SA haematology Flashcards
what is anaemia?
reduction in RBC mass (clinical sign not disease)
what are ways of measuring RBC mass?
PCV/haematocrit
RBC count
total haemoglobin
what are the three causes of anaemia?
inadequate production
increased destruction
loss (haemorrhage)
what is the typical appearance of RBCs in anaemia caused by inadequate production by bone marrow?
normocytic normochromic
what is the typical appearance of RBCs in anaemia caused by increased destruction?
macrocytic hypochromic
what is the typical appearance of RBC in anaemia caused by loss (haemorrhage)?
microcytic hypochromic
how can red blood cell size be described?
microcytic
normocytic
macrocytic
is anaemia due to loss (haemorrhage) regenerative?
not regenerative enough (lack of iron)
what increases in erythrocytes in animals with anaemia?
2,3-DPG
what does an increase in 2-3-DPG in erythrocytes of anaemic animals do?
lowers the oxygen-haemoglobin affinity so more oxygen is delivered to tissue
what does reduced tissue perfusion simulate?
increase erythropoietin levels stimulating erythropoiesis
what are the three ways of classifying anaemia?
severity
erythrocyte index
regenerate response
what is the PCV of a dog with mild anaemia?
30-36%
what is the PCV of a cat with mild anaemia?
20-24%
what is the PCV of a dog with moderate anaemia?
18-29%
what is the PCV of a cat with moderate anaemia?
15-19%
what is the PCV of a dog with severe anaemia?
<18%
what is the PCV of a cat with severe anaemia?
<15%
how can the erythrocyte index be described?
microcytic, normocytic, macrocytic
hypochromic, normochromic
what is used to determine if nan anaemia is regenerative or not?
reticulocyte count
what stain is used to visualise reticulocytes?
new methylene blue (blue speckles)
how long does it take to see an increase in reticulocytes in regenerative anaemia?
2-3 days (peaks at 7 days)
are all polychromatophils reticulocytes?
yes (not all reticulocytes are polychromatophilic)
what are the main causes of regenerative anaemia?
haemorrhage
haemolysis
what are the two types of feline reticulocytes?
aggregate
punctate
when are aggregate reticulocytes seen?
first 24 hours after being released from bone marrow
which feline reticulocyte should be counted when assessing if an anaemia is regenerative or not?
aggregate
how long does it take for iron stores to deplete in cases of chronic bleeding?
> 1 month
what is the cause of anaemia in chronic bleeding patients?
iron deficiency (initially regenerative but becomes less and less)
how do RBCs appear in iron deficiency anaemias?
hypochromic (less iron)
microcytic
what is used to treat iron deficiency anaemia?
iron supplement (ferrous sulphate) blood transfusion (packed red cell)
what are the two classes of haemolysis?
immune mediated
non immune mediated
what are some examples of non immune mediated haemolysis?
oxidative damage (onions, paracetamol...) intra-erythrocytic parasites mechanical damage
how does extravascular haemolysis occur?
antibody binds to RBC and macrophage causes phagocytosis/lysis
what is formed from partial phagocytosis of a RBC?
spherocyte
what system is activated during intravascular haemolysis?
complement (extensive inflammation)
why does intravascular haemolysis lead to renal compromise?
free haemoglobin in blood (haemoglobinaemia) which is toxic to the tubular epithelium
do animals with intravascular or extravascular haemolysis appear sicker?
intravascular
what is typically seen on haematology of a patient with immune mediated haemolytic anaemia?
regenerative anaemia
autoagglutination
spherocytes
how do spherocytes appear compared to RBCs?
smaller, rounder and denser
where should be looked on a blood smear for spherocytes?
monolayer
what are ghost cells?
lysed RBCs
what can cause autoagglutination of RBC in cases of immune mediated haemolytic anaemia?
anti-erythrocyte IgM
high levels of anti-erythrocyte IgG
how does autoagglutination of RBCs appear?
cluster of grapes
what causes rouleaux formations?
increased plasma proteins coating RBCs (stacking of RBCs)
what type of blood should be used for the saline agglutination test?
anticoagulated
what is the Coombs test used for?
detect presence of antierythrocyte antibodies (can’t be done if agglutination present)
what will be seen on biochemistry of animals with immune mediated haemolytic anaemia?
elevated ALT and AP
hyperbilirubinaemia
azotaemia
what is seen on urinalysis of animals with immune mediated haemolytic anaemia?
haemoglobinuria
bilirubinuria
proteinuria
what are the three treatments needed immune mediated haemolytic anaemia?
immunosuppression
antithrombotics
supportive
what is the first choice drug for immunosuppression in immune mediated haemolytic anaemia cases?
prednisolone
dexamethasone, ciclosporin, azathioprine
what are some side effects of corticosteroids?
