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Small Animal Medicine > Clinical Pathology > Flashcards

Clinical Pathology Flashcards

1
Q

What is haematopoiesis?

A

Haematopoiesis is the process of the formation of blood cells. Includes myelopoiesis and lymphopoiesis

Myelopoiesis is the production of all cells in the bone marrow.
Haematopoietic cells are precursors to haemic cells found in the blood or tissue. Consisting chiefly of erythropoiesis, granulopoiesis and thrombopoiesis.

Monocytes are formed in the marrow but also elsewhere.

Lymphopoiesis occurs largely in extramedullary sites such as the spleen, thymus and lymph nodes.

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2
Q

Where do the different cells develop in the bone marrow?

A

Haemotopoietic Stem cells: Develop in niches of bone marrow
Megakaryocytes;: Form adj. to sinusoidal endothelial cells (Become platelets)
Erythroid Cells: Develop around macrophages (Become erythrocytes)
Granulocytes: Develop assosciated with stromal cells away from sinuses (Become macrophages and neutrophils)

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3
Q

What are Haemotopoietic Growth Factors?

A

Proliferation and maturation of stem cells require haemtopoietic growth factors (HGF)
They can produced locally (paracrine or autocrine) or by peripheral tissues (endocrine) and transported by blood to the bone marrow.

The HGF are produced by all cells in the haemtopoietic environment e.g. erythropoietin, thrombopoietin, colony stimulating factors, interleukins

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4
Q

What is erythropoiesis?

A

Erythropoiesis is the production of erythropoietin (HGF), that is produced by peritubular epithelial cells of the kidney, and the bone marrow/liver
Its production is stimulated by reduced tissue oxygen levels.
Then the bone marrow will produce more RBC/erythrocyte

Can test marrow to blood time every 304 days (Rubriblast –> metarubricyte)

Nutrients needed for erythropoiesis:
Iron (Heme synth)
Copper (Transport iron to erythroid cells)
Vit. B6 (Cofactor in heme)

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5
Q

What are the different stages of red cell development/Erythropoiesis?

A

When red cells mature they become smaller. In the process of production, early precursors have a blue cytoplasm due to many basophilic ribosomes and polyribosomes synthesising globin chains.

As cells divide and mature, their size decreases, nuclear chromatin condenses and cytoplasmic basophilia decreases and Hb progressively accumulates –> red colour to the cytoplasm.

Different stagrs:

Rubriblast

Prorubricyte

Rubricyte: Cells in the bone marrow diver (become smaller and smaller )until they reach optimal haemoglobin concentration saturation level.
Not enough haemoglobin –> Extra cell division

Metarubricyte

Reticulocyte or polychromatophil: Network of reticulum that forms by precipitation of ribosomal ribonucleic acids/proteins. (Necessary for globin chains in Hb synthesis).
During staining cololurs the cytoplasm blue.

Erythrocyte

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6
Q

What are species differences in mature erythrocytes?

A

Species differences:

Central pallor: Dogs > Cats > Cows/Sheep

Anisocytosis: Cats & Cattle

Elliptical: Llama, alpaca, avian and reptile

Rouleux: Horses > Cats > Dogs

Size: Canine > Cat > Horses > Cow

Basophilic Stippling: Cow > Sheep > Goat

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7
Q

What are the types of reticulocytes?

A

Aggregate reticulocytes: Mature reticulocytes with high ribosomal material and basophilic staining: Polychromatophilic
- Canine: Develop into erythrocytes in 24 hours
- Feline: 12-14 hours develop into punctate

Punctate Reticulocytes: Older mature reticulocytes with less ribosomal material. Less than 2 discrete granules: normochromic

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8
Q

What are the species differences with reticulocyte maturation and release?

A

Dogs/Cats/Pig: 1-1.5% in the peripheral
Dogs have more immature aggregate polychromatophils and Cats have more punctate reticulocytes. (Few or no aggregate)

Acute or severe anaemia: Will reduce aggregates.
If it is chronic or mild anaemia: Punctate

Horses/Ruminants: Not in healthy peripheral blood, in bone marrow
Survival: 10 days circulation
Diagnosis: Heinz bodies, mycoplasma

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9
Q

What is Leukopoiesis?

A

Leukopoiesis is the process through which leukocytes are generated from haematopoietic stem cells in the bone marrow.
This includes myelopoiesis and lymphopoiesis

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10
Q

What are myelocytes?

A

This cell contains “secondary” or specific granules that are identified by their staining properties as neutrophils, eosinophils and basophils

These granules vary in shape, size and concentration in different species.

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11
Q

What do each of the myelocytes stain?

A

Neutrophils do not stain intensely with either dye.

More mature neutrophils are stored in the bone marrow then present in the blood stream in dogs.
Marrow transit time (Myeloblast to release of mature neutrophil): 6-9 days, shortened with inflammation to 2-3 days
Circulation: 6- 10 hours (Renewed 2-3 x/day)

Eosinophils stain reddish-orange via eosin dye
Production parallels neutrophils
Transit time is 1 week

Basophils have granules which have an affinity for blue/basic dye and mature in the bone marrow.
Mast cells which come from the same progenitor cell mature in tissues.

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12
Q

What is Thrombopoiesis?

A

Formation of thrombocytes/blood platelets in the bone marrow.

Erythrocytes and thrombocytes have the same precursor: Thrombopoietin, the chief stimulator produced in the liver

MOA: Cells stop dividing –> Nuclear division (Endomitosis) & cytoplasm volume increases –> Cytoplasm protrusions form (Pro-platelets) into sinuses and are sheared off by the force of moving blood.

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13
Q

What are the different disorders of the bone marrow?

A
  1. Aplasia/Hypoplasia
  2. Hyperplasia
  3. Dysplasia
  4. Myelopthisis
  5. Neoplasia
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14
Q

How does Aplasia/Hypoplasia of the Bone Marrow occur?

A

Pathogen: Insufficient stem cells, haematopoietic abnormalities, abnormal humeral/cellular control

Causes: IPODs
- Infection: Parvo virus (No anaemia)
- Poisoning: Bracken fern (Cattle/Sheep)
- Oestrogen Toxicity: Sertoil cell tumour (dogs), delayed breeding (Ferrets)
- Drugs: Griseofulvin (Cats)
- Systemic Disease: Chronic renal failure, endocrine deficiencies e.g. Hypothyroidism & Hypoadrenocorticism

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15
Q

How does hyperplasia in the bone marrow occur?

A

Hyperplasia refers to the increased production of cells that can be effective or ineffective

Erythroid
a) Effective: Increased reticulocytosis in response to anaemia
Improved HCT (Hematocrit is a blood test that measures how much of a person’s blood is made up of red blood cells).

b) Ineffective: Severe iron deficiency, non-regenerative IMHA (immune response directed at metarubricytes or reticulocytes) , myeloproliferative/dysplastic disorders

Granulocytic:
a) Effective:
1. Neutrophilia: In response to Bacteria, immune inflammation, necrosis, toxicity, malignancy
2. Eosinophilia: Parasitic, inflammation, immune, hyper-eosinophilic syndrome, neoplasia

b) Ineffective:
1. Persistent neutropenia: BM neutrophil increase in myelodysplasia/acute myelocytic leukeamia
Common in cats with FeLV or FIV

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16
Q

How does dysplasia occur in the bone marrow?

