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     Anemia: Determining the Cause

    by Wendy Fleischman, DVM, DACVIM June 2012 V!l "#, $! %&

    Abstract

     Anemia is a common finding in small animal practice; however, the multitude of potential

    causes can make determining the underlying diagnosis a challenging and frustrating endeavor.

    With a basic understanding of red blood cell production and a systematic diagnostic approach,

    clinicians should be able to clearly define the cause of anemia in most cases.

     Anemia re'ers t! a reduced hem!gl!bin c!ncentrati!n due t! decreased red bl!!d cell mass(

    )his can be e*+ressed as a +aced cell -!lume .CV&, hemat!crit, red bl!!d cell /C& c!unt,

    !r hem!gl!bin le-el bel! the re'erence inter-al( F!r sim+licity, hemat!crit !r .CV ill be used

    in this article(

    Erythropoiesis and Erythrokinetics

     A basic gras+ !' /C +r!ducti!n can c!ntribute much t! understanding the causes !' anemia(

    In adult mammals, /Cs are +r!duced +rimarily in the b!ne marr!(1 )he /C mass can be

    di-ided int! '!ur +hases !r c!m+artments: stem cells, +r!genit!r cells, +recurs!r cells, and

    mature erythr!cytes(2 A diagram illustrating the de-el!+ment !' /Cs is +r!-ided in FIGURE

    1 .

    Stem Cells

    )he hem!+!ietic stem cells are a small +!+ulati!n !' unc!mmitted, sel'reneing germ cells(

    )hese cells can gi-e rise t! all ty+es !' bl!!d cells erythr!cytes, leu!cytes, and +latelets&(

    In3ury t! the stem cell c!m+artment is an unc!mm!n cause !' anemia( In such a situati!n, the

    anemia is acc!m+anied by de'iciencies in the !ther t! cell lines, a c!nditi!n re'erred t!

    as aplastic anemia, !r, m!re c!rrectly, aplastic pancytopenia( /e+!rted causes !' a+lastic

    +ancyt!+enia are listed inBOX 1("45

    BOX 1. Reported Causes of Apastic Ane!ia "Apastic #ancytopenia$ in %o&s and

    Cats'()

    Infectious a&ents

    • .ar-!-irus

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    • Ehrlichia s++

    •  Anaplasma s++

    • Fe6V

    • FIV

    %ru& effects*hor!ones

    • 7y+erestr!genism e*!gen!us !r end!gen!us&

    • Chem!thera+eutics, a8athi!+rine, hydr!*yurea

    • 9rise!'ul-in, 'enbenda8!le, albenda8!le

    • )rimeth!+rimsul'adia8ine, chl!ram+henic!l

    • Methima8!le

    • .henylbuta8!ne

    • )hiacetarsamide

    • ;uinidine

    Radiation

    Idiopathic*i!!une+!ediated

    ,yeophthisis

    • $e!+lasia

    • Fibr!sis

    Progenitor Cells

    7em!+!ietic gr!th 'act!rs dri-e +luri+!tent stemcells t! bec!me +r!genit!r cells c!mmitted t!

    a s+eci'ic cell line( )he cyt!ines and h!rm!nes in the cells< en-ir!nment then

    dri-e'urtherdi''erentiati!n and +r!li'erati!n !' the +r!genit!r cells(In the case !' erythr!cyte

    +r!genit!r cells, the h!rm!ne that causes di''erentiati!n and +r!li'erati!n is

    erythr!+!ietin(%

    =rythr!+!ietin is +r!duced by renal interstitial cells in res+!nse t! renalhy+!*ia(> =rythr!+!ietin inhibits a+!+t!sis +r!grammed cell death& !' the erythr!id +r!genit!r

    cells, all!ing them t! di''erentiate int! erythr!id +recurs!r cells and, e-entually, mature

    erythr!cytes( 6ac !' erythr!+!ietin !r an inability !' the +r!genit!r cells t! res+!nd t!

    erythr!+!ietin are c!mm!n mechanisms leading t! n!nregenerati-e anemia(

    Precursor Cells

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    .recurs!r cells are 'ully c!mmitted t! !ne cell lineage and mae u+ m!st !' the cells ithin the

    b!ne marr!( )hey de-el!+ al!ng a +re+r!grammed +athay !' +r!li'erati!n and

    maturati!n(2Maturati!n and release !' erythr!cyte +recurs!r cells can be en!rm!usly

    accelerated in res+!nse t! erythr!+!ietin( ?nc!mm!nly, -itamin de'iciency !r c!ngenital

    hem!gl!bin !r cyt!seletal de'ects can lead t! dys'uncti!nal maturati!n !' the +recurs!r cells,hich can result in n!nregenerati-e anemia(@, Destructi!n !' +recurs!r cells, such as !ccurs in

