Jul ian Hoad Minor Veterinary Surgery AHandbookfor VeterinaryNurses JulianHoad BSc(Hons)BVetMedMRCVS VeterinarySurgeon,WingraveVeterinaryHospital,Surrey,UK Forewordby MargaretMoore MA VNCertEdFETCMIScT Prinri,dCerberusTraining& Consultancy,Henley-an-Thames,Oxon.UK ELSEVIER EdinburghLondonNew YorkOxfordPhiladelphiaStLouisSydneyToronto2006 BUTTERWORfH HEfNEMANN ELSEVlER 2006,ElsevierLimited.Allrightsreserved. Nopartof thispublicationmaybereproduced,storedinaretrievalsystem,or transmittedinany formorbyanymeans,electronic,mechanical,photocopying, recordingor otherwise,without thepriorpermissionof thePublisher.Permissions maybesought directly fromElsevier'sHealthSciencesRightsDepartment,1600 JohnF.KennedyBoulevard,Suite1800,Philadelphia,PA19103-2899,USA:phone: (+ 1)2152393804;fax:(+1)2152393805;or,e-mail:hea/thpermissions@e/sevier.com. Youmay alsocomplete your requeston-line viatheElsevierhomepage (http://www.elsevier.com).byselecting'Supportandcontact'andthen'Copyright andPermissions'. Firstpublished2006 ISBN0750688076 BritishLibrary CataloguinginPublicationData Acataloguerecordfor thisbookisavailable fromtheBritishLibrary Library of Congress CataloginginPublicationData Acatalogrecordfor thisbookisavailablefromtheLibraryof Congress Knowledgeandbestpracticeinthis fieldareconstantlychanging.Asnew researchandexperiencebroadenourknowledge,changesinpractice,treatment anddrug therapymaybecomenecessary or appropriate.Readersareadvised to checkthemost currentinformationprovided(i)onprocedures featuredor (ii)by themanufacturer of eachproduct tobeadministered,to verify the recommendeddoseor formula,themethodanddurationof administration, andcontraindications.It istheresponsibility of thepractitioner,relyingon their ownexperienceandknowledgeof thepatient,tomakediagnoses,to determine dosagesandthebest treatment for eachindividualpatient,andto takeall appropriate safetyprecautions. Tothe fullestextent of thelaw,neither thepublishernor the author assumesany liability for anyinjury and/or damage. PrintedinChina Working togethertogrow librariesindeveloping countries \vww.elsevier.comI wwv.'.bookaid.orgI \vww.sabre.org ELSEVIERr . ~ ? , ~ ~ ~ , ~Sabre foundation your source for books, journals and multimedia in t he health sciences www.elsevierhealth.com ThePublisher The Publisher's policy is touse paper manufactured fromsustainable forests Contents Forewordvii Prefaceix AcknoWledgementsxi Abbreviationsxiii Part1 Generalprinciples Theveterinarynurseandminor surgery3 2Theminor surgicalpatient9 3Premedicationandpatientpreparation75 4Generalanaesthesia37 5Wounddressingsandbandages55 Part 2 Minor surgicaltechniques 6Woundmanagement77 7Principlesofsoft-tissuesurgery97 8Commonsurgicalprocedures725 9Dentalandoralsurgery163 10Thepostoperativepatient795 Glossary207 (Glossaryentries appear inbold throughout thetext) Furtherreading211 Usefuladdresses213 Appendix1 Suggestedcontentsofemergencybox279 Appendix 2 Emergencyprocedure- cardiopulmonary arrest221 Appendix 3 Emergencyprocedure- status epilepticus223 Index225 v Foreword Atlast- abookonminorsurgicaltechniques writtenforveterinarynursesbyaveterinary surgeonwhoclearly viewshisnursesasvaluable membersoftheveterinaryteam.Thisbook shouldenthuseveterinarynursesandsurgeons alike to embrace the notion of honing the surgical andrelatednursingskillsoflistedveterinary nurses.This canonly contribute tojobsatisfac-tionandofcourseincreasetherevenueofthe practice. Ican highly recommend this excellent tome to alllistedveterinarynursesinterestedinexpand-ingtheirskillsandunderpinningknowledgeof minoractsof veterinarysurgery. Takenasawhole,thechaptersaresequential andguidethereaderthrougheachstageina logicalorderfromassessmentof theminorsur-gicalcase,premedicationandpreparation,and anaesthesia,throughtosuitabledressingsand bandages for wounds arising fromsurgery.Each chapteris,initself,alsoausefulreferencefor theseindividualtopics. The principles of common surgical and dental proceduresarealsodetailedinfullfollowedby adviceoncareof thepostoperativepatient. Thecontentsareillustratedbycolourphoto-graphswhichsupportthetextwhereneeded, making the information easier tounderstand and use. Inconclusion,Iconsiderthisbooktobean essentialadditiontoanyveterinarypracticeor collegelibrary. MargaretCMoore vii Preface Veterinarynursingasaprofessionhaschanged muchinthelastfewyears,withchangestothe VeterinarySurgeons'Act(schedule3amend-ments)andanincreasingnumberofdiploma-holders. The role of the veterinary nurse ismoving awayfromtheoutdated'kennel-maid'/anaes-theticassistanttoencompassawiderrangeof activities,includingnursingconsultationsand healthcareclinics,inorder toutilisemorefully theexcellentknowledgeandtrainingofthe veterinarynurse. Minor surgery is one such role. Allowing nurses toperformminorsurgicaltechniquessuchas intravenous catheter placement, suturing wounds andevenlumpectomiesmakesforamuchmore efficient useof practicetimeand increasesteam-building and job satisfaction,reducing staff turn-over and improving practice profits. This book isaimedatthose veterinarynurses who want to learn more about surgical techniques andthosewhoarealreadyperformingminor surgerybutwhowanttoimprove.Otherthan providinginformationregardingthereasoning behind minor surgical techniques, there are easy-to-follow instructions for performing many minor surgicaltechniques.Itishopedthatveterinary studentsandrecentgraduatesmayalsofindthe bookausefulsourceof reference. Whereverpossible,Ihaveincludedcolour photographstohelpclarifycertainprocedures and toprovideexamplesof different techniques. Whereverrelevant,dosagesaregivenforstan-dardorusefuldrugcombinationsforaverage-sizeddogsand cats. Preoperativeexaminationandpreparationof patientsarediscussedindetail,aswellasthe procedure foradmitting surgicalpatients,advice toowners and suggestionsfororganising surgery lis ts. Any pitfallsor potentialcomplicationsof pro-cedures are detailed, together with relevant after-care.Handyhintsarewidespreadthroughout. Each procedure isdealt with separately,allowing thisbook tobeused either asa'patient-side' ref-erence,or asatextbook. Muchdiscussionisgiventowoundcareand advances in dressing compounds, as wellasprac-ticaladviceondealingwithmosttypesof wound. Dental medicine and surgery aredealt with in somedetail,includingareviewof dentalinstru-mentationandtechniquesforcleaningand polishing dogandcatteeth;rabbitdentalcare is alsocovered. Postoperative care and pain management form thebulkof thelastchapter,withasectionon dealingwithclientconcernsandcomplaints, givingpracticaladviceforimprovingclient communication. Ihopethisbookwillencourageveterinary nursestodeveloptheir surgical skillsandknowl-edge;Ialsohopethatitwillencouragepractices toappreciatemorefullytheabilitiesof their vet-erinarynurses,andtoprovidesupportandhelp forthemtobecomeproficientinvariousminor surgicaltechniques. JulianHoad ix Acknowledgements Therearemanypeoplewhohaveencouragedandsupportedmeinthecourseof writingthisbook, andmyheartfeltthanksgotoallmyfriendsandco-workers.Inparticular,Imustthankmyuncle, Robert Hutchinson,forencouragingmetostart writing,andmyemployer,NicDodds,forallowing mecontinuallytodisrupttheworkingdaytogatherphotographs,andingrantingmeagenerous amount of time off for writing.My computer would liketothank Adrian Ward fordebugging itseveral times. Myfamilyhavebeenverypatient withmeandIwouldliketothankmymother,Alicia,mybrother, Marcel,andmy sister,Giselle,fortoleratingmyrattymoodswhilstIwaswriting. The manyhandsandfacesthat appearinthebookholding patientsor instrumentsbelongtoGiselle Hoad, Josey Killner, Kerry Mead, Nicky Cole and Sandy Griffith. Special thanks alsotoMinky Broad forconsenting tobephotographedindozensof bandages! This book wouldnot havebeen written without the loveand encouragement of Syivia,my fiancee,to whomthisbook isdedicated. xi Abbreviations AChacetylcholineIVintravenous ACPacepromazineIVFTintravenous fluidtherapy AIPMMAantibi otic-impregnatedLDSligatinganddividingsystemstapler polymethylmethacrylateMACminimumalveolarconcentration BID(of dosing) twicedailyMCTmast-celltumour CBAcat-biteabscessMRSAmethicillin-resistant Staphylococcusaureus CO2carbondioxideN20nitrous oxide CoSHHControlof SubstancesHazardous toHealthNaCIsodiumchloride Act1988NSAIDnon-steroidalanti-inf lammatorydrug CPDcontinuingprofessionaldevelopment0,oxygen CRTcapillaryrefilltime (lessthan2-3 sOCRLlOCLodontoclasticresorptionlesions/odonto-normally)clasticlesions CVPcentralvenous pressureODoutside diameter ECGelectrocardiogram PDS"polydioxanone sulphate(suturematerial, E-collarElizabethancollarEthicon) ETendotrachealPOorally FeLV/FIVfelineleukaemiavirus/felineimmuno- PVCpolyvinyl chloride deficiencyvirusRCVSRoyalCollegeof VeterinarySurgeons FNABfine-needleaspirationbiopsyRTAroadtraffic accident Ggauge(thickness)of needleSCsubcutaneous GIAIILAgastrointestinalanastomosisSID(of dosing)oncedaily HMSOHerMajesty'sStationery Office(publishersSpO,arterialhaemoglobin saturation of government documents)TAthoracoabdominal ICintracardiacTID(of dosing)threetimesdaily IMintramuscularVDSVeterinaryDefenceSociety IPPVintermittent positive-pressureventilationVN(listed)veterinary nurse ITintratracheal xiii Part1: Generalprinciples 1Theveterinarynurseandminorsurgery 