A

Dysplasia is when there is abnormal maturation or morphology in the bone marrow.

Dyserythropoiesis: Abnormal erythrocyte maturation/morphology.
Associated with ineffective erythropoiesis E.g. nuclear and cytoplasmic asynchrony
Most common: In myeloproliferative disorders or FeLV

Dysgranulopoiesis: Abnormal granulocyte maturation/morphology.
Assosciated with ineffective granulopoiesis: Results in peripheral neutropenia
Most common in FeLV/FIV
E.g. Myelodysplatic disorders or acute myelocytic leukemia

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17
Q

What is Myelopthisis?

A

Replacement of normal haemopoietic cells with abnormal cells and alteration of marrow microenvironment causing compromised haemopoiesis
E.g. Myelofibrosis, myelodysplasia, myelogenous leukemia, lymphoid leukemia

Myelofibrosis: Excess collagen and/or reticulum in BM: Produced by activated marrow reticular cells
Cause: Sequel to marrow injury e.g. necrosis, vascular damage, inflammation, neoplasia

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18
Q

What is haematopoietic neoplasia?

A

Haematopoietic neoplasia can be broadly classified into:

Myeloid leukaemia or myeloproliferative disorders: RBC, neutro/baso/eosinophils, monocytes, platelets

Lymphoid leukaemia or lymphoproliferative disorder: Lymphocytes

A lymphoid leukaemia originates in the bone marrow
where as a lymphoma originates in the lymph organs: Lymphoid (solid) tissues, lymph nodes, spleen
Diagnose via lymph node or splenic cytology aspirates

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19
Q

What is a Non-Haematopoietic neoplasia?

A

Metastatic carcinoma
Sarcoma of bone

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20
Q

What are the different types of Anti-Coagulants?

A

Types:
1. Red
Sample: Plain –> Clot blood/serum
Test: Serology, bile, biochem, endocrine
Once it has formed a clot, keep it in a fridge to keep it clode or send to lab as the heat can cause the red cells to leak enzymes or haemolyse, affecting quality of the serum tube,

  1. Green: Heparin –> Plasma/whole blood
    Test: Biochem (plasma), Exotic haematology (Whole blood)
  2. Purple: EDTA –> Whole blood
    Test: Haematology, Cytology
    Role: Preserves cell morphology, no stain interference, no clots
  3. Grey: Oxalate/Fluoride –> Whole blood/plasma
    Tests: Glucose - Glycolytic inhibitor
  4. Blue: Na Citrate –> Whole blood/plasma
    Tests: Clotting, PT & APTT, VWB
    Binds calcium, stops it from clotting.
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21
Q

What is the difference between Serum vs Plasma?

A

Serum: allows blood to clot, fibrinogen has been consumed

Plasma: Contains fibrinogen

Serum is the liquid that remains after the blood has clotted. Plasma is the liquid that remains when clotting is prevented with the addition of an anticoagulant

Serum/Plasma Separation: Centrifuging tube rises polymer barrier to cell interface –> Barrier forms separating the serum/plasma

Serum: Draw 2.5 x the required volume –> Allow blood to clot in red (15-20 minute), centrifuge & aspirate supernatant (serum) into red plain tube (has no anticoagulant)

Plasma: Draw full volume, invert tube & centrifuge immediately, aspirate supernatant (plasma) and place in plain red tube (has no anticoagulant).

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22
Q

What is the anticoagulant for Haematology?

A

EDTA: Potassium Salt
Mammals: EDTA
Reptiles: EDTA or heparin

Excess EDTA: Under-filled tube
Shrinkage of RBC’s (due to high osmolality), Dilution of blood/values (decreased PCR, MCV), artefactual RBC distortion, Altered HCT/MCHC, Increased refractometer TP total protein)

Excess Blood: Increased clotting, can affect results/obstruct instrument

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23
Q

What is the correct transportation protocol?

A

In icebox/esky to freeze cell lysis and wrapped in tissue paper
Exposed to moisture: Cells are lysed

Blood smears onsite sent separately

Vet practices store samples in fridge

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24
Q

What is the technique for collection?

A

Goals: Prevent contamination, platelet activation, micro-clots, falsely low platelet counts

Materials:
- Vacutainer: Preferable: appropriate negative pressure for draw
- Syringe: Use appropriate size/pressure to avoid excess pressure
Remove needle pre-transfer to avoid haemolysis, false results and spectrophotometer issues

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25
Q

What is the order of draw for vacutainer blood collections?

A

Serum (red), Citrate (Blue), EDTA (purple), OXF (Grey)
Red/blue can be swapped

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26
Q

What are some types of inappropriate blood collection?

A
  1. Backflow: Regurgitation of tube blood into needle or vein via decreased vein/digital pressure
  2. Decant: Insufficient blood in serum tube, it is fixed via pouring/mixing bloods from other tubes
  3. Lab Tech Error: Incorrect Sample is used
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27
Q

What can you do for patient preparation?

A

Fast for 12 hours prior to blood collection to avoid lipaemia as it may lead to sample haemolysis

Interfere with spectrophotometer & inaccurate Hb/erythrocyte haematology

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28
Q

What manual procedures involve blood mixing and PCV (%)

A

Blood mixing: The percentage of blood composed of erythrocytes/RBC’s
Method: Collect by EDTA/Heparin tube and fill up 3/4th micro-capillary tube, plug one end with plasticine and centrifuge

RBC’s have the highest specific gravity of the cells in blood and therefore gravitate to the bottom of the capillary tube during centrifugation, to appear as a dark red column.

PCV: Packed cell volume: Percentage of whole blood composed of RBCs
Anticoagulant collection (EDTA or Heparin)

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29
Q

How to use a microhaematocrit reader?

A

Align the bottom of the red cells with the zero value, and the top of the plasma with the 100 line.
Move the dial, to measure where the top of the red cells are.

  • Packed RBC’s (bottom) : Higher specific gravity –> Sink
  • Buffy Coat (middle) : WBC, platelets, mast cells & microfilaria
  • Plasma: Total plasma protein
    Yellow: Icterus or carotene pigments with diet
    Red: Increased Hb, in-vitro (Collection/lipemia - normal PCV), in vivo (IV haemolysis)
    White/opaque: Lipemia: Either post-grandial or abnormal lipid metabolism
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30
Q

What is TPP/Refractometer

A

TPP is true plasma protein

A refractometer estimates the concentration of solute in fluid via the bending light relative to distilled water
Measures total plasma protein

Results:
Increased PCV & TP - Clear: Dehydration
Decreased PCV & TP - Clear: Blood loss
Decreased PCV and Increased TP: Red: intavascular haemolysis
Decreased TP and Increased PCV: Clear/yellow: extravascular haemolysis

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31
Q

What are the different haematology analysers in veterinary practice?

