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BVSc 2024 > Pathology Flashcards Weeks 13-18 > Flashcards

Pathology Flashcards Weeks 13-18

1
Q

In terms of analyzers, why are medical labs not good for veterinary use?

A

Medical labs are unlikely to have the correct animal add-on software for their analyzers and differentials may be wrong due to differences in cell size and morphology between animal and human blood

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2
Q

In terms of technicians and pathologists, why are medical laboratories not useful for veterinary use?

A

Technicians in medical labs are unlikely to be trained to deal with animal samples, and human pathologists will not discuss cases with you

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3
Q

In terms of tests and reference ranges, why might medical laboratories not be appropriate for veterinary use?

A

They will not have reliable reference ranges for haematological and biochemical parameters in animals, and tests are likely to be inappropriate for animal use

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4
Q

What is vital to fill in when submitting samples to a lab?

A

Signalment, Clinical Signs and History

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5
Q

How should specimens be packaged when submitting samples to a lab?

A

The specimens should be packaged in such a way that they will not break or leak and are ideally surrounded by soft packing material such as bubble wrap

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6
Q

What are 4 reasons for why it is advantageous to use Veterinary Practice laboratories?

A

Excellent service for vet clients, Rapid Turnaround, Reliable Results, They have Vet Pathologists

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7
Q

Who is responsible for interpretation of laboratory results?

A

The practitioner is responsible, even when interpretive comments are provided by a laboratory pathologist.

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8
Q

What is required when interpreting laboratory results?

A

A table of references is required in order to identify any abnormalities

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9
Q

What do reference ranges represent?

A

The distribution of test results in a healthy population. The range is considered to be the mean (+/- 2 standard deviations)

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10
Q

Why is repeat testing required?

A

If a biochemical test of say 15 tests is performed, there will be a greater than 50% chance of finding one or more values outside the reference range. Therefore, variations from normal are not always straightforward.

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11
Q

What is the quality assurance programme?

A

A standardized set of protocols from handling samples to reporting results which helps ensure the reliability, precision and accuracy of test results.

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12
Q

What are quality control programmes?

A

A set of processes and instruction for a machine or diagnostic test that ensure the results produced are as reliable and accurate as possible

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13
Q

What is internal quality control?

A

Where samples of known value are run and the results are comapred to the known values to make sure they are within acceptable limits

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14
Q

What is external quality control?

A

Where results of tests on unknown controls are compared with “consensus” means calculated from the results of all participating laboratories

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15
Q

What are the five parameters that indicate how good a test is?

A

Accuracy, Precision, Sensitivity, Specificity and Predictive Values

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16
Q

What is the accuracy of a test?

A

Assesses how close the test result is to the actual test

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17
Q

What is the precision of the test?

A

Assesses how repeatable the test result is when testing the same sample

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18
Q

What is the Sensitivity of the test?

A

The measurement of the frequency with which a test result will be positive in an animal that actually has the disease

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19
Q

What is specificity?

A

The measurement of the frequency with which a test result will be negative in an animal that does not have the disease

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20
Q

What is a predictive value of a test?

A

Based on the sensitivity and specificity of a test but also factors in the vets pre-judgement of the likelihood of the disease being present.

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21
Q

What are the 3 major cell types present in the blood, and how much of the body mass is water?

A

Erythrocytes, Leukocytes and Platelets - 60-70% of the total body mass is water

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22
Q

Describe the purpose of the haematopoietic system

A

The haematopoietic system manufactures the cellular components of blood and is widely distributed throughout the body

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23
Q

Describe the role of bone marrow with regards to the haematopoietic system

A

Main source of erythrocytes, granulocytes, monocytes and thrombocytes. Also stores iron for heme synthesis, and is the source of stem cells for T and B-lymphocytes.

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24
Q

Describe the role of the liver with regards to the haematopoietic system

A

Major haematopoietic organ during the first half of embryonic life. Function is gradually overtaken by bone marrow, but still has potential for haematopoiesis in adults.

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25
Q

Describe the role of Lymph Nodes with regards to the haematopoietic system

A

Produces B and T-lymphocytes and plasma cells. Participates in antibody production and cell mediated immunity.

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26
Q

Describe the role of the spleen with regards to the haematopoietic system

A

Produces T and B-lymphocytes and plasma cells, stores erythrocytes and iron, removes aged and abnormal erythrocytes - also degrades haemoglobin.