2Theminorsurgicalpatient 3Premedicationandpatientpreparation 4Generalanaesthesia 5Wounddressingsandbandages 1 Theveterinarynurse andminorsurgery Inthis chapter Definitionandscopeof minor veterinary surgery Roleof the veterinary nurse TheReVSschedule 3 and its application to minor surgery within the practice Ensuringprofessionalsupport Personallearning,development and self-assessment DEFINITIONANDSCOPEOFMINOR VETERINARYSURGERY Minorveterinarysurgeryincludesprocedures ranging from removing skin masses and suturing minorwoundstocertaindentalprocedures. Specifically,minorveterinarysurgery: Doesnotinvolveanyprocedure consideredto belife-threatening or risky Doesnot involveanycomplexprocedure Iscarriedoutonapatientthatisotherwise healthy Does notinvolveentry intoabodycavity IscoveredbytheRoyalCollegeof Veterinary Surgeons(RCVS)VeterinarySurgeons'Act (1966)withschedule3amendments(see later) Thus,suturingaskinlacerationon thetarsusof ahealthy6-year-oldcatwouldbeconsidered minorsurgery,whereasplacementofachest drainandclosingthethoraciccavityclearly wouldnotbe.Similarly,asmallskintearonan eyelid margin may requireprecise repair utilising magnification- certainlynotminorsurgery. However,closingthesubcutaneoustissueand skin after laparotomy or thoracic surgery would beconsideredtobewithinthescopeof minor surgery. Lumpecromiesareusuallyconsideredminor surgery.However,thereisconsiderablediffer-encebetweenagrape-sizedflanklipomaanda football-sizedlipomaintheaxilla- thesizeof lumpforwhichadogneedstobetreatedfor separationanxietyafteritsremoval! Forexample,amast-celltumourwithhigh metastaticpotentialwillneedtoberemoved withalargemarginandmayrequirecomplex skinreconstructiontechniquestoclosethe wound.Noneofthisprocedurewouldbecon-sideredtobeminorsurgery.However,removal ofa1-2-cmcutaneousmass,whichhasbeen 3 GeneralPrinciples demonstratedtobebenignandisnotinanarea of thebody whereskinclosureislikelytocause anyproblem,wouldfallintothedefinitionof minor surgery. Itisthereforedifficulttoproduceadefinitive list of minor surgical procedures. The decision of what constitutesminor surgery willdependon: Size, depth and position of wound (Figures 1.1 and1.2) Conditionof underlying tissue Complexity of surgery,including incisionand repair Competenceandexperienceofsurgeon/ nurse Overallhealthof thepatient Proximity of surgical area todelicate or impor-tantorgans Specificlimitationsundertheschedule3 amendments Practicepolicies ROLEOFTHEVETERINARYNURSE Increasingly,theroleoftheveterinarynurse (VN)in practice ischanging.More practices are Figure1.1Thissmallmasswasshownbyfine- needle aspirationbiopsytobebenign.Removalwouldconsti[Ute minor surgery. Figure 1.2Thislipomaisbenign,but removalwouldnotconstituteminor surgery. 4 utilisingtheirnursingstafftothefull,taking advantage of the excellent training the VN course provides. In addition tomore basic nursing duties, many nursesnow: Runvariousnursingclinics(weight,dental, worming) Regularlyperformminor veterinary surgery Takepartinclienteducationprogrammes withinthepractice Performradiographicprocedures Specifictosurgery,nurses should : Organise the operating-room schedule,taking intoaccountthenumbersandtypesof clean, contaminatedanddirtyprocedurestobe performed Ensurethatstaffinglevelsareadequatefor thenumberofprocedures(arrangenursing rotas) Ensurethatthecorrectlevelsofequipment, materialsanddrugsareavailable Of course,itdependsonthenatureof theprac-tice whether it isfeasibleor efficient forthe nurse tobeperformingsurgery,buttherearestrong reasonstoallowthisinmany settings: Efficient use of personnel: in a hospital setting, anurse can perform a lumpectomy or suture awound,thusallowingthevetmoretimeto undertakediagnosis Moreprocedurescanbeperformed:the number of personneliseffectivelyincreased Atrained,scrubbedassistantcanbeinvalua-bleduring acomplex procedure forretraction oforgans,passinginstrumentsandapplying handpressureoverhaemorrhages Thereislesswaitingtimeforsurgery - bene-fitingpetandowner It increasestheoverallknowledgeandpracti-calabilityof theteam Permitting VNstotakepart inminor surgery encouragespersonaldevelopment Itcanleadtoincreasedjobsatisfaction It isnot intendedthat nursesbecome 'mini vets', rather the nurses' education andtraining areuti-lisedmorefully,allowing forabetter useof per-sonnel.It wouldnotbeacceptable,forexample, 1 /TheVeterinaryNurseandMinor Surgery forasmallpracticetobudgetonanurse-only teamperformingsurgerywhilsttheveterinary surgeon consultsina distantroom.Nor wouldit beacceptable for a nurse toact asboth anaesthet-istandsurgeonatthesametime.Thisclearly fallsoutsidetheReVSrequirement forconstant monitoring. THERCVSSCHEDULE3ANDITS APPLICATIONTOMINOR SURGERYWITHIN THEPRACTICE TheVeterinarySurgeons'Act1966(schedule3 amendment)order 2002/ 2004 dictates what pro-ceduresaVNmaycarryout.Thisscheduleis constantlyrevisedandamended,andisopen toanextraordinaryamountofinterpretation. However,the main points arethat itonly applies tolistedqualifiedVNs,ortostudentVNs whoareenrolledatanapprovedtrainingand assessmentcentreoranapprovedveterinary practice. AVN mayperformanymedicaltreatment or minorsurgerytoanyanimal(petordomestic), providedthat: Theanimalis,forthetimebeing,underthe careof aregisteredveterinarysurgeonor vet-erinary practitioner and the medical treatment orminorsurgeryiscarriedoutbytheVNat thesurgeon'slpractitioner'sdirection Theregisteredveterinarysurgeonorveteri-narypractitioneristheemployerorisacting onbehalf of theemployer of the VN Theregisteredveterinarysurgeonorveteri-narypractitionerdirectingthemedicaltreat-ment or minor surgery issatisfiedthat the VN isqualifiedtocarryoutthetreatmentor surgery AstudentVNmayperformanymedicaltreat-mentorminorsurgerytoanyanimal(petor domestic),providedthat: Theanimalis,forthetimebeing,underthe careof aregisteredveterinarysurgeonor vet-erinary practitioner and the medical treatment or minor surgery iscarriedout by thestudent VNatthesurgeon'slpractitioner'sdirection andinthecourseofthestudentVN's training 5 GeneralPrinciples Thetreatmentorsurgeryissupervisedbya registeredveterinarysurgeon,veterinary practitioner or VN and,in the caseof surgery, thesupervisionisdirect,continuousand personal Theregisteredveterinarysurgeonorveteri-narypractitioneristheemployerorisacting on behalf of theemployerof thestudent VN Confusionalwaysoccursoverwhatconstitutes minorsurgery.TheRCVSisfairlyvagueover this, but stipulates that it should not involve entry intoabodycavity.Somediscretionislefttothe veterinarysurgeontodecidewhetherthenurse iscompetenttoperformthesurgery,orwhether itisappropriateforthatproceduretobeper-formedbyanurse. Dentistryhasalsocausedconfusioninthe professionunderthetermsof schedule3,asthe oral cavity isabody cavity under the terms of the Act.Atthetimeof writing: AVN may not extract teethwithinstruments unlesstheteetharealreadymobile AVNmaynotperformworkunderthegum margin AVNmaynotcreateflapsforperiodontal surgery However,nursesmaystill : Examineteethforevidenceof lesions Use instruments such asultrasonic scalers and mechanicalscraperstocleanteeth Useinstrumentstoremovelooseteeth Polishteeth Althoughmoreamendmentstoschedule3will undoubtedly be made,it isunlikely that substan-tialchangeswilloccurtopreventnursesfrom carryingouttheaboveprocedures. Whatiscertain,though,isthatcompetence playsaveryimportantroleinthedecisionto alloworforbidcertainprocedures(Figure1.3). Thusitisuptoindividualnurses,andtothe professionasawhole,togainexperienceand competenceinminor surgery(Box1.1). ENSURINGPROFESSIONALSUPPORT With increased surgical competence, the number and variety of procedures assigned to a nurse will Figure1.3Efficientuseof time:aqualifiednursemonitorstheanaestheticwhileatraineenursepreparesthesurgical site.The veterinary surgeoncan bescrubbing readyforthecaesareansection. 6 Box1.1 Theinclusionof a specificprocedure in thisbook doesnot necessarilysuggest that it isa minor surgicaltechnique nor that it isappropriate for a veterinary nurse to perform sucha procedure.In most casesthe procedureisincludedfor completeness.Forexample,it makeslittle sense to discussdental treatment without discussing extractions. Thedecision to allow a veterinary nurse to performa specificproce(Jureismadeonthe basis of current schedule3 legislation,individual practicepolky andthe surgicalexperienceand 'competenceof the nurse increase.So,inevitably,willthepressureand accountabilityplacedonthat nurse.Performing a surgicaltechniquethat iswithin one's'comfort zone'of abilityshouldbeenjoyable.However,it cantakesometimetoreachthatlevelof ability. Itisveryimportanttohavethesupportofthe restofthepracticeteamwhilstgainingexperi-ence. The levelof suppOrt may vary from practice topractice,but hereareafewguidelinestohelp reducethestressof learning: UnderthetermsoftheRCVSschedule3, aqualifiedveterinarysurgeonmustbeon handatalltimesduringaprocedureunder anaesthetic There isnostrictrequirement forthisduring non-anaesthetic procedures, but it would seem sensibletoensure that adviceandsupport are availableformostprocedures,certainlywhen theyarebeingperformedforthefirsttime Everybodyhastolearn - don'tmakeextrava-gant claims about your abilities. This willonly leadtodisappointment and lack of trust if