A
  1. Quantitative Buffy Coat Systems: Spins down sample in a tube and based on specific gravity (Density-gradient centrifugation), separates them into layers and adds a special stain (Acrdine orange dye).
    Separates and counts cells
    Order: Platelets, monocytes/lymphocytes, granulocytes, PCV
  2. Impedance analysers - Coulter Counter
    Blood cells pass through an electrical aperture & impedes current flow generating a pulse
    The longer the impedance, the bigger the cell
  3. Laser-based Flow Cytometers: Combination of impedance, laser flow cytometry & stains
    Assess size/internal complexity by measurement of light scatter
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32
Q

What are important terminologies for interpreting an automated haemogram

A

Definitions:
- RBC (x1012/L): Number of red blood cells

  • HCT - Haematocrit (L/L): RBC vol. per L of blood, equivalent to as PCV
    Calculation: PCV/100
    Difference: HCT < PCV (0.01-0.03L) – due to no trapping of plasma between RBCs
    HCT is the percentage of blood volume filled by platelets.
  • HGB - Haemoglobin (g/L): Concentration of Hb
  • MCV – Mean Cell Volume (fL): Average RBC size
    Calculation: (HCT x 1000) / RBC Issue: Does not show range of variation cf. RDW
  • MCHC – Mean Cell Hb Conc (g/L): Average concentration of hb per RBC
    Calculation: HGB/HCT
  • RDW (%): Coefficient of variation for RBC size
    Calculation: (SD MCV/MCV) x 100 Adv: More descriptive cf. MCV
  • Reticulocytes (x109/L): Absolute reticulocyte concentration
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33
Q

What are the rules of haematology?

A
  1. Group RBC, Hb and & Haematocrit together
  2. Haematocrit should be 3x the haemoglobin concentration.
  3. Increased MCHC can be used to identify errors as It is not physiologically possible to have excess haemoglobin.
  4. If either of these are skewed use PCV and blood smear evaluation to identify issues: if it is an artefact or an error.

a) Manual PCV: If HCT does not equal PCV, then there is an increased MCV (aging, agglutination), increased RBC (Platelet included).
If plasma coloured red (haemolysis) or Opaque (Lipemia)

b) Blood smear: Increased MCHC –> Heinz bodies, spherocytes, eccentrocytes
Occur in diseases causing oxidative damage to the red cell

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34
Q

How do you interpret the values on an automated haemogram?

A
  • ↑ RBC, HgB, HCT: Polycythemia (Erythrocytosis)
  • ↓ RBC, HgB, HCT: Anaemia
  • ↑ MCV: Macrocytosis, e.g., Regeneration, FeLV, Artefact (Agglutination/aging)
  • ↓ MCV: Microcytosis, e.g., Iron deficiency, PSS
  • ↑ MCHC: Error
  • ↓ MCHC: Hypochromasia, e.g., Chronic blood loss
  • ↑ RDW %: Sig. macro/microcytosis or regeneration
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35
Q

What is an automated leukogram?

A

Examines the different types of white cells.

The WBC differential count determines the number of each type of white blood cell, present in the blood.
Can be expressed as a percentage (to total WBC), can be misleading,
or absolute value (% x total WBC x 100)

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36
Q

How do you calculate the correct WBC count?

A

nRBC = nucleated RBC
TNCC = Total nucleated cell count

When there is greater than 5 nRBC/100WBC

Method 1: Machine TNCC x (100 / nRBC + 100)

Method 2: Correct WBC = initial WBC - (nRBC)

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37
Q

What are the main values for an automated thrombogram?

A

PLT: Platelet Count
MPV: Mean platelet volume
PDW: Platelet distribution width (PDW)
Plateletcrit (Thrombocrit)

  • ↑ PLT: Thrombocytosis, e.g., Physiological (Epinephrine splenic contraction), 2nd inflam/neoplasia, iron deficiency
  • ↓ PLT: Thrombocytopenia, e.g., <30 x 109 can cause spont. Haemorrhage
  • ↑ MPV: Immature platelets suggesting thrombopoiesis
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38
Q

How do you collect blood for a peripheral blood smear

A

Collection:
EDTA > 1/2 full, unless small patients then fill completely
Make 2x smears
EDTA is anticoagulant of choice

Heparin: Discouraged as cells can clump and invalidate counts, stain incompatability

Citrate: Cannot be used as it dilutes the cells

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39
Q

What is the role of a blood smear and how do you transport blood for peripheral blood smear?

A

Transit: Keep EDTA in fridge until transport with a cold pack,
Don’t place smears in fridge/formalin

Role:
- Check for platelet clumps
- Estimate WBC
- Assess RBC
- Identify parasites

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40
Q

What is the method to make a peripheral blood smear?

A

Method: Wedge slide by Maxwell Wintrobe
- Place drop of blood from EDTA from capillary tube or wooden stick ~3mm in size
- Place spread slide at 30–45-degree angle, drawn backwards first to distribute blood
- Spread forward at a 45-degree angle in a single motion

Preparing the stain:
Preparation – Romanowski Stain:
Dip 4-5x for 2s each → Fixative (Methanol) → Acidic dye (Eosin) → Basic dye (Methylene)
Basic care: Wipe slides between each jar, keep sealed & regularly replace, write date on jar

PARTS OF A BLOOD SMEAR:
- Application point
- Body
- Monolayer
- Feathered Edge

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41
Q

What is the Systemic Examination for a blood smear?

A
  1. On 10x: Assess smear quality
    Feathered edge look for platelet clumps, parasites, large or neoplastic cells, WBC clumping
  2. On 100x: Estimate platelet count and observe platelet morphology
    Feline platelets prone to clumping
    Monolayer/Feathered Edge
  3. On 10x: Estimate WBC count
    Count number of WBC in 3 (10x) fields in the monolayer. Divide by 3 to get the average.
    Divide by 4 to get white cell concentration.

and 100x perform WBC differential count:
Tallying, differential grid, manual cell counter
Count neutrophils, band neutrophils, lymphocytes, monocytes, eosinophils, basophils

  1. Scan on 10x for erythrocyte distribution and 100x for morphology
    - Assess density, shape, colour, size, regeneration/cell types

Rouleaux: Linear branching/non-branching aggregates resembling stacked coins
Common in horses, less in cats
Formed via interactions between RBC membranes and plasma macromolecules.
Increased rouleaux with hyperglobulinaemia and hyperfibrinogenaemia

Aggregates due to agglutination (RBC being held together via antibodies). Immune-mediated response
–> Saline Dispersion/Dilution Test: Disperse RBC aggregates into individual with TPP is diluted

Density/Anaemia:
Reduced RBC density or increased space between RBC
Morphology:
Size: Microcytes, macrocytes, anisocytosis (Different sizes)
Shape: Round, or poikilocytes

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42
Q

What are the different WBC types and how to differentiate?