    +ure red cell a+lasia ./CA& and immunemediated ine''ecti-e erythr!+!iesis, causes a

    n!nregenerati-e anemia(10,11

    Mature Erythrocytes

    )he 'inal c!m+artment !' the /C mass is c!m+!sed !' mature erythr!cytes( Mature

    erythr!cytes e*trude their nuclei and cell !rganelles be'!re being released int! the

    bl!!dstream( Disease +r!cesses that alter this c!m+artment t! cause anemia are /C l!ss

    internal !r e*ternal bleeding& and destructi!n hem!lysis&( In m!st cases, anemia due t! bl!!d

    l!ss !r destructi!n is regenerati-e(

    %ia&nostic -ests

    )he initial e-aluati!n !' anemia reBuires '!ur diagn!stic tests: measurement !' the .CV !r

    hemat!crit, Buanti'icati!n !' t!tal +lasma s!lids ) +lasma +r!tein and 'ibrin!gen&

    c!ncentrati!n by re'ract!metry, e*aminati!n !' a bl!!d smear, and a c!m+lete bl!!d c!unt

    CC&( )hree !' these tests can be +er'!rmed immediately by alm!st all +ractiti!ners and yield

    a great deal !' in'!rmati!n( )he .CV and ) -alues are determined a'ter centri'ugati!n !' a

    small Buantity !' bl!!d in micr!hemat!crit tubes( )he .CV identi'ies the +resence !' anemia

    and all!s determinati!n !' se-erity( )he ) c!ncentrati!n may hel+ distinguish beteen bl!!d

    l!ss and hem!lysis( =*aminati!n !' the serum in the micr!hemat!crit tube ill re-eal

    hy+erbilirubinemia !r hem!gl!binemia, i' +resent( An alg!rithm '!r the diagn!sis !' anemia is

    +resented in FIGURE  .

    The Blood Smear 

    l!!d smear e*aminati!n +r!-ides instantane!us in'!rmati!n ab!ut the nature !' the anemia

    thr!ugh !bser-ati!n !' /C m!r+h!l!gy( Additi!nally, many erythr!cyte abn!rmalities that

    cann!t be detected by !ther tests may be re-ealed !n a bl!!d smear( A 'e e*am+les are the+resence !' s+her!cytes, aut!agglutinati!n, 7ein8 b!dies, +!iil!cytes i(e(, abn!rmally

    sha+ed erythr!cytes&, erythr!+arasites, and nucleated /Cs( +her!cytes a++ear smaller than

    n!rmal /Cs and lac central +all!r( In d!gs, the +resence !' s+her!cytes and

    aut!agglutinati!n suggests immunemediated hem!lytic anemia IM7A&(12 Identi'icati!n !'

    s+her!cytes in cats is n!t +!ssible because n!rmal 'eline /Cs are smaller and dem!nstrate

    less central +all!r than canine /Cs(1" 7ein8 b!dies are small, r!und +ieces !' denatured

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    hem!gl!bin that !'ten +r!trude 'r!m the cell margin( =ccentr!cytes are /Cs in hich the

    hem!gl!bin has shi'ted t! !ne side, lea-ing a clear 8!ne al!ng the !ther side( /u+tured

    eccentr!cytes are called pyknocytes( 6ie s+her!cytes, +yn!cytes are smaller than n!rmal

    /Cs, lac central +all!r, and may be di''icult t! a++reciate in cats( )he +resence !' 7ein8

    b!dies, eccentr!cytes, and +yn!cytes indicates !*idati-e damage t! /Cs, such as !ccursith !ni!n, acetamin!+hen, 8inc, and !ther t!*ic!ses as ell as se-eral metab!lic diseases in

    cats(1#41%

    =chin!cytes, hich ha-e sh!rt, e-enly s+aced s+icules, are !'ten the result !' bl!!d drying

    sl!ly !n the slide but are als! seen ith certain c!nditi!ns such as gl!merul!ne+hritis,

    lym+h!sarc!ma, and rattlesnae en-en!mati!n(1>,1@ Acanth!cytes ha-e large, irregularly

    s+aced +r!3ecti!ns and are m!st c!mm!nly ass!ciated ith hemangi!sarc!ma in d!gs and

    he+atic li+id!sis in cats(1,20chist!cytes and erat!cytes are +ieces !' /Cs, the latter ith

    s+icules( )hese cells indicate /C 'ragmentati!n, as is seen ith disseminated intra-ascular

    c!agulati!n and hemangi!sarc!ma(21 $ucleated /Cs may be n!ted ith acceleratederythr!+!iesis !r may suggest s+lenic disease, b!ne marr! disease, !r lead +!is!ning(22

