Page 320 - The Veterinary Laboratory and Field Manual 3rd Edition

Haematology 289

MCHC = [Hb (g/dl)/PCV %] × 100 cytic) hypochromic red cells are produced as a
result of the lack of iron for haemoglobin synthe-
The normal MCHC value for many common sis (that is, microcytic anaemia). Occasionally
domestic species is about 33%. If red cell popu- there may be an increase in MCHC, this is often
lations have values below this they are referred observed if lipaemic samples are examined and
to as ‘hypochromic’. This can be seen in cases is considered to be an artefact.
of regenerative anaemia, where there is an Examination of blood smears allows assess-
increased population of young red cells (reticu- ment of the degree of reticulocytosis (red cell
locytes) with low Hb content. Low MCHC can production) and the morphology of the red cells
also occur in iron deficiency, where small (micro- as well as the detection of haemoparasites (for

Table 5.3 Characteristics of blood cells in different species of animal.

Species red cell characteristics Mean diameter reticulocytes Approx. White cells
(µm)/special in peripheral neutrophil/ characteristics/
rouleaux Central features blood (%) lymphocyte special features
formation palour
ratio
Dog + ++ 7.0/uniform +/– 1.0 70 : 20 Basophils rare,
size. Crenation eosinophil
not common granules vary in
size. Cytoplasm
pale blue
Cat ++ + 5.8/crenation. +/– 0.5 60 : 30 Basophils rare.
Slight Eosinophil
aniocytosis granules rod like.
Few band cells
(PMN)
Cow - + 5.5/aniocytosis 0 28 : 58 Eosinophil
common granules small,
round and densely
staining. Vacuoles
common in
monocytes
Sheep +/– + 4.5/regular size 0 30 : 60 Neutrophil nucleus
and shape. multibolutated.
Granules in
lymphocytes.
Monocyte nucleus
amoeboid in
clumps
Horse +++ +/– 5.7/marked 0 55 : 35 HB Eosinophils
rouleaux 50 : 45 CB contain large
formation granules and fill
cell. Lymphocytes
small. Monocytes
have a kidney
shaped nucleus

Vet Lab.indb 289 26/03/2019 10:25