PU/PD
muscle wasting
GI (ulcers and gastritis)
when is a second like immunosuppressant used in immune mediated haemolytic anaemia cases?
life threatening disease
no response to first
severe corticosteroid side effects
what type of drug is prednisolone?
corticosteroid
what can be used if an immune mediated haemolytic anaemia patient hasn’t responded to two immunosuppressants?
immunoglobulins (one off treatment)
how long does treatment of immune mediated haemolytic anaemia with immunosuppressants typically last?
4-8 months (some lifelong) - some can relapse
what immune mediated haemolytic anaemia patients is antithrombotic therapy used in?
severe intravascular haemolysis
are blood transfusions indicated for immune mediated haemolytic anaemia?
no - often haemolyse the donor RBCs
what is neonatal isoerythrolysis?
destruction of neonates RBCs by maternal antibodies (antibodies in colostrum)
what cat breed is neonatal isoerythrolysis seen in?
British shorthair
what is microangiopathic haemolytic anaemia?
RBCs damaged/fragmented as they pass through fibrin meshwork of microvasculature
what are some examples of causes of microangiopathic anaemia?
fibrin clots (DIC) glomerulonephritis congenital defects
what are formed from mechanical damage to RBCs (microangiopathic anaemia)?
schistocytes (sheared RBC)
what are acanthocytes?
RBCs with multiple rounded projections
what occurs due to oxidative damage of RBCs?
methaemoglobinaemia
heinz body formation
RBC membrane oxidation
what can cause oxidative injury to RBCs?
onions and zinc (dogs)
paracetamol (cats)
what are Heinz bodies?
round pale inclusions on the inner surface of RBC membranes (aggregates of denatured haemoglobin)
what stain is used to visualise Heinz bodies?
methylene blue
what are three causes of intrinsic haemolytic anaemias?
pyruvate kinase deficiency
phosphofructokinase deficiency
osmotic fragility
what mycoplasma is associated with regenerative anaemia?
Mycoplasma haemofelis
what is used to treat Mycoplasma haemofelis?
doxycycline
prednisolone
(no cure - remain carriers)
what is the characteristic feature of non-regenerative anaemias?
absence of reticulocytes
what causes non-regenertive anaemia?
marrow disease
lack of erythropoietin
what are some causes of intramarrow disease?
drug reactions
oestrogen toxcitiy
pure red cell aplasia
what does oestrogen toxicity cause?
thrombocytopenia
neutropenia
anaemia
(pancytopenia)
what cells are effected by red cell aplasia?
just erythrocytes
what cells are effected by aplastic anaemia?
all cell lines (pancytopenia)
what is myelofibrosis?
proliferation of collagen and reticulin fibres in bone marrow
what type of anaemia is anaemia of chronic disease?
non-regenerative normocytic and normochromic
what is the cause of anaemia in chronic kidney disease?
reduced erythropoietin production
what type of anaemia can FIV/FeLV cause?
non-regenerative
what are the five major leucocytes?
neutrophil monocyte lymphocyte eosinophil basophil
what are the three granulocytes? (polymorphonuclear)
neutrophil
eosinophil
basophil
as an estimate on low power, how many leukocytes would you class as a leukopenia?
<15
as an estimate on low power, how many leukocytes would you class as a leukocytosis??
> 45
what is the morphology of mature neutrophils?
lobed nucleus with clear/pink cytoplasm
what is the morphology of a banded neutrophil?
U shaped parallel nucleus
what is the most abundant leucocyte?
neutrophil
what are the functions of neutrophils?
kill/inactivate bacteria, yeast, fungi, parasites
regulate haemopoiesis
what are the three pools of neutrophils within bone marrow?
proliferative
maturation
storage
what regulate the production of neutrophils?
cytokines
growth factors
what is the average time a neutrophil spends in blood?