A

Neutrophils: Sausage shaped nucleus, granules on the cytoplasm
Band neutrophil: Shaped like a horseshoe

Lymphocytes: Round nucleus.
Metarubicyte: Purple, poly cytoplasm
Natural killer cells: High amount of granules in the cytoplasm
Blue: producing protein

Monocytes
Basophils: Purple or lavender coloured granules
Eosinophils: Bubbly looking

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43
Q

Describe species variation in erythrocytes

A

Canine: Largest in size, greatest in central pallor

Feline: Second largest, minimal central pallor, rouleaux/aniscocytosis mild

Equine: Mid range, central pallor. Prominent rouleaux, no anisocytosis

Bovine: Smaller in size, central pallor, no rouleaux, aniscocytosis

44
Q

What is a polychromatophil?

A

Immature RBC that contains RNA (Ribosomes). Indicates regeneration
Cause: Normal dogs & cats in low numbers (1-1.5%) BUT not in horses/ruminants

45
Q

What are aggregate reticulocytes and what are punctate reticulocytes?

A

Aggregate Reticulocyte:
Immature RBC with RNA precipitate visualised with methylene blue stain – appear polychromatophilic in normal stain
Cause: Indicate regenerative response

Punctate Reticulocyte:
More mature form of reticulocytes with lower ribosomal material (~2 Discrete granules) – Appear normochromic in normal stain

46
Q

What is hypochromasia?

A

Decreased/inhibited Hgb production
Cause: Seen in normal young animals or Iron & copper deficiency or zinc excess

47
Q

What are schistocytes, keratocytes, spherocytes and acanthocytes?

A

Schistocytes:
RBC fragments due to shearing caused by vasculature abnormalities (e.g., Blood flow, Fibrin) or RBC fragility (e.g., Iron deficiency)

Keratocytes:
Fragmentation injury Physiological: Low no. in healthy cats
Causes: Liver dz (Cats: Hepatic lipidosis), EDTA, Fragmentation, Oxidant injury

Spherocytes:
Removal of RBC membrane by macrophages causing sphered RBC
Causes: IMHA, Fragmentation, Snake envenomation, Histiocytic sarcoma

Acanthocyte:
Irregularly space, variably sized spicules ending in club or fist shapes
Causes: DOGS – Dz of fragmentation (E.g., HSA, Liver dz, DIC, GN), GOATS – Normal if young Biomarker: For HSA in Dogs Mechanism: Unknown – lipid composition of RBC?

48
Q

What is agglutination, ghost erythrocytes and eccentrocytes?

A

Agglutination:
Clumping of RBC due to Ab bridging
Causes: EDTA artefact, heparin therapy (Horses), IMHA (IgM/IV)

Ghost Erythrocyte:
Lysed RBC via rupture of membrane causing Hb release, leaving the membrane
Cause: Sample artefact, IV IMHA, Babesia, Zn toxicity (Dog), neonatal isoeryhrolysis

Eccentrocyte:
Mature erythrocytes where the Hgb is pushed to one side of the cell – opposite pale stain Causes: Oxidation causes bonding of RBC membranes → collapses & Hgb is displaced

49
Q

What is a Howell Jolly Body?

A

Cause: Regenerative anaemia, corticosteroids or physiological in low no. (horse and Cats)

50
Q

What is erythrocytosis?

A

Definition: Increased RBC in peripheral blood
Parameters: Increased RBC, Hgb, HCT

CS: Purple mucous membranes, congested retinal blood vessels, seizures

Consequences: Sludging blood, impaired blood flow, poor tissue oxygenation

51
Q

What is a reason for physiological erythrocytosis?

A

Splenic Contraction
Cause: Adrenal mediation –> Excitement, fear, exercise
Clinical tissue: TPP is normal + Physiological leukocytosis, mature neutrophilia, lymphocytosis

Adrenalin causes the spleen to contract, red cells released into the circulation.
When adrenalin disappears, the changes go away –> Transient.

52
Q

What causes increased erythrocyte mass?

A

Increased RBC, HgB, HCT

Primary erythrocytosis: Erythroid Neoplasia/Polycythaemia Vera
Neoplasia of erythroid, myeloid, megakaryocytic cell lines
Neoplasia that causes cell lines to increase.
Erythropoietin is normal: as it is a tumour does not need erythropoietin for stimulus for increase in RBC production.

Secondary Erythrocytosis:

Appropriate SE: Hypoxia erythrocytosis.
- Cardiac failure, respiratory disease or hyperthyroidism
Blood is passing kidney, kidney detects not enough oxygen, increase erythropoietin to increased RBC production

Inappropriate SE: Renal neoplasia, non-renal neoplasia.

53
Q

What is haemoconcentration?

A

Increased conc of blood components due to decreased plasma volume

Dehydration
CS: TPP is elevated (albumin), RBC is the same

Endotoxic Shock
Shift of fluid from intra to extravascular e.g. Vessel damage, osmotic gradient
CS: Inflammatory leukogram

54
Q

What is a leukogram?

A

Complete set of numerical data and any morphological abnormalities noted on blood smear.
Detect inflammatory disease, haemtopoietic neoplasia

Limitations:
Can not identify specific aetiological agents and cannot indicate site of inflammation
Cannot determine if it is chronic, mild or non-invasive inflammation

55
Q

What is the descriptive terminology to communicate abnormalities?

A

Reduction (Penia):
Neutropenia
Lymphopenia
Eosinopenia

Increase (Philia or cytosis)
Neutrophilia
Lymphocytosis
Eosinophilia
Monocytosis

56
Q

What is a physiological leukogram?

A

Common in dogs: Fight or flight response
Blood vessels have a marginal and a central pool
When adrenalin is released, the marginal pool shrinks and the central pool gets bigger.

Dogs have a big central pool and a small marginal pool
Whereas cats have a large marginal pool, thus are prone to physiological induced leucocytosis.

Adrenaline: Causes decrease adherance of lymphocytes and neutrophils to the blood vessel walls. Adrenalin is causing increased blood flow, making the central pool bigger.
As neutrophils are less adhered, they move to the central pool and there increased flow of lymphocytes to blood vessels, tissues and lymph nodes.
There is neutrophilia and lymphocytosis.

URL: Upper reference limit
Magnitute of neutriphilia
2 x URL (dogs horses, cattle)
3 x URL in cats due large marginal pool

Magnitude of lymphocytosis:
2 x URL: common in cats, horses

57
Q

What is a steroid/stress leukogram?

A

Steroidal stress leukogram can be because of extreme stress, endogenous or exogenous steroids
E.g. Cushings: Extreme cortisol excess.

has a classic pattern of neutrophilia, lymphopenia, monocytosis and eosinopenia

Neutrophilia is due to steroids changing neutrophil kinetics:
1. Production of neutrophil adhesion molecules are down regulated, double neutrophils (canine, equine, boine) and greater than in cats due large MNP

  1. Increased release of mostly mature neutrophils from the storage pool
  2. Hyper segmentation
58
Q

How does hyperadrenocorticism relate to a stress leukogram?

A

Disease causes lower than normal production of cortisol by adrenal glands

Neutrophils low
Lymphocytes high
Monoctyes normal
Eosinophils high

59
Q

What is a left shift?

A

Cell maturation proceeds from left to right
A shift to the left means more immature cells
A shift to the right means more mature/aged cells

Neutrophils
Mature neutrophils are segmented
Immature are Horse-shoe shaped: Band neutrophils

An inflammatory leukogram can be seen to have more immature/band neutrophils because they are pulling earlier cells into circulation to deal with the inflammation.