the procedureisnotsuccessful Discussallcaseswithyourcolleaguesbefore starting:thiswayaclearplancanbemade, andanyalternativewaysoftreatingmaybe discussed Learn totake criticism - well-structured criti-cismcanbeveryhelpfulforthefuture 1 / TheVeterinaryNurseandMinor Surgery TrytoadoptamentOrwithinthepractice-this may be a more experienced nurse, or a vet - whowillundertaketoallowyoutoperform minorsurgeryunderhis / herguidance.This isawayofquicklybuildinguptrustand experience PERSONALLEARNING,DEVElOPMENTAND SElF-ASSESSMENT At thetimeof writing,thereisnostrict require-mentfornursestocompleteminimumhoursof continuingprofessionaldevelopment(CPD). TheRCVSdoesmakethepointthatsurgical treatments can become outdated: theimplication isthatoneshouldkeepuptodatewithtech-niques .Itisrecommendedthatnurseskeepa recordof theirCPD. Personallearningcanbeachievedinseveral ways: Revisinganatomyandsurgicalapproaches beforeeachprocedure Readingreviewarticlesinjournals AttendingCPDcourses Attendingotherpracticesandcentresof excellence Discussingcaseswithcolleagues Practising(whereappropriate)oncadaversor suturedummies Beingself-criticalabout cases Thelastpoint ismost important:unfortunately, mistakescanoccur.Learningfromthosemis-takesrequiresthat you : Recognisethemistakeandhowit occurred Askyourcolleagues(veterinarysurgeons, nurses)whethertheyhavehadthesame problem Listentotheir adviceandactpositively onit Ultimately,only practice and dedicationtodetail willallowdevelopment.Atfirst,surgicalinstru-mentswillfeelclumsy andawkward.Withtime, however,familiaritywithinstrumentswillcome andconfidencewillfollow. Do not rush:surgcry isnotaraceand hasteis a bad thing! Nor isit acceptable to spend too long overaprocedure,asthiswillextendanaesthetic timeandoccupytheatretime.Competenceand confidencewillincreasespeedandsafety. 7 2 Theminorsurgical patient Inthischapter Owner communication Admitting thepatient Theconsentform Preanaesthetichistory rev.iew,nurseexamination andhealthcheck Planningoperating-theatrelistsandtime OWNERCOMMUNICATION Everyyear,theVeterinaryDefenceSociety (VDS)handlescomplaintsfromowners;these complaints arise asa result of lack of proper com-municationbetweenthepracticeandtheclient. Ownerstypicallywant: Reassurancethat their pet willbeallright An estimateof costs,together withan under-standingof whenpayment isdue Reassurance that there isa fullunderstanding of the pet's problems and a detailed plan of the procedures Tobekeptuptodatewiththeirpet's progress Ontheotherhand,thepracticewantsfromthe owner: Reassurance that the owner understands what proceduresarebeingcarriedout Understanding of thelikelycosts Anychangesintheanimal'sconditionsince theappointment wasmade Writtenpermissiontoperformtheproce-duresanddealwithanyemergencythatmay arise Contactdetailsincaseof emergency Allof the aboveneedtobe addressedand, where appropriate,notarised. Effectiveownercommunicationisthebest wayof avoidingmisunderstandingsthatleadto complaints. Costs areoften abig issueandveterinary bills are often very high.It isup to the owner to decide whetherheorshecanaffordtherecommended veterinarytreatment,andthereshouldbeno embarrassmentorshynessoverdiscussingesti-mates.Thereshouldbeenoughprideinthe qualityofworkcarriedouratthepracticeto justifythefeecharged. The owner should be fullyaware of the proce-durebeingundertaken 9 GeneralPrinciples Someownershaveanunrealisticexpectation of surgery:theymayassumeaninstantdiag-nosisor curefollowingtreatment l\1akecertainthattheowner understandsthe need for any patient preparation: some owners, forexample,aremoreupsetaboutfurbeing shavedthanaboutalargesurgicalwound Becarefultoavoidcertainties(ofdiagnosis, treatment costSand prognosis)- someowners willpressforananswer whereitmay be inap-propriatetogiveone Makesuretheownerisawareof whoisper-forming the surgery '- any note should be made of requestsforparticular surgeons Anyconcernsshouldbeaddressedbefore admission Itiscommonpracticeinahumanhospitalto havea woundattendedtobyanurse.The doctor maymerelyexaminethewoundanddecideon the nature of treatment. Unfortunately, at present, the public perception isthat the vet will carry om allprocedures,withtheveterinarynurse(VN) acting in amore ancillary capacity.That percep-tion willchange in time,but onlythrough excel-lentowner communicationandeducation. ADMITTINGTHEPATIENT Veryoften,itisthenursewhoadmitssurgical patientstothepracticeor hospital.Itisthusthe nurse'sresponsibilitytoensureallof theabove points are met. The simple question:'do you have anyquestionsregardingtoday'sprocedure?'is notenough. Theplanforthepatientshouldbediscussed openly, tOgether with any requirements or sug-gestion forpreoperativefluidsorbloodtests Anyoptionalextrassuchasmicrochipplace-mentshouldbediscussed(Box2.1) Individualappointmenrsshouldbemadefor admissionwhereverpossible. Thisfocusesattentionontheownerandthe patientandmakesitlesslikelythatanything willbeoverlooked Appointmenrsalsohighlighttheimportance of asurgicalprocedureandmakeadmissions moreformal 10 Box 2.1 Admissionof thepatient istakenas the effective start of anyminor surgicalprocedure,sinceit consistsof some veryimportant aspects that couldaffect the subsequent management of the patient. Thiscreatesanatmosphereofprofessional-ism,whichisofbenefittotheownerand practice Appointmentsalsoallowtimefortheconsent formtobecompletedfully THECONSENTFORM Since a consent form must be signed by the owner whenadmittinganysurgicalpatient,itmakesa great deal of sense forthat formtoact asa check-listtoensureallpointsarecovered.Anexample of aconsent formisshownin Figure2.l. A consenr form should clearly havethe owner's details,including addressandcontact numbers. Thepetname,togetherwiththespeciesand breed,shouldbewritten,anditisagoodideato haveadescriptionof theanimal.Thisbecomes especiallyimportanrif anownerbringsinmore than one animal! The planned procedures should bewrittenclearlyontheformandanestimate shouldalwaysbegiven. If theowner declinesan estimate,anoteshouldbemadeontheconsent form. There should be some statement of riskonthe consent form:this isoften glossed over or ignored bythepersonadmittingtheanimal,perhaps becauseitisfearedthatmentioningriskmay alarmorworrytheowner.However,thisisthe mostcriticalpartof theformanditisvitalthat the owner understands the implications of accept-ingtheriskofanaesthesia,surgeryormedical treatment. Anaestheticdeathsinhealthyanimalsare uncommon: recent studies suggest a figurein the orderof1deathin1000anaesthetics,andother studies pm the figurelowerthan that inpractices withexcellentmonitOring.Thus,foraminor 2 ITheMinor SurgicalPatient e ?etScanCli/). Veterinary Surgery 1(' 1 Halstead Street Lembert Surrey 19th April2005 FORMOFCONSENT FOR ANAESTHETICANDOPERATION Mr B SmithContact numbers: 02081234567 Punters Lane079731234567 Homeville Surrey Patient: Alfie Species: Canine Breed: Labrador Age: 8 years5 months Cotour: Yellow Sex: Male (neutered) Weight: 25kg Vaccinalionstatus: VaccinatedFebruary 2005 Insurance: Legit. Grabbit andRunn Operation/procedure: Lumpectomy andhistology Pre-anaesthetic sheetsent: Yes Last meal: Last night Pre-anaesthetic blood sample: Yes IV nuids: Yes(Hartmanns) Any current medication: Rimadyl50mgBID Lastgiven: Lastnight Any items left: Collar andlead

GHP ( WBCandDiff Other) Cost estimate:I350 I a guide: I V I detailed:I I I hereby givepermissionfor theaboveanimaltobeadmilled for inpalienl tesls,Ireatment,observalionandany other procedures thatmay prove necessary. I understandthat whilevery careandattentionwillbegivento Alfie , thePracticecannot beheldresponsible for any unloward eventsthatmay occur. I alsounderstandthat whiteevery effortwillbemadeto contact meintheevent of unplannedproceduresbeingnecessary,thePractice mustbe permittedtoperformanyproceduresthey feelnecessary tomaintain thewellbeingofAt fieInextreme cases, thismay include euthanasiaif unduesufferingisoccurringandthechancesof recovery arethoughttobepoor. I understandthat the fullfeewillbepayable onreleaseof theanimal. Signed(Owner/authorisedagent) Date:;er /1--/0') "'""- -Figure 2.1Exampleof a consentform. 