    The Reticulocyte Count 

    /eticul!cytes are /Cs that ha-e been released 'r!m the b!ne marr! be'!re c!m+lete

    e*trusi!n !' all /$A and cellular !rganelles( )hey can be dem!nstrated in a bl!!d smear using

    su+ra-ital stains such as ne methylene blue !r brilliant cresyl blue( )hese stains +reci+itate

    the /$A in the reticul!cyte, staining it blue( /eticul!cytes stained ith ne methylene blue

    a++ear as erythr!cytes ith blue granules( /eticul!cytes are generally n!t !bser-ed '!r 2 t! #

    days a'ter an acute e+is!de !' bl!!d l!ss !r hem!lysis( )he reticul!cyte res+!nse generally+eas beteen # and > days a'ter the insult and starts t! decline at 2 t! " ees in d!gs and

    t! 1" days in cats, assuming the underlying cause !' the anemia has been treated(2",2#

    )here are t! ty+es !' reticul!cytes: aggregate and +unctate( Aggregate reticul!cytes are

    larger and less mature than +unctate reticul!cytes( Cats are uniBue in that their +unctate

    reticul!cytes ha-e a l!ng hal'li'e in bl!!d and there'!re can re'lect an insult that !ccurred days

    t! ees +ri!r t! testing(2",2# .unctate reticul!cytes d! n!t accumulate in large numbers in

    d!gs( Aggregate reticul!cytes are c!nsidered an indicat!r !' current regenerati!n in b!th

    s+ecies(

     A reticul!cyte c!unt can be +er'!rmed by incubating a small am!unt !' =D)Aantic!agulated

    bl!!d ith an eBual am!unt !' a su+ra-ital stain such as ne methylene blue '!r 10 minutes

    be'!re maing a bl!!d smear slide( )he number !' reticul!cytes seen +er 1000 /Cs is then

    c!unted( A high+!er 'ield #0E !b3ecti-e& in hich the /Cs are t!uching !r 3ust !-erla++ing

    c!ntains a++r!*imately 200 cells( )he number !' reticul!cytes c!unted in 'i-e such 'ields is

    di-ided by 10 t! yield the reticul!cyte +ercentage number !' reticul!cytes +er 100 /Cs&( In

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    cats, aggregate reticul!cytes are di''erentiated 'r!m +unctate reticul!cytes by the +resence !'

    clum+ed reticulum as !++!sed t! indi-idual +ieces !' reticulum( A c!rrected reticul!cyte c!unt

    '!r the degree !' anemia is calculated by multi+lying the reticul!cyte +ercentage e*+ressed as

    a +ercentage by the rati! !' the +atient

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    In cases !' regenerati-e anemia ith an a++r!+riate marr! res+!nse t! increased

    erythr!+!ietin le-els, /C +r!ducti!n is accelerated and results in the release !' reticul!cytes

    int! the bl!!dstream(2" Changes in the /C indices ith regenerati-e anemia may include

    macr!cyt!sis high MCV&, heter!gene!us cell -!lume high /DW&, and hy+!chr!masia l!

    MC7C&( )he decreased MC7C re'lects a n!rmal hem!gl!bin c!ntent in a largerthann!rmalcell( n bl!!d smear e-aluati!n, /C m!r+h!l!gy sh!s -arying am!unts !' anis!cyt!sis

    -ariati!n in -!lume& and macr!cyt!sis large cells& de+ending !n the degree !' regenerati!n

    and underlying +r!cess( $ucleated /C metarubricytes !r late rubricytes& may als! be n!ted

    ith accelerated erythr!+!iesis(

    .!lychr!mat!+hils are immature /Cs that stain blue+ur+le !n Wrightstained bl!!d smears(

    .!lychr!masia!n bl!!d smear e*aminati!n and reticul!cyt!sis are the hallmars !'

