Lecture 2 8/27/24 Flashcards
What is polychromasia?
morphologic description of what a reticulocyte looks like on routine blood smear
What do spherocytes indicate?
immune-mediated hemolytic anemia
What are spherocytes?
RBCs with membrane-bound antibodies that are removed by macrophages; removal of part of the membrane causes the cells to have a spherical shape
What does agglutination indicate?
immune-mediated hemolytic anemia
What is rouleaux?
linear arrangements of RBCs due to increased globulins
What are heinz bodies?
a projection off of a RBC that indicates oxidant injury
What are eccentrocytes?
RBCs with a white “fingernail” appearance that indicates oxidant injury
What are schistocytes?
torn or fragmented RBCs
What are the potential causes of schistocytes?
-disseminated intravascular coagulation
-hemangiosarcoma
-cardiac disease
What is basophilic stippling?
diffuse stippling of RBCs on a routinely stained blood smear
What are the potential causes of basophilic stippling?
-regenerative anemia in ruminants
-lead toxicity in any species
What are the mechanisms of anemia?
-hemorrhage
-hemolysis
-decreased RBC production in the bone marrow
Which mechanisms of anemia are regenerative?
-hemorrhage
-hemolysis
Which mechanism of anemia is non-regenerative?
decreased bone marrow production of RBCs
What does it mean for an anemia to be regenerative?
bone marrow responds appropriately to RBC loss by increasing RBC production
What findings in the bone marrow and blood are expected in a regenerative anemia?
bone marrow: erythroid hyperplasia
blood: increased numbers of reticulocytes
What findings in the bone marrow and blood are expected in a non-regenerative anemia?
bone marrow: erythroid hypoplasia and/or ineffective erythropoiesis
blood: normal or decreased numbers of reticulocytes
What is the caveat with regenerative anemia?
it takes 3-4 days following hemorrhage or hemolysis for the bone marrow to begin releasing increased reticulocytes into the blood
What is the sole definitive way to distinguish regenerative vs non-regenerative anemia?
absolute reticulocyte count
What are the possible patterns seen on CBC that could indicate a regenerative anemia?
-increased MCV and decreased MCHC
-normal MCV and MCHC, but with MCV at the high end of normal and MCHC at the low end of normal
What are other possible CBC/blood smear findings that can indicate regenerative anemia?
-increased nRBCs
-Howell-Jolly bodies
-increased RDW
-basophilic stippling
How do horses uniquely present with regenerative anemia?
-do not release reticulocytes into circulation during a regenerative response
-instead release macrocytic RBCs
How is anemia definitively classified in horses?
bone marrow evaluation
What indirect indicators of regenerative anemia can be present in horses?
-increased RDW
-increasing MCV
-identified cause of hemorrhage or hemolysis
When is pre-regenerative anemia unlikely?
if an animal has been sick for more than a few days but is not showing a reticulocyte count
When is pre-regenerative anemia more likely?
-acute traumatic blood loss
-acute hemolytic anemia w/ abnormalities on microscopic exam
Why are no changes in CBC values seen a few minutes after a hemorrhagic episode?
even though the animal is hypovolemic, there has not been enough time for proportional changes to occur in the blood
Which changes in CBC values can be seen a few hours after a hemorrhagic episode?
-decreased HCT
-decreased protein
What causes the changes in CBC values seen a few hours after a hemorrhagic episode?
movement of water into the vasculature to replace lost volume, which dilutes the blood components
Which changes in CBC values can be seen 3-5 days after a hemorrhagic episode?
-decreased HCT
-normal to increased MCV
-normal to decreased MCHC
-increased reticulocytes
-normal to decreased protein
What are examples of chronic external hemorrhage causes?
-GI hemorrhage
-ectoparasites
What are the expected CBC results with chronic external hemorrhage?
-regenerative anemia
-possible decrease in total protein
-potential iron deficiency if duration is long enough
Why can chronic hemorrhage result in iron deficiency?
-most iron used for erythropoiesis is recycled from aged RBCs
-loss of RBCs from the body prevents iron recycling
-over time, this can result in bone marrow iron store depletion
What are the consequences of iron-restricted erythropoiesis?
-anemia
-impaired reticulocyte production
-decreased CHr
-decreased MCHC
-decreased MCV