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27
Q

Describe the role of the thymus with regards to the haematopoietic system

A

Controls differentiation of bone marrow derived stem cells into T-lymphocytes

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28
Q

Describe the role of Macrophages of the Monocyte Phagocytic System with regards to the haematopoietic system

A

Macrophage line sinusoids in spleen, liver, lymph nodes, bone marrow and destroy aged or abnormal erythrocytes and haemoglobin. Also stores iron.

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29
Q

Where does erythropoiesis occur and what is involved?

A

In the bone marrow and involves the differentiation of a pluripotential stem cell into an erythroid cell, and after several forms it becomes a mature erythrocyte

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30
Q

In response to eryrthropoietin (EPO) what happens to erythroid stem cells?

A

Erythroid stem cells differentiate into a rubriblast and begin to produce haemoglobin and oter proteins.

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31
Q

Over a period of 3-4 days nucleated erythroid precursor cells progress into what?

A

A series of divisions and maturation processes that result in the production of 8-16 rubicytes from each rubriblast

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32
Q

What is the final stage in erythroid maturation, and when do they become ‘reticulocytes’?

A

Metarubicytes are the final nucleated stage in maturation and once the nucleus is extruded, they become reticulocytes

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33
Q

When is nucleus extrusion triggered?

A

When the erythrocyte reaches a critical level of haemoglobin content

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34
Q

How long does it take for reticulocytes to be released from bone marrow?

A

~7 days from the time of initial stimulation of stem cells by EPO

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35
Q

What are the 3 major pools of erythrocyte storage?

A

Erythrocyte precursors (mainly in bone marrow), Blood (Mainly Mature Erythrocytes and Spleen (Mainly Mature Erythrocytes)

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36
Q

How does the kidneys regulate erythropoiesis?

A

The kidneys produce erythropoietin, which stimulates stem cells to differentiate into rubriblasts and promotes haemoglobin synthesis

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37
Q

What minerals are involved in Erythropoiesis?

A

Vitamin B12, Vitamin B6 and Folic Acid, Iron, Copper and Cobalt are essential for erythrocyte production

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38
Q

What hormones are involved in Erythropoiesis and what are their effects?

A

Androgens, which stimulate erythropoiesis and Oestrogens, which have an inhibitory effect

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39
Q

What is extravascular haemolysis?

A

The process by which old or damaged erythrocytes are removed from circulation

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40
Q

What happens to old red blood cells during extravascular haemolysis?

A

They become less pliable and are phagocytosed by macrophages lining sinusoids in the spleen, liver and bone marrow

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41
Q

During extravascular haemolysis, what is disassembled and what is released?

A

Haemoglobin is disassembled and iron is released. The iron is either stored intracellularly as haemosiderin or transported via transferring back to the bone marrow for re use in erythropoiesis. Billirubin also released.

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42
Q

What is erythrocytosis?

A

An increase in PCV, erythrocyte count or haemoglobin concentration above the normal range

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43
Q

What is relative erythrocytosis?

A

The total red cell mass is normal, but plasma volume is reduced

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44
Q

In terms of plasma proteins, how does relative erythrocytosis affect the concentration?

A

The plasma protein concentration will be increased (not volume!!!!!) as well as PCV, RBC concentration and haemoglobin concentration

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45
Q

What is physiological erythrocytosis?

A

A mild to moderate temporary increase in PCV may be seen due to splenic contraction which leads to release of erythrocytes into circulation

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46
Q

What is absolute erythrocytosis?

A

A true increase in total red cell mass, which can be primary or secondary.

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47
Q

What is primary absolute erythrocytosis?

A

Increased erythrocyte production without increased erythropoietin levels

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48
Q

What is primary absolute erythrocytosis characterised by?

A

Autonomous erythropoiesis in the presence of low levels of EPO and normal oxygen tension. There is hypoproliferation of bone marrow.

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49
Q

What is Secondary Absolute erythrocytosis?

A

Increased erythrocyte production in response to increased erythropoietin production

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50
Q

What is appropriate secondary absolute erythrocytosis?

A

Usually associated with tissue hypoxia, leading to increased EPO production. This stimulates erythrocyte production so that more oxygen can be carried to the tissues.

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51
Q

What is inappropriate secondary absolute erythrocytosis?