    regenerati-e anemia(

    )he reticul!cyte c!unt must be inter+reted in light !' the degree !' anemia( Minimal t! mild

    reticul!cyt!sis in the +resence !' se-ere anemia is c!nsidered n!nregenerati-e i' su''icient

    time '!r an adeBuate res+!nse has +assed( eBuential hem!grams and reticul!cyte c!unts are

    instrumental in maing this determinati!n(

    %ia&nostic %ifferentias

    nce the regenerati-e status !' the anemia has been determined, m!re s+eci'ic tests are

    indicated t! systematically eliminate the -ari!us causes !' each categ!ry !' anemia(

    Nonregenerative Anemia

    In m!st cases !' true n!nregenerati-e anemia i(e(, n!t hem!rrhage !r hem!lysis that has n!t

    yet begun t! regenerate&, the anemia is mild t! m!derate(2% Causes !' n!nregenerati-e anemia

    are listed in BOX ' . )he m!st c!mm!n cause !' n!nregenerati-e anemia in d!gs and cats is

    in'lammat!ry disease( Anemia !' in'lammat!ry disease '!rmerly anemia of chronic disease&

    can be a seBuela !' a multitude !' in'lammat!ry, in'ecti!us, traumatic, and ne!+lastic

    diseases(2>4"0ther causes !' n!nregenerati-e anemia include chr!nic renal 'ailure,

    hy+!thyr!idism in d!gs, and +rimary b!ne marr! disease("1 Certain causes !'

    n!nregenerati-e anemia, such as Fe6V in'ecti!n, ./CA, and laterstage chr!nic renal 'ailure

    erythr!+!ietin de'iciency&, may +resent ith a m!re se-ere anemia(CC and chemistry +r!'ile,

    urinalysis, and th!racic and abd!minal imaging can hel+ identi'y the +resence !' underlying

    disease, ne!+lasia, !r renal 'ailure( /etr!-iral testing is indicated '!r cats( )hyr!id testing may

    be indicated '!r d!gs( I' n! underlying disease can be identi'ied, b!ne marr! e-aluati!n is

    indicated t! hel+ identi'y c!nditi!ns such as ./CA, myel!dys+lasia, leuemia, and a+lastic

    +ancyt!+enia(

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    Regenerative Anemia

    I' the anemia is determined t! be regenerati-e, the ne*t ste+ is t! di''erentiate bl!!d l!ss 'r!m

    hem!lysis( As +re-i!usly stated, e-aluati!n !' the ) is !'ten hel+'ul( Decreased ) is m!re

    c!nsistent ith bl!!d l!ss, hereas n!rmal t! increased ) is suggesti-e !' hem!lysis(

    =le-ated ) in the 'ace !' anemia may suggest dehydrati!n !r hy+ergl!bulinemia(

    Causes !' bl!!d l!ss are listed in BOX 0(

    M!st causes !' bl!!d l!ss can be easily identi'ied( l!!d l!ss related t! trauma is sus+ected

    based !n hist!ry( .hysical e*aminati!n and imaging !' the th!ra* and abd!men can identi'y

    the +resence !' intraca-itary hem!rrhage in cases !' trauma, tum!r ru+ture, !r a bleeding

    diathesis( /ec!-ery !' n!ncl!tting bl!!d !n abd!min!centesis indicates the +resence !'

    hem!abd!men( /esults !' a +latelet c!unt and cl!tting +r!'ile are used t! eliminate a bleeding

    diathesis( 9astr!intestinal 9I& bleeding may be indicated by the +resence !' hematemesis !r

    melena !r may be !ccult and di''icult t! c!n'irm( )ests that may be used in cases !' sus+ected

    9I bleeding include 'ecal analysis, abd!minal imaging, and end!sc!+y( As discussed earlier,

    chr!nic bleeding may e-entually lead t! ir!n de'iciency and, subseBuently, micr!cytic,

    hy+!chr!mic, heter!gene!us anemia(

    BOX 0. Causes of Bood 2oss

    Interna or e3terna

    • C!agulati!n !r +latelet dis!rders antic!agulant r!denticide t!*ic!sis, disseminated

    intra-ascular c!agulati!n, c!ngenital 'act!r de'iciency, thr!mb!cyt!+enia, -!n

    Willebrand disease&

    • )rauma

    • urgery

    Interna

    • +lenic ru+ture hemat!ma, ne!+lasia, trauma&

    • 7em!rrhage 'r!m n!ns+lenic ne!+lasms

    E3terna

    • Chr!nic bleeding9I ne!+lasia, +!ly+, ulcers, h!!!rms, in'lammat!ry b!el

    disease&, res+irat!ry, ur!genital

    • =ct!+arasites usually 3u-enile +atients&'leas, tics

    In cases !' regenerati-e anemia, hem!lysis bec!mes the m!st liely disease +r!cess i' bl!!d

    l!ss is ruled !ut( Causes !' hem!lysis are listed in BOX ) . 7em!lysis can be immune

