Clinical Haematology Flashcards
Which type of collection tube should be used for blood sampling? Why?
EDTA blood tube
Where should blood samples be stored?
In the fridge - do not freeze (ruptures cells)
What can you assess via the circulating RBC mass?
Haematocrit and PCV%
How can you assess RBC morphology?
With a peripheral blood smear exam
How does flow cytometry work?
Individual cells passes through laser beam - cells are counted by interruption in light, cell size/complexity obtained by light scattered
What is impedance testing?
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
What is the packed cell volume?
Percentage of red cells in a volume of blood
What are the main parts of a blood smear? (3 part structure)
Base/head, monolayer, feathered edge
What type of leukocyte is this?
Neutrophil
- Defence against invading microorganisms (esp. bacteria)
- Increased with inflammation/infection/stress
What type of leukocytes are these?
Eosinophils (pink) and basophils (purple)
- defence against parasites (allergic response)
- basophils contain histamine
- known as granulocytes (along with neutrophils)
What type of leukocyte is this?
Lymphocyte
- Involved in cell-mediated immunity
- large nucleus, very little cytoplasm
- T and B cells
What type of leukocyte is this?
Monocyte
- Precursors to macrophages
- Antigen presentation to T cells
- Blob appearance, often have vacuoles
What does the suffix -philia/-cytosis mean?
Cell type increase in number
What does the suffix -penia mean?
Cell type decrease in number
What is the most dominant leukocyte cell type in dogs/cats/horses?
Neutrophils
What is the most dominant leukocyte cell type in healthy cattle and rodents?
Lymphocytes
Why can’t bird/reptile/amphibian blood counting be performed by analysers?
RBCs and thrombocytes (platelet equivalents) are nucleated so cannot be distinguished from RBCs
What are the clinical signs of anaemia?
- mucous membrane pallor
- lethargy
- exercise intolerance
- tachycardia/tachypnoea
- collapse
- icterus
What are the 3 traditional classifications for anaemia?
- RBC index (size/colour)
- Regenerative vs. non-regenerative
- Severity of the anaemia (nased on how low the haematocrit is)
What is regenerative anaemia?
Where bone marrow is responsive but cannot replace lost RBCs fast enough (usually seen in haemorrhage)
What is non-regenerative anaemia?
Where the bone marrow is unresponsive to cell loss
What factors are usually investigated for anaemia?
- PCV/HCT and Hb concentration
- RBC indexes
- Reticulocyte count (determine if regenerative)
- Blood smear for morphological evaluation of RBC
When might there be a high mean corpuscular volume (macrocytic RBCs)?
- Seen in bone marrow disorder
- seen in some types of poodle
- Common artefact in stored/old samples - RBCs swell up
What is a reticulocyte?
Immature precursor to a RBC
What is anisocytosis?
RBCs of different sizes
- anisocytosis + polychromasia (different colours) = regenerative anaemia
What is polychromasia?
RBCs of different colours
- suggest regeneration when seen with anisocytosis
What is hypochromasia?
RBCs reduced in colour
- seen with microcytosis in iron deficiency anaemia
- bicycle wheel with increased central pallor
What are spherocytes and ghost cells?
- spherocytes are small, very round and have no central pallor
- ghost cells are a solid colour but lighter than spherocytes
What is polycthaemia?
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%
What is thrombocytopaenia?
Low platelet numbers
What is leukocytosis?
Abnormally high white cell counts
What is neutrophilia?
High numbers of neutrophils in blood
- increases with inflammation/infection
- part of the physiological and stress leukograms
What is “left shift”?
- release of earlier granulocyte precursors from marrow
- indicate increased neutrophil demand/consumption in infection/inflammation
What are some of the toxic changes which can be seen when dysmature neutrophils are released?
- cytoplasmic basophilia
- Dohle bodies
- ring-form nuclei
- cytoplasmic vacuolation
- persistent primary granules
What is lymphopenia?
reduced lymphocytes
- decreased production due to viral infections/chemo/immunodeficiency
- redistribution in chronic stress, trapped in lymph nodes, lymphocytolysis
