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Haematology > Clinical haematology 2 > Flashcards

Clinical haematology 2 Flashcards

1
Q

What can be diagnosed by a blood smear

A

· Thrombocytopenia (low platelets)
· Regenerative vs non-regenerative anaemia
· Rouleux vs agglutination
· Check the machine WBC differentials or do a manual differential WBC count
· Check if normal or abnormal morphology

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2
Q

Thrombocytopenia

A

decreased platelets
- can cause spontaneous haemorrhage, doesn’t usually happen until very low · (<30 x 10 ^9/L)
Clinical signs:
petechiae, ecchymosis, melaena

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3
Q

Investigations for thrombocytopenia

A

o Always check if it is true thrombocytopenia by:
o Checking blood smear
o Check clinical signs-may be due to poor collection/artefact
o If no clinical signs repat haematology to check for persistence

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4
Q

Additional tests for thromobocytopenia

A

o Other haemostasis tests
o Test for infectious diseases
o Bone marrow analysis

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5
Q

Macroplatelets

A

can lead to false thrombocytopenia, regeneration/increased production, CKCS

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6
Q

Thrombocytosis

A

increased platelet count

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7
Q

Haemostasis

A

· Ability to stop bleeding
· set of mechanisms to maintain an equilibrium
· Disorders of haemostasis may vary from defective haemostasis (leading to haemorrhage and known as coagulopathies) or excessive haemostasis (leading to thrombotic events)
Thrombocytes-used in non-mammal species

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8
Q

Ways to measure platelet count

A
  • automated counts

- estimate from blood smear

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9
Q

Automated counts

A

· Done by analysers
· Commonly lead to artefactual (“false”) thrombocytopenia due to platelet clumping and macroplatelets
· Overlap in size between RBC and platelets often leads to false automated counts (e.g. low counts in cats and high counts in goats)

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10
Q

Estimated from blood smear

A

· Should be checked in every animal with low automated counts
· Should be checked in every animal with clinical signs of haemorrhage

Assuming NO PLT CLUMPS in feathered edge! 10 high power fields (oil immersion) in monolayer

1) Count number of platelets
2) Do the average
3) Multiply by 15 or 20
4) Estimated number (x 10^9/L)

Normal 15-30 platelets/hpf

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11
Q

Normal platelets

A

15-30 platelets/hpf

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12
Q

Anaemia

A

reduced red blood cells

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13
Q

Clinical signs of anaemia

A 
Mucous membrane pallor
· Lethargy
· Exercise intolerance
· Tachycardia (increased heart rate)
· Tachypnoea (increased respiratory rate)
· Heart murmur (if severe)
· Collapse
· Icterus
· Melaena/ Haematuria/haemoglobinuria
· Pica
Not all present in all cases or at the same time
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14
Q

Regneration

A

Increased red blood cell production
· Detection of reduced oxygenation à erythropoietin (EPO) production
· Takes 3-5 days - Erythrocyte maturation journey
· Evidence of immature/less mature red blood cells in circulation - Polychromatophils or reticulocytes
Some causes of anaemia are NON-regenerative

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15
Q

Regenerative anaemia

A
  • haemorrhage: internal and external

- haemolysis: intravascular and extravascular

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16
Q

Non-regenerative Anaemia

A
  • bone marrow

- extra BM (systemic) Dz

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17
Q

Reticylocytes

A

· RBC precursors, enucleated, with increased reticulum (mRNA), larger than a mature RBC
· Can be counted manually (using a vital stain - new methylene blue) or in some of the more modern haematology analysers

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18
Q

Types of reticulocytes in cats

A
  • aggregate

- puncate

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19
Q

Aggregate

A
  • immature reticulocytes, look like canine reticulocytes
  • released by the bone marrow in response to anaemia.
  • mature into punctate reticulocytes after 12 to 24 hours in circulation
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20
Q

Punctate

A

have only scattered dots of reticulum (2-6 dots), have undergone a degree of maturation and can remain in the blood stream for up to 4 weeks after the anaemia has resolved

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21
Q

Reticulocytes-species differences

A

· The reticulocyte concentration determines current regeneration in dogs and cats
· Horses retain retics in bone marrow, not seen in circulation
· Cattle/sheep only with severe anaemia; variable release of retics