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    mediated !r n!n4immune mediated( )he m!st c!mm!n cause !' hem!lysis in small animals is

    IM7A("2 IM7A can be +rimary !r sec!ndary t! !ther diseases e(g(, in'ecti!us disease,

    ne!+lasia&, drug ad-erse e''ects, !r -accine ad-erse reacti!ns(12,""4"> )he +rimary '!rm may

    als! be termed idiopathic  !r autoimmune hemolytic anemia  A#$A&( )he diagn!sis !' IM7A is

    su++!rted by a l! hemat!crit ty+ically K25L& ith !ne !r m!re !' the '!ll!ing:aut!agglutinati!n, +!siti-e C!!mbs test result, s+her!cyt!sis in d!gs&, and increased !sm!tic

    'ragility("@," )he +resence !' n!n4immunemediated hem!lysis may be suggested by the

    hist!ry e(g(, ingesti!n !' !ni!ns, en-en!mati!n&, by breed e(g(, +h!s+h!'ruct!inase !r

    +yru-ate inase de'iciency&, by the +resence !' underlying disease e(g(, micr!angi!+athic

    trauma due t! hemangi!sarc!ma&, !r by 'indings !n imaging e(g(, 8inc t!*ic!sis&(

    7em!lysis can als! be classi'ied as intra-ascular, e*tra-ascular, !r a c!mbinati!n !' b!th(

    =*aminati!n !' serum and urine can s!metimes aid in this determinati!n( Intra-ascular

    hem!lysis results in the release !' hem!gl!bin int! the bl!!d that is then 'iltered int! the urine,

    causing the serum and urine t! de-el!+ a dar red c!l!r( )he di''erential diagn!sis '!r dar red

    urine includes hematuria, hem!gl!binuria, and my!gl!binuria( 7ematuria can be di''erentiated

    'r!m hem!gl!binuria and my!gl!binuria by centri'ugati!n !' the urine( With hematuria, the

    /Cs ill '!rm a +ellet and the su+ernatant ill clear a'ter centri'ugati!n, hereas ith

    hem!gl!binuria and my!gl!binuria, the su+ernatant ill remain +igmented( 7em!gl!binuria

    can be di''erentiated 'r!m my!gl!binuria by analysis !' serum '!r creatine inase acti-ity, hich

    is ty+ically increased in cases !' my!gl!binuria( )he +resence !' hem!gl!binemia and

    hem!gl!binuria in the setting !' regenerati-e anemia is the hallmar !' intra-ascular

    hem!lysis(1" Causes !' intra-ascular hem!lysis include IgMmediated IM7A, 8inc t!*ic!sis,

    +h!s+h!'ruct!inase de'iciency, and s!me cases !' !*idati-e damage such as !ccurs ith

    !ni!n ingesti!n(1",#04#2

    =*tra-ascular hem!lysis, and t! s!me degree intra-ascular hem!lysis, results in the release !' 

    increased am!unts !' bilirubin int! the bl!!d( As a''ected /Cs are +hag!cyt!sed by the

    m!n!nuclear+hag!cyte system in the s+leen and li-er, hem!gl!bin in the /Cs is

    metab!li8ed and aterins!luble unc!n3ugated& bilirubin is released int! +lasma, here it

    binds t! albumin( ?nc!n3ugated bilirubin is taen u+ by he+at!cytes '!r c!n3ugati!n int! a

    aters!luble c!n3ugated& '!rm '!r e*creti!n in bile( Massi-e hem!gl!bin bread!n,

    es+ecially in the setting !' c!ncurrent he+atic in3ury 'r!m hy+!*ia, in'lammati!n, !r thr!mb!sis,

    can lead t! bac'l! !' c!n3ugated and unc!n3ugated bilirubin int! the +lasma( C!n3ugated

    bilirubin is e*creted int! urine by the idneys, !'ten leading t! a dar yell! urine( A small

    am!unt !' bilirubinuria can be n!rmal in d!gs due t! the ability !' the canine idney t!

    c!n3ugate bilirubin( ilirubinuria in cats is alays abn!rmal( )he di''erential diagn!sis !'

    bilirubinuria and hy+erbilirubinemia includes causes !' he+atic dys'uncti!n and biliary

