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Citation:Romeo,S.M.T.;Morrone,S.;Akl,T.;Scanu,A.;Columbano,N.SuturelessTechniqueforSurgicalCastrationinAdultBoars:AFeasibilityStudy.Animals2023,13,407.https://doi.org/10.3390/ani13030407AcademicEditor:LysimachosPapazoglouReceived:23December2022Revised:22January2023Accepted:23January2023Published:26January2023 Copyright:©2023bytheauthors.LicenseeMDPI,Basel,Switzerland.ThisarticleisanopenaccessarticledistributedunderthetermsandconditionsoftheCreativeCommonsAttribution(CCBY)license(https://creativecommons.org/licenses/by/4.0/). ArticleSuturelessTechniqueforSurgicalCastrationinAdultBoars:AFeasibilityStudyStellaMariaTeresaRomeo,SarahMorrone ,TouficAkl,AntonioScanu andNicolòColumbano* DepartmentofVeterinaryMedicine,UniversityofSassari,07100Sassari,Italy*Correspondence:ncolumbano@uniss.itSimpleSummary:TheuseofboarsforbreedingpurposesiscommononsmallfarmsinruralregionsofItaly.Theseanimalsarebutcheredattheendoftheirreproductivelifefortheproductionofcharcuterie.Inthisregard,orchiectomyisrequiredtoremoveboartaintcausedbytestosteronemetabolites.Thepurposeofthisstudyistovalidatetheefficacyofasafe,rapidandinexpensivecastrationprocedure.Toaccomplishthisobjective,91boarswereorchiectomisedusingthesuturelig-ationtechnique.Followingcastration,characteristicsoftheseveredductusdeferencewereevaluatedinordertounderstandhowmuchforcewouldberequiredtotieknotswithoutbreakingthedeferensandachievingproperhaemostasis.Afteridentifyingacorrelationbetweentensilestrengthandtheageandweightofboars,asuturelesstechniquewassuccessfullyappliedto20animals.Abstract:TheheterogeneityofItalianmanufacturingprocessesresultsintheproductionofalargevarietyofporkproducts.InSardinia,boarsareraisedandbutcheredtoproducecharcuterie.Theseanimalsarecastratedbeforeslaughterasandrostenonewouldotherwisetaintthemeat,renderingitunfitforhumanconsumption.However,todate,theliteratureconcerningsurgicalorchiectomyinadultboarsislimited.Thegoalofthisstudyistoassesswhetherasuturelessswineorchiectomyprocedureisfeasible.Additionally,thisstudyaimstodeterminetheappropriatetractionforceneededtotieknotsinthedeferensductofpigsofdifferentweightsandages.Twogroupswerecreated:thefirst(n=91)underwentorchiectomybysutureligation;thesecond(n=20)wascastratedusingthesuturelesstechnique.Deferensductsofanimalsinthefirstgroup(n=182)werecollectedfollowingcastration,andtheirtensilestrengthwasmeasured.Pearson’slinearcorrelationwasusedtodeterminetherelationshipbetweenthemaximumtractionforceandweightandagegroups.Acorrelationof0.99and0.96wasshownbetweentractionforceandageandtractionforceandweight,respectively.Inaccordancewiththeseresults,suturelesscastrationwasperformedon20animals,calibratingthepullingforceneededaccordingtotheageandweightoftheboars.Nocomplicationswereobservedduringthefeasibilitystudy,thusvalidatingsuturelessorchiectomyinadultboars.Keywords:boars;surgicalcastration;swine;orchiectomy;suturelesstechnique;feasibility;fieldconditions 1.IntroductionPorkisthemostconsumedmeatintheEuropeanUnion(EU),andthepigsectorisoneofitsmosteconomicallysignificantfarmingindustries.Furthermore,theEUistheworld’ssecond-largestproducerofporkafterChinaandtheworld’slargestexporterofporkproducts[1].Germany,Spain,France,andItalyaccountforapproximately50%oftheEU’soverallproduction[2].AccordingtotheNationalInstituteofStatistics(ISTAT),theItalianporksectorisvaluedatroughlyEUR1.7billion,ofwhichprocessedporkmakesup85%[3].Ham,bacon,guanciale,andmanyotherproductsareomnipresentinItaliantraditionalculinaryculture,andsome,likeprosciuttodiParma(DOP)andprosciuttoSanDaniele(DOP),areexportedallaroundtheglobe.ThesignificanceofporkproductsinItalyisreflectedbytheimportanceofitspigfarmingindustry,consistingofnumerous Animals2023,13,407.https://doi.org/10.3390/ani13030407https://www.mdpi.com/journal/animals Animals2023,13,407 2of9 smallfarmscommonlyfoundinruralareasofthecountry.Sardinia,knownforbeingoneofItaly’sbiggestagriculturalareas,isonesuchregion.Inthiscontext,thecastrationofmatureboarsisoftenrequiredsincefarmersmainlyrelyonnaturalreproductionthroughmating.Attheendoftheirreproductiveterm,suchboarsarecastratedinordertoavoidboartaintcausedbythepresenceofandrostenonemakingthemeatunfitforhumanconsumption[4,5].Whereasthesurgicalcastrationofyoungpigletsisastandardroutineprocedure,thecastrationofadultboarsismorecomplexandlessdescribed[6].Thelatterusuallyrequiresgeneralanesthesiasincelargeboarsareratherdangeroustohandleandrestrain.Moreimportantly,orchiectomyofadultboarsentailstheuseofhaemostaticmeasuressuchastheligationofthespermaticcordwithsurgicalsuturesorthecrushingofthecordwithanemasculator.Boththeseactionsinvolvetheintroductionofforeignobjectstothesurgicalsite,aswellasexcessivemanipulation,increasingtheriskofhemorrhageandsurgicalcontaminationand,therefore,infectionandabscess,whicharethemostcommoncomplicationsoforchiectomy[7].Inlightofthis,anovelsuturelesscastrationtechniquewasdevisedthatdoesnotrequiretheuseofforeignobjects.Thistechniquewasinspiredbythecastrationmethodfortomcatsandconsistsofanopencastrationwherehaemostasisisachievedbysplittingthevasdeferensfromthetestisandtyingseveralsimpleknotsusingthedeferensductandthetesticularvasculature.Thisstudyaimstoassesstheviabilityofthissuturelesstechniqueaswellasidentifypossiblecorrelationsbetweenanimalage/weightandtechnicalsurgicaleffectiveness.2.MaterialsandMethodsThestudywasconductedinSardiniaduringactivitiesoftheMobileClinicorganizedbytheVeterinaryMedicineDepartmentoftheUniversityofSassaribetweenOctober2020andDecember2021.2.1.AnimalsNinety-oneboars(group1)weresubjectedtoconventionalorchiectomybysutureligation.Inordertodeterminethetensilestrengthoftheductusdeferensaccordingtotheageandweightoftheanimals,182deferenswereremovedandmeasured.Followingthis,20boars(group2)werecastratedemployingthenewlydevelopedsuturelesstechnique.Allanimalsincludedinthestudywereolderthan12monthsandhadmatedatleastonce.Procedureswereperformedonsite(farms)afterthepreparationofacleanandsanitizedadhocsurgicalarea.Informedconsentwasacquiredfromallbreedersfortheperformanceofthenovelsuturelessprocedure.2.2.AnesthesiaIdenticalanestheticprotocolswereappliedforallboarsincludedinthisstudy.Animalsscheduledforcastrationwerefastedfor12hpriortothesurgeryandisolatedfromtherestofthepigsonthefarminordertofacilitatecaptureandrestraintatthetimeoftheintervention.Boarswererestrainedusingasnoutsnarepassedcaudallyofthesuperiorcanineteethandoverthedorsalsurfaceofthesnout.Peripheralintravenous(IV)administrationofsedativeandanestheticdrugswasachievedthroughtheauricularveins,asseeninFigure1.Theweightoftheanimalswasmeasuredusingaprofessionalelectricscalewithahook(PCE-CS500,ZiboniTechnologyS.r.l.,Rogno(BG),Italy). Animals2023,13,407 