A

Due to increased EPO production without tissue hypoxia. This is a fairly uncommon cause of erythrocytosis.

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52
Q

What is anaemia characterised by?

A

A reduction in erythrocyte numbers, which results in reduced RBC count, preduced PCV/HCT and usually reduced haemoglobin concentration

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53
Q

What are the clinical signs of anaemia?

A

Pale mucous membranes, lethargy, reduced exercise tolerance and increased respiratory rate. Heart rate is also increased and there may be murmurs due to turbulence.

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54
Q

Why does anaemia occur?

A

Decreased production of erythrocytes or increased loss of erythrocytes through destruction or haemorrhage

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55
Q

What is regenerative anaemia?

A

Where the bone marrow responds to the reduced cell mass by accelerating erythropoiesis and releasing increased numbers of immature erythrocytes into circulation

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56
Q

How can regenerative anaemia be detected?

A

By the presence of increased number of reticulocytes, anisocytosis (variation in erythrocyte size), polychromasia, basophilic stippling, sometimes macrocytosis and sometimes nucleated erythrocytes.

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57
Q

When is a bone marrow response usually seen following blood loss or RBC destruction?

A

3-5 days of blood loss

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58
Q

What is non-regenerative anaemia?

A

Occurs when the bone marrow cannot produce enough erythrocytes to replace those which are lost by normal attrition

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59
Q

Why might non-regenerative anaemia occur?

A

May be due to deficiency of a factor required for erythrocyte production, inhibition of the bone marrow by certain toxins, infections or neoplasms.

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60
Q

What are pre-regenerative anaemias?

A

Those in which sufficient time to allow a regenerative response has not elapsed. They will look the same on a CBC as non-regenerative and are differentiated by repeating the CBC 3-5 days later.

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61
Q

In terms of erythrocyte size, what are the 3 classifications of anaemias?

A

Normocytic: Normal, Macrocytic: Bigger, Microcytic: Smaller

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62
Q

In terms of Haemoglobin concentration, what are the 2 classifications of anaemia?

A

Normochromic: Normal, Hypochromic: Decreased

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63
Q

What are the two main mechanisms of regenerative anaemia?

A

Haemorrhage (Erythrocyte loss as whole blood loss) and Haemolysis (Erythrocyte only destruction)

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64
Q

In acute blood loss (haemorrhagic anaemia) what happens to all erythrocyte parameters (PCV, RBC Concentration, Hb Concentration, MCV, ECHC)?

A

They will be initially normal because the cellular and fluid components are lost in similar proportions.

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65
Q

If blood volume is acutely reduced to 60-70% of normal, what might the animal develop?

A

Hypovolemic shock

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66
Q

How might the spleen help with PCV count?

A

Splenic contraction may deliver highly concentrated blood into circulation and temporarily elevate the PCV, but this will be reduced as interstitial fluid attempts to restore blood volume.

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67
Q

In terms of platelets and neutrophils, how might these change during acute blood loss?

A

Platelet numbers may increase during the first few hours after haemorrhage and mild neutrophilic leukocytosis may occur by ~3 hours.

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68
Q

Describe RBC production following acute blood loss

A

Increased RBC production in the bone marrow becomes visible in the peripheral blood when reticulocytes are seen. Usually becomes apparent 3-5 days post-haemorrhage

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69
Q

Describe the onset of anaemia and hypovolemia for chronic blood loss

A

In chronic blood loss, the anaemia develops slowly and hypovolemia does not occur because the animal has time to adapt

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70
Q

Describe the PCV of Chronic Blood Loss

A

The PCV may reach a low level before clinical signs of anaemia develop

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71
Q

When blood loss is internal, what happens to erythrocytes?

A

2/3rds of the erythrocytes enter lymphatics and are re-circulated within 24-72 hours. The remainder are lysed or phagocytosed.

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72
Q

When does haemolytic anaemia occur?

A

When accelerated erythrocyte destruction is not balanced by erythropoiesis.

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73
Q

In terms of plasma protein concentration, what is the difference between haemolytic anaemia and external haemorrhage?

A

With haemolytic anaemia, the plasma protein concentration is usually normal and in external haemorrhage the plasma protein concentration is usually decreased

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74
Q

When does intravascular haemolysis occur?

A

Occurs within blood vessels, when the erythrocyte membrane suffers sufficient damage to allow escape of haemoglobin into the plasma

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75
Q

What are some laboratory results characteristic of intravascular haemolysis?

