Erythrocyte Morphology Flashcards
What is the only way to accurately determine RBC morphology?
stained blood film made from blood collected into an EDTA for a CBC - hematology analyzer CANNOT provide this information
What are the 3 main reasons to perform a blood smear?
- confirm CBC data generated from the analyzer
- help determine the cause of certain diseases
- helps identify infectious organisms
What are the 3 zones of a blood smear?
- body
- monolayer (cell counting)
- feathered edge
What 2 stains are most commonly used for blood smears?
- quick Romanowsky (Diff Quik) = clinic
- Romanowsky-type (Wright-Giemsa) = commercial
What are the main 2 characteristics of canine erythrocytes?
- area of central pallor due to biconcave disc structure
- 7 µm in diameter - the largest RBCs
How do feline erythrocytes compare to canine ones? What 2 characteristics are normal to find?
no prominent central pallor coloration and smaller
- poikilocytosis - slight shape variation
- mild Rouleaux formation - clumping
How do bovine erythrocytes compare to canine ones? What characteristic is normal to find?
no prominent central pallor coloration and smaller
anisocytosis - size variation
How do equine erythrocytes compare to canine ones? What characteristic is normal to find?
no prominent central pallor coloration and smaller
Rouleaux formation - RBCs stacked in a row
In what animals is Rouleaux formation normal?
- cat
- horse
- pig
What is the normal morphology of camelid erythrocytes?
(llamas, alpacas, camels)
elliptical to oval
What do avian, reptile, and amphibian erythrocytes look like?
large, nucleated, elliptical
What is anisocytosis?
difference in cell size (normal in bovine)
What are macrocytes? In what 2 situations are they commonly found?
large RBCs
- polychromasia in animals with regenerative anemia (high MCV if significant)
- horses with regenerative anemia (do not release reticulocytes
In what 3 situations is it less common to have circulating macrocytes?
- FeLV
- inherited disorders in Mini and Toy Poodles and Poll Hereford cattle
- vitamin B12 deficiencies common in Giant Schnauzers
What is this? In Which species?
macrocyte
camelid
What are microcytes? In what 3 situations is it commonly found?
small RBCs (decreased MCV when significant)
- iron deficiency (concomitantly with low MCHC)
- vitamin B6 deficiency
- portosystemic shunts
In what animals is it normal to see microcytes?
- Shiba Inus, Akitas
- young animals
What do color differences in erythrocytes indicate?
changes in RBC hemoglobin content
What is polychromasia? What is it indicative of? How does it show on CBC?
“many colors” - presence of both mature RBCs and reticulocytes
regenerative anemia
decreased MCHC and/or MCH
What is hypochromasia? In what 2 situations is it commonly found? How does it show on CBC?
less hemoglobin than usual
- iron deficiency
- lead toxicity (blocks hemoglobin synthesis)
decreased MCHC and/or MCH
What on the CBC indicates hyperchromasia?
increased MCHC and/or MCH - ARTIFACTUAL
What is happening in this blood smear?
polychromasia - immature, anucleated RBCs and normal RBCs
(anemic dog)
What is happening in this blood smear?
hypochromasia - iron deficiency
What is poikilocytosis? What are 4 common causes?
differences in erythrocyte shape
- oxidative damage
- fragmentary injury of RBCs
- diseases, deficiencies
- artifact, envenomation, arthropod bites
In what animals is poikilocytosis normal?
healthy goats, young cattle, and pigs
What kind of RBCs are these? What causes this?
eccenterocytes - wearing a pale hat
oxidative damage
What are Heinz bodies? How can they be visualized?
denatured, precipitated hemoglobin on RBCs due to oxidative damage
new methylene blue stain
What are 6 specific causes of oxidative damage that causes changes in RBC morphology?
- acetaminophen (cats)
- onion and garlic (dogs)
- Brassica (ruminants)
- copper poisoning (sheep)
- zinc
- red maple leaf (horses)
Eccentrocyte vs. Heinz body:
What are the arrows pointing to?
eccentrocytes - “pale hats”
oxidative damage
What are the arrows pointing to?
Heinz bodies
oxidative damage
What are the 3 main erythrocyte changes caused by fragmentary injury?
- keratocytes/pre-keratocytes - piece bitten out
- schistocytes - fragment
- acanthocytes - hand-like projections
What are 4 specific causes of erythrocyte fragmentary injury?
- disseminated intravascular coagulopathy (DIC)
- hemangiosarcoma
- cardiac disease
- diseases that cause turbulent blood flow
What are the arrows pointing to?
schistocytes - fragments
fragmentary injury
What causes the formation of schistocytes? In what 4 situations are they seen in?
shearing by intravascular fibrin or turbulent blood flow inside vasculature
- DIC
- hemangiosarcoma
- glomerulonephritis
- myelofibrosis, vasculitis
What are the arrows pointing to?
acanthocytes - octopus, hands
fragmentary injury
What are acanthocytes? What 4 disorders are they associated with?
spiculated RBC resulting from lipid alteration of RBC’s membrane (no longer have a smooth membrane)
- hemangiosarcoma
- glomerulonephritis
- liver disease
- lymphoma
What is seen in this blood smear?
keratocytes - bitten out, purse-like
fragmentary damage
What are keratocytes? When are they most commonly seen?
RBCs with blister-like vesicle (that can rupture), leaving a bite-shaped defect in the cell outline or 1-2 horn-like projections
DIC (with schistocytes)
What are codocytes? In what 3 situations are they most common?
“target cells” or leptocytes where lipid alteration causes them to fold
- liver disease (portosystemic shunt)
- lipid disorders
- iron deficiency anemia
What are the arrows pointing to?
codocytes - target cells
What are echinocytes/crenation?
star-like spikes on RBCs that are most commonly an artifact due to excess EDTA relative to the amount of blood, or from snake envenomation
When are echinocytes/crenation a helpful hematological marker of snake envenomation?
formation within 24 hours of the snakebite
What is happening in this blood smear?
echinocytes/crenation - star, burr
What are the cell shape patterns seen in DIC, hemangiosarcomas, glomerulonephritis, and liver disease?
DIC = keratocytes, schistocytes
HSA = acanthocytes, schistocytes
GN = acanthocytes, schistocytes
LIVER DZ = acanthocytes, codocytes
What are the general forms of Mycoplasma? What species affect cats, dogs, pigs, cows, camelids, and sheep?
circular, rod-shaped, or ring-shaped
CAT = M. haemofelis
DOG = M. haemocanis
PIG = M. suis, M. parvum
COW = M. wenyonii
CAMELID = M. haemolamae
SHEEP = M. ovis
Mycoplasma felis:
very small (0.1-0.5 µm), needs immersion oil
+ reticulocytes
Mycoplasma suis:
directly on RBC
Anaplasma marginale (ruminant) is shown in the blood smear. What do these findings indicate?
2 macrocytes (large RBC) and polychromatophil are present, indicating a regenerative response
How do Babesia canis and Babesia gibsoni compare? What are they indicative of?
Babesia canis = larger
Babesia gibsoni = smaller
extravascular hemolytic anemia due to parasite lysis of RBC
Babesia canis:
large, tear-shaped
Babesia gibsoni:
smaller
+ neutrophil
What is the characteristic structure of Cytauxzoon felis?
ring or safety pin shape within RBC
What is seen in this blood smear?
larval Dirofilaria immitis, or heartworm
(larva in blood; adult in heart)
