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What is erythropoiesis?
the production of RBC's
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Where are red blood cells produced (all sites)?
- made in bone marrow
- spleen
- liver
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What is the function of blood?
- transports (oxygen, nutrients, waste, hormones)
- temperature regulation
- maintains water balance
- pH maintenance
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What is the function of RBC's?
- carry oxygen to the tissues
- carry CO2 away
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What is the stimulatory hormone for RBC production and where is it produced?
- erythropoietin
- produced in the kidney
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What do RBC's contain?
hemoglobin
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What does it mean to be denatured? Can this happen to RBC's?
- lose normal shape and will no longer carry oxygen
- yes
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Describe the process of how hormones are influenced in the production of erythrocytes.
there is a decrease in arterial oxygen, which causes renal hypoxia. this causes the kidney to release erythropoietin (EPO) which stimulates bone marrow to increase RBC production
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If the bone marrow can't make enough RBC's where else can they be made?
spleen and liver
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How long does the average canine RBC live?
100 - 110 days
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How long does the average feline RBC live?
70 - 85 days
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Define regenerative anemia.
Bone marrow is responding to the need for RBC's by releasing new red blood cells into the blood
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Define nonregenerative anemia.
bone marrow is not responding
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Where does RBC breakdown normally occur?
reticoloendothelial system (macrophages in liver and spleen)
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What happens to the heme when RBC's are broken down?
- turns into a waste product
- processed to unconjugated bilirubin by macrophages in RES
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What happens to the globin when RBC's are broken down?
they are reused
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What happens to the iron when RBC's are broken down?
they are reused.
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List the cells in the erythrocyte production series in order.
- rubriblast
- prorubricyte
- rubricyte
- metarubricyte
- polychromatophil
- erythrocyte
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As a cell goes from rubriblast to mature erythrocyte, what happens to cytoplasmic color? Why?
cytoplasm changes from blue to orange due to a decrease in RNA and an increase in hemoglobin
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As a cell goes from rubriblast to mature erythrocyte, what happens to cell size?
the cell becomes smaller
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As a cell goes from rubriblast to mature erythrocyte, what happens to nuclear size?
nucleus becomes smaller
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As a cell goes from rubriblast to mature erythrocyte, what happens to chromatin pattern?
chromatin pattern becomes more aggregated
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How long does it take to go from rubriblast to reticulocyte?
5 - 7 days
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At waht stage does mitosis cease to occur?
at the metarubricyte stage
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One rubriblast makes how many mature erythrocyte?
16 RBC's
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What is a normal PCV for dogs? Cats? Horses? Cows?
- Dogs: 37 - 55% (in the 40's)
- Cats: 30 - 45% (in the 30's)
- Horses: 27 - 43% (in the 30's)
- Cows: 24 - 46%
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What's the fancy name for a nucleated red blood cell?
metarubricyte
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What five characteristics should you look at when examining RBC morphology?
- pattern
- size
- color
- shape
- inclusions
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How can you differentiate between agglutination and rouleaux?
- add a drop of saline to fresh blood (wet prep)
- rouleaux will dissipate
- agglutination will not
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In what species is rouleaux commonly found?
horses
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What diameter is the normal dog erythrocyte? Cat? Goat?
- Dog: 7 ul
- Cat: 5 - 6 ul
- Goat: 3 ul
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In what species is central pallor considered normal?
dogs
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Define acanthocyte. What causes this?
- 2 or more uneven projections. Can often be confused with crenation.
- Causes: liver disease, hemangiosarcoma
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Define agglutination. What causes this?
- Abnormal grouping of RBC in the monolayer. Looks like bunches of grapes. Antibodies are stuck to the outside of the RBC and act like velcro causing the RBC's to stick together.
- Causes: immune-mediated hemolytic anemia
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Define anisocytosis. What causes this?
- RBC's that are bigger than they should be
- Causes: RBC in polychromatophil form - being sent out before reaching their mature stage
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Define crenation. What causes this?
- Red blood cells who's edges have become distorted
- Causes: drying slides too slow and not making smear soon enough (old RBC's)
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Define distemper inclusion body. What causes this?
- Dot in RBC, WBC, or squamous cells.
- Causes: canine distemper
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Define echinocyte. What causes this?
- Burr cells. Spiculated cells, evenly distributed projections from RBC surface. Can often be confused with crenation.
- Causes: renal disease, lymphosacroma
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Define Heinz body. What causes this?
- Bleb on the edge of RBC
- Causes: denatured hemoglobin
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Define Howell-Jolly body. What causes this?
- One blue dot anywhere in the cell
- Causes: Nuclear remnant
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Define hypochromia. What causes this?
- Large pale area in the center of RBC
- Causes: decrease in hemoglobin (decrease in iron or blood loss)
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Define macrocytosis.
