COMPLETE BLOOD COUNT - Scott E. Mc ?· COMPLETE BLOOD COUNT As a general rule, I do not recommend laboratory…

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<ul><li><p>COMPLETEBLOODCOUNT</p><p>Asageneralrule,Idonotrecommendlaboratorytestsonclinicallyhealthypetbirdsthatarebroughttomeforroutinephysicalexaminationandgroomingonaregularbasis.Inmyexperience,ifabirdisactingnormalathome,ifIseenothingabnormalontheexam,theninalllikelihoodlaboratorytestswillbenormalaswell.Thatbeingsaid,therearetwobasictests(whichcanberequested)thataregood,additionalindicatorsofhealth;thefecalGramstainandthecompletebloodcount.TheGramstainisdiscussedinaseparatepaper.Thecompletebloodcount(CBC)isagood,sensitiveindicatorofthebirdsgeneralhealth.Achangeinthehemogramcanbenotedwhennootherabnormalitiesaredetected.Itisthesinglemostimportantbloodtestthatcanbeperformed.IfallparametersarenormalontheCBC,thenthisisagoodindicationthatthebirdisnotcurrentlyfightingsometypeofgeneralizedinfectionorinflammatorydiseaseprocess.However,anormalCBCdoesnotruleoutthepossibilitythatthebirdisanasymptomaticcarrierofabacterialorviraldiseaseorhasalocalizedinfection.TherearethreetypesofcellswhichareevaluatedontheCBC;redbloodcells(RBCsorerythrocytes),whitebloodcells(WBCs)andthrombocytes.Inaddition,theplasma(noncellularpartoftheblood)isexaminedforcolor,protein,andthepresenceofparasites.ThefollowingisalistofparametersmeasuredontheCBCwitharangeofnormalvalues.Valuescanvarygreatlybecausetherearesomanydifferentkindsofpsittacinebirds.Therearealsodifferencesbetweenjuvenilesandadults.</p></li><li><p>CBCPROFILEPARAMETER RANGEOFNORMALVALUESRBC(millionsofcells/cumm) 2.54.5PCV%(packedcellvolume) 4255Polychromasia slt(slight)Anisocystosis sltMCV 100200WBC(cells/cumm) 500015000Heterophils% 4075Lymphocytes% 2050Basophils% 05Eosinophils% 02Monocytes% 03Buffycoat% 01 COMMENTS noneThrombocytes presentPlasmaColor clearorpaleyellowTotalprotein(gm/dl) 2.55.5Parasites none</p></li><li><p>REDBLOODCELLSExaminationoftheerythrocytesprovidestheveterinarianwithinformationconcerninganemiarelatedproblemsandthebonemarrowresponse(whichiswhereRBCsareproduced).Inahealthybird,mostRBCsshouldbemature,butasmallpercentageofimmatureerythrocytesisexpectedwhichindicatesanormalreplenishmentfromthebonemarrow.ImmatureRBCsareslightlylargerthanmatureRBCsandthecytoplasmislightlystippledwhichproducesadifferenceincolor.ANISOCYTOSIS(sizevariationbetweenRBCs)andPOLYCHROMASIA(colorvariationbetweenRBCs)aretermsusedtoindicatethepresenceofimmatureRBCs.OntheformusedtoindicatetheresultsoftheCBC,aslight(slt)responseisnormalwhilemoderateormaximumindicatesastrongbonemarrowresponsetosometypeofanemiaproblem.Ifabirdisanemicandshowsslighttonopolychromasiaoranisocystosisoveraperiodofseveralweeks,thiscanindicatethatthebonemarrowisdepressedornonregenerativewhichisagravesituation.Meancorpuscularvolume(MCV)isameasurementoftheaveragesizeofRBCs.Thevaluerisesinanemicconditionsthatareregenerativebecausenewlyproducedredbloodcellsincreaseinnumbersandthesecellsarelargerthanmaturecells.Ifthevalueisbelownormalandthebirdisanemic,thenthisindicatesanonregenerativestate.Anemiameansadecreaseinthenormalamountofredbloodcells.ItcanbeduetoeitherbloodlossorlackofproductionofnewRBCsfromthebonemarrow.TheratioofthevolumeofRBCstothevolumeofwholebloodiscalledthePACKEDCELLVOLUME(PCV).Thisnumberisexpressedasapercentage.Itisdeterminedbyputtingasampleofbloodinatinycollectingvialcalledamicrohematocrittube.Atthelaboratorythistubeisspuninacentrifugewhichseparatestheredbloodcellsfromtheplasma.Inanormal,healthybird,thePCVrangesbetween4255%.Smallbirdssuchasbudgiesandcockatielsaverage50%orhigherwhilethevaluesinlargerspeciesareusuallylower,between4245%.Anyvaluelessthan35%indicatesanemiaandobviouslythelowerthevalue,themorecriticalthecondition.Valueshigherthan55%aremostoftencausedbydehydration.</p></li><li><p>TheactualnumberofRBCscanalsobecounted,usingeitherautomatedcellcountingmachinesorbymanualtechniqueswhichprovidegoodestimates.ThenumberofRBCsisrecordedasanumbertimes10tothesixthpowerwhichmeansmillionsofcellspercubicmillimeter(cumm)ofwholeblood.ThenormalnumberofRBCsvariesdependingonwhetherthebirdisajuvenileoradultandthekindofbirdbeingexamined.Ingeneral,mostadult,healthypsittacinesaveragearound2.54.5millionRBCs/cummofblood.Asabirdbecomesanemic,thenumberofRBCsdecreases.WHITEBLOODCELLSWhitebloodcells(WBCs)arepartofthebodysdefenseorimmunesystem.TherearefivetypesofWBCsfoundinbirds.Heterophils,eosinophils,andbasophilsareknownasgranulocytesbecausetheyallcontaincoloredgranules(tinyspindleshapedbodies)intheircytoplasm.Thesecellsareallproducedinthebonemarrow.LymphocytesandmonocytesareknownasmononuclearWBCs.Thesetwotypesofcellshaveasinglenucleusandnogranulesintheircytoplasm.Theyoriginateinthespleenandintinycollectionsoflymphoidtissuefoundthroughoutthebodyasopposedtothebonemarrow.DuringthecollectionofbloodforaCBC,atinydropisplacedonaglassmicroscopecoverslip.Asecondcoverslipisplacedontopandthetwoarepulledapartcreatingabloodsmearonecelllayerthick.Backatthelaboratory,thissmearisstainedwithabluedyewhichcolorsthedifferentcellssotheycanbeidentified.Bylookingatthesmearunderthemicroscope,thetotalwhitebloodcellcountcanbeestimatedaswellasdeterminingthenumberandrelativeproportions(%)ofthefivedifferenttypesofWBCs.Inaddition,theWBCscanbeexaminedforabnormalcharacteristics.Allthesefindingsaresignificantindeterminingwhetherabirdisfightingsometypeofdiseaseandhowseriousitis.</p></li><li><p>WHITEBLOODCELLCOUNTThetotalWBCcountcanalsobedeterminedbyphysicallycountingallofthegranulocytesinadilutionofwholebloodthatisstainedandputinacellcountingchambercalledahemacytometer.Thecytoplasmicgranulesofthesecellsarespecificallyhighlightedbythedyewhichmakesthemeasytocount.ByalsoknowingthepercentageofmononuclearWBCspresentfromthebloodsmear,onecanarriveatafairlyaccuratetotalWBCcount.ThenormalWBCcountcanvaryfromlaboratorytolaboratory.Itisdependentonthestainingqualityofthesmearandtheproperidentificationofcells.Inthelabweuse,thenormalWBCcountinadultpsittacinesvariesbetween500015000cells/cummofblood.Insmallerspecies(i.e.budgies,cockatiels)thenormalrangetendstobelower(500010000cells/cumm)thaninlargerspeciessuchasAmazonsandmacaws(1200015000cells/cumm).JuvenileparrotsusuallyhavehigherWBCcountsthanadults.Itisnotuncommontoseecountsinthe2000025000cells/cummrangeinlargepsittacinesthatarenearweaningage.Acrude,rapidtechniqueforestimatingiftheWBCcountishighisbymeasuringtheBUFFYCOAT.Whenthemicrohematocrittubeisspunatthelaboratorythereisatinylayerofwhitecellsthatseparatesoutatthejunctionbetweentheredcellsandplasma.Thisiscalledthebuffycoat.Inanormal,healthypsittacinebird,thebuffycoatshouldbe1%orlessofthetotalvolumeofblood.Abuffycoatof2%orhigherindicatesahighWBCcount.6%isthehighestamountourlabhasevermeasured.AnincreaseintheWBCcountiscalledleukocytosis.Acommoncauseofleukocytosisistheactualtransportingandhandlingofabirdattheclinic.Thisisaphysiologicalchangeduetostress.Diseasecausesincludebacterialandfungalinfection,psittacosis,avianTB,trauma,toxicities,andcertaincancers,suchasleukemia.AdecreaseintheWBCcountiscalledleucopenia.Themostcommoncausesofthisincludeacuteviralinfectionsandtheendstagesofoverwhelmingsepticemia(bloodpoisoning)inwhichthebodyliterallyrunsoutofWBCswithwhichtofightwith.</p></li><li><p>ThepercentageofthedifferenttypesofWBCsiscalledthedifferential.Asstatedbefore,alternationsofthedifferentialfromthenormalrangeandchangesincellcharacteristicsaresignificantforvariousdiseaseconditions.HETEROPHILSTheheterophilisthemostcommongranulocytefoundinpsittacinebirds.Thenormalpercentageofheterophilsisbetween4075%.Itisconsideredthewindowtothebirdsstateofhealthsinceevensubtlechangesinnumbersandcharacteristicscanoccurwithproblemssuchasstress,lowgradeinfection,andmildinflammation.ThesecellsareinstrumentalinthebodysdefensewithincrediblylargenumbersbeingavailabletodestroyandengulfbacteriaorotherinfectiousagentsseeninacuteoroverwhelminginfectionandinflammationHeterophilsexhibittoxicchangesinstressordiseaseconditionsthatcanbeseenmicroscopically.Alowdegreeoftoxicityiscalleddegranulation.Thisisseenasadecreaseinthenumberandsizeofcytoplasmicgranulesandachangeincolorofthecytoplasmfromcolorlessorlightbluetoamuddypinkorredcolor.Ifdegranulatedheterophilsareseenonthebloodsmear,thiswillbenotedundertheCOMMENTSsection.Ifnothingiswritten,thenthismeansalltheheterophilsappearnormal.Milddegranulationofheterophilscanbeconsiderednormalinbirdsunderstress.However,thisfindingshouldalerttheveterinarianthatsomethingisgoingon,especiallyifthetotalWBCcountishigherthannormal.Insevere,generalizedillnesses,theWBCcountmayriseabovenormalwithavaryingnumberoftheheterophilsappearingdarkandshrunken.Inadditiontodegranulation,thesecellsmayappearfoamy(thepresenceofvacuolesinthecytoplasm),ortohaveruptured.Thepresenceofbacteriamayalsobeevidentinthecytoplasm.Suchheterophilsaredescribedasbeingtoxic.Thedegreeofheterophiltoxicityusuallyincreaseswiththeseverityofthebirdscondition.Birdshavingahighdegreeoftoxicityinmostoralloftheirheterophilsoftenhaveagraveprognosis.Thisisespeciallytrueifleucopeniaispresent.