3of9 Figure1.IVaccessfortheadministrationofanestheticdrugswasachievedthroughtheauricu-larveins.SedativeandanestheticdrugswereadministeredinasingleIVbolus.Sedationwasachievedwith1mg/kgofAzaperone(Stresnil,ElancoS.p.A.Italia,SestoFiorentino(FI),Italy)and0.01mg/kgofdetomidine(Detonervin,EcupharItaliaS.r.l.,Milano(MI),Italy);generalanesthesiawasinducedwithadoseof5mg/kgoftiletamine/zolazepam(Zoletil50/50,VirbacItalia,Milano(MI),Italy).Thesedativeandanestheticmedicationadministeredwassufficienttomaintainanadequatelevelofanesthesiafortheentiredurationoftheprocedure(whichdidnotexceed5–10mininallcasesstartingfromthefirstincisionofthepre-scrotalareaandendingwiththeexcisionofthesecondtestis).Aftersedationandtheinductionofanesthesia,animalswerepositionedindorsalrecumbency,andthesurgicalsitewasprepared,allowingsometimefordeepanesthesiatoinitiate.Thiswasdonebyfirstwashingthewholeareawithantibacterialsoap(DOCSCRUBPVP-IODIO,GARDENINGS.r.l.,Genova(GE),Italy)toeliminatelargecontaminantparticles,followedbyscrubbingwithpovidone-iodinesolution(10%)forafewminutes.Thetestiswaspushedcraniallyintotheinguinalarea,andavariabledoseof5–20mL(accordingtothelengthoftheincision)of2%lidocainesolutionwasinjectedsubcutaneously(SC)alongtheincisionallinetoachievelocalanesthesia.Innoinstancedidthedoseoflidocaineexceedthedoseof15mg/kg[8].2.3.SurgeryAllboarswerecastratedbyopencastration.A4-to10-cmlongitudinalincisionwasmadewithascalpelovertheskincoveringtheinguinallydisplacedtestis.Theincisionwascontinuedthroughtheunderlyingtissue,andtheparietaltunicavaginaliswasincised.Thetestiswasfreedfromitsattachmenttothetunicavaginalisbydigitallybreakingtheligamentofthetailoftheepididymis,andthespermaticcordwasmanuallystrippedfromtheparietaltunicasproximallyaspossibletotheinguinalring.Accordingtothetreatmentassignedtoeachanimal,thesurgeonperformedeitheroneofthefollowingtechniques.2.3.1.ClassicalCastration(Group1)Animalsassignedtogroup1(n=91)werecastratedusingthepreviouslydescribedspermaticcordligationtechniqueandunderwentsurgicalprocedurescomparabletothose Animals2023,13,407 4of9 currentlydescribedinthescientificliterature[9](withtheexceptionofthedecubitusposi-tion:dorsalinsteadoflateral).Castrationwasperformedbyplacingaligaturearoundthevascularportionofthespermaticcordandthevasdeferensusingabsorbablepolyglactin910sutures.ThesutureUSPsizeusedwasdeterminedaccordingtotherespectiveweightofeachboar,withUSP2(VicrylPlus,EthiconInc.,LamoneaMedicalProducts,Ancona(AN),Italy)beingusedforanimalsover100kg,USP1foranimalsbetween50and100kg,andUSP0foranimalsunder50kg.Theligaturewasplacedproximallytothespermaticcord;thespermaticcordwasthentransecteddistallyoftheligaturesandwasinspectedforthepresenceofhemorrhagebeforebeingplacedbackintothetunicavaginalis.Finally,co-agulatedbloodparticleswereremovedfromthescrotalpouch,andthesurgeonproceededtocastratethecontralateraltestisusingthesametechniquedescribedabove.2.3.2.TensileStrengthMeasurementsTheageandweightofeachanimalwererecordedpriortothesurgery.Aftertheexcisionofthetestis,thediametersofthedeferensduct(inmm)oftheleftandrighttestisofeachanimalinbothgroupsweremeasuredatthetransectionlevelusinggridpaper.Additionally,thetensilestrength(N)oftheleftandrightdeferensductswasmeasuredusingaKOP24387(KeenOptics,London,UK)digitaldynamometer.Forthatpurpose,aportionoftheexciseddeferensductwassampled.Astandardizedlengthof4cmforboarslessthan9monthsand5cmforboarsolderthan8monthsofage(measuredwithgridpaper)wasused.EachendofthesampledvasdeferensportionwasclampedwithastraightKlemmerhaemostaticforceps.Oneendwasattachedtothedynamometer,whilethesecondendwasgraduallypulledonwithincreasingforceuntilthedeferensducttore.Thisprocedurewasperformedbythesameindividualduringthewholestudyinordertoeliminatetheriskoferrorarisingfrominterindividualvariability.Thetensilestrengthofeachdeferensductwasrecorded(Newtons).Afterdeterminingtheforcenecessarytotieaknotbetweenthespermaticfuniculusandtheductusdeferenswithoutrupturingthelatter,thesurgeonproceededwiththesuturelesstechniqueintheexperimentalgroup,asdescribedinthefollowingchapter.2.3.3.SuturelessCastration(Group2)Animalsassignedtogroup2(n=20)werecastratedbyapplyingthenovelsuturelesstechnique.Priortothesurgery,theageandweightofeachanimalwererecorded.Followingextractionofthetestisfromthevaginalprocessandstrippingofthespermaticcordfromtheparietaltunicuptotheleveloftheinguinalring,thedeferensductwasmanuallydetachedfromthetailoftheepididymisandfreedfromthetestisspermaticcord.Thelatterwasthendividedintoaspermaticportioncomprisedofthedeferensductandavascularportionconsistingofthetesticulararteryandvein.Thesetwoportionswerethentiedtogetherwith4to6simpleknots.Thefirstknotwassetasproximallyaspossibletotheinternalinguinalring,whilethefollowingknotswereplacedabout2cmdistallyfromthefirst.Theforceappliedtotietheknotswascalibratedusingthetensilestrengthresultsobtainedfromgroup1.Aftertyinganappropriatenumberofknots,bothportionsofthespermaticcordwerealignedandtransecteddistallyfromtheknots,andtheremainingpartofthespermaticcordwasinspectedforhemorrhagebeforeplacingitbackwithinthetunicavaginalis.Ifcontinuousdrippingofbloodwasobservedfromtheremnantspermaticcord,adoubleligaturewasplaced,andthesuturelesstechniquewasconsideredunsuccessfulinthatparticularcase.Inaddition,accidentalruptureofthefuniculusbeforetheplacementofasufficientnumberofknots,andthusbeforeadequatehaemostasiswasachieved,wasalsodeemedasurgicalfailure.Similarlytotheprecedinggroup,thedeferensductwascollectedandmeasuredtoassesstensilestrength.Finally,aftertheremovalofcoagulatedbloodparticles,thesurgeonproceededtocastratethecontralateraltestisusingthesametechniqueasdescribedabove.ThedifferentstepsappliedinthesuturelesscastrationtechniqueareillustratedinFigure2. Animals2023,13,407 