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Preparation and Examination of Blood Smear (view source)
Revision as of 19:28, 23 February 2022
, 19:28, 23 February 2022no edit summary
The area to be examined is the monolayer where 50% or less of cells are in contact. The differential count is performed, and cell morphology is assessed in the monolayer (Fig 2).
The area to be examined is the monolayer where 50% or less of cells are in contact. The differential count is performed, and cell morphology is assessed in the monolayer (Fig 2).
[[File:NationWide Laboratories Fig2.png|thumb|NationWide Laboratories ]]
[[File:NationWide Laboratories Fig2.png|thumb|NationWide Laboratories ]]
[[File:NWLab .jpg|thumb|Echinocytes, a small and large platelet NationWide Laboratories]]
[[File:NWLab .jpg|thumb|Echinocytes, a small and large platelet NationWide Laboratories]]
Echinocytes (crenated red cells). Red cells with many spiny projections which tend to be evenly spaced and uniform. This is often artefact seen in thick smears, which have taken a long time to dry, or due to excess EDTA, if the tube is not filled to the line. Echinocytes can be associated with pathological changes such as uraemia, glomerulonephritis, neoplasia and snake venom.
Echinocytes (crenated red cells). Red cells with many spiny projections which tend to be evenly spaced and uniform. This is often artefact seen in thick smears, which have taken a long time to dry, or due to excess EDTA, if the tube is not filled to the line. Echinocytes can be associated with pathological changes such as uraemia, glomerulonephritis, neoplasia and snake venom.
=== '''Indicators of regeneration''' ===
=== '''Indicators of regeneration''' ===
[[File:NW laboratories.jpg|thumb|Feline Reticulocytes NationWide Laboratories ]]
[[File:NW laboratories.jpg|thumb|Feline Reticulocytes NationWide Laboratories ]]
<u>'''Reticulocytes'''</u>. Immature red cells, their residual RNA and mitochondria stain with new methylene blue.
<u>'''Reticulocytes'''</u>. Immature red cells, their residual RNA and mitochondria stain with new methylene blue.
[[File:NationWide Lab 2016.jpg|thumb|Nucleated red blood cell NationWide Laboratories]]
[[File:NationWide Lab 2016.jpg|thumb|Nucleated red blood cell NationWide Laboratories]]
<u>'''Nucleated red blood cells (metarubricytes)'''.</u> These are immature red cells, which retain a condensed nucleus.
[[File:NWLLabfacts 2.jpg|thumb|Spherocytes with central polychromatophil NationWide Laboratories]]
[[File:NWLLabfacts 2.jpg|thumb|Spherocytes with central polychromatophil NationWide Laboratories]]
<u>'''Spherocytes''':</u> These are spherical erythrocytes which appear smaller in diameter, stain more densely and lack central pallor. They are more obvious in canine blood (feline erythrocytes naturally lack central pallor) and are most commonly associated with IMHA. Other causes include snake bite, zinc toxicity and bee stings.
<u>'''Spherocytes''':</u> These are spherical erythrocytes which appear smaller in diameter, stain more densely and lack central pallor. They are more obvious in canine blood (feline erythrocytes naturally lack central pallor) and are most commonly associated with IMHA. Other causes include snake bite, zinc toxicity and bee stings.
<u>'''Acanthocytes'''</u>. Erythrocytes with a few irregular, asymmetrical projections. In dogs acanthocytes may be associated with haemangiosarcoma, lymphoma, DIC and altered lipid metabolism (hepatic disease). In cats they may be recognised with liver disease including the cholangitis complex and hepatic lipidosis.
<u>'''Acanthocytes'''</u>. Erythrocytes with a few irregular, asymmetrical projections. In dogs acanthocytes may be associated with haemangiosarcoma, lymphoma, DIC and altered lipid metabolism (hepatic disease). In cats they may be recognised with liver disease including the cholangitis complex and hepatic lipidosis.
[[File:NWLLabfacts 4.jpg|thumb|Basophilic stippling NationWide Laboratories]]
[[File:NWLLabfacts 4.jpg|thumb|Basophilic stippling NationWide Laboratories]]
<u>'''Basophilic stippling'''.</u> Reflects the presence of aggregated ribosomal RNA in reticulocytes and is primarily associated with regenerative anaemias. It is also evident with the exaggerated regenerative response seen in many cases of lead poisoning (often in the absence of anaemia), due to the effect of lead on the bone marrow.
