10. Hematopoietic Disorders and Anemia Flashcards
What is anemia?
when O2 carring capacity of erythrocytes reduced.
Could be due to reduced # of circulating RBC’s, PCV and Hgb conc, If RBC prod is dec or RBC’s are being lost
It is only a symptom of another dz process, always an underlying cause
How is anemia classed?
- Bone marrow response
- By RBC size and Hgb conc (MCV and MCHC)
- Underlying etiology
Classification based on bone marrow response and RBC parameters will help to ID the cause of anemia
What are some tests used to deterimine cause of anemia?
reticulocyte count, erythrocyte indices, PCV, RBC morphology, plasma color and turbidity, total plasma protein concentration
What are some specialty tests done to determine the cause of anemia?
coombs test, serum iron lvls, fecal exam for GI blood loss, ag or ab tests for specific dz’s like FeLV, FIV, EIA, feline hemotropic mycoplasmosis, blood borne parasites
Biochemical assays, bone marrow eval
What is the bone marrow response to anemia?
Most clinically applicable classification system that classes as either regenerative or nonregenerative
Bone marrow’s response to anemia should be to inc RBC prod and release immature RBC’s
Assessment of bone marrow response is based don’t the # of immature RBC’s present in circulation - polychromatic RBCs or nucleated RBC’s, determined by performing a reticulocyte count
What does the presence of reticulocytes mean in regards to anemia?
Bone marrow is responding = regenerative response (anemia likely due to either hemorrhage or hemolysis)
takes 4-7d for immature RBC’s to appear in peripheral blood after blood loss or destruction - exception in horses (will not see polychromasia!!)
When is a patient considered to have ana adequate bone marrow response?
When reticulocyte count is = to or > than the expected value for patients PCV
Ex. k9 has PCV of 25%, we expect it to be > or equal to 4.0%
What is important about regernarative anemia in horses?
eq do not release polychromatic cells from bone marrow so you’ll have to do a bone marrow aspirate to eval reticulocyte numbers bc they will release macrocytic, normochromic cells
Reticulocyte count of greater than 5% from bone marrow aspirate indicates a regen. anemia
What is nonregenerative anemia?
Low RBC mass with NO evidence of bone marrow response in peripheral blood
no polychromasia or reticulocytes, RBC’s are normochromic
Bone marrow aspirate indicated after endocrine and metabolic causes have been ruled out
With nonregen anemia, what will we need to look at if we’ve already ruled out endocrine and metabolic causes of nonregen anemia?
attributed to bone marrow dysfunction or inability of bone marrow to prod RBCs
Further classed on whether granulo/thromopoiesis are also involved in bone marrow dysfunction
What could be some causes of nonregenerative anemia?
iron deficiency, ehrlichiosis, drug toxicity, histoplasmosis, hypothyroidism, renal insufficiency, chronic dz/infection/liver dz, nutritional deficiencies or intestinal malabsorption, toxins - lead, hormonal imbalances
How can we class RBC size and hemoglobin concentration
Classifies anemia as either normo/macro/microcytic
Uses MCV and MCHC
Macrocytic anemia - usually seen with regenerative anemia
Microcytic anemia - almost always result of an iron deficiency
What do animals with normocytic anemia typically have?
Nonregen anemia or preregen anemia (too early in response to see if there is a bone marrow response)
What does it mean for animals to have nypochromic or nomocrhomic anemia? What about polychromatic RBCs?
Can be classed as hypochromic or normochromic but will not be hyperchromic
Polychromatic RBC’s contain less hemoglobin than a mature RBC, therefore technically considered hypochromic (appear to be hyperchromic due to staining of the nuclear remnants)
Hypochromic, microcytic anemia is almost aways due to iron deficiencies (low MCV and MCHC)
All other anemias are normochromic
How can anemia be classed by etiology?
Hemolytic, hemorrhagic, iron deficiency, production disorders, or combinations of the above
What is hemolytic anemia?
due to erythrocyte destruction
these animals usually develop regen anemia - during the pre-regen phase they will have a normocytic/chromic anemia
RBC destruction may be intravascular or extravascular
it is caused by immune mediated destruction, erythrocyte parasites, bacterial (mycoplasma haemofelis), and viral agents, toxin exposure
What are the signs of hemolytic anemia
lethargy, splenomegaly, fever, icterus, pale MM, dyspnea, tachycardia, systolic heart murmur, syncope
What are common lab findings with hemolytic anemia?
dec PCV, RBC count, Hgb conc, inflammatory leukogram (inc WBC), hemoglobinemia/uria, hyperbilirubinemia and bilirubinuria
Positive Coomb’s test - w/ immune mediated forms of hemolytic anemia
What can cause hemolytic anemia?
immune-mediated hemolytic anemia
Due to inc RBC descrution. Occurs as a result of Ab directed against the RBC itself or the immune complexes (Ag-Ab) that attach to the RBC, will prod a marked regen anemia, this is most common cause of hemolytic anemia in dogs - common in spaniels, poodles, collies
Also seen in Eq, cattle, cats
What will we see on IMHA blood smears?
Spherocytes**
agglutination
+/- thrombocytopenia
increased polychromasia
What is neonatal isoerythrolysis?
a form of IMHA
due to Ab from the dam against the neonates RBC’s - in most species, there must be either previous exposure to blood products or a prev preg
mismatched blood transfusions can be similar reaction
most common in horses/mules, also in kittens
neonates are health when borna dn become weak, lethargic, pale, anemia, icteric and dyspneic within 12hr-4d post partum