A

Haemoglobinaemia, Haemoglobinuria, Hyperbilirubinaemia and Alterations in Erythrocyte Morphology

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76
Q

What is Extravascular Haemolysis?

A

Occurs within cells, and involves accelerated removal of erythrocytes by phagocytic macrophages, especially those in the spleen.

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77
Q

What occurs in immune-mediates haemolytic anaemias?

A

There is accelerated erythrocyte destruction due to an immunological reaction. The RBCs may be altered antigenically by a drug, infectious agent or be recognised as foreign.

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78
Q

What type of anaemia is usually present in Immune-Mediates Hemolytic Anaemia?

A

Usually strongly regenerative, however, when antibodies are directed against erythrocyte precursors, anaemia can appear non-regenerative.

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79
Q

What are some haematological features of Immune-Mediated Haemolytic Anaemia?

A

Marked Regenerative Response, Spherocytosis, Erythrocyte Autoagglutination, Coomb’s Positive Test and Left Shift Neutrophilia

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80
Q

What is neonatal isoerythrolysis?

A

A form of immune-mediated haemolytic anaemia which occurs in newborn animals

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81
Q

How does neonatal isoerythrolysis arise?

A

Occurs when a small percentage of horses when a foal inherits from the stallion RBC antigens that are incompatible with those of the mare

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82
Q

Describe the pathogenesis of neonatal isoerythrolysis

A

Small amounts of foetal RBC antigen gain access to the maternal circulation via foetal-maternal haemorrhage across the placenta. Mare produces iso-antibodies, which enter the colostrum and induce haemolysis of the foal’s RBC’s.

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83
Q

What usually causes iron deficiency?

A

Almost always due to chronic blood loss, usually into the GIT, but can also occur in suckling animals because of low concentration of iron in milk

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84
Q

Describe Iron Deficiency Anaemia in an acute case vs a chronic case

A

Iron deficiency is usually regenerative initially, but may become non-regenerative in the late stages

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85
Q

What is the hallmark of Iron Deficiency Anaemia?

A

Microcytosis - believed to be due to extra cell divisions in erythroid precursors to establish normal intracellular haemoglobin concentrations

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86
Q

Describe a blood smear of a case of severe Iron deficiency anaemia

A

MCHC is decreased and erythrocytes have an enhanced central pallor, with only a thin rim of peripheral haemoglobin

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87
Q

What are the signs of Sporidesmin Toxicity, and what species does it affect?

A

It is an acute haemolytic crisis and with haemoglobinuria and jaundice which occurs in adult cattle during the facial eczema season in NZ

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88
Q

How is Leptospirosis Pomona infection characterised in young calves, lambs and weaner deer?

A

Characterised by an acute haemolytic crisis with anaemia, haemoglobinuria and jaundice

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89
Q

What do Haemolysis produced by L. pomana cause?

A

Direct lysis of red cells but can also induce immune-mediated haemolysis following adherence to the red cell membrane

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90
Q

What is not a feature of L. Pomana infection in adult animals?

A

Haemolytic anaemia

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91
Q

What is a feature of Chronic Copper Toxicity in sheep, calves, goats and pigs?

A

Acute intravascular haemolysis with haemoglobinuria, jaundice and haemoglobinuria nephrosis

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92
Q

Describe the Acute Haemolytic phase of chronic copper toxicity

A

Occurs when copper is suddenly released from the liver into the bloodstream, usually following some form of stress

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93
Q

Describe how long the period of copper accumulation may be for copper toxicity

A

May extend from as little as a few weeks to more than a year and will be clinically inapparent

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94
Q

Once the haemolytic crisis of copper toxicity is initiated, what is the sequelae?

A

Death usually occurs within 2-3 days

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95
Q

What are the two ways by which blood parasites cause Anaemia?

A
  1. Immune Mediated Extravascular Haemolysis 2. Intravascular Haemolysis
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96
Q

Describe the immune mediated extravascular haemolysis mechanism caused by blood parasites

A

Antibodies against the organism bind to the RBC, leading to phagocytosis by macrophage

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97
Q

What are Non-Regenerative Anaemias associated with?

A

Bone marrow that is unable to produce adequate numbers of erythrocytes, depending on the mechanism neutropenia and thrombocytopenia may also occur

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98
Q

What is Pancytopenia and what is is characteristic of?

