HORSES

*Manyoftherecommendationinthisguiderepresentoff-labeluseofantimicrobials.Compliancewiththelegalrequirementsofyourjurisdictionisyourresponsibility.

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AUSTRALIANVETERINARY

PRESCRIBING GUIDELINES

DOSERATESANTIMICROBIAL

AGENTRECOMMENDED

DOSEROUTE INTER-DOSING

INTERVAL

Procainepenicillin* 22,000IU/kg IM 12hours

Gentamicin* 7.7-9.7 mg/kg IVorIM 24hours

Trimethoprim/sulphonamide

30mg/kg POorIV 12hours

Doxycycline* 10mg/kg PO 12hours

Oxytetracycline* 6.6mg/kg Slow IV 12hours

Metronidazole* 20mg/kg PO 12hours

SURGICAL PROPHYLAXIS

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SURGICALCONTAMINATION

LEVEL

ANTIMICROBIALRECOMMENDATION

DURATIONOFTHERAPY

CLEAN, NOMITIGATINGFACTORS

NONE N/A

CLEAN,MITIGATINGFACTORS

Penicillin &Gentamicin Stopwithin24hours

CLEANCONTAMINATED

Penicillin &Gentamicin 24-48hours

CONTAMINATED Chooseantimicrobialappropriateforinfection

Treatuntil cured

MITIGATINGFACTORS• Surgicalduration>90mins• Surgeryinvolvinganimplant• Surgicalsiteinfectionwouldbeamajorthreattothepatient(i.e.centralnervoussystemsurgery)

TIMING:Tissuelevelsarerequiredatthetimeofincisiontoconferprotectionfromsurgicalsiteinfection.IVantimicrobials:

AVPG SKIN/FEET

WOUNDSNOSYNOVIALSTRUCTURESINVOLVED:noantimicrobialstherapyindicated,evenifcontaminationofthewoundispresent.Systemicantimicrobialsonlywhen:• Systemicallyunwell• Potentialsynovialinvolvement(seebelow)• Immunosuppressedpatient

SYNOVIALSTRUCTUREINVOLVED:Lavageisalmostalwaysrequiredforsuccessfuloutcome.Systemicantimicrobialsalwaysindicated.Therapyshouldbebasedofcultureandsusceptibilitytesting.Empiricaltherapywithpenicillinandgentamicinshouldbeinitiatedpendingcultureresults.

FOOTABSCESS CELLULITISPRIMARY noobviousunderlyingcause.Oftenmoreseverethansecondarycases.SECONDARY:anunderlyingcausecanbeidentified(surgery,jointinjection,wound,blunttrauma).

DIAGNOSTICSFine-needleaspirateshouldbecollectedforcultureandsusceptibilitytesting.Careifneededforcellulitisoccurringoversynovialstructures.

TREATMENTIVRP:gentamicin1/3systemicdoseSystemicantimicrobials:Penicillin&gentamicin(adjustdoseifIVRPperformed)oroxytetracycline.Topicaltherapy:Coldwaterhosingandpressurebandage.Analgesiaespeciallyifnon-weightbearingasrisklaminitisincontralaterallimb.

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Noantimicrobialtherapyindicated.

Curettetoestablishdrainage.Ifrecurrentconsiderunderlyingdisease.Radiographsshouldbetakentoinvestigateforpedalosteitis&ACTHmeasuredtoinvestigateforequineCushing’sdisease(PPID).Systemicantimicrobialsonlywhen:• Immunosuppressedpatient• Ifseverecellulitisispresent

Ensurehorsesarevaccinatedfortetanus.

STRANGLES SINUSITISDIAGNOSTICSNotifiabledisease,samplesshouldbesubmittedforserology,cultureorPCRtoconfirmdiagnosis.

TREATMENTNoantimicrobialrecommended.Mostcasesresolvequicklyoncedrainagehasbeenestablished.Asmallpercentagecontinuetoshed(carriers).Systemicantimicrobialsonlywhen:• Respiratorycompromise• Metastaticdisease(Bastardstrangles)

Inthesecases,penicillinisfirstlinetherapy.

