
associatedstress.
Table1.2.AAHApainmanagementstandards(2003)
Sources:MuirW.W.2007.Considerationsforgeneralanesthesia.In:LumbandJones’VeterinaryAnesthesiaand

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Analgesia,4thed.W.J.Tranquilli,J.C.Thurmon,andK.A.Grimm,eds.Ames,IA:BlackwellPublishing,p.19,andthe
AAHA,Lakewood,CO.
1.Painassessmentforallpatientsregardlessofpresentingcomplaint
2.Painassessmentusingstandardizedscale/scoreandrecordedinthemedicalrecord
3.Painmanagementisindividualizedforeachpatient
4.Practiceutilizespreemptivepainmanagement
5.Appropriatepainmanagementisprovidedfortheanticipatedlevelofpain

6.Painmanagementisprovidedfortheanticipateddurationofpain
7.Patientisreassessedforpainthroughoutpotentiallypainfulprocedure
8.Patientswithpersistentorrecurringdiseaseareevaluatedtodeterminetheirpainmanagementneeds
9.Analgesictherapyisusedasatooltoconfirmtheexistenceofapainfulconditionwhenpainissuspectedbutcannotbeconfirmedbyobjectivemethods
10.Awrittenpainmanagementprotocolisutilized
11.Whenpainmanagementispartofthetherapeuticplan,theclientiseffectivelyeducated

Patientpreparation
Preanestheticfasting
Toooften,operationsareundertakenwithinadequatepreparationofpatients.Withmosttypes
ofgeneralanesthesia,itisbesttohavepatientsofffeedfor12hourspreviously.Somespecies
are adversely affected by fasting. Birds, neonates, and small mammals may become
hypoglycemicwithinafewhoursofstarvation,andmobilizationofglycogenstoresmayalter
rates of drug metabolism and clearance. Induction of anesthesia in animals having a full
stomachshouldbeavoided,ifatallpossible,becauseofthehazardsofaspiration.

Preanestheticfluidtherapy
Inmostspecies,waterisoffereduptothetimethatpreanestheticagentsareadministered.It
shouldberememberedthatmanyolderanimalshaveclinicalorsubclinicalrenalcompromise.
Although these animals remain compensated under ideal conditions, the stress of
hospitalization, water deprivation, and anesthesia, even without surgery, may cause acute
decompensation.Ideally,amildstateofdiuresisshouldbeestablishedwithintravenousfluids
innephriticpatientspriortotheadministrationofanestheticdrugs.
Dehydrated animals should be treated with fluids and appropriate alimentation prior to
operation; fluid therapy should be continued as required. An attempt should be made to
correlatethepatient’selectrolytebalancewiththetypeoffluidthatisadministered.Anemia
and hypovolemia, as determined clinically and hematologically, should be corrected by
administration of whole blood or blood components and balanced electrolyte solutions.
Patients in shock without blood loss or in a state of nutritional deficiency benefit by
administration of plasma or plasma expanders. In any case, it is good anesthetic practice to

administer intravenous fluids during anesthesia to help maintain adequate blood volume and
urineproduction,andtoprovideanavailableroutefordrugadministration.

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Prophylacticantibioticadministration
Systemicadministrationofantibioticspreoperativelyisahelpfulprophylacticmeasureprior
tomajorsurgeryorifcontaminationoftheoperativesiteisanticipated.Antibioticsareideally
givenapproximately1hourbeforeanestheticinduction.

Oxygenationandventilation
Severalconditionsmayseverelyrestricteffectiveoxygenationandventilation.Theseinclude
upper airway obstruction by masses or abscesses, pneumothorax, hemothorax, pyothorax,
chylothorax, diaphragmatic hernia, and gastric distention. Affected animals are often in a
marginalstateofoxygenation.Oxygenadministrationbynasalcatheterormaskisindicatedif
thepatientwillacceptit.Intrapleuralairorfluidshouldberemovedbythoracocentisisprior
toinductionbecausetheeffectivelungvolumemaybegreatlyreducedandsevererespiratory
embarrassmentmayoccuroninduction.Anesthetistsshouldbepreparedtocarryoutallphases
ofinduction,intubation,andcontrolledventilationinonecontinuousoperation.

Heartdisease
Decompensatedheartdiseaseisarelativecontraindicationforgeneralanesthesia.Ifanimals
must be anesthetized, an attempt at stabilization through administration of appropriate
inotropes,antiarrhythmicdrugs,anddiureticsshouldbemadepriortoanesthesia.Ifascitesis
present,fluidmaybeaspiratedtoreduceexcessivepressureonthediaphragm.

Hepatorenaldisease
In cases of severe hepatic or renal insufficiency, the mode of anesthetic elimination should
receiveconsideration,withinhalationanestheticsoftenpreferred.Justpriortoinduction,itis

desirable to encourage defecation and/or urination by giving animals access to a run or
exercisepen.

Patientpositioning
During anesthesia, patients should, if possible, be restrained in a normal physiological
position.Compressionofthechest,acuteangulationoftheneck,overextensionorcompression
of the limbs, and compression of the posterior vena cava by large viscera can all lead to
serious complications, which include hypoventilation, nerve and/or muscle damage, and
impairedvenousreturn.
Tiltinganesthetizedpatientsalterstheamountofrespiratorygasesthatcanbeaccommodated
in the chest (functional residual capacity [FRC]) by as much as 26%. In dogs subjected to
hemorrhage,tiltingthemhead-up(reverseTrendelenburgposition)wasdetrimental,producing
lowered blood pressure, hyperpnea, and depression of cardiac contractile force. When dogs
were tilted head-down (Trendelenburg position), no circulatory improvement occurred. In
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mostspecies,theheadshouldbeextendedtoprovideafreeairwayandtopreventkinkingof
theendotrachealtube.