<u>'''Basophilic stippling'''.</u> Reflects the presence of aggregated ribosomal RNA in reticulocytes and is primarily associated with regenerative anaemias. It is also evident with the exaggerated regenerative response seen in many cases of lead poisoning (often in the absence of anaemia), due to the effect of lead on the bone marrow.
<u>'''Eccentrocytes.'''</u> These are RBCs where, as a result of oxidative injury, the Hb has coalesced, usually at one side of the cell; the remainder of the cell is pale staining.
<u>'''Eccentrocytes.'''</u> These are RBCs where, as a result of oxidative injury, the Hb has coalesced, usually at one side of the cell; the remainder of the cell is pale staining.
[[File:NWLLabfacts 5.jpg|thumb|Heinz Bodies NationWide Laboratories ]]
[[File:NWLLabfacts 5.jpg|thumb|Heinz Bodies NationWide Laboratories ]]
<u>'''Heinz bodies'''</u>. Oxidation of sulphydryl groups on the globin chains of haemoglobin results in the formation of Heinz bodies. These are refractile structures which occur along the internal surface of erythrocyte membranes, seen as pale pink-red projections with Romanowsky stains. Normal cats may have up to 5% Heinz bodies in their erythrocytes. Heinz body formation in the absence of anaemia may occur with feline diabetes mellitus, lymphoma and hyperthyroidism. Increased numbers of Heinz bodies, leading to haemolytic anaemia, may be associated with onion or garlic ingestion, kale or other brassica species consumption by ruminants and consumption of red maple leaves by alpacas and horses.
<u>'''Heinz bodies'''</u>. Oxidation of sulphydryl groups on the globin chains of haemoglobin results in the formation of Heinz bodies. These are refractile structures which occur along the internal surface of erythrocyte membranes, seen as pale pink-red projections with Romanowsky stains. Normal cats may have up to 5% Heinz bodies in their erythrocytes. Heinz body formation in the absence of anaemia may occur with feline diabetes mellitus, lymphoma and hyperthyroidism. Increased numbers of Heinz bodies, leading to haemolytic anaemia, may be associated with onion or garlic ingestion, kale or other brassica species consumption by ruminants and consumption of red maple leaves by alpacas and horses.
[[File:NWLLabfacts 6.jpg|thumb|Howell-Jolly bodies NationWide Laboratories]]
[[File:NWLLabfacts 6.jpg|thumb|Howell-Jolly bodies NationWide Laboratories]]
<u>'''Howell-Jolly bodies.'''</u> These are remnants of nuclear material . They are present in regenerative anaemias possibly due to inability of macrophages to fully remove the nuclei of maturing RBCs during accelerated production. If present without polychromasia, reduced macrophage function could be considered. They may be a common finding following splenectomy.
<u>'''Howell-Jolly bodies.'''</u> These are remnants of nuclear material . They are present in regenerative anaemias possibly due to inability of macrophages to fully remove the nuclei of maturing RBCs during accelerated production. If present without polychromasia, reduced macrophage function could be considered. They may be a common finding following splenectomy.
[[File:NWLLabfacts 7.jpg|thumb|Hypochromasia NationWide Laboratories]]
[[File:NWLLabfacts 7.jpg|thumb|Hypochromasia NationWide Laboratories]]
'''<u>Hypochromasia.</u>''' Pale erythrocytes with a reduced haemoglobin concentration (decreased MCHC). Seen in regenerative anaemia and with iron deficiency.
'''<u>Hypochromasia.</u>''' Pale erythrocytes with a reduced haemoglobin concentration (decreased MCHC). Seen in regenerative anaemia and with iron deficiency.
'''<u>Red cell fragmentation.</u>''' Small fragments are called schistocytes (schizocytes), larger red cell fragments include keratocytes (blister and helmet cells). These reflect metabolic disease or, more commonly, intravascular trauma associated with turbulent blood flow due to cardiac valvular disease, with passage through numerous capillaries in haemangiosarcoma and certain other malignant neoplasms, or fibrin strands cleaving erythrocytes in myelofibrosis or DIC. Severe hepatic disease may also result in red cell fragmentation.
'''<u>Red cell fragmentation.</u>''' Small fragments are called schistocytes (schizocytes), larger red cell fragments include keratocytes (blister and helmet cells). These reflect metabolic disease or, more commonly, intravascular trauma associated with turbulent blood flow due to cardiac valvular disease, with passage through numerous capillaries in haemangiosarcoma and certain other malignant neoplasms, or fibrin strands cleaving erythrocytes in myelofibrosis or DIC. Severe hepatic disease may also result in red cell fragmentation.
