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DiagnosisofDiseases在整个牛群已进入牛棚以备挤奶后，一头母牛躺在草场中央。Theownerlookscloselyatthecowandurgeshertogetup.畜主仔细地检查母牛并催促它站起来。Shemakesafeebleattempttorisebutiseitherunableortoodepressedtotry.母牛徒劳地尝试站起来，但它不能或太消沉而不愿（站起来）。Acowliesinthemiddleofthepastureaftertheherdhasmovedintobemilked.这头母牛受伤了吗？它因吃东西而中毒了吗？Doesshehaveaseveresystemicinfection?Istheresomefunctionalchangeinhernervoussystem,digestivesystem,orurogenitalsystem?它患了严重的全身性感染吗？它的神经系统、消化系统或是泌尿生殖系统发生了功能变化吗？Isthecowinjured?Hasshebecomeintoxicatedbysomethingsheate?确定疾病性质的过程就是诊断。Makingadiagnosisisasystematicprocessofcollectingallthefactsandmakinganobjectiveevaluationofthemwhileconsideringallthatisknownaboutspecificdiseasesandtheirsigns.诊断是在考虑所有熟悉的特定疾病及其症状的情况下，收集全部资料并对这些资料进行客观评价的系统过程。Theprocessofdeterminingthenatureofdiseaseisdiagnosis.为什么需要做出诊断？在这一躺卧母牛的例子中，诊断对保护牛群中的其他牛是必要的。Ifthecauseofherdiseaseisavailabletotherestoftheherd,itmustbeeliminatedtopreventfurtherloss.如果它的病因对牛群的其他牛也存在，就必须消除这一病因以防止进一步的损失。Whymakeadiagnosis?Intheexampleofthe“downer”cow,adiagnosisisnecessaryfortheprotectionoftherestoftheherd.Ofsecondaryimportanceisthecorrectapproachtorestoringthecowtohealth,whichdependsondeterminingthenatureofthedisease.第二重要的是釆用正确方法以恢复那一病牛的健康，这取决于对疾病性质的确定。即使当表面上明显的症状指明特定的疾病时，大多数诊断医生已认识到不能匆忙做结论。Thechanceforerrorfromhastyandsuperficialevaluationsisgreat.因仓促及肤浅评价而(发生)错误的机会很大。Mostdiagnosticianshavelearnednottojumptoconclusions,evenwhenapparentlyclear-cutsignspointtospecificdiseases.要分析的资料可通过问诊和检查各种可能得到的病历来收集；这包括畜群健康、近来的生产及繁殖状况、营养（状况）、过去的疾病及治疗、免疫接种、近来的活动及行为，以及畜主已经注意到的各种症状的所有资料。Factstobeevaluatedarecollectedbyquestioningtheownerandexaminingrecords,ifavailable,regardingalltheinformationaboutthehealthoftheherd,currentproduction,reproductionstatus,nutrition,previoussicknessandtreatment,vaccinations,recentactionsandbehavior,andsignstheownermayhavenoticed.Thisphysicalexaminationinvolvesanappraisaloftheoverallappearanceofthecow,hergeneralcondition,andmentalattitude.这一体检包括对母牛总的外貌、它的总体情况及精神状况的评价。Then,acarefulexaminationofthecowismadetocollectsignsofalteredstructureorfunction.然后，仔细检查母牛以收集结构或功能改变的症状。Italsoincludesthecollectionofindicestohergeneralconditionbydeterminingthebodytemperature,respiratoryrateandquality,andpulserateandquality.体检也包括通过确定体温、呼吸率及质量以及脉搏频率及质量来收集（反映）母牛全身状况的指标。Increaseinbodytemperatureorfevermaybeanindicationofasystemicinfectionormaysimplyindicatehighenvironmentaltemperature.体温升高或发热可能是全身感染的一个指征，或只是表明环境温度高。Decreaseinbodytemperaturecouldindicateintoxication.体温降低可能表明中毒。