Selectionofananestheticandanalgesicdrugs
Theselectionofananestheticisbasedonappraisingseveralfactors,including:
(1)Thepatient’sspecies,breed,andage.
(2)Thepatient’sphysicalstatus.
(3) The time required for the surgical (or other) procedure, its type and severity, and the
surgeon’sskill.
(4)Familiaritywiththeproposedanesthetictechnique.
(5)Equipmentandpersonnelavailable.
In general, veterinarians will have greatest success with drugs they have used most
frequentlyandwithwhichtheyaremostfamiliar.Theskillsofadministrationandmonitoring

are developed only with experience; therefore, change from a familiar drug to a new one is
usuallyaccompaniedbyatemporaryincreaseinanestheticrisk.
Thelengthoftimerequiredtoperformasurgicalprocedureandtheamountofhelpavailable
during this period often dictate the anesthetic that is used. Generally, shorter procedures are
done with short-acting agents, such as propofol, alphaxalone-CD, and etomidate, or with
combinationsusingdissociative,tranquilizing,and/oropioiddrugs.Wherelongeranesthesiais
required,inhalationorbalancedanesthetictechniquesarepreferred.

Druginteractions
When providing anesthesia and analgesia to animals, veterinarians often administer
combinations of drugs without fully appreciating the possible interactions that may and do
occur. Many drug interactions, both beneficial (resulting in decreased anesthetic risk) and
harmful (increasing anesthetic risk), are possible. Although most veterinarians view drug
interactions as undesirable, modern anesthesia and analgesic practice emphasizes the use of
druginteractionsforthebenefitofthepatient(multimodalanesthesiaoranalgesia).
A distinction should be made between drug interactions that occur in vitro (such as in a
syringeorvial)fromthosethatoccurinvivo(inpatients).Veterinariansfrequentlymixdrugs
together (compound) in syringes, vials, or fluids before administration to animals. In vitro
reactions, also called pharmaceutical interactions, may form a drug precipitate or a toxic
product or inactivate one of the drugs in the mixture. Invivo interactions are also possible,
affecting the pharmacokinetics (absorption, distribution, or biotransformation) or the
pharmacodynamics(mechanismofaction)ofthedrugsandcanresultinenhancedorreduced
pharmacologicalactionsorincreasedincidenceofadverseevents.

Nomenclature
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Commonlyusedtermstodescribedruginteractionsareaddition,antagonism,synergism,and
potentiation. In purely pharmacological terms that have underlying theoretical implications,

additionreferstosimpleadditivityoffractionaldosesoftwoormoredrugs,thefractionbeing
expressed relative to the dose of each drug required to produce the same magnitude of
response;thatis,responsetoXamountofdrugA=responsetoYamountofdrugB=response
to1/2XA+1/2YB,1/4XA+3/4YB,andsoon.Additivityisstrongsupportfortheassumption
thatdrugAanddrugBactviathesamemechanism(e.g.,onthesamereceptors).Confirmatory
data are provided by in vitro receptor-binding assays. Minimum alveolar concentration
(MAC) fractions for inhalational anesthetics are additive. All inhalants have similar
mechanismsofactionbutdonotappeartoactonspecificreceptors.
Synergism refers to the situation where the response to fractional doses as described
previouslyisgreaterthantheresponsetothesumofthefractionaldoses(e.g.,1/2XA+1/2YB
producesmorethantheresponsetoXAorYB).
Potentiation refers to the enhancement of action of one drug by a second drug that has no
detectableactionofitsown.
Antagonism refers to the opposing action of one drug toward another. Antagonism may be
competitiveornoncompetitive.Incompetitiveantagonism,theagonistandantagonistcompete
forthesamereceptorsite.Noncompetitiveantagonismoccurswhentheagonistandantagonist
actviadifferentreceptors.
Thewayanestheticdrugsareusuallyusedraisesspecialconsiderationswithregardtodrug
interactions. For example, (1) drugs that act rapidly are usually used; (2) responses to
administered drugs are measured, often very precisely; (3) drug antagonism is often relied
upon;and(4)dosesorconcentrationsofdrugsareusuallytitratedtoeffect.Minorincreasesor
decreasesinresponsesareusuallyoflittleconsequenceandaredealtwithroutinely.

Commonlyusedanestheticdruginteractions
Two or more different kinds of injectable neuroactive agents are frequently used to induce
anesthesiawiththegoalofachievingabetterqualityofanesthesiawithminimalsideeffects.
Agentsfrequentlyhavecomplementaryeffectsonthebrain,butoneagentmayalsoantagonize
anundesirableeffectoftheother.Examplesofsuchcombinationsaretiletamineandzolazepam
(Telazol®)orketamineandmidazolam.Tiletamineandketamineproducesedation,immobility,
amnesia, and differential analgesia, but may also produce muscle rigidity and grand mal

seizures. Zolazepam and midazolam produce sedation, reduce anxiety, and minimize the
likelihoodofinducingmusclerigidityandseizures.
Tobettermanagethepainassociatedwithsurgicalprocedures,itisbecomingincreasingly
commontocombinetheuseofregionallyadministeredanalgesicsandlightgeneralanesthesia
(twilightanesthesia).Anexampleofsuchanapproachistoadministeralocalanestheticalone
orincombinationwithanopioidoranalpha2adrenergicagonistintotheepiduralspacebefore
orduringgeneralanesthesia.Benefitssoughtwiththisapproacharereductionintheamountof
general anesthetic required and the provision of preemptive analgesia. Reducing general
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