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Lymphoreticular and haematopoeitic > Abnormalities - erythron 1 > Flashcards

Abnormalities - erythron 1 Flashcards

1
Q

Outline regeneration

A
  • response to fall in O2 tension
  • kidneys produce EPO
  • EPO stimulates BM to increase RBC production
  • tales 2-3 days, younger RBCs (polychromatophils/ reticulocytes) increase in circulation
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2
Q

What is non-regeneration?

A

where BM doesn’t respond to EPO the way you’d expect

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3
Q

2 differentials for regenerative anaemia

A
  • haemorrhage

- haemolysis

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4
Q

What are reticulocytes?

A

= polychromatophils

  • stain with New Methylene Blue
  • RNA precipitates forming aggregates/ ‘reticulum’: reticulocytes
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5
Q

What are polychromatophils?

A

= reticulocytes

  • DiffQuick or Giemsa
  • young cell containing rRNA show up as large blue cells and these are polychromatophils
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6
Q

Describe reticulocytes in cats

A
  • cat retics released as aggregate retics maturing to punctate retics over time
  • retic counts should record either aggregate or both
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7
Q

Define reticulocyte %

A

1000 RBCs counted, the retics expressed as a percentage

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8
Q

Define corrected reticulocyte %

A

the same number of reticulocytes will take up more of a % in a very anaemic animal
= retic % * (patient PCV/ normal PCV)
- 45% normal dog
- 35% normal cat

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9
Q

Define absolute reticulocyte concentratin

A

= [RBC] * Retic %

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10
Q

Examples - increased loss

A 
EXTERNAL HAEMORRHAGE
- melena (GI bleed)
- UT
- epistaxis
- post-trauma/ sx
INTERNAL HAEMORRHAGE
- bleeding tumours
- trauma
- into tissue (bleeding diathesis)
- sx
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11
Q

Describe melena

A
  • not always visible
  • faecal occult blood is very sensitive but not very specific
  • meat free diet (white fish/chicken ok) for 5d before test or WILL be positive
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12
Q

Outline haemolysis

A
  • increased internal RBC destruction
  • intravascular/ extravascular
  • normal erythrocytes or abnormal / damaged
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13
Q

Describe immune-mediated haemolysis

A
  • anti RBC Ab (IgG, IgM, IgA)
  • RBCs opsonised and either lyse (more common with IgM) or are phagocytosed
  • may agglutinate
  • coomb’s test positive (for anti-RBC Ab)
  • may be severe/ rapid, usually strongly regenerative
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14
Q

How can you use corrected reticulocyte % to work out if an anaemia is regenerative in dogs and cats?

A
  • cats: regenerative if >0.4% corrected reticulocyte %

- dogs: regenerative if >1% corrected reticulocyte %

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15
Q

Describe the agglutination test

A
  • screening test
  • one drop of saline and one drop of EDTA anticoagulated blood mixed on slide and rocked
  • look for flecking before it starts to dry
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16
Q

What can appear like agglutination macroscopically?

A
  • Rouleaux
  • these are artefacts (not a problem unless increased protein)
  • classic appearance on a slide is like a stack of coins
  • by bringing down {protein] with saline dilution, will reduce Rouleaux formation
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17
Q

Describe ghost cells

A
  • remnants of RBCs that have lost Hb
  • membrane only
  • associated with deposition of complement and INTRAVASCULAR haemolysis
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18
Q

Describe IMHA (extravascular)

A
  • macrophages in spleen/ liver attack RBCs with Ab on.
  • complete phagocytosis or partial where RBC membrane fuses with that of macrophage and forms spherocyte (small and dark - d/t much Hb)
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19
Q

Other lab findings of IMHA

A
  • increased bilirubin (esp if extravascular haemolysis)
  • may have neutrophilia, monocytosis (marrow upregulation)
  • PLTs may als be affected - check carefully
  • IMHA + I-M platelet destruction = EVAN’S SYNDROME
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20
Q

Describe haemolysis induced by parasites

A
  • Mycoplasma haemofelis and M. haemominutum (formerly Haemobartonella)
  • blood borne
  • epiceulla rparasite
  • large and small forms
  • increases fragility and haemolysis
  • cyclical (3-8wks)
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21
Q

Dx - Mycoplasma haemfelis

A
  • PCR excellent

- blood smear exam (unreliable)

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22
Q

Describe Babesia in RBCs

A
  • USA > UK
  • tick borne
  • 2-4 pyyriform bodies in RBC
  • haemolytic
  • tx (successful if caught early) = imidocarb
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23
Q

Describe Cytauxzoon felis in RBCs

A
  • southern US
  • intracellular parasite
  • prominent splenic RBC removal
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24
Q

What is Heinz-body associated anaemia?

A
  • denatured Hb = Heiz body
  • cats more vulnerable than dogs
  • low #s unremarkable in cats
  • oxidative injury: onions, paracetamol, vit K, propylene glycol
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25
Q

What are eccentrocytes?