A

Term used when a decrease in all the cell lines is present. Generally associated with Aplastic Anaemia.

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99
Q

When Pancytopenia is present, what does this suggest in terms of cells affected?

A

Suggests damage to the stem cells, or replacement of the functional haematopoietic tissue with another tissue.

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100
Q

What can cause damage to stem cells?

A

Drugs, chemicals and toxins, hormones and infectious agents

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101
Q

What are the most common examples of non-regenerative anaemia?

A

Anaemia of chronic disease and anaemia of chronic renal disease

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102
Q

When might you observe Anaemia of Chronic Disease/Inflammatory Disease?

A

Can be seen with inflammation/infection, trauma and neoplasia. It is usually mild to moderate, normocytic and normochromic.

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103
Q

What is Anaemia of Chronic Disease/Inflammatory Disease mediated by?

A

Inflammatory cytokines, and may occur even if there is no clinical or lab evidence of overt inflammation in animal

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104
Q

When might anaemia of chronic renal disease occur?

A

In chronic renal failure due to decreased erythropoietin production by the kidneys.

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105
Q

Describe the anaemia present in hypothyroidism-related patients

A

Commonly have a mild normocytic, normochromic, non-regenerative anaemia

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106
Q

Describe the anaemia present in hypoadrenocorticism-related patients

A

May have mild, normocytic non-regenerative anaemia but can be hard to detect if it is masked by concurrent dehydration

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107
Q

What type of anaemia is Iron Deficiency Anaemia associated with?

A

Iron deficiency anaemia is usually regenerative initially, and may become non-regenerative in the late stages

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108
Q

Describe the anaemia that can be seen with lead toxicity

A

A mild non-regenerative or poorly regenerative anaemia may accompany lead toxicity, especially in young dogs

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109
Q

Describe the RBCs and Cells present in Lead Toxicity anaemia

A

An innapropriately high number of nucleated RBCs and polychromatic cells are present

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110
Q

What is the most characteristic feature of lead toxicity anaemia?

A

Basophilic stippling of erythrocytes due to the presence of clumped ribosomes. Also inhibits enzymes involved in heme synthesis.

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111
Q

In terms of haemoglobin concentration and size, describe the anaemia of lead toxicity and what is happening in the bone marrow

A

It is typically normochromic, normocytic with some reticulocytes. There is erythroid hyperplasia and ineffective erythropoiesis in the bone marrow

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112
Q

What are the 5 focus points used to assess RBC in a blood smear?

A

Number, Size, Shape, Colour and ‘Other’ - ‘Other’ refers to structures in or on the erythrocytes and unusualy arrangements on the blood film

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113
Q

How is erythrocyte number measured?

A

By the RBC indices in the CBC or by measuing a PCV. Cannot be estimated accurately from a blood smear alone.

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114
Q

What is Anisocytosis?

A

The variation in RBC cell size, can be due to the presence of large cells, small cells or both

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115
Q

What is Microcytosis?

A

Presence of smaller erythrocytes

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116
Q

What is Macrocytosis?

A

Presence of large red blood cells

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117
Q

What are the hallmarks of regenerative anaemia on a blood smear?

A

Anisocytosis and Polychromasia

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118
Q

What is hypochromasia?

A

Refers to increased central pallor of cells due to decreased haemoglobin content - i.e. less colour

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119
Q

What is Polychromasia?

A

Refers to the variation in colour of erythrocytes, caused by the presence of more basophilic reticulocytes in addition to normal mature erythrocytes

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120
Q

What are Polychromatophils?

A

Immature/younger erythrocytes that have been released earlier from the bone marrow

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121
Q

What are reticculocytes?

A

Large, non-nucleated erythrocyte containing sufficient RNA/organelles to stain as granules

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122
Q

What dose an increased number of reticulocytes indicate?

A

Presence of regenerative anaemia in most species

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123
Q

What is the general term for any abnormally shaped erythrocytes?

A

Poikilocytosis

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124
Q

What are Acanthocytes?

A

Cells with few too many irregular surface projections of varying length.

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125
Q

What causes Acanthocytes?

A

Thought to occur due to changes in cholesterol/phospholipid concentrations in the red cell membrane

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126
Q

What are Echinocytes?