    !bstructi!n( $!t all cases !' e*tra-ascular hem!lysis dem!nstrate bilirubinuria and

    hy+erbilirubinemia due t! the li-er

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     An easy but crude inh!use test t! identi'y agglutinati!n caused by IM7A is the saline

    dis+ersi!n test( F!r this test, clum+s !' /Cs must 'irst be seen !n a glass slide c!ntaining !ne

    dr!+ !' h!le !r =D)Aantic!agulated bl!!d and 2 t! 5 dr!+s !' saline s!luti!n( )! di''erentiate

    r!uleau* /Cs adhered in chains !r stacs& 'r!m agglutinati!n, a c!-ersli+ is +laced !-er a

    dr!+ !' =D)Aantic!agulated bl!!d !n a ne slide, and se-eral dr!+s !' saline s!luti!n are+laced al!ng the edge !' the c!-ersli+( )he /Cs are !bser-ed thr!ugh a micr!sc!+e t! see

    hether clum+s dis+erse !r +ersist hen the saline s!luti!n rushes in( .ersistent agglutinati!n

    indicates the +resence !' anti/C immun!gl!bulin !n the sur'ace !' /Cs and su++!rts a

    diagn!sis !' IM7A( It d!es n!t indicate hether the IM7A is +rimaryaut!immune !r sec!ndary(

     As this is a crude test, results sh!uld be c!nsidered as su++!rti-e !nly(

    In d!gs, the m!st c!mm!n cause !' s+her!cyt!sis is immunemediated hem!lysis as the

    immun!gl!bulinc!-ered /C membranes are attaced by macr!+hages in the li-er and

    s+leen( 6ess c!mm!n reas!ns '!r the +resence !' s+her!cytes include n!n4immunemediated

    causes !' hem!lysis such as micr!angi!+athic trauma, 8inc t!*ic!sis, and trans'usi!n !' st!redbl!!d(1",#0+her!cytes can als! be seen ith se-ere snaebite and beesting

    en-en!mati!n(#",##

    )he direct antigl!bulin !r C!!mbs test identi'ies the +resence !' immun!gl!bulin !r

    c!m+lement !n the sur'ace !' /Cs(#5,#% A +!siti-e result su++!rts IM7A but d!es n!t

    distinguish hether it is +rimary !r sec!ndary( Falsenegati-e and, less c!mm!nly, 'alse

    +!siti-e results can !ccur( )he utility !' a C!!mbs test in cats has hist!rically been c!nsidered

    dubi!us, but results !' a 200% study dem!nstrated reas!nable sensiti-ity and s+eci'icity '!r the

    diagn!sis !' IM7A in cats("5

    In d!gs, IM7A is usually +rimary !r idi!+athic("2,",#> )he diagn!sis !' +rimaryaut!immune

    IM7A is !ne !' e*clusi!n thus, !nce IM7A has been diagn!sed and an ass!ciati!n ith a drug

    ad-erse e''ect !r -accine ad-erse reacti!n has been eliminated, tests t! rule !ut an underlying

    ne!+lastic !r in'ecti!us disease are indicated, es+ecially in !lder +atients( Cats ha-e l!ng been

    c!nsidered m!re liely t! ha-e sec!ndary IM7A,1","%,">,#@ but +rimary IM7A is being rec!gni8ed

    m!re 'reBuently in this s+ecies("5 It is im+!rtant t! rule !ut Fe6V in'ecti!n, FIV in'ecti!n, and

    hem!tr!+ic myc!+lasm!sis '!rmerly $emobartonella in'ecti!n& in cats ith IM7A and t!

    c!nsider 'eline in'ecti!us +erit!nitis, ehrlichi!sis, ana+lasm!sis, drug e''ects, and ne!+lasia

    hen a++r!+riate(1","%,">,#>,#,50

    Concusion

    )he many causes !' anemia in cats and d!gs can mae the r!ad t! a diagn!sis seem

    daunting( 7!e-er, a systematic a++r!ach m!st !'ten yields the c!rrect diagn!sis( In'!rmati!n

    ra+idly deri-ed at initial e-aluati!n .CV) and bl!!d 'ilm e*aminati!n& can be used al!ng

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    ith data 'r!m an aut!mated CC erythr!cyte c!unt and indices& '!r this +ur+!se( Additi!nal

    tests, including reticul!cyte c!unt, seBuential bl!!d smear e*aminati!ns, C!!mbs test, and

    saline dis+ersi!n, !'ten hel+ t! 'urther characteri8e the anemia(

    )his article as m!di'ied by the rem!-al !' a table 'r!m !* 2 !n January @, 201"(

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