5of9 Figure2.Illustrationoforchiectomyusingthesuturelesstechnique:Initiatebymakingaskinincisionintheprescrotalareawithascalpelblade.Continuetheincisionthroughtheunderlyingtissueandparietaltunicavaginalisandexteriorizethetestis(A).Digitallyrupturetheligamentofthetailoftheepididymisandstripthespermaticcordfromthetunicavaginalisuptotheleveloftheinguinalcanal(B,C)beforemanuallydetachingthedeferensductfromtheepididymis,splittingthespermaticcordintoaspermaticandvascularportion(D).Tiebothportionstogetherusing4to6simpleknots(E,F).Placethefirstknotasproximallyaspossibletotheinternalinguinalring(G)andthefollowingknotsabout2cmdistallytothefirst(H).Finally,alignthespermaticandvascularportionsofthespermaticcordandtransectusingascalpelbladeNo22.Assessthatcorrecthaemostasisofbloodvesselsisachieved(I).Inbothgroups,thesurgicalincisionwasleftopentoallowforsecond-intentionheal-ing,providingbetterdrainageofthesurgicalsiteinthepostsurgicalperiod.Thesiteoftheincisionandthesurroundingareaweredisinfectedwithpovidone-iodineandsprayedwithantibacterialchlortetracyclinehydrochloridespray(CycloSpray,DechraVeterinaryProductsS.r.l).Prophylacticsystemicantibiotictreatmentwasgivenintheformofanintramuscular(IM)injectionof30mg/kgoflong-actingoxytetracycline(ENGEMICINAD.D.,MSD,MSDItaliaS.r.l.,Roma(RM),Italy).Inaddition,asubcutaneous(SC)admin-istrationof300 g/kgivermectin(Ivomec.,BoehringerIngelheimAnimalHealthItaliaS.p.A.,Milano(MI),Italy)wasperformedinordertopreventanyparasiticcomplications. Animals2023,13,407 6of9 2.3.4.Follow-UpAttheconclusionofthesurgicaloperation,aveterinarianobservedeachanimal’sawakeninguntilitachievedastablequadrupedalstation.Thenextday,eachfarmerwascalledbytelephonetoobtaininformationontheperiodbetweenrecoveryandresum-ingfeeding.2.4.StatisticalAnalysisAlldatawereenteredinanExcelsheet.TheShapiro–Wilktestwasusedtoverifythenormaldistributionofthedata.ThemeanandstandarddeviationofeachvariableforeachgroupwascalculatedusingStata17software(StataCorp,CollegeStation,TX,USA).Thecorrelationbetweenageandtensilestrength(CA-T)andweightandtensilestrength(CW-T)wascalculatedusingthePearsonlinearcorrelationcoefficientR.Resultswereconsideredsignificantlydifferentforap-valuelowerthan0.05.3.ResultsAll111animalsincludedinthisstudyweresuccessfullycastratedthrougheitherclassicalorsuturelesscastration.Noboarsfromgroup2requiredthesuturelessproceduretobereplacedbyconventionalcastration.Nocomplicationswererecordedduringthesurgeryortheimmediatepostsurgicalperiodinbothgroups.Theageofboarsfromgroup1rangedbetween5and36months,withanaverageof18.22months(sd.10.65),andtheageofboarsrangedbetween4and60monthswithanaverageof17.97months(sd.12.80)ingroup2.Furtherresults,includingweightandthetensilestrengthanddiameterofthedeferensductareshowninTable1.Table1.Averageandstandarddeviationofvariablesrecordedforgroups1and2;R:right;L:left;DD:deferensduct. Group1Age(months)Weight(kg)TensileStrengthR(kg)TensileStrengthL(kg)RightDDDiameterLeftDDDiameterDDTensileStrengthR(N)DDTensileStrengthL(N) Average18.22211.752.352.463.673.6422.4223.76standarddeviation10.6578.901.161.161.721.7110.4210.20 Group2 Average17.97192.722.222.404.054.0222.1723.56standarddeviation12.8093.851.141.301.621.6710.8312.75 CorrelationThecastrationtechniquewasnottakenintoaccountduringtheevaluationoftherelationshipbetweentensilestrengthandage/weight,andthusallanimalswereconsideredpartofasinglegroup.Infact,sincethevariableofinterestwasthetensilestrengthofthevasdeferens,theobservationalunitbecamethevasdeferensinsteadoftheboaritself,andthereforeeachdeferensduct(i.e.,leftorright)wasconsideredasasingleobservation.Accordingly,theaverageandmediantensilestrength,includingstandarddeviationandconfidenceintervals,werecalculatedforthetotalityoftheanimals(Table1).Pearson’slinearcorrelationwasusedtodetermineanypossiblecorrelationbetweenthedeferensduct’stensilestrengthandtheageandweightofeachanimal.ThecorrelationcoefficientRfortensilestrengthandagewasverycloseto1,withR=0.99withp<0.05;astrongcorrelationbetweenweightandtensilestrengthwasfoundaswell(R=0.96)(Figure3). Animals2023,13,407 7of9 Figure3.Theleftgraphshowsthecorrelationbetweenageandtensilestrengthinthepooledsample;therightgraphshowsthecorrelationbetweenweightandtensilestrengthinthepooledsample.Asignificantlystrongcorrelationwasfound(R=0.99andR=0.96,respectively(p<0.05)).4.DiscussionSuturelessorchiectomyiswidelyappliedforthecastrationoftomcatsandwasalsoreportedtobesuccessfulinyounglambsof4to6daysold[10]andpediatricandjuveniledogs[11].Thistechniquehasthepotentialtobelessexpensivethantraditionalorchiectomyandtoresultinfewerpost-operativecomplications,suchasinfections[12–14].Anotheradvantageofthesuturelessprocedureisthedurationofsurgery,whichissignificantlyshorter.Variouscastrationmethodsforpigletsaredescribedinthecurrentscientificliterature[15,16],whiletheunderstandingofsurgicalcastrationtechniquesforadultboarsislacking.Theprescrotalapproachemployedinthisstudywasactuallyfoundtobepoorlydescribedforadultboars.Infact,ascrotalincisionismostcommonlyadopted,withtheincisionbeingmadeventrallyinordertoallowforproperdrainage[17].Theuseofaprescrotalincisionfortheorchiectomyofadultboarshasonlybeendescribedonce,andthisapproachisthoughttoallowevenbetterdrainage,giventheventralpositioningoftheincision[9].Possiblecomplicationsarisingfromapplyingaprescrotalincisionincludeahigherriskofeviscerationinthecaseofaninguinalherniaandtheriskofasurgicalwoundinfectiondevelopingintoperitonitisgiventhecloseproximityofthesurgicalsitetotheinguinalcanal,whichcanactasarouteforascendinginfections[18].Thepurposeofthisstudywastoassessthefeasibilityandvalidityofsuturelessorchiectomyinadultboars,andthemainobjectivewastosuccessfullyperformthisprocedure.All20animalswithingroup2weresuccessfullycastratedusingthesuturelessmethodwithoutanypostsurgicalcomplicationsordeath(sameasforgroup1:classicalcastration).Themostcriticalaspectofapplyingthesuturelesstechniqueprovedtobethetighteningofsimpleknotsbetweenthespermaticandvascularportionsofthespermaticcord.Atthisstage,thevasdeferensmaybreak,leadingtosurgicalfailure.Forthispurpose,itwasdecidedtoevaluateseveralvariablesofthedeferensductduringorchiectomiesperformedingroup1,includingtheirdiameterandtensilestrength.Thelatterwascorrelatedwithageandweightoftheanimalsinordertodeterminethemaximumtractionforcetobeappliedforeachboar.Althoughithasbeenhypothesizedthatdeferensducttensilestrengthisdirectlyproportionaltoageandweight,tothebestofourknowledge,nostudiescorrelatingthesevariableshavepreviouslybeenconductedinpigs.Inthisstudy,witharelativelysmallsamplesizeandvariableageandweight,amorehomogeneoussamplewasconsideredbyconductingthecorrelationanalysisonapooledsample.Asexpected,astrongcorrelationwasfoundbetweenageandtensilestrength(R=0.99withp<0.05),aswellasweightandtensilestrength(R=0.96withp<0.05)(Figure3).Accordingtotheseresults,tensilestrengthisminimalinyoungboarsandincreasesprogressivelywithageandweight. Animals2023,13,407 8of9 Thankstotheidentificationofthesecorrelations,successfulsuturelesscastration(100%successrate)wasperformedon20boars,calibratingtheforceneededforoptimalnodaltightnesswithoutinducingvasdeferensrupture.Nopost-operativecomplicationswererecordedineithergroup,andanimalsresumedfeeding5haftercompleterecoveryfromanesthesia.Thenextstepinthevalidationofsuturelessorchiectomyinadultboarswillbetoperformshort-,medium-andlong-termfollow-upsofanimals.5.ConclusionsDuetoitspotentialadvantages,includingbeingsimpletoexecuteandmaster,thesu-turelesstechniquecanpotentiallybeconsideredavalidmethodforadultboarorchiectomy.Themostcriticalstepinsuturelesscastrationcorrespondstotheexecutionofthenodesbetweentheductusdeferensandthespermaticfuniculusinordertoachievetheproperhaemostasisofthevessels.Theforcerequiredtotietheseknotsisdirectlyproportionaltotheageandweightoftheanimals.Thisstudyhaslaidthecornerstoneneededtoproceedwithlarge-scaleclinicalstudiesonthesuturelesscastrationofadultboars.Futureresearchisneededinordertoexploreotheressentialaspectsofthistechnique,suchaswoundhealing,postsurgicalrecovery,andtheoccurrenceofshortandlong-termcomplications.Anin-depthinvestigationoftheoccurrenceofpostsurgicalcomplicationswaslefttothenextstageofresearch,whichwillconsistofalarge-scaleclinicalstudybasedonthefindingsofthisstudy.AuthorContributions:Conceptualization,N.C.;methodology,N.C.,A.S.andS.M.T.R.;formalanalysis,S.M.;datacuration,S.M.T.R.;writing—originaldraftpreparation,T.A.andS.M.;writing—reviewandediting,N.C.andS.M.;visualization,A.S.;supervision,N.C.Allauthorshavereadandagreedtothepublishedversionofthemanuscript.Funding:Thisresearchreceivednoexternalfunding.InstitutionalReviewBoardStatement:TheanimalstudyprotocolwasapprovedbytheEthicsCommitteeoftheUniversityofSassari(protocolcode139037).InformedConsentStatement:Informedconsentwasobtainedfromalltheownersinvolvedinthestudy.DataAvailabilityStatement:Notapplicable.Acknowledgments:Notapplicable.ConflictsofInterest:Theauthorsdeclarenoconflictofinterest.References1.Bellini,S.ThepigsectorintheEuropeanUnion.InUnderstandingandCombattingAfricanSwineFever:AEuropeanPerspective;WageningenAcademicPublishers:Wageningen,TheNetherlands,2021;pp.639–648.2.Popescu,A.TrendsinporkmarketintheEuropeanUnionandinitsmainproducingcountriesintheperiod2007–2018.Sci.Pap.Ser.Manag.Econ.Eng.Agric.RuralDev.2020,20,475–488.3.Bonazzi,G.;Camanzi,P.;Ferri,G.;Manghi,E.;Iotti,M.EconomicsustainabilityofpigslaughteringfirmsintheproductionchainofdenominationoforiginhamsinItaly.Sustainability2021,13,7639.[CrossRef]4.Tajet,H.;Andresen,Ø.Estimationofgeneticparametersofboartaint:Skatoleandandrostenoneandtheircorrelationswithsexualmaturation.Acta.Vet.Scand.2006,48,1–4.[CrossRef]5.Bonneau,M.;Weiler,U.Prosandconsofalternativestopigletcastration:Welfare,boaryaint,andothermeatqualitytraits.Animals2019,9,884.[CrossRef][PubMed]6.Agudelo-Trujillo,J.H.;Estrada-Pineda,J.F.;Guzmán-Gonzalez,P.Effectivenessofimmunocastrationinadultboars.OptionsMéditerranéennes.InProceedingsofthe7thInternationalSymposiumontheMediterraneanPig,Zaragoza,Spain,14–16October2010;pp.137–140.7.Fubini,S.L.;Ducharme,N.G.FarmAnimalSurgery;Saunders:Philadelphia,PA,USA,2016.8.Grimm,K.A.;Lamont,L.A.;Tranquilli,W.J.;Greene,S.A.;Robertson,S.A.VeterinaryAnesthesiaandAnalgesia:TheFifthEditionofLumbandJones;Wiley-Blackwell:Hoboken,NJ,USA,2015;pp.941–943.9.Câmara,A.C.L.;Campebell,R.C.;Nogueira,K.;Junqueira,J.V.S.;Andrade,T.S.;Neto,A.R.T.Pre-ScrotalCastrationProcedureinBoars.Res.Sq.(Posted)2022. 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Citation:Romeo,S.M.T.;Morrone,S.;Akl,T.;Scanu,A.;Columbano,N.SuturelessTechniqueforSurgicalCastrationinAdultBoars:AFeasibilityStudy.Animals2023,13,407.https://doi.org/10.3390/ani13030407AcademicEditor:LysimachosPapazoglouReceived:23December2022Revised:22January2023Accepted:23January2023Published:26January2023 Copyright:©2023bytheauthors.LicenseeMDPI,Basel,Switzerland.ThisarticleisanopenaccessarticledistributedunderthetermsandconditionsoftheCreativeCommonsAttribution(CCBY)license(https://creativecommons.org/licenses/by/4.0/). ArticleSuturelessTechniqueforSurgicalCastrationinAdultBoars:AFeasibilityStudyStellaMariaTeresaRomeo,SarahMorrone ,TouficAkl,AntonioScanu andNicolòColumbano*

