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Polychromasia: variation in staining, and it is likely that these polychromatic, large cells are reticulocytes
Anisocytosis: variation in size of RBCs and is commonly found as a result of a regenerative response. This is typically due to the presence of large, immature RBCs.
If this slide had been stained with NMB instead of DQ, the large basophilic red cell at the end of the pointer would likely contain organelles designating it as a reticulocyte.
"Macrocytes" also sometimes called polychromatophils are usually young, polychromatophilic erythroctyes and may be increased during a responsive anemia
Oxidation of RBCs may occur during some disease states and as well as exposure to some drugs or toxins. This oxidation an denaturation of hemoglobin in RBCs results in the formation of protrusions from the RBC cell membranes that are known as Heinz bodies.
Heinz bodies are commonly seen in cats
When using NMB, thery will appear as a greenish-blue protrusion on the periphery of the RBC
When using DQ, they will appear as a pale blister or colorless area on the edge of the erythrocye. A thin rim of the cell membrane may be visible at the protrusion.
This distinctive appearance is the result of an increased membrane surface relative to the cell volume. Target cells have a central area of pigment surrounded by a clear area and then a dense ring of peripheral cytoplasm.
A few may be seen in a normal blood smear.
They may also be a result of technique errors in making and drying the blood smear.
Increased numbers can be associated with anemias, liver disease, and some inherited disorders.
appears as very small, variably sized granules within the RBC
These granules are retained RNA aggregates
Can be seen in response to lead poisoning
red cells have increased central pallor and decreased staining density of the membrane due to decreased hemoglobin content.
This is commonly due to insufficient iron or blood loss.
This slide is from a kitten infested with fleas resulting in anemia.
Schistocytes are fragmented erythrocytes usually formed as a result of shearing of the red cell by intravascular trauma.
These are seen in cases of DIC (disseminated intravascular coagulation) where fibrin within the vascular system mechanically cleave the RBC
Vascular neoplasia, severe burns and some organisms may result in Schistocytes as well.
RBCs with irregular projections unevenly distributed on the surface.
Projections are variable in length, diameter and shape.
Occur in patients with altered lipid metabolism and consistently in dogs with hemangiosarcoma
Do no confuse with echinocytes that have numerous, short, evenly place projections that are uniform in shape and size. These are often artifacts caused by slow drying of blood films or underfilling an EDTA tube. Non-artifactual findings include poisonous snake bites, renal disease, and lymphosacrcoma in dogs.
The RBC at the end of the pointer contains a Howell-Jolly body.
Howell Jolly bodies are basophilic inclusions of young erythrocytes representing nuclear remnants. They are often seen in most domestic species during a regenerative anemia.
In ruminants, they can be confused with an intracellular parasite, Anaplasma sp...
Rouleaux formation is the grouping of erythrocytes in stacks or columns and is related to charges on the cell membrane
Marked rouleaux formation may be seen in healthy horses. In addition, rouleaux may be seen in blood that is held too long before preparing the blood smear or has been refrigerated. Inflammatory disease can result in increased rouleaux formation.
To distinguish rouleaux and agglutination, mix saline and fresh blood then examine the sample microscopically. Rouleaux will disperse into individual cells while agglutination will remain in clusters.
Observe the rouleaux formation evident in this field.
Agglutination is the unorganized three-dimensional clustering of red blood cells. The formation of these grape-like clusters is due to antibodies that coat the erythrocytes resulting in the bridging and clumping of the cells.
Agglutination can be seen both macroscopically and microscopically and just be distinguished from rouleaux formation.
Agglutination may be seen in animals with immune-mediated anemia.
Observe the clumps of RBCs in this field.
Observe the group of small, dense erythrocytes at the end of the pointer.
These "ball shaped" spherocytes do not have the biconcave shape found in normal canine RBCs
Spherocytes are darkly staining red cells with no central pallor. They are not easily recognized in species other than dogs. They appear smaller than normal RBCs due to the loss of the normal biconcave shape.
Spherocytes are significant because they suggest immune-mediated destruction of RBCs, resulting in hemolytic anemia. They may also be seen after transfusion with mismatched blood.
Although spherocytes have a decreased diameter and appear smaller, their volume is not decreased.
Tears after returning from the long voyage of the Beagle, Charles Darwin started to feel not-so-well dizziness, muscle spasms, fatigue and othe symptoms. Some speculate that the naturalist may have acquired Chagas Disease while he was traveling in South America as humans are readily infected.
This malady is caused by a single-celled parasite known as Trypanosoma cruzi which is carried by biting insects.
Animals such as opossums, bats, and livestock serve as reservoirs for the parasites
This is a disease seen in domestic animals in Va.
Reticulocytes are immature erythrocytes that contain organelles that are lost as the cell matures. These organelles clump into visible granules referred to as reticulum when stained with NMB
Cats, unlike any other species, demonstrate 2 morphologic forms of retics. The aggregate form contains large clumps of reticulum and is similar to reticulocytes found in other species. The punctuate form, which is unique to cats, contains 2 - 8 small, singluar, basophilic granules.
- Intracellular blood parasite
- most prevalent tick borne cattle pathogen
- also affects wild ruminants
- causes a hemolytic anemia
- small coccoid granules on the edge of the erythrocytes
- do not always stain well
Do not confuse with Howell - Jolly bodies
Lymph vs. Nucleated RBCs
Observe the cells in this field that have a dark, basophilic, round nucleus.