6-10 hours
what blood cell has the shortest lifespan?
neutrophils (6-10 hours)
what happens to the number of neutrophils in circulation when there is a strong inflammatory stimulus?
increase in banded neutrophils
what is left shift?
increase in the number of immature cells in circulation
what is a degenerative left shift?
normal/low mature neutrophil count with increased immature cells (marrow not coping)
what are the common causes a neutrophilia?
physiological (stress)
acute inflammatory response
stress/corticosteroid induced
what mediates physiological neutrophilia?
adrenalin
what species is a physiological neutrophilia commonly seen in?
cats
in cats what is often also seen with a physiological neutrophilia?
marked lymphocytosis
what is the mediator of a stress leukogram?
cortisol/corticosteroid
what are the features of a stress leukogram?
neutrophilia
lymphopenia
eosinophilia
what is often seen with a neutrophilia in an acute inflammatory response?
left shift
what is toxic change of neutrophils due to?
reduced maturation time in bone marrow due to intense stimulation of myelopoiesis
how do neutrophils undergoing toxic change appear?
blue cytoplasm and granules
foamy vacuoles
less condensed chromatin
what are some causes of neutrophil dysfunction?
immunodeficiency syndromes
diabetes mellitus
neoplasia
FeLV
what are the two general causes of neutropenia?
overwhelming demand/decreased survival
reduced/ineffective granulopoiesis
when is there overwhelming demand of neutrophils?
severe bacterial infection - prothorax, pyometra, peritonitis…
what are the main functions of eosinophils?
kill parasites
control hypersensitivity
allergic disease and inflammation
why is it hard to have an eosinopenia?
most normal levels extend to zero
what are the functions of basophils?
potentiate inflammation
histamine release
respond with eosinophils
what is the function of monocytes?
circulating precursor of macrophage
when does a monocytosis occur?
chronic inflammation acute inflammatory response tissue necrosis immune mediated disease stress leukogram
what are the majority of the circulating lymphocytes?
memory T cells
when is a lymphocytosis seen?
physiological stress prolonged immune stimualtion youth lymphoproliferative disease hypoadrenocorticism
when is a lymphopenia seen?
corticosteroids viral disease loss of lymphocyte rich lymph (chylothorax) sepsis lymphoma
what are the three most likely clincopathological abnormalities seen in a frightened kitten?
hyperglycaemic
neutrophilia
lymphocytosis
what is polycytaemia also known as?
erythrocytosis
what is erythrocytosis?
increase in PCV/hct, RBC count of haemoglobin
what is a relative erythrocytosis?
increased RBC numbers due to decreased plasma volume or RBC redistribution
what is an absolute erythrocytosis?
true increase in RBC numbers due to erythropoiesis
what breeds is it normal to have a high PCV?
greyhounds (sighthounds)
what can cause a decrease in plasma volume leading to relative erythrocytosis?
dehydration
fluid shift
what causes RBC redistribution leading to a relative erythrocytosis?
splenic contraction (exercise/adrenalin)
what is absolute erythrocytosis secondary to?
increased erythropoietin
what is an appropriate reason for increased erythropoietin?
generalised hypoxia and hypoxaemia
what can cause an appropriate secondary absolute erythrocytosis?
severe heart disease
high altitude
alveolar hypoventilation
what can cause inappropriate secondary absolute erythrocytosis?
renal tumors/lesions (localised renal hypoxia)
non-renal tumors (producing erythropoietin)
what disorder causes primary absolute polycytaemia?
myeloproliferative (leukaemia)
how is absolute erythrocytosis treated?
phlebotomy
treat underlying disease
what percentage blood volume loss can most health animals withstand?
15-25%
what is done to stabilise a bleeding patient?
control haemorrhage
fluid replacement
if hypovolaemic what kind of fluid should be used as a volume replacer?
crystalloid
what is the shock rate bolus volume?
1/5 to 1/4 of animals normal blood volume (40-50ml/kg)
what percentage blood loss is an indication a blood transfusion is needed?
> 25%
what are the steps of haemostasis?
vessel injury vascular contraction primary haemostasis secondary haemostasis tertiary haemostasis
what happens during primary haemostasis?
platelet plug forms
what is platelet plug formation dependant on?
platelets
von Willebrand factor (for binding)
endothelium exposure
what is involved in secondary haemostasis?
coagulation cascade resulting in thrombin generation
what is the role of thrombin?
stabilises the blood clot
what happens during tertiary haemostasis?
fibrinolysis (ensures clot doesn’t get too big)
what are the clinical signs of a primary haemostasis defect?
small hole (petechiae) - lack of platelet melena
if an animal is suspected of having a clotting disorder, where should you not take blood from?
jugular - difficult to stop and apply pressure
what biochemistry test are done to assess disorders of haemostasis?
whole blood clotting time
activated clotting time
buccal mucosal bleeding time
what must be excluded before carrying out a buccal mucosal bleeding time?
thrombocytopenia (don’t do if present)
what is being assessed when looking for a primary coagulopathy?
platelet function and number
what are the main tests done for secondary haemoostasis disorders?
prothrombin time
activated partial thromboplastin time
what are some disorders of primary haemostasis?
thrombocytopenia
von Willebrand disease
(thrombocytopathia and vascular disorders)
what are the causes of thrombocytopenia?
lack of production (bone marrow disorder)
increased consumption (DIC)
increased destruction (immune mediated)
increased sequestration (splenic torsion)
spurious (lab error)
what breeds have inherited thrombocytopenia?