11 GeneralPrinciples surgicalprocedureonayounganimal,itwould bereasonabletosaysomethingalongthelines that,althoughthereisalwaysariskwithany procedure,theriskissmallandthepractice makeseveryefforttoreducethatriskstill further. Any changes tothe planned treatment must be notedontheconsentform,alongwithrequire-mentsforintravenousfluidsandpreanaesthetic bloodor urinetests . The owner should be given ample time toread theconsentform Informedconsentiscrucial,soensurethat theownerunderstandswhatheorsheis signing Itmay be a good ideatoread the consent form outloudaftertheclienthasreadit The consent form should make some reference to the postoperative care of the patient: whether itisexpectedthatthepet willbegoinghome afterthesurgery,orwhether itisintended,or possible,that hospitalisationforoneor several dayswillberequired Theconsentformservesnotonlyasalegal document,butalsoasanaide-memoireto ensurealltreatmentsarecarriedout Anyrelevantpreviousdrugreactionsshould benotedontheform Oncetheowner hassignedtheconsentform,it isnotadvisabletomakeanyalterationsoraddi-tionstotheform. Alsonotethatitisnotacceptableforanyone lessthan16yearsof agetosignaconsentform. PREANAESTHETICHISTORYREVIEW,NURSE EXAMINATIONANDHEALTHCHECK Duringtheadmissionappointment,areviewof theclinicalhistoryshouldbeperformed,to ensurethat: Anypreviousanaestheticproblemsordrug reactionsarenoted Relevantbloodorlabtestsarerechecked Anychangeintheclinicalconditioncanbe noted(forexample,increaseordecreasein sizeof lump,changeinposition,increasein number) 12 Anyconcurrentillnessisconsidered(for example,diabetes,epilepsy) Anyprescribedcurrentmedicationisnoted A fullclinicalexamination should be performed, toinclude : Examinationof mucousmembranes andeval-uationof capillaryrefilltime Temperature,pulseandrespiration Anysignof dehydration Anysignofclottingdisorder(petechiae, ecchymoses) Anyconcurrentdisease(dentaldisease,skin infections,etc.) Anysignof cardiopulmonarydisorder(heart murmur,cough,etc.) The positionof skinmasses or wounds should benotedontheconsentform Theownershouldbequestionedastothepet's currenthealth:hastherebeenanyrecentdiar-rhoeaorvomiting,lethargyorinappetance, increasedordecreasedthirst? If the owner has not previously been informed oradvisedaboutpreoperativebloodorurine tests,orintraoperativeintravenousfluids,nowis agoodtimetodiscussthese.Manypractices sendoutapreanaestheticleaflettoownersonce surgeryhasbeenbooked:theseleafletsdiscuss thebenefitsof preanaesthetictestingandintra-venousfluidsandaretobeencouraged. However,thefactthataleafletwassentisno guaranteethattheclientreadit!Bepreparedto spendtimegoingoveranyadvicegiveninthe leaflet . Remember, what isroutinetoyoumay be ahighlystressfulanduniqueexperiencetothe client . Anyqualmsshouldbenotedandveterinary advice sought either before or after admission,as appropriate.Anyconcernswhichmayleadto postponementofsurgeryareobviouslybest addressedbeforeadmission. PLANNINGOPERATING-THEATRELISTS AND TIME Whether the practice isasmall,one-vet practice oralargehospital,theatrelistsshouldbe priori-tisedonthebasisof: Sterility:clean,cleancontaminated,con-taminatedsurgeryshouldbeperformedin that order Healthstatusof patient:agedpatientsshould beoperatedonbeforeyoung,healthy patients There are several reasons forscheduling geriatric patientsbeforeyoungpatients: Anaesthetic patients willhavebeen starved for severalhours,frequentlyovernight:older patientsmayhaveamorecatabolicmetabo-lismandrequirefeedingmorefrequently. Schedulingtheirsurgeryearlyonwillmean thattheywillbeabletoeatsooner Thesameistrueof drinking- watershould be left down for geriatric patients until an hour or sobeforesurgery Olderpatientsmaybemoresusceptibleto stressduetoleaving their home environment. Stressed patientsshouldbescheduledearly in thedayinordertobeallowedhomeassoon astheyhaverecoveredproperly Older or geriatricpatientsoftentakelonger to recoverthan youngones.Schedulinganearly anaestheticallowsforrecoverytotakeplace duringthemorningandreducesthechance thatthepatientmayneedtobehospitalised foranextranight 2 ITheMinor SurgicalPatient Other considerationsare: Arrangingatimewhenmorestaff willbeon duty forlongprocedures Whether to get quick operations our of the way beforestartingcomplexones Ensuringthattherewillbeenoughkits(or personnel)availablefortherequirednumber of procedures If more thanone theatre isavailable,then one shouldbedesignatedforcontaminatedpro-cedures,suchasdentals Whatpostoperativetreatmentorcareis required for a patient? forexample, scheduling aroutinethoracotomyforaFridaymaybea bad idea if there isgoing tobe a reduced staff-ing levelattheweekendtoprovideaftercare Whatorderof surgerywillmakethemostof availablepersonnel? In any case, when firstperforming minor surgical procedures,itisimportant toleaveenoughtime nottofeelrushed.Better toreschedule,or allow amoreexperiencedsurgeontoperformthe surgery,thantopanicandoperateunderpres-sure.Whereverpossible,ensurethatwhen attemptinganovelprocedure,therestofthe teamisexperiencedandcompetentwithintheir role(forexample,theanaesthetist) .Inthisway, therewillbefewerdistractions. 13 3 Premedicationand patientpreparation Inthischapter Rationale andreview of c;ommonsedative! premedicationdrugs Commonlyusedpremedication drugs Recordingpreanaesthetic drug aGlministration Injectionroutes and techniques for premedication Basicsof surgicalfluiGladministration Analgesic drugs andpainmanagement Pre- andpostoperative antibiotics RATIONALEANDREVIEWOFCOMMON SEDATIVE/PREMEDICATIONDRUGS Generalanaesthesiaiscommonlyprecededby premedication with one or,moreusually,several drugs.Premedicationdrugs: Reducetheamountofanaestheticrequired (injectableandinhalant),soreducingside-effects(andcosts!) Relaxmuscles Provideanalgesia Providesedation Suppressvomitreflexes Mayhelpcalmastressedanimal- this makeshospitalisationpriortosurgerymore comfortable Mayhelpmaketheanimaleasiertohandle Improverecovery(fewertremorsandless vocalising)- thismaybelargelyduetothe analgesicaction The choice of premedication drugs varies accord-ingto: Practice/vetpreference,depending onexperi-enceofthedrugs :itisalwayssafesttousea drug or a combination of drugs with which the vet isfamiliar and knows the effects. It ismuch easier to note anyadverse reactions tomedica-tionifthereisexperienceofthenormal response Age or health status of the patient: some drugs maynotbelicensedforuseinimmature animals.Conversely,there may be contraindi-cations forthe use of certain drugs in an older or unwellanimal.For example,acepromazine (ACP)shouldnotbeusedinanimalswith epilepsy,asitismayreducethethresholdat whichseizurescanoccur.Morphineshould not beusedinpatientswithsevereuraemia Pregnancy:ACPandopioidscancausea reductioninfetalbloodsupplyorblood 15 GeneralPrinciples pressure.Otherdrugsmayhavespecificcon-traindicationsinpregnancy Routeof injection:itmaybedifficultorrisky attemptingtoadministeranintravenous(IV) injectiontoanervousor fractiouscat Speciesorbreed:ACPshouldbeusedwith cautioninboxersandshouldbeusedat reduceddoseingreyhounds Procedureplanned:oneshouldtakeinto accountanyspecificcontra indicationsfor certainprocedures(forexample,ACPshould notbeadministeredtopatientsundergoing myelography).Considerationshouldalsobe giventothesuitabilityof drugcombinations forspecificprocedures.Forexample,using morphine before radiography may be excessive andneedlesslyextendthesoporificeffectof the anaesthetic. Alternatively, using butorpha-nolbeforeligamentsurgeryisunlikelyto providesufficientanalgesia Concurrentdrugusage:butorphanolmay antagonise (reverse the effects of)metoclopra-mide;theuseof atropineinpatientsonlong-termcorticosteroidtreatmentmayresultin increasedintraocular pressure Planned postoperative treatment: if the animal isgoingtorequiremorphinepostoperatively, thenincludingbuprenorphineinthepremed maycauseantagonismoftheanalgesic effects COMMONLYUSEDPREMEDICATIONDRUGS Thefollowinglistisnotexhaustive:itismerely intendedasanoverviewof themostcommonly usedpremedicationdrugs.Suggestionsforpre-anaesthetic or sedative combinations are shown in Table 3.1. Where a standard proprietary formula-tion isgiven,the dose in millilitres per 4-kg cat or lO-kg dog isstated. For convenience, and to avoid unnecessaryrepetition,theanalgesicproperties of the drugs are discussed alongside their sedative properties.Dosesforanalgesiaratherthanpre-medication are suggested in Table 3.2. Acepromazinemaleate Phenothiazine:thefullchemicalnameis 2-acetyl-10 -(3 -dimethylaminopropyl) phenothiazine 16 Itisusedextensivelyasatranquilliserto calmaggressiveandapprehensiveanimals Useasapremedicantreducestheamountof injectableandinhalantanaestheticsrequired Often used alone or incombination toprovide sedationforminorprocedures(ultrasound, dressingchanges)orforhomemedicationas asedative,e.g.fortravelling Alsooftenusedforthemanagement of sound phobias,includingfireworks,butthisuseis contraindicated ACP has little or no analgesic action: this must beborneinmindwhenusingitasasedative forminorprocedures ACPcausesareductioninarterialpressure: increaseddosesdonot seem todecreasepres-surefurther,butincreasethedurationof hypotension ACPshouldnotbeusedinanimalsthatare hypovolaemic Increaseddosesdonotappeartoincrease sedationeither,but doincreaseduration Onoccasion,ACPhasbeenseentoincrease aggressionindogsandcats,presumablyby removingfearof theaggressor TheIV,IM,SCororaldosemaybeusedin thedogor cat Doses:dogs:0.01-0.1 mg/kgIV,intramuscu-larly(lM),subcutaneously(SC),1-3mg/kg oral; cats:0.05-1.0mg/kg IV,IM, SC,1-3mg/ kgoral Atropine Atropineisaparasympatholytic,blocking acetylcholine(ACh) Historically,itwasusedtodecreasesalivary andairwaysecretionsduring anaesthetics Moderninhalantanaestheticsarelessirritat-ing tothe airways,and sothereislittle ration-ale for the rou tine use of atropine preopera tively thesedays Atropinecanincreasetheoccurrenceof cardiacdysrrhythmias The main uses of atropine now are tofacilitate ophthalmicexaminationbydilatingthepupil (mydriasis)or totreat or prevent certain types of bradycardia orbradyarrhythmias 3 IPremedicationandPatient Preparation Table3.1Preanaesthetic or sedativecombinations DrugProprietaryname,Suggestedsedative,DoselDosel combinationconcentrationpreanaesthetic or10-kg4-kg suppliedanaesthetic doses(allIMdog (ml)cat (ml) unlessotherwise stated) ACP,ACP(NovartisSedative buprenorphineAnimalHealth)ACP: dogs,cats 0.05 mg/kg0.250.1 2mg/mlVetergesic:0.01mg/kg0.330.13 Vetergesic(AlstoePreanaesthetic AnimalHealth)ACP: dogs0.02 mg/kg0.1 0.3mg/mlcats0.05 mg/kg0.1 Vetergesic:0.01mg/kg0.130.13 -----Diazepam,DiazepaminjectionSedative k.etamine(PhoenixValium: dogs 0.2mg/kg0.4 Pharma)5 mg/mlcats0.5mg/kg0.4 Ketaset(FortKetaset: dogs11mg/kg1.1 Dodge)cats20 mg/kg0.8 100mg/mlPreanaesthetic Valium:dogs 0.2 mg/kg0.4 cats0.2 mg/kg0.16 Ketaset:cats5 mg/kg0.2 Midazolam,Hypnovel(Roche)Sedative ketamine5mg/mlHypnovel : 0.25 mg/kg0.50.2 Ketaset100mg/mlKetaset : dogs11mg/kg1.1 cats20 mg/kg0.8 Preanaesthetic ACP,ACP2mg/mlACP:dogs0.02 mg/kg0.1 morphineMorphine(Evanscats0.05 mg/kg0.1 Pharmaceutical)Morphine:dogs 0.25 mg/kg0.25 10mg/mlcats0.2 mg/kg0.08 ACP,ACP2mg/mlSedative/preanaesthetic butorphanolTorbugesic(FortACP:dogs0.02 mg/kg0.1 Dodge)10 mg/mlcats0.05 mg/kg0.1 Torbugesic:dogs0.1mg/kg0.1 cats0.4 mg/kg0.16 - ----------Medetomidine,Sedative butorphanolDomitor (Pfizer)Domitor:dogs0.025 mg/kg0.25 (reversewith1 mg/mlcats0.05 mg/kg0.2 atipamezole)Torbugesic10 mg/mlTorbugesiC:dogs0.1mg/kg0.1 Antisedan(Pfizer)cats0.4 mg/kg0.16 5mg/mlReversewithAntisedan0.10 Preanaesthetic Domitor:dogsonly0.10 0.01mg/kg Torbugesic: dogs0.1mg/kg0.10 cats0.4 mg/kg(IM,SC)0.16 Medetomidine,Anaesthetic butorphanol,Domitor1 mg/mlDomitor: dogs 0.025 mg/kg0.25 ketamineTorbugesic10 mg/mlcats0.08 mg/kg0.32 Ketaset100 mg/mlTorbugesic:dogs0.1mg/kg0.1 cats0.4 mg/kg0.16 Ketaset:dogs5 mg/kg0.5 (15 minlater indogs)0.2 cats5 mg/kg ReversewithAntisedan0.16 (catsonly,after 45 min) ACP,acepromazine;IM,intramuscular;SC,subcutaneously. 17 GeneralPrinciples Table3.2Analgesics:dosagesandfrequency Drug(generic andDoseand frequency tradename, eats (mg/kg)ml/4-kg catDogs (mg/kg)mll10-kg dog concentration) Morphine(morphine,0.1 mg/kgIV0.04ml0.1-0.25 mg/kg0.1-0.25ml Evans0.1-0.5mg/kg0.04-0.2mlIV IMse Pharmaceutical,IMseq4-6h 10mg/ml)q6-Bh Buprenorphine0.006-0.03 mg/kg0.OB-0.39 ml0.006-0.03 mg/kg0.2-1ml (Vetergesic,Alstoe,IVIMseIV IMse 0.3mg/ml)q3-6hq3-6h --------Pethidine(pethidine2-10mg/kgIMse0.16-0.Bml2-10mg/kgIM se0.4-2ml injection, Arnoldsq4-6hq4-6h Veterinary Products,50mg/ml) -----."---- ------- ----Fentanyl(fentanyl0.004mg/kg25J.1.g/hfor0.004mg/kg25 !-1g/h patch,Durogesic,transdermallycatstransdermally(3.2,..6.B kg) Janssen-eilag)q3-5 daysbetweenq3-5days5 0 ~ l g / h 3.2 and(6.B-1B.2 kg) 6.Bkg75!-1g/h (lB.2-27.3 kg) 100J.l.9/h (>27.3 kg) earprofen(Rimadyl4mg/kgIVse0.32ml4mg/kgIVseO.Bml small-animalprior toprior to injection,Pfizer,anaesthesiaanaesthesia 50mg/ml,RimadylOngoinguse4mg/kgPO2 x20-mg tablets 20mg,50mg)contraindicatedoncedailytablets Meloxicam(Metacam0.3 mg/kgseprior0.24ml0.2 mg/kgIVseO.4ml solution forto surgery.prior to injection,BoehringerOngoingusesurgery Ingelheim,5 mg/ml,not0.1mg/kgPO0.7Sml oralsuspensionrecommendedoncedaily 1.5mg/ml) Tepoxalin(Zubrin,N/A10mg/kgPOOne tablet Schering-Ploughoncedaily AnimalHealth,50 mg, 100 mg,200 mgoral Iyophilisates) Ketoprofen(Ketofen,2 mg/kgseonceO.Bml2 mg/kgIVIMse2ml MerialAnimaldaily. Notoncedaily. Not Health,10mg/ml,recommendedrecommended Ketofentablets5 mg,prior toprior to 20mg)anaesthesiaanaesthesia 1 mg/kgPOonce1 x5-mg1 mg/kgPO'12x20-mg dailytabletonce dailytablet MedetomidineSO-100J.l.g/kgIM0.2-0.4ml30-BOJ.l.g/kgIV IM0.3-0.Bml (Domitor,Pfizer,se every3 hseevery3h 1 mg/ml)(sedation(sedation outlastsoutlasts analgesia)analgesia) Ketamine(Ketaset,O.S-l mg/kgIMse0.02-0.04mlO.S-l mg/kgIMseO.OS-O.lml Fort Dodgeevery 3-4hevery3-4h AnimalHealth, 100mg/ml) IV,intravenously;IM,intramuscularly;Se,subcutaneously;PO,orally. 18 Doses:dogs/cats :0.02 mg/kgIV,0.045 mg/kg IM orSC Diazepam Diazepamisabenzodiazepine Ithasvarioususes,includingasasedative, tranquilliser, anticonvulsant, skeletal muscle relaxantandappetitestimulant(incats) Whenusedalone,diazepamoccasionally resultsinexcitationrather than sedation, soit is most often used in combination with another sedative,usuallyketamine The amount of sedation may vary considerably frompatienttopatient:anincreaseddose usuallyresultsinanincreaseddurationof actionaswellasanincreasedeffect It isespecially usefulasapremedicant inepi-lepticpatients,orinpatientsundergoing myelography The oral presentationappears tobe quite suc-cessfulinmanagingsoundphobiassuchas fireworks Care shouldbeusedwhen injecting diazepam IV:phlebitiscanoccur.Extravasationmay resultinlocalnecrosisandagooddealof pain Littleornoanalgesiaisprovided,although in humans diazepam has an amnesic effect, so that nopainisremembered Intheauthor'sexperience,IVadministration of diazepam andketamine results in a variable degreeofsedationindogsandcatsandis usually sufficient for minor procedures such as dressingchanges,ultrasoundorradiographs (5-20 min of sedation : addition of incremental half-dosesofdiazepammayextendsedation forafurther20-40 min) Dose:dogs/cats:0.1-0.5mg/kg IV Ketamine Ketamineisunrelatedtoanyotheranaes-thetic/sedativeagent It iseffective if administered by any route(lV, SC, IM,ora1),makingitespeciallyusefulfor fractiouscats(theauthorhasinducedanaes-3 IPremedicationandPatient Preparation thesiaorallyfrom10pacesinthecaseof an extremelyaggressivecat,bycarefulaim) TheremaybesomepainwithIMinjection Littlecardiacdepressionisseenwithketa-mine,althoughit shouldbeusedwithcaution inpatientswithseverecardiacdiseaseasit increasestheheartmuscle'soxygendemand Similarly,ketamineresultsinlittleornores-piratory depression Ketamineisapotentanalgesic,evenbelow anaesthetic doses,making it ausefulpremedi-cant prior topainfulsurgery A disadvantage of ketamine isthat itresults in hypertonicityofmuscles :patientsarequite plastic.Thiscanbeoffsetbyconcurrentuse of asecondagent Doses:dogs :11-22 mg/kgIM,IV,SC;cats: 1.0-33mg/kg IM,SC, IV Medetomidine Medetomidineisan CX:l-adrenergicagonist Goodskeletal musclerelaxation, sedation and analgesia areinducedbyadministration The analgesia ismore potent against visceral thanskeletalpainandisreversedbythe antagonist (atipamezole) Thereisagreatdealofcontroversyover thecardiovasculareffects :thereisadose-dependentreductioninarterialpressure. Cardiacoutputisatfirstreduced,thennor-malises .Ingeneral,itshouldnotbeusedin animalswithcardiacdysfunction AlthoughIMorIVroutesarepreferred, absorption from SC injection is good, meaning that intra-animal injectionindifficult patients ispossible Sedationisreversedbyadministrationof ati-pamezole,makingitaverypopulardrugfor quickprocedures,especiallyminorsurgical proceduresduring evening surgery!However, the convenience of a reversible sedative should not result in a slipshod technique : normal pre-cautionsof preanaestheticevaluation,includ-ing bloodtests and IV fluidtherapy, shouldbe observedasappropriate Althoughsedationisgenerallyverygood, evenapparentlywell-sedateddogscan,on 19 GeneralPrinciples occasion,wakenextremelyrapidly,andbite without warning Doses:dogs:O.Ol-O.OSmg/kgIV,IM,SC; cats:0.05-0.15 mg/kgIV,IM,SC Midazolam Midazolamissimilartodiazepam;itis another member of thebenzodiazepinegroup of drugs Aswith diazepam,thereislittleor noanalge-sicaction Lessirritanttotissuesthandiazepam,itis unlikelytocausetissuedamageif extravasa-tionoccursduring IVadministration Midazolamisshorter-actingthandiazepam, butwhenusedincombinationwithACPor ketamine,seemstoprovide adeeper sedation Doses :dogs /cats :0.06-0.3mg/ kgIV,IM, SC Non-steroidalanti-inflammatory drugs(NSAIDs) NSAIDsshouldbeadministeredbeforeanaes-thesiainanyminorormajorsurgicalproce-dureunlessthereareclearcontra indicationsto theiruse(suchasrenalimpairmentorhepatic failure) .Theincreaseinanalgesiaperiopera-tivelyfollowingtheuseofanon-steroidalis considerable. SeveralNSAIDsarelicensedforpre- or post-operativeadministrationindogsandcats(e.g. carprofen,meloxicam,ketoprofen). However,NSAIDsdohavethepotentialfor severe adverse reactions, including, most notably: gastriculceration,liverorkidneyfailure.These side-effectsareseenmostcommonlywhen NSAIDsareusedinappropriately,or outsidethe data sheet recommendations.Preoperative blood andurinetests,accuratedosinganduseof IV fluidsallhelpreducetherisks. Opioids Opioids include buprenorphine, butorphanol, fentanyl,morphineandpethidine 20 Opioidsareallrelatedtoopium,thedrug obtained from a certain type of poppy, Papaver somniferum Opioids work by interacting with opiate recep-torspresent within thecentral nervoussystem andthroughoutthebody Therearevariousreceptortypes(11,0,K,cr) whichmediate analgesia,respiratory depres-sion,emesis and other psychotropic effects. Differentopioidsaremoreorlessspecific fordifferentreceptortypes,makingthem strongerorweakeranalgesicsandrespiratory depressants.In general,1-1rreceptorsaremost important foranalgesia Opioidsareincreasinglyusedinepidural injectionstoprovideveryeffectiveprolonged analgesiaforsurgeryof thehindlimbs,tail andperineum Allopioidstendtocauserespiratorydepres-siontosome extent,andmorphine andbutor-phanolareveryeffectivecoughsuppress ants Althoughmostopioidscauseemesis,butor-phanolisamildantiemeticandmaybeused beforechemotherapeuticadministrationto reducevomiting Opioidstendtoreducegutmovementand cancauseconstipation Effectson thecardiovascular system are dose-dependent andgenerallyof littleconsequence atusualdoses Buprenorphine BuprenorphineisapartialIl-opioid