Left shift: An increase in immature neutrophils and is usually a sign of inflammation

Degenerative Left shift: Band neutrophil count is higher than the mature segmented neutrophil count
Bone marrow is not coping with the inflammatory process.
*Cattle: A degenerative left shift may not be poor prognosis as neutrophils leave the blood to gather at side of inflamm

60
Q

What is toxic change?

A

Toxic change is in the presence of severe inflammation. There is defective maturation due to accelerated bone marrow production
Produce very immature cells that are toxic cells.

61
Q

What are the types of toxic neutrophils?

A

Cytoplasmic basophilia: Cytoplasmic RNA & ribsomes retained

Dohle Body Inclusions: Retained rough ER grey-blue round aggregates in the cytoplasm

Cytoplasmic Vacuolation: Loss of granule & membrane integrity

Toxic Granulation: Retention of mucopolysaccharides & ↑ permeability of primary granule membranes to romanowsky stains (Pink) – DO NOT confuse w/ secondary granules

62
Q

What are patterns with neutrophils in acute inflammation?

A

Neutrophilia: Release from storage pool.
Left shift can occur with depletion of storage pool

Dogs/Cats: Common to see neutrophilia as they have a higher bone marrow reserve. Will release if there is an inflammatory stimulus
If there is neutropenia is it a very severe lesion.

Horses/Cows: Slower to release as there is less capacity.

63
Q

What is the leukemoid response?

A

Extreme inflammation, a lot of white cells in peripheral bloods.

64
Q

What are patterns with lymphocytes and monocytes in acute inflammation?

A

Increased margination and emigration of lymphocytes to inflamed tissue
Lymphocytes to lymph noes and reduced exit of lymphocytes from lymph nodes
Therefore it is LYMPHOPENIA

Monocytosis as neutrophils have common stem cell with other monocytes
As there is neutrophila there is no monocyte bone marrow storage pool (released earlier). Recovery when there is neutropenia.

65
Q

What are the patterns of chronic inflammation?

A

Neutrophilia initially.
If the inflammation becomes overwhelimg there is neutropenia due to supply not meeting demand, left shift.

Lymphocytosis: Lymph nodes struggle in its production of lymphocytes
Common in young animlas

66
Q

What is overwhelming/endotoxaemia patterns in a leukogram?

A

Shift: Neutropenia, Eosinopenia, Lymphopenia

Pathogenesis:
- Inflammatory Neutropenia:
↑ Margination & emigration to tissues > Release from BM
Shift: Within hours of infection - Left shift, 2d post infection - ↑ BM stimulation

Incidence: Common in cattle (Small storage & slow BM response) +- Horses

  • Endotoxic Neutropenia:
    1-3hrs: Rapid shift from CNP (Central pool) to MNP via ↑ endothelial adhesion
    8-12hrs: Released neutrophils from BM
    3-5d: Neutrophilia due to ↑ production
    Importance: Neutropenia is seen depending on the time samples are taken
67
Q

What causes Eosinophilia i and Basophilia in a leukogram?

A

Eosinophilia
Causes:
- Hypersensitivity, e.g., Flea bite
- Mast cell degranulation, e.g., Skin, RT, GT, UT
- Idiopathic conditions
- Parasites, e.g., Tissue migration ONLY
- Addison’s
- Eosinophilic leukaemia

Basophilia
Cause: Imprecise leukocyte differential counts OR allergic, parasitic, neoplasia
Only a substantial or persistent mild increase is significant

Mastocythemia:
Cats: Seen with systemic or splenic mastocytosis

Dogs: assosciated with inflammatory conditions

68
Q

What is Anaemia?

A

It is a decrease in RBC, Hgb, HCT/PCV

CS: Weakness, tachypnoea, decreased exercise intolerance, pale MM + Murmur (decreased blood viscosity)

Diagnostic Approach:
1. Bone Marrow Response: Determine if the RBC is regenerative or not.
Time for bone marrow response:
Dogs/Cats: 3-4 days
Horses: 4 days
Cows: 5-7 days

  1. Erythrocyte Indices
  2. Pathophysiological
69
Q

How can you diagnose anaemia with an automated haemogram?

A
  1. Automated Haemogram:
    Specific: Absolute reticulocyte count

Method: Count aggregate reticulocytes, except mild/cr. anaemic cats → count punctate

Calculation: Reticulocytes x RBC x 1000 = x109

Results: Dogs - >60-80 x 109, Cats - >50 x 109 is evidence of regeneration

  • Non-Specific: Elevated MCV (In horses), RDW
70
Q

How can you diagnose anaemia with a blood smear?

A

Blood Smear:
- Specific: Polychromatophil, Reticulocytes (NMB – Punctate & Aggregate)

  • Non-Specific: anisocytosis, Metarubricyte, basophilic stippling (In Ruminants)
  • Other: Agglutination, spherocytes, Heinz body, eccentrocytes, parasites, acanthocytes,
    schistocytes, keratocytes
71
Q

Regenerative anaemia can be due to?

A

Haemorrhage:
Plasma protein concentration/TPP is decreased in per-acute (ECF not replenished) or compensated in chronic (proteins are released)

Plasma colour: Clear

  1. Acute or Chronic
    The acute patient with haemorrhage will be collapsed
    However the chronic patient will not be tired as the body has learned to compensate for low oxygen concentration.
  2. Internal vs External
    If it is internal the animal will recover quicker as all the iron/blood is still in the body and can be reabsorbed into the body/vasculature

If it is external it is lost to the outside. Has to reabsorb iron.

Haemolysis:
TPP is normal or increased
Plasma colour is haemolysed or icteric
Dx: Urine colour, blood smear, methaemoglobin imaging

72
Q

What are the different types of haemolysis? Regenerative Anaemia

A

Extravascular: Issue with RBC so breakdown occurs in a macrophage in the liver/spleen = ↑ Bilirubin

Intravascular: Occurs in blood vessel & releases Hgb → ↑ bilirubin via liver/macrophage AND release of Hb through blood and urine (Hemoglobinemia, haemoglobinuria)

Importance: Free Hgb causes tissue injury → I/v kidney = haemoglobinuric nephropathy

73
Q

What is non regenerative anaemia?

A

Caused by:
Reduce rate of erythropoiesis
Via Inflammatory disease, renal disease, marrow hypoplasia or aplasia

OR

Ineffective erythropoiesis
Nutritional: Fe, copper, cobalt, folate, vit. B21
FeLV induced erythroid neoplasia
–> Vit. b12/cobalt deficiency of FeLV positive cat: Macrocytic normochromic anaemia

–> Fe deficiency can lead to microcytosis as compensation. Making smaller cells.
Microcytic normochromic anaemia.
Also have schistocytes, keratocytes.
can be caused by chronic haemorrhage (e.g. parasites, tumours, ulcers)
CS: Tarry faeces, parasites, neoplasia, faecal occult blood test

Anaemia is mild if it only affects the RBC from the bone marrow

Normocytic, normochromic anaemia is when more than 1 cell line has been affected from the bone marrow. Severity and degree of anaemia effects the pathways

74
Q

How can you diagnose mild normocytic normochromic non regenerative anaemia?