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22
Q

Manual reticulocyte counts

A

1) Mix an equal amount of blood and vital stain (new methylene blue or brilliant cresyl violet)
2) Incubate at Room Temperature (10’ NMB; 15’ BCB)
3) Do a normal blood smear with the mixture
4) Evaluate 500 - 1000 stained RBC to determine % of reticulocytes
5) Use %retics and RBC to determine absolute value

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23
Q

Anaemia- based on MCV

A
  • normocytic
  • microcytic
  • macrocytic
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24
Q

normocytic

A

erythrocytes of normal size

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25
Q

Microcytic

A
  • low MCV
  • red cell haemoglobin concentration determines when division stops - iron deficiency allows one more division: smaller red cells.
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26
Q

Macrocytic

A
  • high MCV
  • Presence of immature RBCs (larger than mature RBCs)
  • Poodles
  • Bone marrow disorders
  • A common artefact in stored/old (usually posted) blood samples (RBCs swell up)
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27
Q

Anaemia- based on MCHC/MCH

A
  • Normochromic
  • hypochromic
  • hyperchromic
28
Q

Normochromic

A

normal RBC colour

29
Q

Hypochromic

A
  • in iron deficiency/ poor iron incorporation (with microcytosis)
  • Presence of immature RBCs (are not fully haemoglobinised)
30
Q

Hyperchromic

A

Usually artefact (i.e. look for haemolysis; lipemia; Heinz bodies)

31
Q

Polycythaemia/Erythrocytosis

A

increased high concentration of red blood cells in blood:

  • erythrocytosis
  • true polycythaemia
32
Q

Erythrocytosis

A

relative due to a loss of plasma volume/dehydration

33
Q

True polycythaemia

A

absolute where red cell mass is increased

34
Q

When looking at blood smears evaluate:

A

· RBC density - does it look anaemic?
· RBC regeneration - is the marrow trying to regenerate?
· RBC morphology - are there any clues to the cause of an anaemia? (e.g. spherocytes, organisms, etc) are there any changes that can lead to the cause of disease?

35
Q

RBCs most common morphological changes

A 
· Anisocytosis
· Polychromasia
· Macro or microcytosis
· Hypochromasia
· Spherocytes/ghost cells
· Acanthocytes
· Keratocytes and Blister cells
· Schistocytes
· Heinz bodies
36
Q

RBCs less common morphological changes

A 
· Poykilocytes (common)
· Echinocytes (crenated RBC)(common) Codocytes or Target cells (common) Eccentrocytes
· Ovalocytes
· Dacreocytes
· Organisms and inclusion bodies
37
Q

Anisocytosis

A

Different cell sizes

must ask 3 questions:

1) Is there macrocytosis? Is there microcytosis?
2) Is there polychromasia?
3) In an anaemic animal anisocytosis and polychromasia suggest RBC regeneration

38
Q

Polychromasia

A

Indicative of regeneration

· Polychromatophils are “younger RBC”
· All polychromatophils are reticulocytes
· More noticeable in some species e.g. dog

39
Q

Hypochromasia

A

· Usually seen alongside microcytosis in iron deficiency anaemia
· Hypochromic RBC often are described as bicycle wheel with increased central pallor

40
Q

Spherocytes and ghost cells

A

· can both be seen with haemolysis (imune mediated haemolytic anaemia - IMHA)
· Spherocytes are round, smaller, darker and have no central palor
· Spherocytes can also be seen in low numbers concurrently with evidence of shear damage injury

41
Q

Agglutination

A

red cells organised like bunch of grapes, indicative of haemolysis

42
Q

Rouleux

A

red cells organised like stacks of coins, usually happens when increase in proteins in blood

43
Q

Haematology analyser

A

total WBC count and WBC differential count

44
Q

Blood smear examination: manual WBC differential count

A

· The percentages of the different leucocyte types
- May use two smears if leukopenic
- X40/50 lens
· Ideally count 100 cells per 10x10^9/L WBC count
· Percentages (%) MUST be converted to absolute numbers (x109/L) using Total WBC count

45
Q

WBC disorders

A
  • leukogram

- neoplasia

46
Q

Common leukogram

A

· “Stress” leukogram
· Inflammatory leukograms
· Epinephrine/adrenaline (“White coat”) leukogram
· Inverted “stress” leukogram

47
Q

Neoplasia

A

· Leukaemias (acute or chronic; lymphoid/myeloid…)
· Stage V lymphoma
· Mast cell disease
· Others (rare)