- enlargement of RBC's
- can be determined by the mean corpuscular volume
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Define microcytosis
- unusually small RBC's
- can be determined by the mean corpuscular volume
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Define poikilocytosis.
general term for any abnormally shaped RBC
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Define polychromasia. What causes this?
- Variation in RBC color (immature cells are basophilic)
- Causes: regenerative anemia
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Define reticulocyte.
Immature RBC's
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Define rouleaux. What causes this?
- Stacking of RBC's like coins. Can only be seen in the monolayer.
- Causes: inflammation, neoplasia
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Define schistocyte. What causes this?
- RBC fragments
- Causes: sign of IV trauma within the animal
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Define spherocyte. What causes this?
- Smaller RBCs, denser staining, lacks central pallor
- Causes: seen in immune-mediated anemias
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Define stomatocyte. What causes this?
- Oval-shaped areas of central pallor (looks like a mouth)
- Causes: can be hereditary in malamutes and schnauzers, can be an artifact
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Define target cells/leptocyte. What causes this?
- Thin cells with increased membrane
- Causes: can be an artifact, caused by porto-systemic shunts
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Define basophilic stippling. What causes this?
- Multiple small blue dots in RBC's stained with Diff Quik
- Causes: regenerative anemias, NRBC's, lead poisoning
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What are common artifacts on a blood smear?
- stain preciptate
- refractile areas
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Describe the appearance of regenerative anemia on a blood slide.
look for cells released too early into the circulation (polychromatophils - reticulocytes, metarubricytes - NRBC's)
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Will a regenerative anemia more likely to be normocytic, microcytic, or macrocytic?
macrocytic
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What are causes of regenerative anemia?
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What are causes of nonregenerative anemia?
bone marrow affected (destruction, depression, depletion, and degeneration) or bone marrow isnot getting the message (lack of erythropoietin in kidneys - renal disease)
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How can you tell the difference between a regenerative and a nonregenerative anemia?
Regenerative anemia will have a lot of cells that were released too early into circulation and nonregenerative anemia will not
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You draw blood from an anemic dog. The PCV = 15% and you count 42 retics per 1000 RBC's.
a. What is the observed retic count?
b. What is the corrected retic count?
c. Is this anemia regenerative or nonregenerative?
- a. 4.2% (42/1000 x 100)
- b. (4.2% x 15%)/45% = 1.4%....(retic count x actual PCV)/normal PCV
- normal PCV: Dog - 45, Cat - 35
- c. slightly regenerative
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What is MCV? What does an increased or decreased value mean?
- Mean Corpuscular Volume (average volume of a RBC). Normocytic (normal), macrocytic (higher than normal), microcytic (smaller than normal).
- Increased: regenerative anemia
- Decreased: iron deficiency
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How do you determine the MCV?
(PCV x 10)/RBC count in millions
- example: PCV 44, RBC 9.8 million
- (44 x 10)/9.8 = 44.9 fl (femtoliter)
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What is MCHC? What does an increased or decreased value mean?
- Mean Corpuscular Hemoglobin Concentration
- average concentration of hemoglobin in a RBC
- Increased: hemolyzed sample
- Decreased: hypochromic
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How do we determine MCHC?
(Hb x 100)/PCV
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What kind of cell is this?
Acanthocytes (2 or more uneven projections)
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What kind of cells are these?
Stomatocytes (oval-shaped areas of central pallor - resembles mouth)
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What's wrong with these cells?
Agglutination (stuck together like grapes)
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What kinds of cells are these?
Spherocytes (smaller RBCs, lack central pallor, darker staining)
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What's wrong with these cells?
Anisocytosis (variation in cell size)
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What kind of cell is this?
Schistocytes (RBC fragments)
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What animals have RBC's that look like this?
Avian and Reptiles
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What is wrong with these cells?
Rouleaux (stacking of RBC's like coins)
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What is wrong with this cell?
Basophilic Stippling (multiple blue dots in RBC's stained with Diff Quik)
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What kind of cells are these?
Reticulocytes (immature RBCs, reticulum picked up blue stain)
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What animal has RBC's that look like this?
Deer
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What is wrong with these cells?
Polychromasia (variation in cell color)
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What is wrong with these cells?
Distemper Inclusion Bodies (size varies from cell to cell)
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What kind of cell is the black arrow pointing to?
Metarubricyte (nucleated RBC)
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What kind of cells are these?
Echinocytes (burr cells, spiculated cells - evenly distributed projections from RBC surface)
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What kind of cell is this?
Leptocyte (target cell)
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What's on these cells?
Heinz Bodies (bleb on the edge of RBC)
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What's wrong with these cells?
Hypochromia (large pale area in center of RBC)
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What's wrong with these cells?
Howell Jolly Body (little pieces of nucleus left behind)
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