King Charles cavaliers
cairn terriers
(don’t need to be worried)
what causes primary immune mediated thrombocytopenia?
IgG binding to platelets
what causes secondary immune mediated thrombocytopenia?
drugs, infectious disease, neoplasia, antibiotics
what is the main treatment option for primary immune mediated thrombocytopenia?
immunosuppression (glucocorticoids)
what are common causes of thrombocytopathia?
hepatic and renal disease
cancers
von Willebrand disease
what is thrombocytopathia?
normal platelets count and coagulation but still excessive bleeding
how long should a buccal mucosal bleed time be?
2-4 minutes
where is von Willebrands factor synthesised and stored?
endothelial cells
what is von Willebrand factor needed for?
platelet adherence
what is done to test for von Willebrand disease?
antigenic test
genetic testing
what can be done to treat von Willebrand disease?
cryoprecipitate (rich in vWF and factor VIII)
what are the most common causes of acquired disorders of secondary haemostasis?
vitamin K deficiency (rodenticides)
liver disease
DIC
what are inherited disorders of secondary haemostasis?
haemophilia A (VIII deficiency) haemophilia B (IX deficiency)
what are the clinical signs of vitamin K deficiency?
epistaxis melaena haematoma haematuria gingival bleeding
what is the best way to administer vitamin K therapy?
orally
what is DIC?
widespread activation of coagulation leading to microthrombi in organs (consumptive coagulopathy)
what is the most common cause of DIC?
septicaemia
immune mediated disease
what lab abnormalities are found in animals with DIC?
prolonged clotting times thrombocytopenia schistocytes decreased fibrinogen increased D-dimers
what is done to treat DIC?
treat underlying disease
heparin
whole blood
what are D-dimers?
specific product of breakdown of cross linked fibrin (from clot)
what should whether a patient needs a blood transfusion or not be based on?
clinical signs (reduced tissue perfusion)
what must you ensure before deciding to give a transfusion?
the patient in normovolaemic
what blood product should blood loss be replaced with?
whole blood (or packed red cells)
what blood product should be used to replace low PCV due to haemolysis?
packed red cells
if the patient has a coagulopathy, what blood product should be used if a transfusion if required?
fresh frozen plasma
regular plasam
cryoprecipitate
if in doubt what blood type should be given to dogs?
DEA 1 negative
what type of blood is it imperative to give to cats?
type-matched
what is the pathophysiology of naive exposure in regards to transfusion medicine?
DEA 1 positive blood given to a DEA 1 negative recipient
what is sensitised exposure in regards to transfusion medicine?
DEA 1 negative dog has previously been given DEA 1 positive blood so now has antigens for them (haemolysis)
what does DEA stand for?
dog erythrocyte antigen
can a DEA 1 positive dog receive DEA 1 negative blood?
yes (and won’t become sensitised)
why is it imperative to type match acts?
have naturally occurring auto-antibodies against other blood types
can type B cats be given type A blood?
no - severe haemolytic reaction (BAd)
can type A cats be given type B blood?
has a mild delayed reaction (not As Bad)
what can be used to boot type cats/dogs?
card or cassette (wash blood in saline first - auto-agglutination)
what does crossmatching do?
detect the majority of antibody-antigen incompatibilities in blood
what is a major crossmatch?
recipient has antibodies against donor RBCs (don’t give)
what is a minor crossmatch?
donor has antibodies against recipient RBCs (can give)
when do patients need crossmatching?
if they have had a previous transfusion
why should blood transfusions be started at a slow rate?
to see if there is any reaction
what is used to administer blood transfusions?
transfusion set with in-line filter (stop microthrombi)
what speed is a blood transfusion initially given at?
0.5-1ml/kg/hr
what should the IV line of blood transfusions be flushed with?
NaCl (not Ca)
should blood be warmed prior to a transfusions?
no (sepsis risk) - give at room temperature
how fast do haemolytic reactions to a transfusion occur?
acute (rapid)
delayed (days) - mild reaction or formation of new antibodies
how do non-haemolytic transfusion reactions present?
pyrexia
anaphylaxis
(can be citrate toxicity)
sepsis
how does citrate toxicity transfusion reaction present?
similar to hypocalcaemia
do plasma products need typing/crossmatching?
no (most DEA 1 negative)