Species?

A
  • Hb has uneven distribution within the cell (eccentric distribution)
  • oxidative damage to membrane
  • usually dogs
  • horses (red maple toxicosis)
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26
Q

Name 2 RBC shear injury products

A
  • schistocytes
  • keratocytes
  • acanthocytes
  • pre-keratocytes - keratocytes
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27
Q

When do shear injuries accompany?

A
  • microangiopathic damage
  • tumours with narrow BVs (e,g. HSA) or organ inflammatory beds (severe hepatitis, DIC) where there is fibrin stranding)
  • clue to cause
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28
Q

What is an acanthocyte?

A
  • RBC with surface projections of variable length
  • projections are unevenly spaced on RBC surface
  • associated with splenic dz (HSA)
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29
Q

What are pre-keratocytes?

A
  • shear injury BC
  • RBCs with apposed and sealed membrane
  • Helmet shaped cells
  • associated with shearing - intravascular trauma (e.g. vasculitis, DIC)
  • seen with schistocytes
30
Q

What are schistocytes?

A
  • RBC fragments that occur secondary t shear injury
  • associated with fibrin deposition in vessels
  • DIC
31
Q

Describe pyruvate kinase (PK) deficiency

A
  • Basenjis and Beagles
  • chronic, severe haemolysis
  • initially v regenerative but may go on to develop myelofibrosis
  • die at 1 year
32
Q

Give 3 examples of non-immune- mediated haemolysis

A
  • PK deficiency
  • Phosphofructokinase (PFK) deficiency
  • feline porphyria
33
Q

Describe PFK deficiency

A
  • english springers
  • RBCs sensitive to alkaline pH
  • low grade haemolysis with severe episodes superimposed
34
Q

Describe non-regenerative anaemia d/t inflammatory/ chronic dz

A
  • most common non-regenerative
  • normocytic, normochromic
  • usually mild, slow progressing
  • Fe sequestration, inflammatory mediators, shortened erythrocyte survival
35
Q

Describe non-regenerative anaemia d/t renal

A
  • kidneys produce EPO
  • with chronic renal failure, production decreases
  • normocytic, normochromic
  • mild to moderate
  • impacts QoL
  • EPO injection available but may develop Abs
  • aim to increase PCV but not necessarily to normal
36
Q

Describe non-regenerative anaemia d/t endocrine causes

A
  • hypothyroid and endocrine
  • normocytic, normochromic, mild
  • thyroid hormone and cortisol have a facultative effect on RBC production
37
Q

List causes of non-regenerative anaemia

A
  • inflammatory / chronic dz
  • renal
  • endocrine
  • FeLV
38
Q

Describe non-regenerative anaemia d/t FeLV infection

A
  • up to 70% anaemic cats
  • selective depression of erythropoiesis
  • dysplastic production
  • myeloproliferative dz crowding out
  • usually non-specific erythroid hypoplasia
  • may be normocytic, normochromic BUT many macrocytic
  • associated with FeLV subgroup C
39
Q

What is aplastic anaemia?

A

all precursors wiped out, leaves fat, plasma cells and mast cells

40
Q

Dx - aplastic anaemia

A

core biopsy

41
Q

Causes - non-regenerative marrow

A
  • FeLV (rarer nowadays)
  • estrogen toxicity
  • phenylbutazone
  • chemotherapy
  • unknown
42
Q

What is myelodysplasia?

A
  • adequate cellularity in marrow but abnormal maturation / production of cells (ineffective erythropoiesis)
  • Marrow: erythrocyte macrocytosis, binucelates, maturation defects, giant neutrophils, hypersegmented neutrophils, macrroplatelets, may go on to leukaemia
43
Q

What is myelopthisis?

A
  • non-regenerative
  • is neoplasia ‘crowding out’ the BM –> altered environment
  • usually haemopoietic neoplasms (especially lymphoid)
44
Q

What is myelofibrosis?

A
  • often response to injury of fibrous elements of marrow: dry taps. may be reactive following prolonged regenerative attempts
  • need core: reticulin stains up the fibrous elements
  • osteosclerosis: cortical bone increases
  • may get marked extramedullary haematopoiesis
45
Q

T/F: non-regenerative anaemia may become non-regenerative in the long term

A

True

46
Q

T/F: I-M attack against RBC precursors (not peripheral mature RBCs) may give a non-regenerative anaemia

A

True

47
Q

How can anaemia be classified?

A
  • mild, moderate, severe
  • regenerative or non-regenerative
  • macro or microcytic
  • hypochromic or normochromic
  • specific morphology changes
  • sample give answer?
48
Q

What is erythrocytosis (polycythemia)?