A

MNEL
Monocytosis
Neutrophilia
Eosinophilia
Lymphocytosis

Hyperglobulinaemia or hyperfibrinogenaemia
Acute phase proteins

75
Q

How does inflammatory disease cause non-regenerative anaemia

A
  1. Functional Fe Deficiency: Fe trapped in macrophages
  2. Shortened RBC life span due to inflammatory. mediators/oxidative injury
  3. Impaired erythropoietin mediated RBC production in bone marrow
76
Q

How does chronic renal disease cause non-regenerative anaemia?

A

Reduced erythropoietin production (kidney is a source of production alongside the bone marrow)

Reduced RBC survival time due to reduced toxic clearance by the kidneys

Haemorrhage (GIT ulcers)

77
Q

How do endocrinopathies and hepatopathies cause non-regenerative anaemia?

A

Mild to moderate normocytic normochromic anaemia

Endocrinopathies:
1. Hypothyroidism: low TT4/TT3 –> decreased metabolic rate –> decreased O2 requirements –> Decrease EpO production –> compensate with new homeostasis/metabolic needs met by lower RBC

  1. Hypoadrenocorticism
    Reduced production of RBC in the bone marrow.
    Cortisol deficiency and cortisol promots RBC production

Hepatopathy:
Hepatic disease causes mild normocytic normochromic anaemia
Increase in liver enzymes
Defective protein and lipid metabolism, affects RBC lifespan.

Portosystemic shunts:
Microcytic normochromic anaemia.
Defective protein synthesis, defective Fe transport and thus potential functional Fe deficiency.

78
Q

How does hypoplasia or aplasia of the bone marrow cause anaemia?

A

Severe normocytic normochromic anaemia
Can be caused by:
- damage to bone marrow microenvironment due to inflammation, infection

Neoplasia
Chemotherapeutic agents
Hyperoestrogenism (sertoli or granulosa cell tumour or admin. of oestrogen)
Bracken fern toxicity

79
Q

What are different types of haemolytic anaemia?

A

Causes accelerated RBC destruction

  1. Immune mediated
  2. Erythrocyte metabolic defect
    a. Oxidative Damage
    b. Defect in ATP generation
  3. Erythrocyte fragmentation
  4. Infectious
  5. Other
80
Q

What is Immune Mediate Haemolytic Anaemia (IMHA)

A

IMHA is caused by antibodies directed against erythrocyte surface- associated immunoglobulin to destroy RBC.
1. Extravascular haemolysis in macrophages removes the erythrocyte
2. It is converted to a spherocyte by the macrophage, removing part of the RBC membrane
3. Ab binds to complement, activates cascade and forms a membrane attack complex (agglutination)

It causes a left shift inflammatory leukogram due to hypoxia causing tissue damage.
Can be diagnosed with the Coombs test - Direct antiglobulin test

81
Q

What are the different types of IMHA?

A

Extravascular: Most likely
IgG antibodies against RBC and increased destruction of RBC by splenic macrophages
Smear: Spherocytes

Intravascular: IgM RBC destruction and complement membrane attack complex (C5b-9)
Marked severity
Smear: Agglutination, spherocytes –> Ghosts (C5b-9)

82
Q

What are the causes of IMHA

A
  • Idiopathic (Autoimmune): Immune response directed at normal self isotypes
  • Drug Induced: Develops abnormal antigens on the erythrocyte cell membrane
  • Vaccine
  • Alloimmune:
    a) Blood transfusion reactions
    b) Neonatal Isoerythrolysis:
83
Q

What is Neonatal Isoerythrolysis?

A

Immune mediated destruction of RBCs caused by maternal antibodies ingested in colostrum
Common in horses, can occur in cats.

Timeline: Born healthy (0-8d) → haemolytic anaemia

CS: <24-48hrs – Anaemic (PCV 10-20%), icteric (Bili ~20mg), dyspnoea, ↓ suckling, death, Haemoglobinuria/haemoglobinuric nephropathy

In cats: Occurs when Queen type B (Anti-A) breeds to Tom type A – kitten at risk if type A/AB

84
Q

What are some diagnostic tests for Neonatal Isoerythrolysis?

A

Dx:
1. Smear: Agglutination, anisocytosis, Metarubricyte, Howell-Jolly bodies, ghosts, spherocyte
2. Coomb’s Test: Antiglobulin tests – Not specific as Dx immune Dz
3. Presumptive Evidence: Ab in serum/plasma of dam’s colostrum reacts to foal/sire Ag
4. Jaundiced Foal Agglutination: Pre suckling to assess risk with colostrum ingestion. Monitor decline in colostral antibody over time to determine where it is safe to allow foal to nurse.

If it agglutinates in saline control tube: RBC coated with Ab
If agglutinates in low dilutions: Check it is not RBC clumping by adding colostrum to Dam’s RBC

85
Q

How to prevent Neonatal Isoerythrolysis?

A
  1. Test mares for antibodies
  2. Mate negative mares to negative stallions OR prevent suckling until testing colostrum Ab
  3. If Ab positive, give plasma transfusion/other mares colostrum. Keep testing colostrum unti it is below 1:16 titre
86
Q

What are different types of oxidative damage in erythrocyte metabolic defects?

A

a. Oxidative Damage

  1. Heinz Body Haemolysis:
  2. Eccentrocytic haemolysis
  3. Methaemoglobinaemia

Anaemia occurs

Extravascular: RBC’s more rigid as they are less able to pass through splenic sinusoids –> trapped and removed by macrophages

Intravascular: More fragile due to damaged membrane: may rupture spontaneously in blood vessels

Ag Formation (Heinz body); Heinz body binds to RBC membrane

87
Q

What is Heinz Body Haemolysis?

A
  1. Heinz Body Haemolysis:
    They are aggregates of denatured HgB caused by oxidative damage.
    Zinc can cause Heinz bodies as it causes oxidative damage.

Pathogenesis: Oxyhaemoglobin –> Methaemoglobin –> Hgb-Fe3+ turns into hemi-chromes or heme-depleted Hgb –> Hemi-chromes precipitate into heinz bodies –> Sulfhydryl groups are oxidised and form disulphide bonds.

Stain: NMB - Pale blue protruding round structures on RBC membranes
Wrights & Diff Quik – Slightly pale membrane defects/protrusions

Cats:
Normal <5% Heinz body in spleen
Pathogenic: >5% large Heinz bodies/multiple on RBC
Causes:
- Paracetamol (Acetaminophen):
Lack glucuronyl transferase (No conjugation) → reactive metabolites → deplete glutathione → ↓ protection from oxidative injury
- Diabetes Mellitus
- Ketoacidosis
- Hyperthryoidism
- Lymphoma
- Onion/garlic, benzocaine, propylene Glycol, propofol

Dogs – Causes: Onion, garlic, Vit K1/K3, Paracetamol, Moth ball, Zn

Horses – Causes: Onion, Maple lead, Phenothiazine

Ruminants – Causes: Onion, Ryegrass, Brassica, Cu (Sheep)

88
Q

What is Eccentrocyte Haemolysis

A

Eccentrocytes are mature erythrocytes in which the haemoglobin is
pushed to one side of the cell leaving an opposing pale staining region.

