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Haematology cases – red cells
Kathleen Tennant
Clinical Lead, Diagnostic Laboratories
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Langford Veterinary Services Ltd is a wholly owned subsidiary of the University of Bristol
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Langford Veterinary Services Ltd is a wholly owned subsidiary of the University of Bristol
Machine measurements
• Machine methods –
impedence and optical
• Sample is mixed with
diluent/ sheath fluid andv
red cells streamed
through laser or electrical
field
• Number and size of cells
measured
• Agglutination/ lipaemia
may affect results
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Flourescence methods (Lasercyte)
• These methods can
distinguish the adult
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red cell population
from reticulocytes
using size and
increased nucleic
acid content to allow
automated counting
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Red cell measurements
• Of the three measures of red
cells mass (HCT, RBC, Hb)
haemoglobin is the ultimate
determinant of oxygen
v
carrying capacity
• (A cat with a haematocrit or
PCV of 5% is given
haemoglobin in the form of
‘oxyglobin’…the haematocrit
doesn’t change, but the cat
looks better…)
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mean cell volume
Cell
numbers
v
platelets
Cell size
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Red cell distribution width (RDW)
Cell
numbers
v
platelets
Cell size
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MCV - Normocytic
• Erythrocytes formed
correctly
• Mild to moderate non
- regenerative anaemia
of chronic disease
• Acute haemorrhage
• Renal disease
• Decreased production
of marrow origin
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MCV - Microcytic
• Red cell haemoglobin concentration
determines when division stops – iron
deficiency allows one more division: smaller
red cells.
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• External blood loss, portosystemic shunts,
liver disease, dietary Fe deficiency
• Early iron deficiency both macrocytic
polychromatophils and microcytes may be
present – MCV depends on dominant cell
type
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Microcytosis and macrocytosis
together
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Microcytosis
• Artefactual machine change in
hyponatraemia – sudden normalisation of the
osmotic levels in the diluent used causes
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shrinkage of the adapted
red cells
• Anaemia of chronic/ inflammatory disease
• Goodfellow et al. (2008) Res Vet Sci June, pp
490-493 showed storage of microcytic
samples for 24 hours could lead to
misclassification as normocytic
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MCV
• Macrocytic - in
regeneration –
polychromatophils
larger than mature
reds, also in some
FeLV affected cats, in
myelodysplasia and as
a common artefact in
stored (usually posted)
blood
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Macrocytosis
• Artefactual in hypernatraemic animals: up
to 10.4 fL in a cat with Na+ of 186 mmol/L
– Boisvert et al (1999)
Vet Clin path 28 (3)
v
p91 - 96
• Artefactual in hyperglycaemia (Holt et al
{1982} Am J Clin Path 77 (5) 561 - 7
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Normochromic/hypochromic
• Measures of haemoglobin concentration in
the red cell mass
• MCHC / MCH on panel – MCHC preferable
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as takes MCV into account
• Decreased in iron deficiency/ poor iron
incorporation (usually with microcytosis) and
in regenerative anaemias (immature reds not
fully haemoglobinised)
• Hyperchromic not possible: haemolysis
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Hypochromic
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Iron deficiency anaemia
• Weiser and O’Grady (1983) Vet Pathol Mar;20
(2):230-41.
• 12 dogs with iron deficiency
• Moderate to marked reticulocytosis,
decreased
v
mean corpuscular volume, and decreased mean
corpuscular hemoglobin concentration
• Only 4/12 hypoproteinaemic
• Therapy resulted in rapid production of
normochromic, normocytic cells
• ?Situation in cats
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Assessing regeneration
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Polychromatophils
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Reticulocytes
• Some directly measured relying on increased
cell size and more RNA content
• New Methylene blue smears
(equal volumes
v
EDTA blood and filtered New Methylene blue
for 15 – 20 minutes), then smear
• Count 500 cells and derive %
• (New Methylene Blue smears also very good
for seeing Heinz bodies in red cells)
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Absolute reticulocyte count –
accounts for degree of anaemia
9/l) =
Absolute reticulocyte
count
(x10
v
observed % retics X RBC count (x1012/l) X 10
Regenerative if > 50 x109/l
Strongly regenerative if > 200 x109/l
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Reticulocytes (white arrow punctate, black arrow
aggregate)
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Case 3296
• 4 y.o FN Old English Sheepdog
• Sudden onset lethargy, dyspnoea, pallor
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Parameter
Patient
value
Units
Reference interval
Hb
3.66
g/dl
12.00 – 18.00
HCT
12.0
%
35 - 55
RBC
1.28
X 10^12/l
5.40 – 8.00
MCV
93.8
fl
MCH
28.6
pg
22.0 – 25.0
MCHC
30.5
g/dl
34.0 – 37.0
Plt
213
X 10^9/l
170 - 500
WBC
Corrected
65.20
X 10^9/l
5.50 – 17.00
v
65.0 – 75.0
Nucleated 3.9
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red cells
Which is more likely?
• Regenerative, because of macrocytosis
and hypochromasia
1.
