Hematology - Anemia Flashcards

1
Q

What is anemia?

A

Decrease in circulating RBC mass expressed by reduction in RBC count, hemoglobin, and Hct (PCV)

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2
Q

What is anemia caused by?

A

Decreased production, increased destruction, and increased loss

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3
Q

What are clinical signs of anemia due to?

A

Decreased O2 carrying capacity, reduced blood volume, and underlying disease

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4
Q

What do the severity of anemia signs depend on?

A

Rapidity of onset, degree and cause of anemia, and extent of physical activity

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5
Q

What is the normal response to anemia?

A

Accelerated erythropoiesis

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6
Q

How does accelerated erythropoiesis occur?

A

There is reduced oxygen carrying capacity which results in renal hypoxia. Renal hypoxia stimulates erythropoietin (EPO) release

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7
Q

After acute blood loss, dogs increase RBC production to __ to ___ times the normal rate.

A

6 to 8 times

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8
Q

After acute blood loss, cats increase RBC procution _ to _ fold.

A

3 to 5

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9
Q

What is the most useful marker of regeneration?

A

increased number of reticulocytes

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10
Q

What are reticulocytes?

A

immature non-nucleated erythrocytes

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11
Q

How long does it take reticulocytosis to develop? When does it peak? When does it decline in dogs? Cats?

A

Takes 2 to 4 days to develop.
Peaks between 4 and 7 days.
Declines at 2-3 weeks in dogs.
Declines in 9-13 days in cats.

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12
Q

What type of reticulocytes do cats have?

A

Aggregate and punctate

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13
Q

Which feline reticulocyte is present in the circulation for longer?

A

punctate

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14
Q

Which feline reticulocyte is counted in the laboratory reticulocyte count?

A

Aggregate

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15
Q

What is the reticulocyte percentage?

A

The percentage of RBC that are reticulocytes

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16
Q

What reticulocyte percentage indicates regenerative anemia in dogs? Cats?

A

0-1.0% in dogs, 0-0.4% in cats

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17
Q

How do you calculate the absolute reticulocyte count?

A

RBC count x RP

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18
Q

At what number of reticulocytes is considered to be a sign of regenerative anemia in dogs?

A

> 80,000 reticulocytes

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19
Q

At what number of reticulocytes is considered to be a sign of regenerative anemia in cats?

A

> 50,000 reticulocytes

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20
Q

True or False: Reticuocytes are the only absolute thing that you can use to determine if a patient has regnerative anemia.

A

TRUE

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21
Q

What are some other indicators of regeneration?

A

Increased MCV (macrocytic), increased RDW, decreased MCHC (hypochromic), polychromasia, and Howell-Jolly bodies

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22
Q

What is the hallmark of external blood loss? (Hint: it is a triad)

A

Anemia, hypoproteinemia, and reticulocytosis

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23
Q

What are some signs of a primary hemostatic defect?

A

Petechiae, ecchymoses, hematuria, melena, and epistaxis

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24
Q

What are some signs of a secondary hemostatic defect?

A

Hemoabdomen, hemothorax, hematomas, and joint bleeding

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25
Q

What factors can be measured to determine if there is a primary hemostatic defect?

A

Platelet count and von Willebrand factor (vWF)

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26
Q

What tests can be done to determine if there is a secondary hemostatic defect?

A

Coagulation times - PT and aPTT

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27
Q

Are there any clues on the CBC of acute bleed anemia?

A

Shistocytes (DIC and hemangiosarcoma) and possibly decreased platelets

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28
Q

Below what number of platelets are patients at risk for spontaneous bleeding?

A

below 30,000 platelets/microliter

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29
Q

If the cause of acute (regenerative) anemia is not obvious, what other diagnostics can be done? What should not be done?

A

Radiographs, ultrasound, and endoscopy

Bone Marrow evaluation is not indicated for a regenerative anemia

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30
Q

How much is the canine blood volume?

A

90 ml/kg - it is 8-10% of body weight

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31
Q

How much is the feline blood volume?

A

60 ml/kg - it is 6-8% of body weight

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32
Q

When hemorrhage is greater than 20% of blood volume, what signs occur?

A

cardiovascular signs

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33
Q

Initially, what clinical signs are present in acute blood loss anemia?

A

Peripheral vasoconstriction and tachycardia

34
Q

Why is regional blood flow to the skin and spleen curtailed during early stages of acute blood loss anemia?

A

To protect perfusion to the brain, heart, and viscera

35
Q

What occurs when blood loss is greater than 30-40% of the blood volume?

A

CO decreases, hypotension with cardiovascular collapse, the animal is immobile with rapid/thready pulse, and the skin and extremities are cold

36
Q

What occurs when blood loss is greater than 50% of the total blood volume?

A

Shock and death occurs within hours

37
Q

True or False: Initially PCV and total protein are decreased in cases of acute blood loss anemia.

A

False - initially PCV and total protein are normal

38
Q

When do PCV and TP decrease in acute blood loss anemia and why?

A

2-3 hours after the onset of bleeding, and continuing for 48-72 hours, blood volume replacement occurs by the addition of interstitial fluid

39
Q

When will total protein begin to rise after an acute bleed?

A

2-3 days after a beed

40
Q

Will TP or HCT normalize first after an acute bleed?