Forms when Oxidation causes bonding of RBC membranes –> Collapse & Hgb is displaced
Causes:
Exogenous oxidants: onions, garlic, acetaminophen, propylene glycol, zinc.
Stain: Wrights or Diff Quick

Endogenous oxidants: in very sick patients e.g. diabetes mellitus

89
Q

What is Methemoglobinemia?

A

Oxidant overwhelms RBC mechanisms to keep Hgb in reduced state
- Oxyhaemoglobin (Fe2) → Methemoglobin (Fe3 – CAN’T deliver O2)

Effects:
Initially cyanotic (cannot deliver O2), Later as Fe3+ –> 10% mucous membranes appear brown.
Causes: Paracetamol (Dog/Cat), onions, Red maple (Horses), Nitrite

90
Q

What are defects in ATP?

A
  1. Hypophosphataemic haemolysis
    Severe hypophosphatemia may lead to reduced RBC ATP production. This leads to an unstable RBC membrane, causing haemolysis
    CS: Depressed myocardium, Rhabdomyopathy, seizures, coma, acute respiratory failure
  2. PFK & K Deficiency
91
Q

What are the types of hypophosphataemic haemolysis?

A

a) Post parturient haemoglobinuria
Hosts: Cattle
Cause: 3-8wk post-calving (multi-parous) ↓P bone mobilisation & ↑ P loss via milk
Dx: ↓ ATP& Glutathione, moderate-marked IV anaemia haemolysis,
hypophosphataemia
Ddx: Complicated by concurrent ketosis, generates oxygen radicals → heinz bodies

b) Hyperinsulinism ass. hyperglycaemia
Hosts: Domestic animals
Pathogenesis: Insulin promotes movement of P & glucose in non-RBC cells
Diabetic cats:
Polyuria –> Hypophosphataemia and haemolysis
Can have concurrent ketosis (heinz body). Combination of hypophosphataemia and ketotic haemolytic anaemia.

c) Sporadic Hypophosphatemia Hosts: Horses, dogs, cats

d) Artefact
Via: Bilirubin interference – depends on analyser & method

92
Q

What is Erythrocyte Fragmentation?

A

Smear: Schistocytes, keratocytes, acanthocytes
Form when blood is forced to flow through an altered vascular channel or turbulent blood flow.

Causes:
- Fibrin – Traumatic injury to RBC membrane: Disseminated (Or local), Vasculitis

  • Membrane lipid changes – Fragility: Haemangiosarcoma
    Morph: Acanthocytes. If ruptured: regenerative anaemia +- NRBC’s, Schistocytes, DIC)
  • Rheological (Blood Flow) process: Cardiac valvular disease (E.g., Endocarditis), Dirofilariasis
93
Q

What is a keratocyte?

A

RBC’s that appear to have one or more intact or ruptured clear “vesicles”.
If they rupture: Looks like it has one or two projections.

When it is present in large numbers:
Fragmentation Injury: Microangiopathic haemolysis, haemangiosarcoma, DIC

Oxidant Injury:
Keratocytes may accompany eccentrocytes & possible Heinz Bodies

Liver Disease in cats e.g. hepatic lipidosis

94
Q

What is an Acanthocyte?

A

Have irregularly spaced, variably sized spicules usually ending in a “club-shaped” or “fish”
Diseases with Increased fragmentation
e.g. Heamangiosarcoma, liver disease, DIC, glomerulonephritis

95
Q

What are some infectious agents that can cause regenerative anaemia?

A

Agents: Distemper, Anaplasma (Centrale, marginale), Babesia, Mycoplasma (Haemofelis, haemocanis), Candidatus Mycoplasma Haemominutum, Theileria

Diagnosis:
- Presence of Organism: Absence does not rule out presence. Degree of parasitaemia does not necessarily correlate with the degree of clinical disease.

  • Blood smear:
    Morph: Spherocytes, agglutination (Due to concurrent immune-mediated components)

Sample: Fresh blood to avoid dislodging from membrane, capillary blood smears usually more helpful than jugular or cephalic, buffy coat smears may help conc organism

96
Q

What are some other causes of haemolytic anaemia?

A
  1. Heparin Induced haemolysis
    In horses heparin anticoagulant therapy can cause RBC agglutination
    CS: Hyperbilirubinemia, 6-8hrs post treatment and resolves after 5d
  2. Envenomation (snakes)
    Pathogenesis:
    - Cobra venom: Activates Complement system
    - Rattlesnakes: Haemolysins (Phospholipase A2) cause direct haemolysis
    - Bees: Haemolysins (Phospholipase A2) cause spherocytic haemolytic anaemia
97
Q

What are the phases of haemostasis?

A

Primary: Blood vessels, platelets, von williebran factor

Secondary: Cascade and models produce thrombin which converts fibrinogen to Fibrin. Fibrin stimulates cross-linking between fibrin to form a stable clot

Tertiary: Fibrinolysis to cause the breakdown of a clot via plasmin to re-instate blood flow

98
Q

How can you do sample collection for haemostatic disorders?

A

Sample Collection
Tube: Citrate vacuum + Non-hep catheter flushed w/ 5mL saline & discard 6x dead space (5ml)
Method: Centrifuge immediately for 10 minutes, collect plasma with pipette –> Place in plain plastic tube.
This will be stable at room temperature except for slight decrease in fibrinogen, for 48 hours.

Ratio: 1:9 (Citrate to blood).
Under filled: there is prolonged times and reduced coagulation as over-citrated
Over fill: Reduced times, hyper coagulable as under citrated

Avoid:
- Heparinized catheters
- Excess vacuum (Platelet activation)
- Prolonged vessel occlusion
- Activation of platelet, coagulation, fibrinolytic activation
- Traumatic venipuncture → produces tissue factor → initiates coagulation & affects results
- Drawing into dry syringe
- Incomplete blood draw
- Air in vacutainer (Depletes or dilutes)

99
Q

What are the diagnostic tests for primary haemostasis?

