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PLT - Coggle Diagram
PLT
Lab eval
conc
gen performed using automated analyzer
EVAL OF BLOOD SMEAR
FOR CLUMPS
semiquant estim = 8-10 plts/HPF
feline plt conc inaccurate and low b/c on tendency to form clumps
hemorr from thrombocytopenia (alone) =
<25,000 plts/uL
hemorr at >50,000 plts/uL = consider DIC
morph
macroplts (lg)
lg plts often released from BM in response to thrombocytopenia and are indicator of BM regener/response
hyperfunc
= even ani w/ low plt conc may not bleed
sig #s = MPV inc
mean plt vol
plt distrib width
sim to RDW
coeffic of plt vol
inc #s of lg and/or sm plts will inc
plateletcrit
% vol of blood taken up by plts
calc from plt conc and MPV
measure of circu plt mass
impt in congenital macrothrombocytopenia
buccal mucosal bleeding time
performed by creating sm std incision in buccal mucosa or gingiva and measuring time it takes for bleeding to cease
inc w/ mod to mk thrombocytopenia, inherited or acq plt func defects, and vascu abnorm
coag factor abnorm will
NOT
prolong
most approp used to eval plt func when relatively norm #s of plts present
Hemostasis
primary
init activ of plts w/ adh to ea other and ves wall w/ forma of plt plug
clin signs: petechiae, ecchymoses, bleeding from muc, and prolonged bleeding from injec sites
secondary
forma of fibrin clot via coag cascade
clin signs: hematomas, bleeding into jts, body cavities, and musc
def: process by which bleeding is stopped and involves complex interation btwn 1) blood ves, 2) plts, 3) plasma prot
disorders can result in hypocoag (hemorr) or hypercoag (thromboembolic dz)
disorders
thrombocytopenia
inc plt destruc/consump
DIC
sys uncontrolled activ of coag
ALWAYS secondary to underlying pathog process
neoplasia, sepsis, toxicosis, heat stroke, heartworm, immu-medi dz
mild to mod dec in plt conc
subclin or localized intravasc coag can = thrombocytopenia
vasculitis
exposure of subendothel to prothrombotic state
infec (RMSF), immu-medi, phys, chem causes
blood loss
mild to mod blood loss alone doesn't cause sig thrombocyopenia
severe, acute blood loss = mild to mod thrombocytopenia b/c of rpt attempts to form clots
immu-medi (ITP)
common cause of mk thrombocytopenia in dogs (<50,000)
Ab medi destruc of plts
may be primary and directed against norm Ag on plt surf or secondary (drugs, infec agents, neoplasia, neonatal alloimmune thrombocytopenia)
dec plt produc
aplastic pancytopenia
immu-medi destruc of precursors, rarely can be specifically directed at only megakar precursors
gen BM damage/replacement
viral infec, tick borne infec, estrogen, chemo agents, bracken fern poisoning, mycotoxins, myelophthisis, myelofibrosis, myeonecrosis, irrad, marrow neoplasia
abnorm plt distrib
splenic conges/splenomegaly
may cause pooling of plts in spleen, contrib to and
rarely
cause thrombocytopenia
multifactorial
neoplasia
many types assoc w/ thrombocytopenia
mech incl dec produc and inc consump via immu-medi mech, enh adh to ves and tis, or DIC
infec agents
Ehrlichia and Anaplasma spp likely cause thru multi mech such as suppr plt produc, and inc plt destruc/consump
inherited
macrothrombocytopenia of Cavalier King Charles Spaniels
inherited disorder reported to be autosomal recessive
muta in gene encoding beta-tubulin - impairs microtubule assembly and stabil = aberrant proplt forma and release
charac by
thrombocytopenia and macrothrombocytosis
, plt conc 30,000-100,000
PCT is better way to eval plt mass in these ptx
affec ani do
NOT
have clin bleeding problems
dec plt CONC
thrombocytosis
inc produc
rebound thromcocytosis
thrombocytopenia can sometimes stim enough plt produc that plt conc are transiently elev (overcomp)
vinca alkaloids
stim thrombopoiesis
iron defic
common but inconsistent finding in canine
possibly due to cross talk btwn EPO and TPO
splenectomy
due to inc blood conc of TPO, as a lg % of total plt mass is removed w/ the spleen
inflamm
inflamm cyk (IL-6) stim TPO produc = inc thrombopoiesis
secondary to neoplasia, infec, trauma, etc
redistrib
exercise and epi
strenuous exercise and/or epi release = mild transient physio thrombocytosis in some ani
leukocytosis, mature neutrophilia, lymphocytosis
hemic neoplasia
paraneoplastic
primary (essential) thrombocytosis/megakaryocytic leukemia
chronic myeloprolif disorder of plt precursors that = lg #s of rela norm plts
other
hyperadrenocorticism (Cushing's dz)
inc plt CONC
thrombopathy
dec plt FUNC
inherited
vWF dz
also forms complexes w/ and stabil circu coag factor VIII
most common hereditary bleeding disorder in dogs
exists in diff multimeric wts (lg are most func)
affec ani have
bleeding tendencies in spite or norm plt #s and coag times
bridges plts to subendothel collagen and contrib to plt-plt bridging
BMBT is prolonged w/ norm plt #
vWF is multimeric glycoprot prod by endothel c and megakar
3 types
Type 1
Welsh corgi and Doberman
all multimers dec
most common w/ vari severity
Type 2
German shorthair pointers
dec lvls of vWF w/ dispropor dec in lg multimers
uncommon but severe
Type 3
Scottish terrier, Chesapeake Bay Retriever, Shetland sheepdog
cause severe dz
undetectable lvls of vWF
diag
confirmed w/ vWF Ag assay and vWF multimeric analysis
others
acq
secondary to...
drugs (NSAIDs)
DIC
hepatic dz
hyperglobulinemia
uremia
General
produc and kinetics
mammalian plts produc by megakaryocytes in BM
plts are sm cytoplasmic frags released into circu
megakaryocytes are lg c w/ mulitlobulated nucleus
primary stim is TPO (thrombopoietin)
TPO is prod in liver and cont cleared from ciruc by recep medi uptake by plts and megakar
therefore, inverse rela btwn plt mass and free TPO
as plts # dec in periph blood, less TPO is cleared from circu = avail to stim megakar
don't see thrombocytopenia w/ liver failure
plt lifespan is 6 d
blood plt conc dep on rates of PRODUC, CONSUMP, DESTRUC, and REDISTRIB
pathog states can affect 1+
morph and func
sm, anucleate, discoid
phospholipid bilayer, sev glycoprot recep (func in activ and adh)
recep for fibrinogen, vWF, collagen, ADP
2 types of granules
1) alpha: coag and growth factors
2) dense: contain ADP, Ca2+, and serotonin
plts activ by
exposure to subendoth collagen
plt activ factor
inflamm mediators
thrombin
plts impt for inflamm processes, maint of vascu integrity, and tis repair