A
  • increase in the HCT, RBC count and Hb

- may be spurious or relative (dehydration = volume contraction OR RBC redistribution = splenic contraction

49
Q

Types of erythrocytosis (polycythemia)

A
  • PRIMARY (polycythemia vera)

- SECONDARY (appropriate or inappropriate)

50
Q

Describe primary erythrocytosis

A

= polycythemia vera

  • myeloproliferative disorder or erythroid stem cells
  • EPO levels normal or decreased
  • PO2 normal
51
Q

Describe secondary erythrocytosis

A
  • appropriate or inappropriate
  • chronic hypoxia
  • EPO secreting tumours
  • EPO levels elevated
52
Q

Guidelines for taking smears

A
  • always make a fresh blood smear and submit it with EDTA blood sample to ensure good WBC and RBC morphology is maintained
  • store blood in fridge until analysis (slows changes)
  • smears should be stored at room temp and not in fridge
53
Q

Guidelines for taking smears

A
  • always make a fresh blood smear and submit it with EDTA blood sample to ensure good WBC and RBC morphology is maintained
  • store blood in fridge until analysis (slows changes)
  • smears should be stored at room temp and not in fridge
54
Q

Describe RBC appearance

A
  • biconcave disk most spp
  • central pallor (dogs)
  • high SA: volume which allows for deformability
  • camelids have elliptical RBCs
  • anucleat (mammals), nucleated (birds, reptiles)
55
Q

RBC production sites

A
  • liver/spleen in foetus
  • BM in neonate
  • growing animals: marrow of all bones
  • red/yellow marrow (femur/ humerus) in long bones, flat bones remain active
  • liver and spleen maintain erythropoeitc capacity, especially if increased demand (extramedullary haematopoeisis) as do long bones (reversion to red marrow)
56
Q

Production requirements - RBCs

A
  • stem cells
  • space in marrow (caution tumour)
  • growth factors (IL-3, GMCSF, GCSF, EPO)
  • Fe
  • cholesterol/ lipids (membrane)
  • enzyme pathways (construction/ maintenance)
57
Q

Describe RBC maturation appearance

A
  • early: large nucleus, dark blue cytoplasm (d/t blue dye which is basic binding to the acidic RNA elements)
  • older: less RNA/ribosome so less blue and more pink
58
Q

Eryhtrocyte lifespan:

  • dog
  • cat
  • horse/cattle
A
  • dog: 100d
  • cat: 70d
  • horse/cattle: 150d
59
Q

Normal RBC removal

A
  • MAJOR ROUTE: senscent RBCs taken up by phagocytic macrophages, components recycled.
  • MINOR ROUTE: intravascular haemolysis
60
Q

What is anaemia evidenced by?

A 
Reduction in red cell mass, evidenced by:
- [Hgb]
= PCV
- HCT
- [RBC]
61
Q

How do HCT and PCV differ?

A
  • essentially the same but HCT is calculated by machine whereas PCV is manual and red cells are red as a % of column after being centrifuged. HCT relies on red cell count and volume
  • benefit of PCV over HCT is that you can assess plasma colour (clear/straw or pink if haemolysed), allows buffy coat assessment (WBCs), TP measurement
62
Q

Describe mild anaemia

A
  • from just below the normal PCV to approx 10% below
  • may not affect animal until exercised
  • common in animals with longstanding dz, endocrine disorders etc
  • usually these animals won’t present to you with mild anaemia as clinical case. More likely that you will discover the animal has mild anaemia when running minimum database
63
Q

Describe moderate anaemia

A
  • varies b/w spp, depends on normal PCV for each
  • may show weakness, may be well-adapted: takes time
  • MM pallor, fast bounding pulse
64
Q

Describe moderate anaemia

A
  • varies b/w spp, depends on normal PCV for each
  • may show weakness, may be well-adapted: takes time
  • MM pallor, fast bounding pulse
65
Q

Describe severe anaemia

A
  • PCV in lower teens downwards
  • pale, weak, unable to exercise
  • may need O2 and stabilisation before diagnostic procedures - brittle
  • don’t fight with very anaemic cats!
66
Q

What is normochromic/ hypochromic?

A
  • Hg concentration
  • MCHC/ MCH on panel
  • decreased in Fe deficiency/ poor Fe incorporation (with microcytosis)
  • hyperchromic not possible as haemolysis occurs before this point
67
Q

How do you determine if a cell is micro/normo/macro cytic?

A
  • determine MCV
68
Q

Describe a normocytic RBC

A
  • erythrocytes of unremarkable size, often associated with mild non-regenerative anaemia, acute haemorrhage etc
69
Q

Describe microcytic RBCs

A
  • red cell hg concentration determines when division stops - Fe deficiency allows one more division: smaller red cells
  • PSS, Fe deficiency, hepatic failure
  • Akitas/ japanese dogs (normal variation)
70
Q

Describe macrocytic RBCs

A
  • in regeneration - polychromatophils are larger than mature RBCs
  • some poodles
    OTHER CAUSES:
  • FeLV-affected cats (as virus in BM)
  • in myelodysplasia
  • common artefact in stored (usually posted) blood

Lymphoreticular and haematopoeitic (21 decks)

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