[[File:NWLLabfacts 9.jpg|thumb|Rouleaux in an equine blood smear NationWide Laboratories]]
[[File:NWLLabfacts 9.jpg|thumb|Rouleaux in an equine blood smear NationWide Laboratories]]
'''<u>Rouleaux.</u>''' These are stacks of erythrocytes resembling a pile of coins, which disperse in saline. Rouleaux are most obvious when examining the body of the blood smear.
'''<u>Rouleaux.</u>''' These are stacks of erythrocytes resembling a pile of coins, which disperse in saline. Rouleaux are most obvious when examining the body of the blood smear.
[[File:NWLLabfacts 10.jpg|thumb|Target Cells (codocytes) NationWide Laboratories]]
[[File:NWLLabfacts 10.jpg|thumb|Target Cells (codocytes) NationWide Laboratories]]
'''<u>Target cells (codocytes)</u>'''. These are bell-shaped in-vivo but resemble a target on a blood smear due to accumulation of haemoglobin around the periphery and centre.
'''<u>Target cells (codocytes)</u>'''. These are bell-shaped in-vivo but resemble a target on a blood smear due to accumulation of haemoglobin around the periphery and centre.
[[File:NWLLabfacts 16.jpg|thumb|Metamyelocyte NationWide Laboratories]]
[[File:NWLLabfacts 16.jpg|thumb|Metamyelocyte NationWide Laboratories]]
Sometimes less differentiated myeloid cells (metamyelocytes and myelocytes) are seen in the blood, usually associated with a severe acute inflammatory response. This is called a left shift.
Sometimes less differentiated myeloid cells (metamyelocytes and myelocytes) are seen in the blood, usually associated with a severe acute inflammatory response. This is called a left shift.
[[File:NWLLabfacts 18.jpg|thumb|Neutrophil with toxic granulation NationWide Laboratories]]
[[File:NWLLabfacts 18.jpg|thumb|Neutrophil with toxic granulation NationWide Laboratories]]
There may be toxic granulation due to staining of primary granules.
There may be toxic granulation due to staining of primary granules.
[[File:NWLLabfacts 19.jpg|thumb|Hypersegmented neutrophil NationWide Laboratories]]
[[File:NWLLabfacts 19.jpg|thumb|Hypersegmented neutrophil NationWide Laboratories]]
'''<u>Hypersegmented neutrophil.</u>''' There are more than 5 nuclear lobes. Found in dogs on corticosteroid therapy (which prolongs the half life of the neutrophil) and may be associated with uraemia. Also seen in Poodles with familial macrocytosis.
'''<u>Hypersegmented neutrophil.</u>''' There are more than 5 nuclear lobes. Found in dogs on corticosteroid therapy (which prolongs the half life of the neutrophil) and may be associated with uraemia. Also seen in Poodles with familial macrocytosis.
Distemper viral inclusions can occasionally be seen in neutrophils of infected dogs (see section on white cell inclusions).
Distemper viral inclusions can occasionally be seen in neutrophils of infected dogs (see section on white cell inclusions).
[[File:NWLLabfacts 20.jpg|thumb|Equine eosinophil NationWide Laboratories]]
'''<u>Eosinophil.</u>''' Mature eosinophils have a segmented nucleus and red intracytoplasmic granules. The granules in the dog are round and vary in size. In the cat they are small, uniform in size and rod shaped while in the horse the granules are round and very large. In rabbits, eosinophils have larger red granules than neutrophils although often the two cell types are difficult to differentiate and may be counted together as heterophils. Band eosinophils are immature cells showing less distinct nuclear segmentation.
[[File:NWLLabfacts 21.jpg|thumb|Basophil NationWide Laboratories]]
'''<u>Basophil.</u>''' Rare in blood smears from healthy animals. Basophils are similar in size to eosinophils, with a segmented, ribbon-like nucleus and variable numbers of cytoplasmic granules. In dogs these are deep purple and sparse. Cats have more numerous lilac coloured granules with occasional deep purple granules.
'''<u>Basophil.</u>''' Rare in blood smears from healthy animals. Basophils are similar in size to eosinophils, with a segmented, ribbon-like nucleus and variable numbers of cytoplasmic granules. In dogs these are deep purple and sparse. Cats have more numerous lilac coloured granules with occasional deep purple granules.