agonist/antagonist It ismoderatelyanalgesic Itisfairlylong-acting:between3andSh Itisaschedule3controlleddrug,somust be keptinalockedcupboard,butthedangerous drugsbookdoesnotneedtobesignedeach timeitisused Itisrarelyusedasapremedicantonitsown, butitenhancesthesedativeeffectof ACPat lowdosesof bothdrugs(thecombinationof anopioidwithatranquilliserisknownas neuroleptanalges ia) Themuch-malignedbell-shapedcurveof dosagesuggeststhattoppingupbuprenor-phinemayleadtoareductioninanalgesia due toself-antagonism.In fact,thisisunlikely tohappenat usualdoses SC injectionmay markedly reduce the analge-siceffect,soIMorIVadministrationis preferred Doses :dogs /cats:0.006-0.3mg/kgIV,IM, SC.Canberepeatedevery3-6 h Butorphanol Butorphanolisapartialopioidagonistl antagonist Analgesicactionisnotaseffectiveasother opioids Itprovidesgoodsedationwhenusedwith otheragentsandiscommonlyusedwith medetomidineand/orketaminefordogand cat sedation It isnotaschedule3controlleddrug,which hasincreaseditspopularity It has a quicker onset of action than buprenor-phine(lSminorsocomparedto30minfor buprenorphine),butashorterdurationof action(around3h) Doses:dogs/cats:0.OS-0.6mg/kgIV,IM,SC every6-8h Fentanyl Fentanylisaschedule2controlleddrug It has a very rapid onset of activity(2 min after IVinjection),but very short duration of activ-ity(lS-20min) . This hasmade itlesspopular asapremedicationdrug,butincreasingly popularasananalgesicinabalancedanaes-theticprotocol It gives approximately1000 times more potent analgesiathanmorphine Fentanylhasamoremarkedrespiratory depressiveeffect than morphine,and sointer-mittentpositive-pressureventilationprecau-tionsmustbeonhand Slow-releasepatchesareavailableforongoing analgesia(seelater) Dose:dogs/cats:2-1OIlg/kgIV Morphine Morphineisthefirstof theopioidalkaloids to be isolatedand regarded tobe the standard analgesicagainst whichothersaremeasured 3/ PremedicationandPatient Preparation Itisaschedule2controlleddrug,meaning that it must be kept in a locked dangerous drug cupboardtowhichonlyveterinarysurgeons mayhaveaccess .The dangerousdrugsbook mustbesignedeachtimemorphineis dispensed Theminorinconveniencethiscauses,and theconcernsformisuseordrugabuse, discouragealotofpracticesfromusing morphine It isapowerfulanalgesic andprovides reason-able sedation: sedationisimproved whenused withACP Itisveryinexpensive The onset of actionismuchmorerapidwhen administered IM or IV (lO-IS min) than when theSCrouteisused(30-4S min),although the analgesic actionappears to be similar with either route The duration of activityisfairlyshort (1-2h), thusrequiringmorefrequentdosingthan buprenorphineor butorphanol IVinjectionshouldbeperformedslowlyas histamine release(with rapidIV injection) can causecollapseorhyperactivity - theseeffects arereducedif ACPisused Doses: dogs:0.1-0.2S mg/ kgIV,IM, SC every 4-6h;cats:0. 1 mg/kgIV,O. I-O.Smg/ kgIM, SCevery6-8h Pethidine PethidineisapureIl-agonistderivedfrom morphine It isa schedule 2controlled drug, thus subject tothesamecontrolsasmorphine Itisquick-acting(lOmin)butshort-lasting (30-4Smin) Itisafairlystronganalgesic,withlessofa sedativeeffectthanmorphine TheIVroutecancausemarkedhistamine release,sothisrouteisnotgenerally used It is probably less useful than some ofthe other opioidsduetotheshortdurationofaction, althoughitprovidesgoodsedation whenused withACP Dose:dogs/cats:2-lOmg/ kgIM,SCevery 4-6h 21 GeneralPrinciples RECORDINGPREANAESTHETICDRUG ADMINISTRATION Clear notes should be made ofthe drug given and thetimeandrouteof administration,andany notesmadeof difficultyorpainonadministra-tion.Inadditiontothis,itisgoodpracticeto recordanyvisualeffectsof administration.For example: '0.1 mlACP,0.3ml buprenorphineadministered IMat9.45a.m. 10a.m.:third eyelids protruding, patient appears wobbly.' INJECTIONROUTESAND TECHNIQUESFOR PREM EDICATION Generally,IMorIVroutesshouldbeusedfor most premedication combinations. SC routes fre-quentlyresultindrugabsorptionordistribution that istoo lowor slowto provide reasonable seda-tionand/oranalgesia.Exceptionsarerabbits, where the SC route appears aseffective asthe IM routeformany drugs. If theIM routeistobeused,then: Ensurethecombinationcanbegiveninthe samesyringe,orelseuseseparatesyringes Useafreshneedleforeachdrugtobedrawn up Indecidingwhichdrugtodrawupfirst,asa generalrule,drawfromamulti-usebottle before a single-use vial,or elsedraw the larger volumeof drug first Palpatetheinjectionsitetoensurethereare no lesions or wounds which may allow forcon-tamination of theinjectionor bepainful Iprefertoinjectoverthelumbararea:inmy experiencethissiteelicitslesspainresponse fromtheanimals If injectingintothehindlimb,thenusethe quadriceps(cranialtothefemur):thereisa riskof damagingthesciaticnerveif injection intothecaudal musclegroupsisattempted If theIVrouteisused,then: Theskinoverlyingtheveinshouldbeclose-clippedandabrief surgicalscrubperformed AnIVcannulashouldbeplaced:thisreduces theriskofextravasationofthedrugduring 22 administration.Itprovidesaportalforeasy accessforincremental doses of anaesthetic, or forotherdrugs .AnIVcannulaalsoprovides emergency venousaccessandallowsforaddi-tionof afluidadministrationset Havesomesterilesalineathandincaseof accidentalperivascularadministration(for example,ofdiazepam) .If thisoccurs,then inject2-15 mlof sterile salineintotheinjec-tion site. Be very wary of injecting lidocaine to numbthe site,asIVinjection can havesevere orfatalconsequences.Theapplicationofa localanaestheticcream(suchasEmlacream (eutectic mixof localanalgesics,AstraZeneca) 5%(lidocaine25 mg/g,prilocaine25 mg/g) , AstraZeneca)canbevery soothing If an IVadministrationset isnot tobeplaced atthisstage,thecannulashouldbeflushed with heparinised saline after administration of thepremedandaninjectionbungorstylet placed Becarefulnottoinjecttoorapidly,aswith somedrugsthiscancauseasuddendropin vasovagaltone,resultinginfaintingorcol-lapse.If thishappens,thenfollowstandard resuscitationprocedures(seeAppendix2) Having giventhepremedication,allowsufficient timeforittoworkbeforeattemptingtoinduce anaesthesia.Most premedicationdrugsbeginto showclinicaleffectsofsedation(ataxia,third eyelidprotrusion)15-20min afterIMinjection, 5-10 min after IV injection and up to 45 min after SCinjection.However,fullanalgesiceffectmay notbe achieveduntil sometimeafter sedation is noted.Ingeneral,atleast20-30 minshouldbe allowedafterIVorIMinjection,andabout1 h followingSCinjection. Theanimalshouldbeleftquietly duringthat time,preferablyinaslightlydarkenedroom. Placementofintravenouscannulae Foraminorsurgicalpatient,aperipheralvein suchasthecephalicveinisusuallysuitableand convenient. Youwillneed: Clippers Emlacream Cottonwool/swabs Surgicalscrubsolution(chlorhexidine,tri-closan,povidone-iodine) 23Ghypodermicneedle(forcut-down: optional) IVcannula Stickytape(e.g.Duraporetape,3M)pre-cut intostripsof about10-15cm(dependingon sizeof patient) Bandagingmaterial:OpSitedressing,or Soffban,K-Band,Co-flex 2-mlsyringecontainingheparinflushClunit heparinpermlof0.9%sodiumchloride (NaCI)) Sterilebung or stylet Theskinoverlyingtheproposedcathetersite shouldbeclose-clippedandasmallamountof Emlacreamapplied.Havingallowed20 minfor the localanaesthetic cream totake effect, a surgi-calscrubisperformed.Anoptionalstephereis tousetheendof a23Gneedletomakeasmall incisionoverthevein.Thishasthebenefitof reducingthe amount of forcenecessarytoinsert the catheter and reducesthe chanceof thesleeve becomingcaughtorcrumpledontheskin. The catheter issecured inplace with astrip of sticky tape (Figure 3.1)and the catheter is flushed with0.5 mlheparinisedsaline.If theIVfluid administrationsetisnotduetobeconnectedat A thisstage,asterile bung or styletisplaced.TheB catheteriscoveredwithadressing. Careof indwellingcatheters Variousproblemscanoccur withcatheters,even if they are only in place fora relatively short time. The most common problem isforthecatheter to becomekinkedorblockedduetopositional placement.Toavoidthis: Figure 3.1Placement of cephalic catheter.CA)The skin overlyingthecatheter sireisclippedandabrief surgical prepperformed.The veinisraisedbyanassistant. CB)The catherer ispassedandtapedinplace.The cathe-ter isflushedwirhheparinisedsaline.ApadCSoffban)isC placedunder theconnectOr sitetoincrease comfort. CC)The intravenouslineisattachedandtapedintoplace. Finally,abandageisplaced. 