RESPIRATORY

PNEUMONIA

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AVPG

DIAGNOSTICSAsampleoffluidfromthesinusshouldbeobtainedtoconfirmthediagnosis.Cultureisnotusuallyrequired.Considerunderlyingdisease(dentalorequineCushing’s)especiallyifrecurs.

TREATMENTSinuslavagealonemaybesufficientandisalmostalwaysrequiredforsuccessfuloutcome(minimallyinvasivetechniqueinthefieldcanbeused).Systemicantimicrobialswhen:• Recurrentdisease• SystemicallyunwellInthesecases,penicillinortrimethoprim/sulphonamideisfirstlinetherapy.

DIAGNOSTICSTranstracheal wash,orendoscopictrachealwashwithatripleguardedcatheter,shouldbeperformedforcytologicalevaluation.Cultureandsusceptibilitytestingshouldbeperformedinallcases.Cultureofbronchoalveolar lavagespecimensisneverappropriateasthesesamplesarecontaminatedbytheupperairway.

TREATMENTShouldbebasedoncultureandsusceptibilityresults.Empiricaltherapywithpenicillin&gentamicinshouldbeinitiatedpendingresults.Metronidazoleshouldbeaddedifanaerobesaresuspected(foulsmelltotrachealfluid).

PNEUMONIA SEPTICARTHRITISDIAGNOSTICSStreptococcuszooepidemicus andRhodococcus equi areequallycommon.Transtracheal washisrequiredforcytologicalexaminationandcultureandsusceptibilitytestinginallcases.

TREATMENTBasedoncultureandsusceptibilityresults.Empirictherapycanbeinitiatedwhileresultspending.IfS.zooepidemicus issuspectedpenicillinisappropriate.IfR.equi issuspectedclarithromycinandrifampinisrecommended.

DURATIONOFTHERAPYVariesbypathogen;1weekgenerallyadequateforS.zooepidemicus,4-6weekgenerallyrecommendedforR.equi.

FOALSSEPSIS

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AVPG

DIAGNOSTICSSepsisscorecanbeusedtoassessrisk(seewebsite).Bloodforcultureandsusceptibilityshouldbecollectedbutfalsenegativesarecommon.

TREATMENTBasedoncultureandsusceptibilityresultsifpossible.Empirictherapycanbeinitiatedwhileresultspending.Penicillin&gentamicinisrecommended.Carewithgentamicinifrenalfunctioniscompromised.Intravenoustrimethoprim/sulphonamideisalternate.

DURATIONOFTHERAPY2weeksisgenerallyconsideredtobeadequate,unlessfocalinfectiondevelops(i.e.septicarthritis).

DIAGNOSTICSArthrocentesisshouldbeperformedtoobtainfluidforcytologicalevaluationandforcultureandsusceptibilitytestinginallcases.Radiographsshouldbetakentoinvestigateboneinvolvement.

TREATMENTBasedoncultureandsusceptibilityresults.Empirictherapycanbeinitiatedwhileresultspending.Penicillin&gentamicinisrecommended.Oxytetracyclineisanalternative,especiallyifosteomyelitisisdiagnosed.

DURATIONOFTHERAPYTreatfor1weekpastresolutionofclinicalsigns,longerifosteomyelitisispresent.

DIAGNOSTICSUltrasoundevaluationshouldbeperformedtoruleoutomphalophlebitis.Ifnoenlargementoftheumbilicalremnantsisidentifiedantimicrobialtherapyisnotindicated.

TREATMENTNoantimicrobialtherapyindicated.Frequenttopicalantibacterialtherapywithchlorhexidineisrecommendeduntilpatencyresolves.

FOALSPATENTURACHUS OMPHALOPHLEBITIS(NAVELILL) HIGH-RISKFOALS

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AVPG

DIAGNOSTICSUltrasoundevaluationshouldbeperformedtodefinetheinfectedstructureandtoallowformonitoringwithtreatment.

TREATMENTPenicillin&gentamicinismosteffectivebutoftennottoleratedwell.Trimethoprim/sulphonamideordoxycyclinearesuitablealternativesthatcanbegivenorally.