</p></li><li><p>EOSINOPHILSANDBASOPHILSEosinophilsaresimilarinappearancetoheterophilsbutcanbedifferentiatedbythecolorandshapeoftheircytoplasmicgranulesandthedarkerstainingnucleus.Eosinophilsoccurinverysmallnumberswiththenormalrangeconsideredtobe02%.Thefunctionoftheavianeosinophilisunclear;however,increasednumbersaretypicallyassociatedwithparasiticinfections,allergicreactions,andsignificanttissuedamage.Changesincellmorphologyhavenotprovenhelpful.Basophilsareeasytoidentifybecauseoftheirdarkstaining(basophilic)cytoplasmicgranules.Theyalsooccurinsmallnumberswithanormalrangeof05%.Theexactfunctionofthebasophilisnotknown.Increasednumbersareoftenassociatedwithchronic,longtermillnesses.Theyalsoappeartoplayaroleintheearlystagesofinflammation.LYMPHOCYTESLymphocytesandheterophilsarethemostnumerousWBCsseeninpsittacinebirds.Thenormalproportionoflymphocytesis2050%butitvariesbetweenspecies.SomespeciessuchascockatielsandAmazonparrotsarenaturallylymphocyticwhichmeansmorelymphocytesthanheterophilsareseennormally.Lymphocytesareaveryimportantpartofthebirdsimmunesystem.Lymphocytesincreaseinnumbers(lymphocytosis)incertaintypesofchronicinfectionsandlymphoidleukemia.Theydecreaseinnumbersinacuteviralinfections.Inadiseasestate,lymphocyteswillbecomereactive.Microscopically,thenormallypalebluecytoplasmbecomesmulticoloredwithlightblue,clear,andpinkareasandthecytoplasmbecomesvacuolated(thepresenceoftinybubblelikestructures).Inchronicconditionslymphocyteswithazurophilic(purple)granulesinthecytoplasmhavebeennoted.Afewreactivelymphocytesonabloodsmearisnormalbutifmanyarereactivethenthisisasignificantfindingthatthebodyisrespondingtoaninfectionofsomesort.Ifreactivelymphocytesarepresent,thiswillbenotedundertheCOMMENTSsection.Reactivelymphocytessynthesizeantibodiesandotheragentsinvolvedinthehostimmunesystem.</p></li><li><p>Birdswithamarkedlymphocytosisinwhichmostorallofthelymphocytesappearabnormalorimmatureisconsistentwithleukemia.TheWBCcountinsuchbirdscanbegreaterthan100,000cells/cummofwhichmostarelymphocytes.MONOCYTESThesearethelargestWBCsfoundinavianbloodandtheyareverysimilarinappearancetolymphocytes.Theyoccurinsmallnumberswithanormalrangeof03%.Anincreaseinthepercentageofmonocytes(upto10%)isseenwithcertainchronicdiseasessuchaspsittacosis,systemicfungalinfections,TB,andmassivetissuedestruction.Changesincellmorphologyarenotsignificant.TheevaluationoftheWBCcount,thedifferential,andcellmorphologyisveryusefulintheassessmentoftheprogressofanavianpatient.Forexample,abirdwithaninitialleukocytosis,increasedheterophilswhichappeartoxicandreactivelymphocyteswouldbeshowingafavorableresponsetotherapyifthetotalWBCandheterophilcountsweredecreasing,thetoxicheterophilshaddisappeared,andthereactivelymphocytesreturnedtonormal.THROMBOCYTESThrombocytesarethethirdtypeofcellsfoundinavianbloodandtheseareactiveparticipantsinbloodcoagulationorclotting.Birdsdonothaveplatelets(cellcytoplasmicfragments)whichperformthisfunctioninmammals.Thrombocytesareproducedinthebonemarrow,areslightlysmallerthanerythrocytes,andareoftenclumpedtogetherinsmallnumberswhenviewedonabloodsmearunderthemicroscope.Inadditiontobloodclotting,thesecellsmayhavetheabilitytophagocytize(oreat)bacteriaandforeignmaterial(likesomeWBCs)andtheymaybeabletocarryoxygen(likeRBCs)ifanextremeanemicconditionexists.