Absenceofchangesfromthenormalinanyofthesevaluesisjustasimportantasthepresenceofachange.这些（指标中的）任何一个值未发生变化和发生变化同样重要。Anincreaseinrespirationcouldindicateexcitement,fever,lunginfection,oranemia.呼吸加快可能表明兴奋，发热，肺部感染或贫血。Pulseconditionandrateareaffectedbypain,fever,bloodvolume,andgeneralcirculatorychanges.脉搏状况和频率受疼痛，发热，血量和一般性循环（系统）变化的影响。通过分别或同时对每个系统（如循环、呼吸、消化、神经、肌肉-骨骼、泌尿）所需细节进行评价来进行检查。Bydoingso,thediagnosticiancontinuestocollectfactsastowhatisnormalandwhatisaltered.由此医生继续汇集正常和异常资料。Theexaminationproceedsbyevaluationofeachsystem(i.e.,circulatory,respiratory,digestive,nervous,musculoskeletal,urogenital),separatelyorconcurrently,inasmuchdetailasnecessary.如果全面体检后疾病仍不能确诊，就需采集组织、血液、分泌物或排泄物进行实验室分析。Otherdiagnostictools,suchasradiographs,mayhelpbutareinconvenienttouseinanopenpasture.其他诊断工具（如X光片）可能有用，但在开放牧场中不方便使用。Iftheexactdiseaseisstillquestionableafteracompletephysicalexaminationismade,itmaybenecessarytocollecttissues,blood,secretions,orexcretionsforlaboratoryanalysis.一经确诊，控制或预防疾病影响其他牛以及治疗病牛的方案即可启动。Ifthediseaseismetabolic,nutritionalchangescanbemade.如果是代谢疾病，就需调整营养成分。Ifthediseaseisinfectious,stepsmustbetakentopreventtheothercattlefromcontact.如果是感染性疾病，就必须采取防止其他牛接触的措施。Oncethediagnosisismade,thecourseofactionselectedtocontrolorpreventthediseasefromaffectingtherestoftheherdandtotreatthecowcanbeinitiated.Ifthediseaseisduetoatumororindividualanomaly,theherdisnotthreatened.如果是肿瘤或个体异常导致的疾病，牛群就不会被危及。Ifthediseaseistraumatic,thecausemustbedeterminedandeliminated.如果是外伤引起的疾病，就需确定并消除病因。Ifthediseaseisintoxication,thesource,plantorchemical,mustbefoundandremoved.如果是中毒，就必须找到并清除毒源（植物或化学药品）。Theneedforandbenefitfromdiagnosisofasickanimaloranimalsinaherdareobvious.对畜群中患病动物的诊断的需求和益处是显而易见的。But,whatifthecowintheexamplewerealreadydead?但是，如果上例中的奶牛死了该怎么办？仍需保护牛群，可能更为急迫，因为此病因能致死牛群中的其他牛。Thediagnosticexaminationentailsthesamecollectionoffacts,butinthisinstance,thefactsarecollectedfromtheanimalcarcassbypostmortemexaminationornecropsy.诊断检查势必需要收集资料，但是在这种情况下，是通过尸检来收集资料的。Theneedtoprotecttheherdisstillpresent,perhapsevenmoreurgentlybecausethecausecankilltheothersintheherd.由于家畜通常成群饲养，除非立即采取积极措施清除或隔离病因并保护易感动物，否则疾病导致的损失可能是迅速而严重的。Lossescanbereducedbymakingcertainthatnosickordeadanimalisundiagnosed.可通过对患病或死亡动物进行诊断而减少损失。Sincefarmanimalsusuallycondensedintoherds,thelossesfromdiseasecanberapidandsevereunlessimmediateactivestepsaretakentoremoveorblockthecauseandprotectsusceptibleanimals.兽医在诊断技能上训练有素。Theobjectiveoftheireducationandexperienceisfundamentallytodevelopanunderstandingofthesignsofdiseaseandtheeffectsofdiseaseprocesses.他们所受教育和工作经历的目的从根本上理解疾病的症状及疾病进程的影响。Veterinariansaretrainedi