3/ Premedication andPatientPreparation 23 GeneralPrinciples Alwaysusean appropriatelysizedcatheter for thepatient- thereisrarelyaneedtousea 25G catheter on any but the smallest of kittens or puppies;they willblockmuchmorereadily thana23G Alwaysensurethecatheterisplacedinthe distalthirdof thelimb,if acephaliccatheter, andawayfroma joint. Most cephalic catheters blockbecausetheyareplacedtooclosetothe elbow.If necessary,acathetersplintmaybe used,but intheauthor'sexperiencetheseare rarelyneededifthecatheteriscorrectly placed Makesurethatthecatheterissecurelytaped overthe hub of thecatheter andatone or two pointsalongtheIVadministrationset.Avoid using very sticky tapes,asthis can irritate skin andbetrickytoremove Make sure thetapeand the overlying bandage arenottootight:relyonpaddingholding thingsinplaceratherthan pressure! Thebandageshouldbecheckedregularly(at leastfourtimesdaily)tomakesureithasnot slippedandiscleananddry. Thecatheter shouldbe flushedwithheparin-isedsalinefourtimesdailyandthecathetersite should be checked daily for any signs of phlebitis (reddening,swellingorpain) .Generally,cathe-tersshouldnotbeleftinplaceformorethan 3days,butprovidedthesiteiscleanandfree frominflammationthisrulecanbestretcheda littletosparethepatient'sotherlimbs! BASICSOFSURGICALFLUID ADMINISTRATION Althoughourminorsurgicalpatientsshouldbe otherwisehealthy,andwewouldhopethatthe anaesthetictimeisshort,itisgoodpracticeto administer IV fluidstoallanaesthetised patients. There are variousreasonsforthis: Thepatientwillhavebeenstarvedpriorto surgery:althoughonly4-6 hstarvationis required,manyof our patientswillhavebeen starvedformuchlonger,oftenfor17 horso. Itisnotnecessarytowithholdwaterfrom 24 anaestheticpatients,butmostcatsandmany dogswillnotdrinkadequatequantitiesof waterathomewithouteatingandmaynot drinkatallintheveterinarypractice Thepremedicationandtheanaestheticwill reduce cardiovascular function to some degree, oftenreducingcardiacoutputandrenal perfusion IV fluidadministration during surgery ensures thepresenceof apatentvenousaccessatall times, should emergencies occur, or for routine administrationof IV drugsduring surgery Althoughmostminorsurgerypatientsare expectedtogohomethesameday,maintain-ing IV fluidadministration during their recov-eryensuresthatthepatientdoesnotbecome dehydratedpostoperativelyandisprepared forongoinghospitalisationifthatbecomes necessary Whichfluids?What rate? Table3.3liststhemostcommonIVfluidsand suggested usage. For most minor surgery patients, 0.9%NaCIorlactatedRinger's(Hartmann's solution)willbemostappropriate. Fluids should be administered at maintenance rate(2 ml/kgperh)untilanaesthesia,and increased to5-10 ml/kg per h during anaesthesia . Depending onlengthof surgeryandrecoveryof patient,thefluidrateshouldthenbereduced backtomaintenanceuntilthepatientiseating. AneasycalculationchartispresentedinTable 3.4. Aswith any patient onIV fluidtherapy,minor surgicalpatientsshouldbemonitoredforurine production:catsmaynotusealittertrayina cage,inwhichcaseregularpalpation(every3 h orso)ofthebladderisrecommended.Dogs shouldbetakenouttourinateregularly(every 3-4h)andthebladderpalpatedifnot urinating. Ifreducedurineoutputissuspected,the patient shouldbe catheterisedandurine produc-tionmonitored.Urine output lowerthan1 mllkg per hsuggestsrenalperfusionisreduced. 3 IPremedicationandPatient Preparation Table3.3Commonfluids for intravenous administration Fluidtype NaCI0.9%(AqupharmNo.1, AnimalCare) NaCl0.9%,glucose5% (AqupharmNo.3, AnimalCare) Ringer's solution(Aqupharm No.9,AnimalCare) Hartmann's solution (Ringer'slactate) (AqupharmNo.11, AnimalCare) NaCl0.18%,glucose4% (AqupharmNo. 18, AnimalCare) Main composition Application - -----------------Na+154 mmol/l CI - 154 mmol/l K+Ommol/l Na+154 mmol/l CI - 154mmol/l Glucose50 g/l Na+ 147 mmol/l CI - 155 mmol/l K+ 4mmol/l Ca2+ 2 mmol/l Na + 131mmol/l CI- 111mmol/l K+5mmol/l Ca2+ 2 mmol/l HC03 - (lactate) 29mmol/l Na+ 30mmol/l CI - 30mmol/l Glucose40g/1 Correctionof water andelectrolyte depletion,especially after vomiting. Not suitableforprolonged administration Correctionof water andelectrolyte depletion, where there hasalsobeen reductionincarbohydrateintake. Indicatedforaddisonian crisisand urethralobstruction. Not suitable for prolongedadministration Correctionof water and electrolyte depletion,especially after prolonged vomiting,wherelossof potassiumis likely tohaveoccurred ----------- -------------------Asabove,but moresuitable for prolongeduseandfor treatment of metabolic acidosis.Thisisthe most versatileof crystalloids andcanbeused inmost fluid therapy cases Maintenance therapy,having already correctedwater andelectrolyte depletion ---------------- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - ~ Hypertonic saline(7.5%) SanofiAnimalHealthNa+ 1283 mmol/l CI - 1283 mmol/l Management of severeshock. Not suitableforprolonged administration. Must onlybeadministeredintravenously -----------------------------------------Haemaccel(lntervetUK) Oxyglobin(Arnolds VeterinaryProducts) NaCl,sodiumchloride. Na+147 mmol/l CI- 155 mmol/l K+5mmol/l Ca25 mmol/l Gelatin(average molecular weight 30000)35 g/l Bovine haemoglobin 130g/l Asa plasmavolumeexpander incases of shock.Not suitable for prolongeduse -- -- - -----------Toimproveclinicalsignsof anaemiain catsanddogs.Not suitable for prolongeduse 25 GeneralPrinciples Table3.4Intravenous fluidrates Weight of patient (kg) 2 3 4 5 6 7 -- - ~ 8 9 10 Rateof fluid administration:1 drop every ____seconds (AnimalCareburette set 60drops/ml) (drops/second) 2ml/kg10mllkg per hperh ----306 153 102 7.51.5 - --- --61.2 Weight of patient (kg) 516 4.30.86(1.2)7 3.80.75(1.3)8 3.30.67(1 .5)9 -----30.6(1.7)10 Rateof fluid administration:1 drop every ____seconds (AnimalCare giving set 20drops/ml) (drops/second) 2mllkg per h 10ml/kg per h ------.--- -- -153 12.82.6 11.32.2 ---102 91.8 ------------ ---------127.51.5 ----146.41.3 ---165.61.1 ---185 ---204.50.9(1.1) ----- --- ------ -----253.60.7(1.4) - - ~ -3030.6(1 .7) 352.60.5 (2) ~ - - - --------- -------- - - - - - - ~ - - -402.20.45(2.2) 4520.4 (2.5) 501.80.35(2.9) ----- -----551.60.33(3) 601.50.3(3.3) ----_._------------------------------------26 ANALGESICDRUGSANDPAIN MANAGEMENT Table3.2listsanalgesicdrugdosagesand frequencies . Balancedanalgesia Theperceptionofpainevolvedasaprotective measure :itallowsthebodytorealiseinjury has occurredandtoavoidusingandthusfurther damagingthetraumatisedregion.Paininour patientsisunnecessary,asingeneralwehave correctedthetrauma . Inresponsetoclinicallyinducedpain,the peripheralandcentralnervoussystemsbecome sensitised(theso-called'wind-up' of pain) . This leadsto increased perception of pain andreduces the efficacy of analgesics. Pre-emptive analgesia countersthissensitisation.Byusingmorethan oneformofanalgesicwecansuppressseveral painpathways(sequentialanalgesia)and increaseanalgesiceffecttremendously.Itisnot acceptabletoassumethatdogsorcatsfeelpain anydifferentlyfromourselvesandsoweshould not denythemanypainrelief. Recognitionof paininanimals In order tomanagepain,itisnecessary torecog-nisepaininour minor surgicalpatients.Clearly, any wound or trauma must be considered painful : thisincludesanywoundthatwemayinflict throughsurgery. Animalsinpainmay: Vocalisewhentouchedoverapainfulareaor whenmovingapainfullimborpartofthe body Pantorhaveanincreasedrespiratoryrateor heartrate Becomeaggressiveorfearful:trytoattack or tohide Becomeinappetant Sit hunched, reluctant tomove, or else become restlessandnotsettle Apart from being unpleasant for the patient, pain slows healing, both directly and by reducing food 3 /PremedicationandPatient Preparation intakeorcreatingdisuseatrophyofoperated limbs. Itisagoodideatousesomesortof scoring systemforpain,sothatindividualpatientscan be more effectively assessedandmonitored. Pain monitoring shouldbe an integral part of the hos-pitalisationchart. Veryyoungorveryoldpatientsmayhave reducedpainthresholds:theywillalsohave reduced drug metabolism and excretion. In these patientsitmaybebesttousestronger andmore rapidlymetaboliseddrugssuchaspethidine, ratherthanbuprenorphine.Somebreedsmay feelpain morethanothers(e.g.labradorsappear morestoicalthangreyhounds) . Anoutdatedargumentforwithholdinganal-gesicisthat asmall amount of pain willresult in the animalrestricting itsmovementpostsurgery, thuspreventingdisruptionof thewoundsiteor fracture.Thisisnottoberecommendedfor severalreasons: Howcanasmallamountof painbequanti-fied?It islikelythatareductioninanalgesia willleavethepatientinagonyorseveredis-comfortatthe veryleast A repair should be strong or stable enough that thepatient'sownmovementwillnotdamage therepair. If not,thenthetechnique of repair shouldcome under question There is overwhelming evidence that pain reduces healing:this islikely to occur through metabolic/ physiologic mechanisms, and also through disuse atrophy,of anaffectedlimb,forexample. Other formsof painmanagement Theuseof sequentialpainblockadehasalready been mentioned, using several drugs that interact atdifferentstagesalongthepainpathwaysto preventthebuild-upofpain.Inadditionto NSAIDsandopioids,localanaesthetics,epi-durals,bandagesandgoodoldtenderloving caremay beusedtomanagepain. Fentanyl patches Continuousabsorptionoffentanylfromtrans-dermalpatchesisausefulwayofproviding 27 GeneralPrinciples prolongedanalgesiapostoperatively.The patchesareavailableinavarietyof sizes(Table 3.2)andcangiveapproximately3daysof anal-gesiaindogsandcats.A drawback isthat itcan take24htoreachtherapeuticconcentrationsin dogs.Guidelinesforuseare: Hair overthelateralthoraxorneck shouldbe clipped,but not cleaned with alcoholor surgi-calscrubasthismayaffecttheabsorption Glovesshouldbeworntoapplythepatch Bandagesmaybeappliedtohelpholdthe patch inplace.Tissue adhesivescan affectthe absorptionofthepatchandshouldnotbe used Patches must be stored in the dangerous drugs cupboard and signed out.Used patches should beflusheddownatoiletinthepresenceof a witness Patientsshouldberegularlyassessedforade-quateanalgesia,respiratorydepressionand sedation Duetotheriskofaccidentalcontact,care must be exercised when allowing