48
Q

Epinephrine response (physiological)

A
  • leukocytes move from the margunated pool into the circulating pool
  • short duration
  • fear/excitement/exercise
49
Q

Chronic stress/steroid leukogram

A

response to glucocorticoid: hyperadrenocorticism, exogenous (e.g. prednisolone)

50
Q

‘acute’ inflammation and ‘chronic’ inflammation

A

related with an inflammatory process

51
Q

‘absent’ chronic stress leukogram

A
  • may be see with hypoadrenocortism (Addison’s)

- suspect when seeing an animal that should have a ‘stress leukogram’ and doesn’t

52
Q

Leukaemia

A

marked increase in one leucocyte type, in acute leukaemias with the presence of blasts

53
Q

Band neutrophil

A

left shift:

U shaped or S shaped nucleus with parallel sides i.e. minimal indentation/ segmentation

54
Q

Signs of toxicity in neutrophils

A

Döhle bodies, Foamy cytoplasm, Bluish cytoplasm, Toxic granules

55
Q

Left shift

A

· Release of earlier granulocyte precursors from marrow
· Indication of increased neutrophil demand/consumption
· Inflammation/infection
· “Band” neutrophils

56
Q

Toxic changes in neutrophil

A

· Response to overwhelming demand, dysmature neutrophils released, toxic change is often seen alongside left shift
· Organelles normally removed before the neutrophil is released from the bone marrow persist when the neutrophil is in circulation, other organelles not fully matured can also be present.
- Cytoplasmic basophilia
- Döhle bodies
- Cytoplasmic vacuolation
- Persistent primary granules (toxic granulation)
- Ring form nuclei
- Giant forms

57
Q

Neutropenia

A

· Slight decreases in otherwise healthy adult animals may be normal
- Breed variations (Greyhounds/ sight hounds)
- Some cats also sit on the lower end of the reference interval
· Neutrophils are the first to decrease when there is BM destruction
· Marked neutropenia can predispose to infections and sepsis
· First steps: assess blood smear and repeat to check if persistent

58
Q

causes of neutropenia

A

· secondary to decreased production with marrow disease
· Increased use with marked inflammation
· immune mediated destruction

59
Q

Lymphocytosis

A

Young animals “lymphocytosis”
· Epinephrine release (i.e. cats, foals)
· Mobilization of cells (hypoadrenocorticism )
· Increased demand
· Persistent antigenic stimulation
· Post vaccination (?little support from literature)
· Neoplasia (lymphoproliferative disease): leucemia, stage V lymphoma

60
Q

Lymphopenia

A

Loss of lymphocytes
· Loss of chylous fluid (rich in lymphocytes)
· Protein losing enteropathy (lymphangiectasia)

Decreased production
· Viral infections, drugs (e.g. chemotherapy), immunodeficiency

Redistribution
· Chronic stress, glucocorticoids (steroids, endogenous or exogenous)
· Trapped in lymph nodes
· Move from circulation into bone marrow and tissues
· Lymphocytolysis

61
Q

Monocytosis

A

Increased demand (for macrophages)
- chronic inflammation
- transient monocytosis
Redistribution (part of the stress leukogram)
· increased glucocorticoid levels particularly in dogs
Increased production independent of demand
· monocytic, myelo-monocytic leukaemia

62
Q

Eosinophilia

A

Increased demand (also basophilia)
- Allergy/hypersensitivity
- Parasitism
- Inflammation of mast cell rich tissue (gut, skin, lungs, uterus) leading to mast cell degranulation Idiopathic eosinophilic conditions (Eosinophilic granuloma complex, etc)
· Paraneoplastic (mast cells, lymphoma, etc)
· Hypereosinophilic syndrome/eosinophilic leukemia
· Hypoadrenocortisolism

63
Q

Degenerative left shift

A

overwhelming tissue demands (exceeds bm production)

64
Q

Leukopenia

A

overwhelming tissue demands (exceeds bm production) or bm disease

65
Q

Leukemoid relation

A

excessive numbers of neutrophils due to marked inflammatory stimulus

66
Q

Toxic neutrophils

A

due to accelerated production. Associate with longer hospitlisation, higher costs of treatment and increased morbility

67
Q

Severe or persistent lymphopenia

A

indicates severe and persistent stress

Haematology (2 decks)

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