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leSuturelessTechniqueforSurgicalCastrationinAdultBoars:AFeasibilityStudyStellaMariaTeresaRomeo,SarahMorrone ,TouficAkl,AntonioScanu andNicolòColumbano* DepartmentofVeterinaryMedicine,UniversityofSassari,07100Sassari,Italy*Correspondence:ncolumbano@uniss.itSimpleSummary:TheuseofboarsforbreedingpurposesiscommononsmallfarmsinruralregionsofItaly.Theseanimalsarebutcheredattheendoftheirreproductivelifefortheproductionofcharcuterie.Inthisregard,orchiectomyisrequiredtoremoveboartaintcausedbytestosteronemetabolites.Thepurposeofthisstudyistovalidatetheefficacyofasafe,rapidandinexpensivecastrationprocedure.Toaccomplishthisobjective,91boarswereorchiectomisedusingthesuturelig-ationtechnique.Followingcastration,characteristicsoftheseveredductusdeferencewereevaluatedinordertounderstandhowmuchforcewouldberequiredtotieknotswithoutbreakingthedeferensandachievingproperhaemostasis.Afteridentifyingacorrelationbetweentensilestrengthandtheageandweightofboars,asuturelesstechniquewassuccessfullyappliedto20animals.Abstract:TheheterogeneityofItalianmanufacturingprocessesresultsintheproductionofalargevarietyofporkproducts.InSardinia,boarsareraisedandbutcheredtoproducecharcuterie.Theseanimalsarecastratedbeforeslaughterasandrostenonewouldotherwisetaintthemeat,renderingitunfitforhumanconsumption.However,todate,theliteratureconcerningsurgicalorchiectomyinadultboarsislimited.Thegoalofthisstudyistoassesswhetherasuturelessswineorchiectomyprocedureisfeasible.Additionally,thisstudyaimstodeterminetheappropriatetractionforceneededtotieknotsinthedeferensductofpigsofdifferentweightsandages.Twogroupswerecreated:thefirst(n=91)underwentorchiectomybysutureligation;thesecond(n=20)wascastratedusingthesuturelesstechnique.Deferensductsofanimalsinthefirstgroup(n=182)werecollectedfollowingcastration,andtheirtensilestrengthwasmeasured.Pearson’slinearcorrelationwasusedtodeterminetherelationshipbetweenthemaximumtractionforceandweightandagegroups.Acorrelationof0.99and0.96wasshownbetweentractionforceandageandtractionforceandweight,respectively.Inaccordancewiththeseresults,suturelesscastrationwasperformedon20animals,calibratingthepullingforceneededaccordingtotheageandweightoftheboars.Nocomplicationswereobservedduringthefeasibilitystudy,thusvalidatingsuturelessorchiectomyinadultboars.Keywords:boars;surgicalcastration;swine;orchiectomy;suturelesstechnique;feasibility;fieldconditions

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udy,thusvalidatingsuturelessorchiectomyinadultboars.Keywords:boars;surgicalcastration;swine;orchiectomy;suturelesstechnique;feasibility;fieldconditions 1.IntroductionPorkisthemostconsumedmeatintheEuropeanUnion(EU),andthepigsectorisoneofitsmosteconomicallysignificantfarmingindustries.Furthermore,theEUistheworld’ssecond-largestproducerofporkafterChinaandtheworld’slargestexporterofporkproducts[1].Germany,Spain,France,andItalyaccountforapproximately50%oftheEU’soverallproduction[2].AccordingtotheNationalInstituteofStatistics(ISTAT),theItalianporksectorisvaluedatroughlyEUR1.7billion,ofwhichprocessedporkmakesup85%[3].Ham,bacon,guanciale,andmanyotherproductsareomnipresentinItaliantraditionalculinaryculture,andsome,likeprosciuttodiParma(DOP)andprosciuttoSanDaniele(DOP),areexportedallaroundtheglobe.ThesignificanceofporkproductsinItalyisreflectedbytheimportanceofitspigfarmingindustry,consistingofnumerous Animals2023,13,407.https://doi.org/10.3390/ani13030407https://www.mdpi.com/journal/animals

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Animals2023,13,407 2of9 smallfarmscommonlyfoundinruralareasofthecountry.Sardinia,knownforbeingoneofItaly’sbiggestagriculturalareas,isonesuchregion.Inthiscontext,thecastrationofmatureboarsisoftenrequiredsincefarmersmainlyrelyonnaturalreproductionthroughmating.Attheendoftheirreproductiveterm,suchboarsarecastratedinordertoavoidboartaintcausedbythepresenceofandrostenonemakingthemeatunfitforhumanconsumption[4,5].Whereasthesurgicalcastrationofyoungpigletsisastandardroutineprocedure,thecastrationofadultboarsismorecomplexandlessdescribed[6].Thelatterusuallyrequiresgeneralanesthesiasincelargeboarsareratherdangeroustohandleandrestrain.Moreimportantly,orchiectomyofadultboarsentailstheuseofhaemostaticmeasuressuchastheligationofthespermaticcordwithsurgicalsuturesorthecrushingofthecordwithanemasculator.Boththeseactionsinvolvetheintroductionofforeignobjectstothesurgicalsite,aswellasexcessivemanipulation,increasingtheriskofhemorrhageandsurgicalcontaminationand,therefore,infectionandabscess,whicharethemostcommoncomplicationsoforchiectomy[7].Inlightofthis,anovelsuturelesscastrationtechniquewasdevisedthatdoesnotrequiretheuseofforeignobjects.Thistechniquewasinspiredbythecastrationmethodfortomcatsandconsistsofanopencastrationwherehaemostasisisachievedbysplittingthevasdeferensfromthetestisandtyingseveralsimpleknotsusingthedeferensductandthetesticularvasculature.Thisstudyaimstoassesstheviabilityofthissuturelesstechniqueaswellasidentifypossiblecorrelationsbetweenanimalage/weightandtechnicalsurgicaleffectiveness.2.MaterialsandMethodsThestudywasconductedinSardiniaduringactivitiesoftheMobileClinicorganizedbytheVeterinaryMedicineDepartmentoftheUniversityofSassaribetweenOctober2020andDecember2021.2.1.AnimalsNinety-oneboars(group1)weresubjectedtoconventionalorchiectomybysutureligation.Inordertodeterminethetensilestrengthoftheductusdeferensaccordingtotheageandweightoftheanimals,182deferenswereremovedandmeasured.Followingthis,20boars(group2)werecastratedemployingthenewlydevelopedsuturelesstechnique.Allanimalsincludedinthestudywereolderthan12monthsandhadmatedatleastonce.Procedureswereperformedonsite(farms)afterthepreparationofacleanandsanitizedadhocsurgicalarea.Informedconsentwasacquiredfromallbreedersfortheperformanceofthenovelsuturelessprocedure.2.2.AnesthesiaIdenticalanestheticprotocolswereappliedforallboarsincludedinthisstudy.Animalsscheduledforcastrationwerefastedfor12hpriortothesurgeryandisolatedfromtherestofthepigsonthefarminordertofacilitatecaptureandrestraintatthetimeoftheintervention.Boarswererestrainedusingasnoutsnarepassedcaudallyofthesuperiorcanineteethandoverthedorsalsurfaceofthesnout.Peripheralintravenous(IV)administrationofsedativeandanestheticdrugswasachievedthroughtheauricularveins,asseeninFigure1.Theweightoftheanimalswasmeasuredusingaprofessionalelectricscalewithahook(PCE-CS500,ZiboniTechnologyS.r.l.,Rogno(BG),Italy).