</p></li><li><p>DuringtheCBCevaluation,thepresenceofthrombocytesisnotedontheformandifthenumbersseemdecreasedorincreased,thisisalsoindicated.Increasednumbersofreactivethrombocytescanindicateachronicdiseasecondition.PLASMAPlasmaisthefluidportionofbloodinwhichparticulatecomponentsaresuspended.Plasmaisdistinguishedfromserumwhichisthecellfreeportionofthebloodfromwhichfibrinogen(bloodclottingfactors)hasbeenseparatedintheprocessofclotting.WhenbloodisdrawnforaCBC,thecellcomponentsneedtobeevaluated;therefore,thebloodmustnotclot.Heparinistheanticoagulantofchoiceinbirds.ThemicrohematocrittubesorlargervialsusedtocollectbloodforaCBCareheparinizedtopreventcoagulation.ColorAfterthemicrohematocrittubeisspunatthelaboratorytheplasmaisvisuallyexaminedforcolor.Inmostbirdsitshouldbeclearorpaleyellowincolor.Theyellowcolorisduetothepresenceofcaroteneswhichareyellowpigmentsfoundinavarietyofplantmaterials,includingsomeseeds.Yellowcoloredplasmashouldnotbemisinterpretedasictericplasma.Inmammals,icterusorjaundiceisduetoincreasedamountsofbilirubinpigmentsinplasmaasaresultofliverdisease.Birdsdonothavebilirubin;thereforetheydonotbecomeictericiftheyhaveliverdisease.Sometimestheplasmaappearspinkincolor.ThisisduetohemolysiswhichisthebreakingapartofRBCsandthesubsequentreleaseofredhemoglobinmoleculesintotheplasma.Hemolysisismostcommonlycausedbyimproperhandlingofbloodsamples,suchasforciblyexpellingbloodthroughtheneedleofthesyringe,shakingratherthansimplyinvertingthetubetomixbloodwiththeanticoagulant,overcentrifugation,orfreezingandthawingofthesample.Sometoxicitiescancauselysisofbloodcells,themostcommonexamplebeingleadpoisoning.Occasionallyanoverwhelminginfectioncausingsepticemiawillalsocausehemolysis.</p></li><li><p>Theplasmacanalsoappearwhiteormilkyincolorwhichisduetothepresenceoffat.Thisiscalledlipemia.Lipemicplasmaismostcommonlyseenifabloodsampleisdrawnshortlyafterthebirdeatsamealhighinfat(i.e.oilyseeds).Sometimesifthebirdisexcessivelyoverweight,theserumwillalwaysappearmildlylipemic.Liverorpancreaticdisorderscancauselipemia.Lastly,infemalebirdsthatarereproductivelyactive,theplasmawillbelipemicduetoyolkglobules(fatsandprotein)whicharesynthesizedintheliverandtransportedviatheplasmatotheovarywheretheyareincorporatedintheoocyte.TotalProteinWhileplasmaismainlywater,itdoescontainasubstantialamountofprotein.Mostplasmaproteins,withtheexceptionofantibodiesandhormones,aresynthesizedintheliver.Proteinsformthebasisoforganandtissuestructure,operateascatalysts(enzymes)inbiochemicalreactions,areregulators(hormones),andarethetransportandcarriercompoundsformostoftheconstituentsofplasma.Thetotalproteinlevelintheplasmaisoftenusedasanindicatorforthehealthstatusofthepatient.Themeasurementoftotalproteinisasimpletesttoruninthelaboratory.Mostpractitionersuseaninstrumentcalledarefractometerwhichgivesagoodestimateoftheproteinlevelaslongastheplasmaisclear.Hemolysisorlipemiawillgiveafalselyelevatedlevel.Thenormalvalueforpsittacinespeciesisinarangebetween2.55.5grams/deciliter(...</p></li></ul>

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