A

Clinical Signs: Petechiae, Ecchymoses, Bleeding post injection, GI bleed/melena, epistaxis, haematuria

Components:
1. Vascular: No tests available

  1. Platelet Count:
    - Automated Analyser (EDTA)
    - Blood smear (EDTA): Not accurate count as platelets are clumps. 100x objective and count 10 points. Normal 10 plt/hpf (100x). If there is less than 3 platelets: Spontaneous haemorrhage (IMT)
  2. Platelet Function
    - Buccal mucosal bleeding time
    Normal: 1-4m (dog), 1.3m (Cat)
    Testing primary haemostasis or if vWB < 20%
    Increased BMBT indicates vascular lesions/capillary fragility OR lack of platelets/platelet defect
    Method: 5mm cut is made in the upper lip and the time until bleeding ceases & crescend blood no longer forms on filter paper is recorded
    Increased: Severe thrombocytopenia or anaemia, thrombocytopathy
  • Clot Retraction Time
    Method: 2mL blood collected from 2 animals and control into a plain tube. It is left to clot at 37 degrees, after 1 hr clot retraction of the 3 vials is compared
    Normal: Serum production 30-50%
    Defective: Thrombocytopenia/pathy, erythrocytosis, hypofirinogenemia
    Increased: Anaemia
    DIC: Clot is small & ragged, partially disintegrated via excess plasmin.
    Disseminated intravascular coagulation

vWB Factor:
- vWB Factor (Elise/Antigen)
Method: Plasma Harvested after blood collection in EDTA or citrate –> Shipped to lab
Interpretation: Reported as and relative to pool of healthy species references
Free of vWD: Ag >70%, Carriers: 50-69% but not at risk of bleeding
Greater than 70% is considered as normal.
Dogs with less than 50% are carriers that will transmit to offspring. Risk of clinical von willieburns disease.
Dogs that will bleed: <35%
There may be false decrease in vWF is the sample has clotted or haemolysed
There may be false increases in vWF due to excercise, pregnancy, epinephrine, endotoxin, azotaemia or liver disease.

  • DNA Test
    Method: Buccal swab and smear submitted
    Interpretation: Genetic tests don’t always correlate to CS; will tell if clear, carrier or affected
100
Q

What are some diagnostic tests for secondary haemostasis?

A

Clinical signs: Bleeding into cavities/joints/muscles/haematomas + GI bleed, hematuria, epistaxis
Proenzymes II, VII, IX, X are Vitamin K dependent
Coagulation factors

IX deficiency (Haemophilia B): Subcutaneous haematoma of head
VII Defieciency (Haemophilia A): Haematoma of stifle, perirenal haemotoma.

  1. Activated Clotting Time (ACT)
    Tests: Intrinsic & Common Pathway
    –> Intrinsic Pathway: Propagation of thrombofibrinogen to fibrin using co-factors XI, VIII, V
    ACT: Prolonged if: <10% of factors (90% loss)
    Prolonged test results may be due to: Anticoagulant rodenticide intoxication, Disseminated intravsacular coagulation (DIC)
    Normal: Dogs - 60-90s, Cats - < 165 s

Modified APTT: Tests for severe primary or secondary coagulopathy. < 30% of factors

MOA: Depends on platelet phospholipid to support reaction
Method: 2mL is added to a diatomaceous earth activator for factor XIII tube and are inverted until a clot forms.

  1. APTT
    Tests: Intrinsic and common pathway
    Prolonged if: <30% of factors (70% loss)
    MOA: Depends on adding of a phospholipid in a lab setting
    Inflammation: Can cause shorter time then expected as fibrinogen, factor V & VIII may increase with inflammation.
  2. PT
    Tests: Extrinsic
    Indication: K deficiency, influences II, VII, IX, X
    Prolonged (6-10secds): Factor < 20-25% suggestive of pathology/disease
  3. Thrombin Clot Time: Direct measurement of functional fibrinogen & clotting time can be converted to determine fibrinogen concentration
    Tests: Common Pathway
    Method: Time for clot formation in citrate + Ca + Thrombin
    Hyperfibrinogenemia: Acute phase protein that increases with inflammation
    Hypofibrinogenemia: DIC, synthetic liver failure via inhibitor of thrombin (Heparin) or fibrin polymerisation or paraproteinemia
101
Q

What are diagnostic testing for tertiary haemostasis?

A
  1. APTT
  2. PT
  3. FDP: Detects fibrinogenolysis & Fibrinolysis
  4. D-Dimer
    D-dimer presence indicates the generation of thrombin & plasmin that breaks down clot. Marker of hypercoagulability
    Detects: Thrombin generated for fibrinolysis of cross-linked fibrins and activates FXIII & Plasmin
    - Physiological causes: Wound healing/post-surgery there is increased in D-Dimer
    - Pathological: Internal haemorrhage, any cause of thrombosis/thromboembolism (DIC, Sepsis, Neoplasia)
    False Increase: Sample haemolysis
102
Q

What are the inhibitors of haemostasis?

A
  1. Antithrombin III
    Decreased: Protein losing nephropathies and enteropathies
    Chronic hepatitis/Cirrhosis
    Sepsis
    Hypercoaguable states
    Cats: Behave like an acute phase protein and increased with varied conditions
  2. Tissue Factor Pathway Inhibitor: Inhibits FX & Thrombin
  3. Protein C: Cleaves FVa and FVIIIa
103
Q

What are important haemostatic diseases due to impaired primary haemostasis?

A

Thrombocytopenia: Platelet destruction/consumption: IMT, DIC
Decrease in the production of haemic cell lines in the bone marrow
Can be due to:
- Chemotherapy
- Oestrogen in dogs
- Bracken ferm poisoning
Can be reduced temporarily if sequestered in the spleen

Cattle
CS: Petechiae found on the gums, ventral tongue, conjunctival sclera
Causes: Acute bracken fern, acute BVDV, trichothecene mycotoxicosism bleeding calf syndrome

IMT: Immune mediated thrombocytopenia
Platelet destruction common in dogs

Thrombocytopathy

vWD:
The function vWB: Platelet adhesion and Stabilising & Protective Carrier Molecule
Cause: Hereditary especially in dogs
Type 1: All Multimers present in decreased concentration. With mild-severe bleeding
Hosts: Dobermans,
Incidence: Most Common

Type 2: Disproportionate decrease in large multimers with severe bleeding
Uncommon

Type 3: All multimers are absent causing severe bleeding

CS:
Prolonged haemorrhage
Pattern of haemorrhage: Absence of petechia. Cutaneous bruises and mucosal bleeds
Prolonged BMBT: Normal usually
APTT: Prlonged only in horses

104
Q

What are the main disorders due to impaired secondary haemostasis?

A
  1. Hereditary Disorders:
    CS: Bleeding tends to occur within first year of life
    Prolonged PT: Factor VII deficiency
    Prolonged APTT: Factor XII, XI, IX, VIII deficiency

Prolonged PT & APTT: Factor X, Factor V, prothrombin, fibrinogen or combined factor deficiency.

  1. Acquired Disorders:
  2. Vitamin K antagonist: Rait Bait, Mouldy Sweet Clover
    Direct ingestion or poisoned rodent
    Pathogenesis: Factor deficiency/Inactivity of 2, 7, 9, 10
    Vit K. Synth: Carboxylation by Vit K. Dependent enzyme to allow Ca binding –> Allows phospholipid binding –> Coagulation on area of injury

Anticoagulant rodenticites:
Hydroxycoumarins: 1st Gen, effect takes 1 week and takes multiple doses
Inandiones: Second gen, 4-6 weeks, single dose of toxin or rate that are the poison

  1. Vitamin K deficiency: Severe choleostasis disease/GIT Disease
  2. Liver DIsease: Coagulation factor decifiency, acute liver disease.
    CS: Bleeding is uncommon but can occur if it is severe
  3. DIC
105
Q

What are the main diseases associated with tertiary haemostasis?

A

Cause: Secondary to other disease process

  • Primary haemostasis: Systemic platelet activation –

Small Animal Medicine (16 decks)

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