Lecture 4 - Haem 1

Question 1

Briefly describe what the functions of blood are:

Answer 1

1. Transport - nutrient, waste, oxygen, CO2 2. Osmotic pressure 3. Oncotic pressure (proteins) 4. Buffering pH (acid-base balance) 5. Haemostasis (platelets and coagulation factors) 6. Immunity (leukocytes)

Question 2

What are the stages of erythrocyte life span, ageing and destruction?

Answer 2

1. Production of RBC cells by the bone marrow 2. The macrophages in the spleen, liver and bone marrow consume the old red blood cells 3. In the process they release globin, iron, bilirubin 4. Unconjugated bilirubin-albumin complex is converted to conjugated bilirubin in the liver 5. Urobilinogen and stercobilinogen are excreted from the liver

Question 3

Briefly explain how the process of erythropoiesis is regulated:

Answer 3

1. RBC pass through the kidneys and the kidneys measure O2 consumption (blood flow) and O2 supply (influenced by blood flow, oxygen content and oxygen affinity) 2. EPO - erythropoietin is released by the kidney 3. EPO then stimulates the bone marrow precursors to increase production

Question 4

What is the first cell involved in erythropoiesis and what is the last one?

Answer 4

The first cell (part of the proliferative pool) is a Rubriblast and the final cell is a reticulocyte

Question 5

What is the lifespan of an erythrocyte?

Answer 5

months

Question 6

Fill in the table below

Answer 6

Question 7

What is the HCT/PCV and what is the formula for HCT?

Answer 7

Haematocrit or packed cell volume. PCV is the proportion of blood volume that is filled by RBC. The HCT = the haematocrit = RBC/ul x MCV/10

Question 8

What is the MCV and what is high, normal and low reading mean in practical terms? What is the formula

Answer 8

MCV is the mean corpuscular volume. The MCV = (HCT x 10)/(RBC/uL). A high MCV is macrocytic (meaning bigger than normal), a normal MCV is normocytic (meaning a normal volume), a low MCV is microcytic which means that they are smaller than normal.

Question 9

What is MCHC, what is the formula and what does a high and low value mean?

Answer 9

Mean corpuscular haemoglobin content. MCHC = (HGB x 100)/HCT. A high MCHC is hyperchromic, a normal MCHC is normochromic, a low MCHC is hypochromic

Question 10

Provide a conditon where anaemia could be masked and a condition under which a false interpretation of anaemia could be made:

Answer 10

Anaemia is decreased eryhtrocyte mass within the body. Anaemia can be masked by concomitant dehydration. Low erythorycte numbers can also be identified in the body even when the total-body erythrocyte mass is normal. Over hydration (erythrocyte dilution) and splenic sequestration

Question 11

What blood test can be used to asses the degree of regeneration within eryhtrocytes? What species can this this not be used in? Explain what levels should be seen in canines and felines

Answer 11

RET - expressed as a percentage and also in raw number terms. Reticulocytes are typically absent within horses. See the numbers that should be seen within canines and felines below:

Question 12

Briefly explain the process, name it and state any abnormalities you might see in the blood test:

Answer 12

Regeneration is occuring the bone marrow is releasing reticulocytes permature;y into the blood. This can be seen by the bigger and bluer erytrhocytes. This is called polychromasia. The MCV should be high and the MCHC is low

Question 13

Breifly explain the three processes that are invovled in the diagnosis of anaemia:

Answer 13

1. Assess the severity
2. Assess the regeneration
3. Classify using erythrocyte indices

Question 14

What are the differentials that should be considered when there is a case of normocytic, normochromic anaemia?

Answer 14

1. Pre-regenerative anaemia
2. Chronic renal disease
3. Selective eryhtroid hypoplasia
4. Aplasia or hypoplastic anaemia

Question 15

What are some examples of causes of macrocytic, normochromic anaemia?

Answer 15

FeLV infections

Poodle macrocytosis

Spurious with persistent hypernatremia

Question 16

What could be a cause of macrocytic, hypochromic anaemia?

Answer 16

Regenerative anaemia

Question 17

What could be a potential cause of microcytic, hypochromic anaemia?

Answer 17

Iron deficiency

Anaemia of inflammatory disease

Normal in Akita and Shiba dogs

Question 18

Complete the table below for classification of anaemia:

Answer 18

Question 19

What is aplastic anaemia a bad name for it and what should it actually be called?

Answer 19

It is an improper name because it is not only anaemia it should be called bone marrow aplasia. It is where haematopoietic bone marrow is replaced by adipose tissue leading to the destruction of progenitor and proliferative cells.

Question 20

Name the process that is occuring in the image below and state the process that is occuring:

Answer 20

Bone marrow aplasia

Question 21

Briefly explain how haematology and the concept of half lives can be used to differentiate between acute aplastic anaemia and chronic aplastic anaemia:

Answer 21

Neutropenia - 5 to 6 day half-life

Thrombocytopenia - 8 to 10 day half-life

Anaemia 60-70 days (cats) 100-120 days (dogs)

ACUTE APLASTIC ANAEMIA: neutropneia and thrombocytopenia

CHRONIC APLASTIC ANAEMIA: moderate non regenerative anaemia, normocytic, normochromic neutropenia and thrombocytopenia

Question 22

Briefly explain the two different pathogenesis of aplastic anaemia proving an example for each:

Answer 22

Primary: idiopathic (an insufficient number of stem cells, abnormalities in haematopoietic environment (rare in dogs and cats)

Secondary: infectious agents (acute parvovrisu infections), chemica/physical agents, drugs, toxins (estrogen toxicity - particularly common in dogs and in ferrets) , immune-mediated