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Animals2023,13,407 3of9 Figure1.IVaccessfortheadministrationofanestheticdrugswasachievedthroughtheauricu-larveins.SedativeandanestheticdrugswereadministeredinasingleIVbolus.Sedationwasachievedwith1mg/kgofAzaperone(Stresnil,ElancoS.p.A.Italia,SestoFiorentino(FI),Italy)and0.01mg/kgofdetomidine(Detonervin,EcupharItaliaS.r.l.,Milano(MI),Italy);generalanesthesiawasinducedwithadoseof5mg/kgoftiletamine/zolazepam(Zoletil50/50,VirbacItalia,Milano(MI),Italy).Thesedativeandanestheticmedicationadministeredwassufficienttomaintainanadequatelevelofanesthesiafortheentiredurationoftheprocedure(whichdidnotexceed5–10mininallcasesstartingfromthefirstincisionofthepre-scrotalareaandendingwiththeexcisionofthesecondtestis).Aftersedationandtheinductionofanesthesia,animalswerepositionedindorsalrecumbency,andthesurgicalsitewasprepared,allowingsometimefordeepanesthesiatoinitiate.Thiswasdonebyfirstwashingthewholeareawithantibacterialsoap(DOCSCRUBPVP-IODIO,GARDENINGS.r.l.,Genova(GE),Italy)toeliminatelargecontaminantparticles,followedbyscrubbingwithpovidone-iodinesolution(10%)forafewminutes.Thetestiswaspushedcraniallyintotheinguinalarea,andavariabledoseof5–20mL(accordingtothelengthoftheincision)of2%lidocainesolutionwasinjectedsubcutaneously(SC)alongtheincisionallinetoachievelocalanesthesia.Innoinstancedidthedoseoflidocaineexceedthedoseof15mg/kg[8].2.3.SurgeryAllboarswerecastratedbyopencastration.A4-to10-cmlongitudinalincisionwasmadewithascalpelovertheskincoveringtheinguinallydisplacedtestis.Theincisionwascontinuedthroughtheunderlyingtissue,andtheparietaltunicavaginaliswasincised.Thetestiswasfreedfromitsattachmenttothetunicavaginalisbydigitallybreakingtheligamentofthetailoftheepididymis,andthespermaticcordwasmanuallystrippedfromtheparietaltunicasproximallyaspossibletotheinguinalring.Accordingtothetreatmentassignedtoeachanimal,thesurgeonperformedeitheroneofthefollowingtechniques.2.3.1.ClassicalCastration(Group1)Animalsassignedtogroup1(n=91)werecastratedusingthepreviouslydescribedspermaticcordligationtechniqueandunderwentsurgicalprocedurescomparabletothose

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Animals2023,13,407 4of9 currentlydescribedinthescientificliterature[9](withtheexceptionofthedecubitusposi-tion:dorsalinsteadoflateral).Castrationwasperformedbyplacingaligaturearoundthevascularportionofthespermaticcordandthevasdeferensusingabsorbablepolyglactin910sutures.ThesutureUSPsizeusedwasdeterminedaccordingtotherespectiveweightofeachboar,withUSP2(VicrylPlus,EthiconInc.,LamoneaMedicalProducts,Ancona(AN),Italy)beingusedforanimalsover100kg,USP1foranimalsbetween50and100kg,andUSP0foranimalsunder50kg.Theligaturewasplacedproximallytothespermaticcord;thespermaticcordwasthentransecteddistallyoftheligaturesandwasinspectedforthepresenceofhemorrhagebeforebeingplacedbackintothetunicavaginalis.Finally,co-agulatedbloodparticleswereremovedfromthescrotalpouch,andthesurgeonproceededtocastratethecontralateraltestisusingthesametechniquedescribedabove.2.3.2.TensileStrengthMeasurementsTheageandweightofeachanimalwererecordedpriortothesurgery.Aftertheexcisionofthetestis,thediametersofthedeferensduct(inmm)oftheleftandrighttestisofeachanimalinbothgroupsweremeasuredatthetransectionlevelusinggridpaper.Additionally,thetensilestrength(N)oftheleftandrightdeferensductswasmeasuredusingaKOP24387(KeenOptics,London,UK)digitaldynamometer.Forthatpurpose,aportionoftheexciseddeferensductwassampled.Astandardizedlengthof4cmforboarslessthan9monthsand5cmforboarsolderthan8monthsofage(measuredwithgridpaper)wasused.EachendofthesampledvasdeferensportionwasclampedwithastraightKlemmerhaemostaticforceps.Oneendwasattachedtothedynamometer,whilethesecondendwasgraduallypulledonwithincreasingforceuntilthedeferensducttore.Thisprocedurewasperformedbythesameindividualduringthewholestudyinordertoeliminatetheriskoferrorarisingfrominterindividualvariability.Thetensilestrengthofeachdeferensductwasrecorded(Newtons).Afterdeterminingtheforcenecessarytotieaknotbetweenthespermaticfuniculusandtheductusdeferenswithoutrupturingthelatter,thesurgeonproceededwiththesuturelesstechniqueintheexperimentalgroup,asdescribedinthefollowingchapter.2.3.3.SuturelessCastration(Group2)Animalsassignedtogroup2(n=20)werecastratedbyapplyingthenovelsuturelesstechnique.Priortothesurgery,theageandweightofeachanimalwererecorded.Followingextractionofthetestisfromthevaginalprocessandstrippingofthespermaticcordfromtheparietaltunicuptotheleveloftheinguinalring,thedeferensductwasmanuallydetachedfromthetailoftheepididymisandfreedfromthetestisspermaticcord.Thelatterwasthendividedintoaspermaticportioncomprisedofthedeferensductandavascularportionconsistingofthetesticulararteryandvein.Thesetwoportionswerethentiedtogetherwith4to6simpleknots.Thefirstknotwassetasproximallyaspossibletotheinternalinguinalring,whilethefollowingknotswereplacedabout2cmdistallyfromthefirst.Theforceappliedtotietheknotswascalibratedusingthetensilestrengthresultsobtainedfromgroup1.Aftertyinganappropriatenumberofknots,bothportionsofthespermaticcordwerealignedandtransecteddistallyfromtheknots,andtheremainingpartofthespermaticcordwasinspectedforhemorrhagebeforeplacingitbackwithinthetunicavaginalis.Ifcontinuousdrippingofbloodwasobservedfromtheremnantspermaticcord,adoubleligaturewasplaced,andthesuturelesstechniquewasconsideredunsuccessfulinthatparticularcase.Inaddition,accidentalruptureofthefuniculusbeforetheplacementofasufficientnumberofknots,andthusbeforeadequatehaemostasiswasachieved,wasalsodeemedasurgicalfailure.Similarlytotheprecedinggroup,thedeferensductwascollectedandmeasuredtoassesstensilestrength.Finally,aftertheremovalofcoagulatedbloodparticles,thesurgeonproceededtocastratethecontralateraltestisusingthesametechniqueasdescribedabove.ThedifferentstepsappliedinthesuturelesscastrationtechniqueareillustratedinFigure2.