[[File:NWLLabfacts 22.jpg|thumb|Mast cell NationWide Labs]]
'''<u>Mast cell.</u>''' These are not present in the blood of healthy animals but may be present with severe inflammatory disease or metastatic mast cell tumours (mastocytaemia). They are round cells with a round nucleus surrounded by a moderate volume of cytoplasm containing large numbers of purple granules.
[[File:NWLLabfacts 23.jpg|thumb|Small, medium and large Lymphocytes NationWide Labs]]
<u>'''Lymphocyte'''</u>. Mature lymphocytes are small cells with round, occasionally cleft nuclei which are approximately one red cell width in diameter; they have condensed nuclear chromatin and a narrow rim of pale cytoplasm.
<u>'''Lymphocyte'''</u>. Mature lymphocytes are small cells with round, occasionally cleft nuclei which are approximately one red cell width in diameter; they have condensed nuclear chromatin and a narrow rim of pale cytoplasm.
'''<u>Reactive lymphocyte.</u>''' Slightly larger than a mature lymphocyte. Cells have round nuclei with condensed nuclear chromatin, surrounded by a rim of pale basophilic cytoplasm.
'''<u>Reactive lymphocyte.</u>''' Slightly larger than a mature lymphocyte. Cells have round nuclei with condensed nuclear chromatin, surrounded by a rim of pale basophilic cytoplasm.
[[File:NWLLabfacts 24.jpg|thumb|Lymphoblast NationWide Labs]]
<u>'''Lymphoblast.'''</u> A large cell with a large nucleus, two to three red cell widths in diameter, with one or more prominent nucleoli. These are rarely seen in blood smears from healthy animals but may be present with lymphoid neoplasia.
<u>'''Lymphoblast.'''</u> A large cell with a large nucleus, two to three red cell widths in diameter, with one or more prominent nucleoli. These are rarely seen in blood smears from healthy animals but may be present with lymphoid neoplasia.
<u>'''Monocyte'''</u>. These are large cells with a deeply indented nucleus showing pale, finely granular nuclear chromatin. They have a moderate amount of blue-grey cytoplasm, which may contain vacuoles.
[[File:NWLLabfacts 25.jpg|thumb|Large granular Lymphocyte NationWide Labs]]
'''<u>Large granular lymphocyte</u>'''. Lymphocyte containing several prominent magenta coloured cytoplasmic granules. Rarely seen in peripheral blood but are numerous in large granular cell leukaemia in the dog
[[File:NWLLabfacts 26.jpg|thumb|Monocyte NationWide Labs]]
<u>'''Monocyte'''</u>. These are large cells with a deeply indented nucleus showing pale, finely granular nuclear chromatin. They have a moderate amount of blue-grey cytoplasm, which may contain vacuoles.
=== Leucocyte Inclusions ===
[[File:NWLLabfacts 27.jpg|thumb|Canine distemper intracytoplasmic inclusion in a neutrophil NationWide Labs]]
[[File:NWL 1.jpg|thumb|Ehrlichia canis morula in a monocyte NationWide Labs]]
[[File:NWL 2.jpg|thumb|Leishmania in the cytoplasm of neutrophil NationWide Labs]]
[[File:NWL 3.jpg|thumb|Anaplasma platys elementary bodies NationWide Labs]]
[[File:NWL 4.jpg|thumb|Hepatozoon gametocytes and Ehrlichia Morula NationWide Labs]]
=== Platelet Evaluation ===
[[File:NWL 5.jpg|thumb|Clumps of platelets, often found in the feathered edge NationWide Labs]]
Platelet numbers can be estimated from the blood smear as described previously. The smear should be checked for any platelet clumps which are often found in the tail (feathered edge) of the smear. Clumping of platelets is frequently seen in cats and results in a spuriously low platelet count.
[[File:NWL 6.jpg|thumb|Macrothrombocyte Nation Wide Labs (the one in the middle)]]
'''<u>Macrothrombocyte.</u>''' A large platelet indicating enhanced thrombopoiesis. Larger platelets are more functionally active and this may explain why some dogs with thrombocytopaenia, but largeplatelets, do not bleed.
[[File:NWL 7.jpg|thumb|Inherited macrothrombocytopaenia NationWide Labs]]
Primary platelet disorders such as thrombasthenic thrombopathia of otter hounds are rare, producing large and morphologically bizarre platelets. Cavalier King Charles spaniels may have large platelets with decreased platelet counts due to inherited macrothrombocytopaenia.
== Authors and References ==
[[NationWide Laboratories#In Partnership with NationWide Laboratories]]
[[Category:Pathological Sample Collection|5]]
[[Category:Pathological Sample Collection|5]]