A

TP

41
Q

When does a CBC return to normal after an acute bleed?

A

in about 2 weeks

42
Q

If you have reticulocytosis for more than 2-3 weeks, what should you suspect?

A

There is an ongoing bleed

43
Q

Initially, acute blood loss is of what type? (think about MCV, MCHC)

A

Normocytic, normochromic, and non-regenerative

44
Q

When does acute blood loss anemia become macrocytic and regenerative?

A

After 3-4 days

45
Q

What are the four main objectives to treating acute blood loss anemia?

A

Stop the bleeding and prevent future bleeding, replace the lost red cells, careful volume rescusitation, and treatment of underlying disorder

46
Q

A healthy, normovolemic animal may tolerate a HCT of what percentage?

A

5-10% HCT

47
Q

Signs of ______ develop much earlier in the hypovolemic, anemic animal.

A

hypoxia

48
Q

Where is most iron located and in what form?

A

Most iron is located in RBC’s as hemoglobin

49
Q

Where does iron storage occur?

A

In the spleen, liver, and bone marrow

50
Q

What is a major cause of iron deficiency anemia?

A

Chronic external blood loss

51
Q

Initially iron deficiency anemia is regenerative/nonregenerative.

A

regenerative

52
Q

What are some common causes of iron deficiency anemia?

A

Fleas, hookworms, bleeding GI neoplasia, Ulcerogenic drugs, and frequent phelobotomies

53
Q

Pica can be found in patients with chronic blood loss anemia. Why?

A

Due to the iron deficiency

54
Q

How does chronic blood loss anemia present?

A

Anemia, decreased Hgb synthesis, microcytes, hypochromasia, +/- thrombocytosis

55
Q

True or False: Chronic blood loss anemia can be microcytic and hypochromic, or microcytic and normochromic.

A

TRUE

56
Q

Why is there decreased Hgb in patients with chronic blood loss anemia?

A

because of the iron deficiency

57
Q

What will you see on peripheral blood smear in patients with chronic blood loss anemia?

A

hypochromia, fragmentation (schistocytes), and keratocytes

58
Q

If there is anemia with a high platelet count in patients with chronic blood loss anemia, what should you search for?

A

blood loss

59
Q

What may a chemistry panel show in patients with chronic blood loss anemia?

A

low total protein

60
Q

What chemistry change may be associated with GI blood loss?

A

Increased BUN

61
Q

How do we treat chronic blood loss anemia?

A

Find and correct the underlying cause, correct anemia, correct iron deficiency, withdraw ulcerogenic drugs, control ecto- or endoparasites, surgical resction of tumor

62
Q

When is a transfusion indicated in patients with chronic blood loss anemia?

A

With severe anemia or in preparation for anesthesia/surgery to find/correct GI hemorrhage

63
Q

Patients with chornic blood loss anemia are _____volemic with an ______ cardiac output.

A

normo; increased

64
Q

When is iron supplementation indicated?

A

Only in patients with iron deficiency anemia

65
Q

What type of iron supplementation is recommended first in patients with iron deficient anemia?

A

Parenteral (IM iron dextran)

66
Q

After using parenteral iron supplementation, how can iron be supplemented next?

A

Orally with ferrous sulfate

67
Q

How do you treat patients with non-external blood loss anemias?

A

Autotransfusion - with resorption of approximately 80% of RBCs within 1-2 weeks

68
Q

What is the normal RBC lifespan in the dog?

A

120 days

69
Q

What is the normal RBC lifespan in the cat?

A

70 days

70
Q

Hemolysis indicates shortened RBC lifespan due to what?

A

Intrinsic defect or an extrensic mechanism that leads to premature erythrocyte removal such as antibodies against erythrocytes

71
Q

What type of hemolysis predominates in hemolytic anemia?

A

extravascular hemolysis

72
Q

What does extravascular hemolysis refer to?

A

erythrophagocytosis in the spleen, liver, and bone marrow

73
Q

What is extravascular hemolysis?

A

When RBCs are degraded within macrophages, so no Hgb is released from the cytoplasm

74
Q

What is intravascular hemolysis?

A

When RBCs are lysed within the circulation as a result of membrane permeability changes or cellular fragmentation

75
Q

Is hemoglobinuria and hemoglobinemia associated with extravascular or intravascular hemolysis?

A

intravascular

76
Q

Is bilirubinemia and bilirubunuria associated with extravascular or intravascular hemolysis?

A

extravascular

77
Q

Why does hemoglobinuria occur during intravascular hemolysis?

A

When the amount filtered through the kidneys exceeds the limited capacity of the tubule to resorb Hgb

78
Q

What can cause artifactual hemolysis?

A

Poor venipuncture technique, prolonged blood storage, exposure to temperature extremes

79
Q

What clinical signs are associated with hemolytic anemia?

A

Pallor, weakness, jaundice, pigmenturia - signs can be acute/fulminant or subacute/chronic

80
Q

Is hemolytic anemia usually regenerative or nonregenerative?

A

regenerative

81
Q

What is a common finding on CBC with patients with hemolytic anemia?

A

spherocytes +/- agglutination

82
Q

What will you find on a chemistry panel in patients with hemolytic anemia?

A

Normal proteins and elevated bilirubin