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
What are some lab findings with neonatal isoerythrolysis?
coombs test positive
dam can be tested 2 wks prior to parturition to predict the likelihood of neonatal isoerythrolysis
Eq - mares most frequently develop Ab to blood types Aa and Qa
Feline - type A or AB kittens born to type B queens
What are some erythrocyte parasites cause hemolytic anemia?
mycoplasma haemofelis, anaplasma, babesia, ehrlichia
What are some infectious agents that could cause hemolytic anemia?
FeLV, leptospira, EIA virus
How can heinz body anemia cause hemolytic anemia?
oxidative damage to RBC
cats more susceptible than other domestic species
can be due to medications, chemicals, plants, inherited enzyme deficiencies and nutritional deficiencies or toxicities
What drugs and plans can cause heinz body anemia?
Allium family: onions and garlic
Brassica family: cabbage, kale, canola seed
DRUGS: acetaminophen, propylene glycol, zinc/copper toxicity, methylene blue
What are some other conditions that may cause heinz body anemia?
diabetes, hyperthyroidism, lymphoma, hypophosphatemia, EIA, bacterial infection (clostridial), inherited membrane defects, metabolic disorders
What is hemorrhagic anemia?
Can be external or internal
External blood loss causes loss of RBCs, iron and plasma proteins
Internal blood loss does not lead to loss of protein or iron - some RBCs will be re-absorbed and return to circulation
chronic or acute
What are some common causes of hemorrhagic anemia?
trauma, surgical losses, parasites like fleas, ticks or hookworms
coagulopathy, thrombocytopenia, thrombopathia, neoplasia, cystitis, bleeding lesions like GI ulceration and IBD
What are some lab findings common with hemorrhagic anemia?
dec PCV, +/- dec plasma proteins, inc polychromasia - not acutely, normal RBC morphology unless in acute cases
What is hemangiosarcoma?
malignant vascular tumors - most common in the spleen, liver and right atrium. spreads quickly to the lungs and other organs
lab results will be as follows - polychromasia, transiet hypoproteinemia, acanthocytes and schistocytes, thrombocytopenia, possibly DIC - BADD!!!
What is iron deficiency anemia?
chronic blood loss results in iron deficiency anemia?
In adults, almost always due to blood loss
in neonates, almost always insufficient iron intake - affects all neonatal domestic species, piglets highest risk bc they do not have access to iron rich soil - often given injections shortly after birth,
common in dogs but rare in cats/eq
What are lab findings common with iron deficiency anemia?
dec MCV** and MCHC
inc total iron binding capacity (TIBC) - referred out test
measurement of serum ferritin lvls - reflects total iron stores in the body
What will the blood smear show with iron deficiency anemia?
inc central pallor - pale RBC’s, often with just a ring of hemoglobin
Keratocytes, schistocytes, folded RBCs, microcytosis, thrombocytosis in ~50% of cases
What are production disorders? What might cause them?
due to reduced rates of erythropoiesis or defective erythropoiesis
Generally results in normochromic anemia - non regen
Causes: chronic renal dz, hypothyroidism, hypoadrenocorticism, bracken fern poisoning, iron and copper deficiency, parvovirus and lead toxicity
How will chronic renal failure cause production disorder?
usually results in a moderate to severe anemia, nonregenerative, normocytic
the more severe the kidney failure, more severe the anemia
occurs due to a lack of erythropoietin prod by kidneys, particularly in dogs/cats
How can hypothyroidism cause production disorders?
results in mild, nonregen, normocytic anemia
hematocrit of ~0.30 L/L
once the hypothyroidism is addressed, anemia will resolve
believed to be due to a lower metabolic rate
How might hypoadrenocorticism cause production disorder?
addision’s dz
results in a mild, nonregen, normocytic anemia
often masked by hydration - dehydration causes PCV to be artificially inc
What are reticulocytes?
immature RBC’s that contain organelles
cells are macrocytic and blue-purple staining with wright’s stain - polychromasia
new methylene blue makes organelles stain dark blue and cell appears green
What are the 2 types of reticulocytes?
puntate and aggregate
Aggregate reticulocyte appear as polychromatophilic cells on blood smears (weights staines)
Cats have higher #’s of punctate reticulocytes than aggregate reticulocytes
What are the normal reticulocyte values for bovine, ovine, caprine, and equine?
0%
What are the normal reticulocyte values for porcine?
0-2%
What are the normal reticulocyte values for for canines?
0.5-1.5%
What are the normal reticulocyte values for for feline
0.5-1
What are the normal reticulocyte values for rabbit, guinea pig, rat, mouse
2-4%
What is a reticulocyte count?
used to determine whether the animal is responding to an anemia event
Regen anemia: bone marrow responding w/ releasing immature RBC’s, Non-regen is no response of the bone marrow
Always report inc of polychromasia or lack of polychromasia
A reticulocyte stain should be performed on all anemic animals (except eq)
How is a reticulocyte count performed?
done by automated analyzers or in clinic;
Place drop of blood + new methylene blue in sm test tube > sit for 10-15 > drop of solution to make blood smear > examine the smear as is, or counterstain with wright’s stain > 1000 RBCs are counted under oil immersion lens
reticulocyte count = % of RBCs that are reticulocytes
% reticulocyte = # of retics counted x 100
How are reticulocytes counted?
results are interpreted according to degree of anemia for the following reasons - anemic animals have fewer mature erythrocites
retics are released earlier and persist longer in anemic animals
What is a corrected reticulocyte count?
corrected reticulocyte count = reticulocyte % x (PCV/normal PCV)
Use a normal PCV of 45% for dogs, 45% for fel
EX. Dog has an observed reticulocyte percentage of 12% and PCV of 15%. What is the corrected reticulocyte count?
Reticulocyte % x (PCV/normal PCV)
12% x (15% / 45%) = 4%
What is the reticulocyte production index?
RP = corrected reticulocyte count/reticulocyte maturation time
requires the use of the following chart
ex. corrected retic count of 4% / 2.5 = 1.6
An RPI of 1.6 means that reticulocytes are being produced 1.6x faster than normal in this patient
What is polycythemia?
rfers to inc of conc of erythrocytes in blood (inc PVC, inc RBC count, or inc Hgb conc)
Erythrocytosis is preferred term when only RBCs are affected
In some instances, RBC’s proliferate uncontrollably
there is normal maturation sequence and normal proportions of immature to mature cell #’s, but total RBC # inc
Common in dogs/cats, also affects Eq, cattle, llamas
What migth cause polycythemia?
may be due to dehydration, splenic contraction (exercise or epinephrine release - fear, pain, or excitement), hypoxia, or increased erythropoietin production
What do we need to always make note of at the time the sample was collected?
if the patient was dehydrated, excited, fearful or painful. It will help identify the reason for an increased PCV