• Non – regenerative because
of
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macrocytosis and severity – possible bone
marrow disorder
2.
• Iron deficiency because of marked
hypochromasia
3.
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1000x field – which cell type is
arrowed?
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Which cell type?
•
•
•
•
•
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Macroplatelet
Neutrophil
v
Polychromatophil (immature
red)
Adult erythrocyte
Spherocyte
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1.
2.
3.
4.
5.
Polychromatophil – larger and with less hemoglobin (so
increased MCV and decreased MCH and MHC) - regeneration
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Same blood film, different area – what
is the cell type?
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What is the cell type?
• Microcyte, associated with iron deficiency 1.
• Red cell shear injury product, as might be seen
in a dog with haemangiosarcoma
2.
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• Spherocyte, as might be seen in immune
mediated hemolytic anaemia
3.
• Adult, normochromic, normocytic red cell
4.
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Spherocyte – small, perfectly round, no central pallor,
slightly darker staining than normal red cells
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Immune mediated hemolytic anaemia
• Classic presentation of severe, rapidly developing,
strongly regenerative anaemia
• The immune mediated destruction usually
provokes a marked neutrophilia,
with or without
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left shift and toxic change
• Spherocytes may be seen with extravascular
destruction. Difficult to see in cats
• Ghost cells (red cell membranes) may be seen in
intravascular hemolysis, along with possible
INCREASES in MCH and MCHC because of free
hemoglobin
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Ghost cell – intravascular haemolysis
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Neutrophils – left shift only – bands
and metamyelocytes present
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Autoimmune haemolytic anaemia
• Don’t get so carried away with the red cell
and leucocyte changes that you forget to
check the platelet values!
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In immune mediated hemolytic anaemia, make a point
of checking platelets are alright
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Case 96072
• 15 year old FE Crossbred dog
Hb
14.40
g/dl
12.00 – 18.00
• 2 week44.6
history of
lethargy35 - 55
HCT
%
v
• Spleen6.22
feels large
and
irregular
on
RBC
X 10^12/l
5.40 – 8.00
MCVpalpation
71.7
fl
65.0 – 75.0
Parameter
Patient value
Units
Reference interval
MCH
23.1
pg
22.0 – 25.0
MCHC
32.2
g/dl
34.0 – 37.0
Plt
353
X 10^9/l
170 - 500
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What is this?
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What is this?
• Acanthocyte – associated with shear injury to
the red cell/ liver disease/ lipid disorders
1.
• Schistocyte – associated with shear injury to the
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red cell, as might be seen with some tumours,
D.I.C., endocarditis
2.
• Crenated red cell/ echinocyte – seen in slow
drying smears as an artefact and in some
glomerulonephritis cases
3.
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Acanthocyte
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• Red cells with large blunt
ended projections
• May be seen in lipid
disorders, liver disease
• Often where red cells
have ‘shear injury’ from
being forced through
small vessels in tumours
or through strands of
fibrin when there are clots
in vessels: schistocytes,
blister cells, keratocytes
all share this origin
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Schistocytes – red cell fragments
which are thin and tapered
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Shear injury – schistocytes/
keratocytes/ blister cells
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Echinocytes/ crenated red cells
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• Small, spiky
cytoplasmic
projections.
• If these are
artefactual (most
common) they may
be unevenly
distributed across the
smear
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5 y.o. Griffon with intermittent exercise intolerance/
pallor – what is the red cell abnormality?
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What is the red cell abnormality?
• Howell – Jolly bodies
• Haemoplasmas
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• Heinz bodies
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1.
2.
3.
Heinz bodies in a dog frequently fed pickled onions!
v
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• A result of oxidative
damage, cats are more
vulnerable (up to 25%
of red cells affected in
clinically normal cats)
• Paracetomol (cats),
alliums, diabetic
ketoacidosis
• Easier to see and
enumerate using New
Methylene blue stain
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Heinz bodies with New Methylene
blue stain
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What is arrowed?
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What is arrowed
•
•
•
•
•
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Howell Jolly body
Small lymphocyte
Neoplastic lymphoidvcell
Nucleated red cell
Immature platelet
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1.
2.
3.
4.
5.
Nucleated red cell – seen in red cell regeneration and also
more with splenic disease/ splenectomy
There is also a Howell Jolly body (white arrow), a nuclear
fragment also seen more with red cell regeneration
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What is/ are these?
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What is/ are these?
•
•
•
•
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Haemoplasmas (Mycoplasma hemofelis)
Basophilic stippling from lead poisoning
Howell Jolly Bodies
v
Stain precipitate
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1.
2.
3.
4.
Mycoplasma hemofelis
•
•
v
•
•
•
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These are VERY infrequently seen
on ordinary blood smears –
epierythrocytic position
Most times we’re asked for a
second opinion, we find stain
precipitate or Howell Jolly bodies
(yellow arrow)
Much more sensitive to test by
qPCR – can also speciate
M hemofelis and M turicensis
always clinically significant
M haemominutum can be carried
asymptomatically and become
significant with
immunosuppression/ other illness
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