Clinical Haematology

Question 1

Which type of collection tube should be used for blood sampling? Why?

Answer 1

EDTA blood tube

Question 2

Where should blood samples be stored?

Answer 2

In the fridge - do not freeze (ruptures cells)

Question 3

What can you assess via the circulating RBC mass?

Answer 3

Haematocrit and PCV%

Question 4

How can you assess RBC morphology?

Answer 4

With a peripheral blood smear exam

Question 5

How does flow cytometry work?

Answer 5

Individual cells passes through laser beam - cells are counted by interruption in light, cell size/complexity obtained by light scattered

Question 6

What is impedance testing?

Answer 6

Passing cells in an isotonic solution between 2 electrodes - cells produce a change in electrical impedance that is proportional to the size of the cell

Question 7

What is the packed cell volume?

Answer 7

Percentage of red cells in a volume of blood

Question 8

What are the main parts of a blood smear? (3 part structure)

Answer 8

Base/head, monolayer, feathered edge

Question 9

What type of leukocyte is this?

Answer 9

Neutrophil

• Defence against invading microorganisms (esp. bacteria)
• Increased with inflammation/infection/stress

Question 10

What type of leukocytes are these?

Answer 10

Eosinophils (pink) and basophils (purple)

• defence against parasites (allergic response)
• basophils contain histamine
• known as granulocytes (along with neutrophils)

Question 11

What type of leukocyte is this?

Answer 11

Lymphocyte

• Involved in cell-mediated immunity
• large nucleus, very little cytoplasm
• T and B cells

Question 12

What type of leukocyte is this?

Answer 12

Monocyte

• Precursors to macrophages
• Antigen presentation to T cells
• Blob appearance, often have vacuoles

Question 13

What does the suffix -philia/-cytosis mean?

Answer 13

Cell type increase in number

Question 14

What does the suffix -penia mean?

Answer 14

Cell type decrease in number

Question 15

What is the most dominant leukocyte cell type in dogs/cats/horses?

Answer 15

Neutrophils

Question 16

What is the most dominant leukocyte cell type in healthy cattle and rodents?

Answer 16

Lymphocytes

Question 17

Why can’t bird/reptile/amphibian blood counting be performed by analysers?

Answer 17

RBCs and thrombocytes (platelet equivalents) are nucleated so cannot be distinguished from RBCs

Question 18

What are the clinical signs of anaemia?

Answer 18

• mucous membrane pallor
• lethargy
• exercise intolerance
• tachycardia/tachypnoea
• collapse
• icterus

Question 19

What are the 3 traditional classifications for anaemia?

Answer 19

• RBC index (size/colour)
• Regenerative vs. non-regenerative
• Severity of the anaemia (nased on how low the haematocrit is)

Question 20

What is regenerative anaemia?

Answer 20

Where bone marrow is responsive but cannot replace lost RBCs fast enough (usually seen in haemorrhage)

Question 21

What is non-regenerative anaemia?

Answer 21

Where the bone marrow is unresponsive to cell loss

Question 22

What factors are usually investigated for anaemia?

Answer 22

• PCV/HCT and Hb concentration
• RBC indexes
• Reticulocyte count (determine if regenerative)
• Blood smear for morphological evaluation of RBC

Question 23

When might there be a high mean corpuscular volume (macrocytic RBCs)?

Answer 23

• Seen in bone marrow disorder
• seen in some types of poodle
• Common artefact in stored/old samples - RBCs swell up

Question 24

What is a reticulocyte?

Answer 24

Immature precursor to a RBC

Question 25

What is anisocytosis?

Answer 25

RBCs of different sizes

• anisocytosis + polychromasia (different colours) = regenerative anaemia

Question 26

What is polychromasia?

Answer 26

RBCs of different colours

• suggest regeneration when seen with anisocytosis

Question 27

What is hypochromasia?

Answer 27

RBCs reduced in colour

• seen with microcytosis in iron deficiency anaemia
• bicycle wheel with increased central pallor

Question 28

What are spherocytes and ghost cells?

Answer 28

• spherocytes are small, very round and have no central pallor
• ghost cells are a solid colour but lighter than spherocytes

Question 29

What is polycthaemia?

Answer 29

Increased red cell mass

• can be relative due to loss of plasma/dehydration OR
• absolute, where red cell mass is increase (true polycythaemia)
• PCV 70-85%

Question 30

What is thrombocytopaenia?

Answer 30

Low platelet numbers

Question 31

What is leukocytosis?

Answer 31

Abnormally high white cell counts

Question 32

What is neutrophilia?

Answer 32

High numbers of neutrophils in blood

• increases with inflammation/infection
• part of the physiological and stress leukograms

Question 33

What is “left shift”?

Answer 33

• release of earlier granulocyte precursors from marrow
• indicate increased neutrophil demand/consumption in infection/inflammation

Question 34

What are some of the toxic changes which can be seen when dysmature neutrophils are released?

Answer 34

• cytoplasmic basophilia
• Dohle bodies
• ring-form nuclei
• cytoplasmic vacuolation
• persistent primary granules

Question 35

What is lymphopenia?

Answer 35

reduced lymphocytes

• decreased production due to viral infections/chemo/immunodeficiency
• redistribution in chronic stress, trapped in lymph nodes, lymphocytolysis