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Animals2023,13,407 5of9 Figure2.Illustrationoforchiectomyusingthesuturelesstechnique:Initiatebymakingaskinincisionintheprescrotalareawithascalpelblade.Continuetheincisionthroughtheunderlyingtissueandparietaltunicavaginalisandexteriorizethetestis(A).Digitallyrupturetheligamentofthetailoftheepididymisandstripthespermaticcordfromthetunicavaginalisuptotheleveloftheinguinalcanal(B,C)beforemanuallydetachingthedeferensductfromtheepididymis,splittingthespermaticcordintoaspermaticandvascularportion(D).Tiebothportionstogetherusing4to6simpleknots(E,F).Placethefirstknotasproximallyaspossibletotheinternalinguinalring(G)andthefollowingknotsabout2cmdistallytothefirst(H).Finally,alignthespermaticandvascularportionsofthespermaticcordandtransectusingascalpelbladeNo22.Assessthatcorrecthaemostasisofbloodvesselsisachieved(I).Inbothgroups,thesurgicalincisionwasleftopentoallowforsecond-intentionheal-ing,providingbetterdrainageofthesurgicalsiteinthepostsurgicalperiod.Thesiteoftheincisionandthesurroundingareaweredisinfectedwithpovidone-iodineandsprayedwithantibacterialchlortetracyclinehydrochloridespray(CycloSpray,DechraVeterinaryProductsS.r.l).Prophylacticsystemicantibiotictreatmentwasgivenintheformofanintramuscular(IM)injectionof30mg/kgoflong-actingoxytetracycline(ENGEMICINAD.D.,MSD,MSDItaliaS.r.l.,Roma(RM),Italy).Inaddition,asubcutaneous(SC)admin-istrationof300 g/kgivermectin(Ivomec.,BoehringerIngelheimAnimalHealthItaliaS.p.A.,Milano(MI),Italy)wasperformedinordertopreventanyparasiticcomplications.

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Animals2023,13,407 6of9 2.3.4.Follow-UpAttheconclusionofthesurgicaloperation,aveterinarianobservedeachanimal’sawakeninguntilitachievedastablequadrupedalstation.Thenextday,eachfarmerwascalledbytelephonetoobtaininformationontheperiodbetweenrecoveryandresum-ingfeeding.2.4.StatisticalAnalysisAlldatawereenteredinanExcelsheet.TheShapiro–Wilktestwasusedtoverifythenormaldistributionofthedata.ThemeanandstandarddeviationofeachvariableforeachgroupwascalculatedusingStata17software(StataCorp,CollegeStation,TX,USA).Thecorrelationbetweenageandtensilestrength(CA-T)andweightandtensilestrength(CW-T)wascalculatedusingthePearsonlinearcorrelationcoefficientR.Resultswereconsideredsignificantlydifferentforap-valuelowerthan0.05.3.ResultsAll111animalsincludedinthisstudyweresuccessfullycastratedthrougheitherclassicalorsuturelesscastration.Noboarsfromgroup2requiredthesuturelessproceduretobereplacedbyconventionalcastration.Nocomplicationswererecordedduringthesurgeryortheimmediatepostsurgicalperiodinbothgroups.Theageofboarsfromgroup1rangedbetween5and36months,withanaverageof18.22months(sd.10.65),andtheageofboarsrangedbetween4and60monthswithanaverageof17.97months(sd.12.80)ingroup2.Furtherresults,includingweightandthetensilestrengthanddiameterofthedeferensductareshowninTable1.Table1.Averageandstandarddeviationofvariablesrecordedforgroups1and2;R:right;L:left;DD:deferensduct. Group1Age(months)Weight(kg)TensileStrengthR(kg)TensileStrengthL(kg)RightDDDiameterLeftDDDiameterDDTensileStrengthR(N)DDTensileStrengthL(N) Average18.22211.752.352.463.673.6422.4223.76standarddeviation10.6578.901.161.161.721.7110.4210.20 Group2 Average17.97192.722.222.404.054.0222.1723.56standarddeviation12.8093.851.141.301.621.6710.8312.75

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deviation10.6578.901.161.161.721.7110.4210.20 Group2 Average17.97192.722.222.404.054.0222.1723.56standarddeviation12.8093.851.141.301.621.6710.8312.75 CorrelationThecastrationtechniquewasnottakenintoaccountduringtheevaluationoftherelationshipbetweentensilestrengthandage/weight,andthusallanimalswereconsideredpartofasinglegroup.Infact,sincethevariableofinterestwasthetensilestrengthofthevasdeferens,theobservationalunitbecamethevasdeferensinsteadoftheboaritself,andthereforeeachdeferensduct(i.e.,leftorright)wasconsideredasasingleobservation.Accordingly,theaverageandmediantensilestrength,includingstandarddeviationandconfidenceintervals,werecalculatedforthetotalityoftheanimals(Table1).Pearson’slinearcorrelationwasusedtodetermineanypossiblecorrelationbetweenthedeferensduct’stensilestrengthandtheageandweightofeachanimal.ThecorrelationcoefficientRfortensilestrengthandagewasverycloseto1,withR=0.99withp<0.05;astrongcorrelationbetweenweightandtensilestrengthwasfoundaswell(R=0.96)(Figure3).