Note that the cytoplasm of the lymphocyte is lighter blue compared to the cytoplasm of the nucleated RBC. The cytoplasm of the nucleated RBC is more similar to the opacity and color of the erythrocytes.
In addition, the nucleated RBCs have a nucleus that is denser and often (though not always) eccentrically located.
All automated cell counters incorrectly include nucleated RBCs in the leukocyte count.
This is one excellent reason for looking at a blood smear in addition to using automated counters.
What is this?
a bacterial parasite of feline red blood cells that causes hemolytic anemia (feline infectious anemia)
- this organism can be challenging to find on a blood smear. the following techniques are helpful in increasing the probability of visualizing this organism in an infected cat.
- use no anticoagulant when obtaining the blood sample. the organism often detach from the red cells in the presence of anticoagulants
- take multiple samples at different times of the day. the circulating numbers of the organism fluctuate during the day
- samples taken from a capillary bed (ear margin) may show more organisms due to the difficulty of distorted cells passing through the tiny veins
What is this?
observe the intracellular inclusion found in the erythrocyte - note the "signet ring" or "safety pin" shape of the organism
Cytauxzoon felis is a protozoal parasite that causes a fatal disease in domestic cats. Bob-cats infected with Cytauxzoon are usually asymptomatic
This is no known effective treatment
one of the several species of Babesia organisms that cause clinical disease in dogs. As with Babesia canis, anemia with hemolysis is characteristic finding. This organism is seen in 50% of pit bulls
How do you distinguish between agglutination or rouleaux?
- add a drop of EDTA blood to a slide
- add a drop of EDTA blood plus 1 ml saline into a test tube and mix gently, then place the drop on the slide
- put a cover slip on both drops
- observe the plain drop of blood and then observe the drop of blood mixed with saline
- if the the drop mixed with saline looks like individual cells than it is rouleaux, if it still looks like clumps of grapes then its agglutination
What is the purpose of doing a reticulocyte count?
to determine if the bone marrow is responding appropriately to anemia (regenerative vs nonregenerative) by counting the number of reticulocytes per 1,000 RBCs.
What do we stain our smear with to count reticulocytes?
new methylene blue
How do you do an actual reticulocyte count?
under oil, count 1,000 RBCs including reticulocytes. as you count keep the reticulocytes and RBCs separate
How do you do an estimated reticulocyte count?
- under oil, count the number of RBCs per 1 representative field. At this step count ALL rbcs including reticulocytes
- multiply the number of rbcs per field by 10 (if this is less than 1000 cells, you will need to count additional fields to reach a minimum of 1000 rbcs)
- next, count only the reticulocytes in the number of fields you have calculated (a minimum of 10, but may be more)
- adjust your reticulocyte count if you have counted > than 1000 RBCs...(total # of reticulocytes observed) x (1000)/(estimated # of RBCs) = # of reticulocytes per 1000 RBCs
- divide the total number of reticulocytes observed by 10 to get the percentage
How do you do a corrected reticulocyte count?
measured retic. count x (measured PCV)/(normal PCV) = corrected retic. count
Why do we do a corrected retic. count?
an initial measured retic count needs to be corrected to factor in the degree of anemia. doing so gives a better estimate of whether or not the circulating population of reticulocytes has increased by the expanded production in the bone marrow
How do you do an absolute retic count?
multiply the RBC count by the corrected retic count (be sure to convert the % to a decimal form for the corrected retic count - divide by 100 to get the decimal)
How do we prepare a slide for a reticulocyte count?
- to an empty test tube, add equal amounts of EDTA blood and NMB (2 - 3 drops of each)
- mix and allow to sit for 10 minutes
- after 10 minutes, mix stained sample and make a blood smear
- observe this slide under oil and do the count
How do we calculate MCV?
(PCV - drop the %/Total RBC count - drop the scientific notation) x 10 = MCV
What are the normal ranges of MCV for dog and cat?
- dog: 60 - 77 fl
- cat: 39 - 55 fl
What does an increase in MCV mean? Decrease?
- increased MCV: macrocytosis (reticulocytosis, FeLV in cats)
- decreased MCV: microcytosis (iron deficiency, chronic blood loss)
How do we calculated the MCHC?
(hemoglobin/PCV - drop %) x 100 = MCHC
For MCHC anything less than 31 g/dl means _____.
Does hyperchromia exist?
no, it would be an artifact like rbc clumping
How do we calculate the corrected leukocyte count?
(# WBC evaluated on differential/100 + # nucleated RBCs) x total leukocyte count = corrected WBC count
- 8 nucleated RBCs seen, total leukocyte count - 10,500/ul
- (100/100 + 8) x 10,500 = 9,722.22 ~ round to 9,722/ul
How do we estimate the hemoglobin?
PCV/3 = HgB g/dl
How do we estimate the RBC count?
(PCV/6) x 10^6 = RBC estimate
List 5 broad categories used to describe morphologic characteristics of erythrocytes.
______ is the variation in erythrocyte size.
_____ is the variation in cell color.
_____ is the decreased staining intensity of RBCs caused by insufficient _____ within the cell.
_____ are immature erythrocytes that contain ribosomes which clump together into visible granules when stained.
RBC indicies are valuable tools used to classify types of _____.
_____ are erythrocyte inclusions that represent denatured hemoglobin caused by oxidative drugs or chemicals.
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