DURATIONOFTHERAPYSerialultrasonographic examinationshouldbeperformedandtherapycontinueduntil1weekafterresolutionofdisease.

Prematurefoalandthosewithneonatalencephalopathy(’DummyFoalSyndrome’)areatincreasedriskofsepsis.Failureofpassivetransfershouldbeaddressedwithplasmatransfusion.Thereisnoevidenceforanybenefitfromprophylacticantimicrobialsinplaceofplasmatransfusion.

DIAGNOSTICSSerialhaematologic evaluationandsepsisscoremayguidenecessityforantimicrobialtherapy.

TREATMENTProphylactictherapyiswarrantedwhenleukopaenia ispresentorsepsisscoreishigh.Penicillin&gentamicinismostappropriatebutcareshouldbetakeninfoalswithimpairedrenalfunction.Trimethoprim/sulphonamideIVisanalternative.

DIARRHOEA PERITONITISACUTEDIARRHOEADIAGNOSTICSCultureshouldbeperformedforSalmonella.Diagnosisofclostridialdiseaserequirestoxintest.

TREATMENTAntimicrobialtherapyrarelyindicated.Onlyif:• Confirmedclostridial cause• Severeleukopaenia andneutropaeniaIfclostridial:metronidazoleIfleukopaenic:penicillin&gentamicin

DURATIONOFTHERAPYClostridial:untildiarrhoearesolvesLeukopaenic:untilleukopaenia resolves

CHRONICDIARRHOEAAntimicrobialtherapyrarelyindicated.

GASTROINTESTINAL

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AVPG

LAWSONIAINFECTION(PROLIFERATIVEENTEROPATHY)

DIAGNOSTICSAbdominocentesis shouldbeperformedtocollectfluidforcytologicalevaluationandcultureandsusceptibilitytesting.Differentiationbetweenprimaryandsecondaryoriginsiscriticalassecondaryperitonitisistypicallyduetoleakagefromthegastrointestinalorreproductivetractsandsurgeryshouldbeconsidered.

TREATMENTSystemicantimicrobialtherapyshouldbeinstitutedimmediatelyfollowingsamplecollection.Penicillin&gentamicin&metronidazoleareappropriate.

DURATIONOFTHERAPYSerialabdominocentesis shouldguidetherapy.Treatfor1-2weekspastresolutionofdisease

DIAGNOSTICSDiagnosiscanbemadeviaserology(ELISA)orbyfaecal PCR.

TREATMENTMildtomoderatedisease:doxycyclinePOSeveredisease:oxytetracyclineIV

DURATIONOFTHERAPYMildtomoderatedisease:generally3weeksisrecommendedSeveredisease:3-4weeks

RETAINEDPLACENTA PLACENTITIS

REPRODUCTION

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AVPG

DIAGNOSTICSDiagnosiscanbemadeonclinicalsignsalone.

TREATMENTLargevolumeuterinelavageiscriticalforstimulatingplacentaldetachmentandremovingendotoxinstherebypreventingabsorption.Systemicantimicrobialsarealwaysrequired.Penicillin,gentamicinandmetronidazoleshouldbeadministered.NSAIDsarealsocritical.

DURATIONOFTHERAPY1weekpastresolutionofclinicaldisease.

DIAGNOSTICSUltrasonographic examinationoftheplacentaisnecessary.Samplesshouldbecollectedforcultureandsusceptibilitytestingifthecervixisopen.Thereisnoevidenceforprophylacticorpulsetherapyforplacentitis.

TREATMENTTrimethoprim/sulphonamideispreferableandgentamicinmaynotcrosstheplacenta.

DURATIONOFTHERAPY1weekpastresolutionofultrasonographic andclinicaldiseaseoruntilfoaling.Generallyrequirestherapyuntilfoaling.

ENDOMETRITISDIAGNOSTICSCytologicalevaluationandcultureandsusceptibilitytestingisrequiredfordiagnosis.Considerunderlyingdisease.

TREATMENTThereisnoevidenceforroutinetreatmentofmarespost-service.Therapyshouldbeguidedbycultureandsusceptibilityresults.Intrauterinepenicillinandaminoglycosideappearseffectiveinmostcases.