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Animals2023,13,407 7of9 Figure3.Theleftgraphshowsthecorrelationbetweenageandtensilestrengthinthepooledsample;therightgraphshowsthecorrelationbetweenweightandtensilestrengthinthepooledsample.Asignificantlystrongcorrelationwasfound(R=0.99andR=0.96,respectively(p<0.05)).4.DiscussionSuturelessorchiectomyiswidelyappliedforthecastrationoftomcatsandwasalsoreportedtobesuccessfulinyounglambsof4to6daysold[10]andpediatricandjuveniledogs[11].Thistechniquehasthepotentialtobelessexpensivethantraditionalorchiectomyandtoresultinfewerpost-operativecomplications,suchasinfections[12–14].Anotheradvantageofthesuturelessprocedureisthedurationofsurgery,whichissignificantlyshorter.Variouscastrationmethodsforpigletsaredescribedinthecurrentscientificliterature[15,16],whiletheunderstandingofsurgicalcastrationtechniquesforadultboarsislacking.Theprescrotalapproachemployedinthisstudywasactuallyfoundtobepoorlydescribedforadultboars.Infact,ascrotalincisionismostcommonlyadopted,withtheincisionbeingmadeventrallyinordertoallowforproperdrainage[17].Theuseofaprescrotalincisionfortheorchiectomyofadultboarshasonlybeendescribedonce,andthisapproachisthoughttoallowevenbetterdrainage,giventheventralpositioningoftheincision[9].Possiblecomplicationsarisingfromapplyingaprescrotalincisionincludeahigherriskofeviscerationinthecaseofaninguinalherniaandtheriskofasurgicalwoundinfectiondevelopingintoperitonitisgiventhecloseproximityofthesurgicalsitetotheinguinalcanal,whichcanactasarouteforascendinginfections[18].Thepurposeofthisstudywastoassessthefeasibilityandvalidityofsuturelessorchiectomyinadultboars,andthemainobjectivewastosuccessfullyperformthisprocedure.All20animalswithingroup2weresuccessfullycastratedusingthesuturelessmethodwithoutanypostsurgicalcomplicationsordeath(sameasforgroup1:classicalcastration).Themostcriticalaspectofapplyingthesuturelesstechniqueprovedtobethetighteningofsimpleknotsbetweenthespermaticandvascularportionsofthespermaticcord.Atthisstage,thevasdeferensmaybreak,leadingtosurgicalfailure.Forthispurpose,itwasdecidedtoevaluateseveralvariablesofthedeferensductduringorchiectomiesperformedingroup1,includingtheirdiameterandtensilestrength.Thelatterwascorrelatedwithageandweightoftheanimalsinordertodeterminethemaximumtractionforcetobeappliedforeachboar.Althoughithasbeenhypothesizedthatdeferensducttensilestrengthisdirectlyproportionaltoageandweight,tothebestofourknowledge,nostudiescorrelatingthesevariableshavepreviouslybeenconductedinpigs.Inthisstudy,witharelativelysmallsamplesizeandvariableageandweight,amorehomogeneoussamplewasconsideredbyconductingthecorrelationanalysisonapooledsample.Asexpected,astrongcorrelationwasfoundbetweenageandtensilestrength(R=0.99withp<0.05),aswellasweightandtensilestrength(R=0.96withp<0.05)(Figure3).Accordingtotheseresults,tensilestrengthisminimalinyoungboarsandincreasesprogressivelywithageandweight.

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Animals2023,13,407 8of9 Thankstotheidentificationofthesecorrelations,successfulsuturelesscastration(100%successrate)wasperformedon20boars,calibratingtheforceneededforoptimalnodaltightnesswithoutinducingvasdeferensrupture.Nopost-operativecomplicationswererecordedineithergroup,andanimalsresumedfeeding5haftercompleterecoveryfromanesthesia.Thenextstepinthevalidationofsuturelessorchiectomyinadultboarswillbetoperformshort-,medium-andlong-termfollow-upsofanimals.5.ConclusionsDuetoitspotentialadvantages,includingbeingsimpletoexecuteandmaster,thesu-turelesstechniquecanpotentiallybeconsideredavalidmethodforadultboarorchiectomy.Themostcriticalstepinsuturelesscastrationcorrespondstotheexecutionofthenodesbetweentheductusdeferensandthespermaticfuniculusinordertoachievetheproperhaemostasisofthevessels.Theforcerequiredtotietheseknotsisdirectlyproportionaltotheageandweightoftheanimals.Thisstudyhaslaidthecornerstoneneededtoproceedwithlarge-scaleclinicalstudiesonthesuturelesscastrationofadultboars.Futureresearchisneededinordertoexploreotheressentialaspectsofthistechnique,suchaswoundhealing,postsurgicalrecovery,andtheoccurrenceofshortandlong-termcomplications.Anin-depthinvestigationoftheoccurrenceofpostsurgicalcomplicationswaslefttothenextstageofresearch,whichwillconsistofalarge-scaleclinicalstudybasedonthefindingsofthisstudy.AuthorContributions:Conceptualization,N.C.;methodology,N.C.,A.S.andS.M.T.R.;formalanalysis,S.M.;datacuration,S.M.T.R.;writing—originaldraftpreparation,T.A.andS.M.;writing—reviewandediting,N.C.andS.M.;visualization,A.S.;supervision,N.C.Allauthorshavereadandagreedtothepublishedversionofthemanuscript.Funding:Thisresearchreceivednoexternalfunding.InstitutionalReviewBoardStatement:TheanimalstudyprotocolwasapprovedbytheEthicsCommitteeoftheUniversityofSassari(protocolcode139037).InformedConsentStatement:Informedconsentwasobtainedfromalltheownersinvolvedinthestudy.DataAvailabilityStatement:Notapplicable.Acknowledgments:Notapplicable.ConflictsofInterest:Theauthorsdeclarenoconflictofinterest.References1.Bellini,S.ThepigsectorintheEuropeanUnion.InUnderstandingandCombattingAfricanSwineFever:AEuropeanPerspective;WageningenAcademicPublishers:Wageningen,TheNetherlands,2021;pp.639–648.2.Popescu,A.TrendsinporkmarketintheEuropeanUnionandinitsmainproducingcountriesintheperiod2007–2018.Sci.Pap.Ser.Manag.Econ.Eng.Agric.RuralDev.2020,20,475–488.3.Bonazzi,G.;Camanzi,P.;Ferri,G.;Manghi,E.;Iotti,M.EconomicsustainabilityofpigslaughteringfirmsintheproductionchainofdenominationoforiginhamsinItaly.Sustainability2021,13,7639.[CrossRef]4.Tajet,H.;Andresen,Ø.Estimationofgeneticparametersofboartaint:Skatoleandandrostenoneandtheircorrelationswithsexualmaturation.Acta.Vet.Scand.2006,48,1–4.[CrossRef]5.Bonneau,M.;Weiler,U.Prosandconsofalternativestopigletcastration:Welfare,boaryaint,andothermeatqualitytraits.Animals2019,9,884.[CrossRef][PubMed]6.Agudelo-Trujillo,J.H.;Estrada-Pineda,J.F.;Guzmán-Gonzalez,P.Effectivenessofimmunocastrationinadultboars.OptionsMéditerranéennes.InProceedingsofthe7thInternationalSymposiumontheMediterraneanPig,Zaragoza,Spain,14–16October2010;pp.137–140.7.Fubini,S.L.;Ducharme,N.G.FarmAnimalSurgery;Saunders:Philadelphia,PA,USA,2016.8.Grimm,K.A.;Lamont,L.A.;Tranquilli,W.J.;Greene,S.A.;Robertson,S.A.VeterinaryAnesthesiaandAnalgesia:TheFifthEditionofLumbandJones;Wiley-Blackwell:Hoboken,NJ,USA,2015;pp.941–943.9.Câmara,A.C.L.;Campebell,R.C.;Nogueira,K.;Junqueira,J.V.S.;Andrade,T.S.;Neto,A.R.T.Pre-ScrotalCastrationProcedureinBoars.Res.Sq.(Posted)2022.

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