patients with patchestogohome Local anaesthesia Local anaesthetics are underused in small-animal practice,althoughtheyareafundamentalcom-ponentof large-animalandequinesurgery. Localanaestheticsmaybeusedinminor vet-erinary surgery in several ways:topical or surface, infiltration,nerveblock/paravertebralblocks, epidural andIVregional. Topicalanaesthesia Thisinvolvesdirectapplicationofalocal anaesthetictoskinormucousmembrane. Emlacreamismostcommonlyapplieddirect toskin:ingeneral,however,penetration throughcornifiedepidermisispoor Eyedropscontainingtetracaineareusedto examineorperformminorcornealsurgery: thepenetrationthroughthecorneaisgood Localanaestheticcanbeapplieddirectlyto wounds to numb them before surgery, or whilst preparingthepatient ortheatre forsurgery. It ISquestionablehowsuccessfulthisis,asthe 28 anaestheticisfairlyrapidlyremovedfromthe areabythecirculatory system Theapplicationoflocalanaesthetic(Emla creamoraninjectabletrickledon)toapatch of wet eczema seems to provide moderate relief tothepatient Topicalapplication of localanaesthetic ismost oftenusedbeforetakingbloodsamplesor placingIVcannulaeornaso-oesophageal tubes Infiltrationanaeslhesia Thisisthemostusualwayofusinglocal anaesthesiaandinvolvesinjectingsmall amounts(l-2ml inO.1-0.2-mlblebs)around awoundor asurgicalsite Local anaesthetics often sting on injection and cancausequiteastrongpainresponse.Itis recommendedthatlocalanaestheticinjection beperformedaftergeneralanaesthesiais induced Injectinglocalanaestheticbeforemakingan incision seemstobequite effective at decreas-ing postoperative pain in the area (Figure 3.2). Thereislittlepointininjectinglocalanaes-theticaftertheincisionhasbeenmade A specificformof infiltration anaesthesiamay beusedwhenamputating tailsincasesof tail tiptrauma(seeChapter 8).Especially in cats, Figure 3.2Injecrionof localanaesrhesiapriortomidline birchspay. useoflocalanaestheticinthiswayreduces postoperativeself trauma Caremustbetakennottoinjectthelocal anaestheticintravenously,nortoinjecttoo much.Thisisof particularimportancewhen dealing with very young or verysmall patients (themaximumdoseforlidocaineis 10mg/kg) Thepresenceof localanaestheticinawound canretardhealingorreducebloodsupply. This israrely of anything other than theoreti-cal importance with small doses of local anaes-thetic, but may become a problem if adrenaline (epinephrine)ispresentinthelocalanaes-thetic, resulting in necrosis of the wound edges duetovasoconstriction Nerveblocks/paravertebralblocks Localanaestheticisinjectedintothearea directlysurroundinganerveinadistallimb oraspinalnerveasitexitstheintervertebral foramen Thisapproachisofmoreuseincattleor horses, where localanaesthesia isusedinstead of generalanaesthesia It isusedmost routinely inthoracic surgery in smallanimals,wheretheintercostalnerves runningalongthecaudalsurfaceofthe ribsmaybeblockeddorsally,providing3-4 h ofgoodanalgesiafollowingparacostal incisions It may be useful in digit amputations, although infiltrationanaesthesiaiseasiertoperformin smallanimals Epidural anaesthesia Thisapproachinvolvesadmini strationof localanaesthetic into the epidural space in thelumbar region Injectionmustbeperformedonananaes-thetisedorsedatedpatienttoreducethe riskof damagetothespinalcord Thisprocedureisbecomingmorepopular and affords a prolongednumbing period for thehindlimbs,tailandperineum Itmustbeperformedbyaveterinary surgeon Additionof morphinetotheepidural mix (0.1mg/kg)mayextendanalgesiato around24h 3 IPremedicationandPatient Preparation Intravenousregionalanaesthesia Localanaesthesiaisinjectedintravenously into a distallimb, having temporarily occluded circulationinthelimb withatourniquet This achieves surgical anaesthesia in that limb foraslong asthetourniquet remainsinplace, usual\y30-120min Care must be taken not to allow the tourniquet toloosen before about 30 min, asthere isa risk of IVlocalanaestheticthenentering systemic circulationandstabilisingthecardiacneuro-nalpathways After30 minorso,mostofthelocalanaes-thetic hasdiffusedfromtheblood vesselsand thetourniquetmaybesafelyremoved Thetechniqueispopularinhumansurgery, but is probably more applicable to large-animal surgerywheregeneralanaesthesiaisavoided whereverpossible Although local anaesthetics can andmay be used toimproveanalgesiaperioperativelyinsmall animals, it should rarely be used instead of general anaesthesia.Althoughit istempting toavoidthe needfora fullgeneralanaesthesiain some cases, smallanimalsaredifficulttorestrainadequately forareasonableamountof time,andmovement cancompromiseasepsisandleadtopoortech-niqueandarushedjob. Veterinaryacupuncture Increasingly,acupunctureisbeingusedincom-panionanimalstosupplementwesternmedica-tion. One of the major applications is in controlling chronicpaininconditionssuchasarthritisor neoplasia.Althoughnotusedextensivelyfor postoperativepain,itseemslikelythatacupunc-turemayprovidefurtheranalgesiainthese cases.However,considerable training isrequired tobecomeproficientatacupuncture,sinceits correct userequiresknowledgeof highlyspecific anatomicalpointsandcombinationsofneedle placements.Acupunctureinanimalsisconsid-ered an act of veterinary surgery and assuch can onlybeperformedbyqualifiedandregistered veterinary surgeons. 29 GeneralPrinciples PRE- ANDPOSTOPERATIVEANTIBIOTICS Theaimof perioperativeantibiosisistoprevent thegrowthofcontaminatingbacteriafromthe patient'sskinorenvironmentfrommultiplying tohighenoughnumberstocauseinfection. Another aim istoreducebacterial numbersprior tosurgery tolevels where contamination of surgi-calwoundsisunlikelytooccur. This isacontentiousissue,asthereareoften strong feelingsaboutwhether or not toadminis-terantibioticspre- or postoperatively. Forroutinecleansurgery(castration,spay, lumpectomy):aslongasstrictaseptictech-nique isfollowed,and the patient isnot immu-no compromised,thereisnorequirementfor perioperativeantibiotics Forcleansurgerywheretherehasbeena breachinaseptictechnique(forexample, drapeslippage) :antibioticsshouldbeadmin-isteredintraoperativelyandpostoperatively Forcleansurgerythattakesanappreciable amountof time(usuallyover120 min) :peri-operativeantibioticsshouldbeadministered Forcleansurgerywhereanyinfectionwould becatastrophic(spinalsurgery,joint surgery) : perioperativeantibioticsshouldbe administered Forcleancontaminatedsurgery(surgeryof thegasrrointestinaltract,urinarytract) :peri-operativeantibioticsshouldbeadministered For contaminated surgery (abscess-lancing, dentalsurgery) :perioperativeantibiotics shouldbeadministered,plusafollow-up courseof antibiotics Whichantibiotictouse? Antibioticchoiceisinfluencedby: Thetypeof bacteriaexpected Distributionof antibiotictothesurgicalarea Anyknownorsuspectedcontraindicationsto that antibiotic,withregardtotypeof surgery 30 (forexample,gentamIcinisknowntoretard corneal healing and sowouldbe apoor choice followingcornealsurgery) Any history of hypersensitivity or adverse reac-tiontothatantibioticorarelatedone(for example, do not use anyantibiotic in apatientknownor suspectedtobeallergicto penicillin).Similarly,donotsendthepatient homeona antibioticiftheowner isknownorsuspectedtobeallergicto penicillin Otherfactorssuchaspalatabilityoftablets ifanongoingcourseofantibioticsistobe prescribed,knownbreedsenSItivItiesto antibiotics(avoidtrimethoprim/sulfonamide combinationsinbreedspronetodryeye (keratoconjunctivitis sicca)) Bearinginmindthatwoundsinsmallanimals tendtoculture Escherichia coli or coagulase-posi-tiveStaphylococcusspp.,itisrecommendedthat anantibioticthattargetstheseorganismsbe used. Agoodchoiceisasecond-generationcepha-losporin,suchascefuroxime(Zinacef,Glaxo) 20-50mg/kg IV,IM. Administrationintravenouslyatthetimeof inductionisrecommended. Duetoperioperative reductioninskinvasculatureperfusion,se administrationislikelynottoresultinarapid enoughabsorptionofantibiotictobeofany benefitduringthesurgery. It isoftentempting toadminister intralesional antibiotics(intra-abdominalduringexploratory laparotomyorintra-articularduringjoint surgery)asonefeelsthatdeliveringantibiotics rightwheretheyarerequiredmustbehelpful. However,thereislittleevidencetosuggestthat antibiotics are of much benefit as they are usually absorbed from the site fairly rapidly. Nevertheless, slow-releaseantibioticformulationssuchasgen-tamicin-soakedbeadscanbe veryusefulincon-trollingortreatingsomechronicallyinfected wounds . 4Generalanaesthesia ControlofSubstancesHazardoustoHealth Inthischapter(CoSHH)1988- restrictstheuseandstorage Theroleof the veterinary nurseinanaesthesia Rationaleandreview of commonlyused drugs Intubation Commonanaestheticbreathing systems Monitoring anaesthesia Extubation Anaesthetic emergencies andresuscitation Therearevariouslawsconcerningtheuseof anaesthesiainveterinarypractice: Protection of Animals (Anaesthetics) Act1964 - veryfewprocedurescanbecarriedout without anaesthesia: castration in some species belowacertainage,taildocking,dewclaw removal,disbudding of , ....... ,.......... 0.... ""1"'".... _. ___ _.n ...... ,..,;....... ,...............r.. .... , ..... ,on, ..,,.,... ,,....,,,010IV..... 'n'M'''''''.,.- , ...",n' '...... , "' .... .,.- "' .. _.""', cO',to. ... , ..,,' ...........1)"....... 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