A

These have multiple, short, blunt, evenly spaced surface projections and are most commonly seen due to drying of a blood smear

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127
Q

What are Schistocytes?

A

Irregularly shaped erythrocyte fragments due to intravascular trauma

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128
Q

What are Spherocytes?

A

Small, dark staining, spherical erythrocytes which result from partial phagocytes by macrophages in the spleen and liver

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129
Q

What are Eccentrocytes?

A

Cells that have their Hb shifted to one side due to oxidative damage. The end result is a clear area to the side of the cell

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130
Q

What is meant by Basophilic Stippling?

A

Refers to erythrocytes with blue dots in the cytoplasm. Occurs in ruminants and cats as part of regenerative anaemia.

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131
Q

If basophilic stippling is seen without anaemia and reticulocytosis, what is it indicative of?

A

Lead poisoning

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132
Q

What are Heinz Bodies?

A

Clumps of denatured haemoglobin on the internal surface of the erythrocyte membrane due to oxidative damage. Most cats have these in up to 10% of their erythrocytes

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133
Q

What are Howell-Jolly bodies?

A

Nuclear remnants. They appear as small, darkly staining, spherical bodies within erythrocytes. Usually occur with regenerative anaemia

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134
Q

What are Metarubicytes?

A

They are the last nucleated stage of erythrocytes and can be seen in several stages including the regenerative response and bone marrow damage.

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135
Q

What are Siderocytes?

A

These mature erythrocytes contain iron granules and are seen with lead poisoning and certain anaemias

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136
Q

What is useful about a Bone Marrow Examination?

A

Can help to confirm or exclude differential daignoses based on the examination of peripheral blood and provide a more reliable indciation of prognosis.

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137
Q

What are the indications of Bone Marrow Examination?

A

Non-regenerative Anaemia, Persistent Leucopenia, Thrombocytopenia and Presence of Atypical Cells Suggestive of Neoplasia

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138
Q

What should be collected in addition to a bone marrow aspirate, during the bone marrow examination?

A

Always collect a peripheral blood sample for a CBC at the same time, as bone marrow aspirates need to be interpreted with concurrent peripheral blood results.

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139
Q

What is the function of Leukocytes?

A

They are primarily involved in body defence mechanisms and are capable of countering a wide variety of different infectious agents or foreign material

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140
Q

What are the 2 basic mechanisms for which granulocytes defeat the baddies?

A

Phagocytosis and Antibody production

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141
Q

What leukocytes have phagocytic properties?

A

Granulocytes and Monocytes

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142
Q

What cells are grouped within ‘Granulocytes’?

A

Neutrophils, eosinophils and basophils

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143
Q

What is Granulocytopoiesis?

A

The maturation process by which granulocytes are formed in the bone marrow

144
Q

In the bone marrow, what are the 3 main pools granulocytes are found in?

A

The dividing pool, mautration pool and storage pool

145
Q

What is the function of Neutrophils?

A

They phagocytose microorganisms and foreign material. They are attracted to sites of infection by chemotactic factors where they perform this.

146
Q

What happens to the neutrophil nucleus as it matures?

A

It becomse progressively smaller and more indented

147
Q

What are the stages of neutrophil maturation?

A

Myeloblast, Promyelocyte, Metamyelocyte, Band, Mature Segmented Neutrophil.

148
Q

What are the 3 sub-pools of the bone marrow with regards to neutrophils?

A

Dividing Pool, Maturation Pool and Storage Pool

149
Q

What are the sub-pools of the blood for neutrophils?

A

Circulating Pool and Marginal Neutrophil

150
Q

What does the circulating neutrophil pool in the blood consist of?

A

Neutrophils circulating freely together with erythrocytes and other blood cells

151
Q

What does the marginal neutrophil pool in the blood consist of?

A

Consists of neutrophils loosely adherent to the vascular endothelium

152
Q

How long do neutrophils remain in the blood of healthy animals?

A

They remain in the blood for an average of 10 hours, with all blood neutrophils being replaced 2.5x each day

153
Q

What is Neutrophilia?

A

An increase in the neutrophil count

154
Q

What is physiological neutrophilia?

A

Adrenaline release occurs in response to a stimulus, leading to mobilisation of neutrophils from the marginal pool into the circulating pool. Lasts 20-30 minutes

155
Q

What is Corticosteroid Neutrophilia?

A

Induced by endogenous or exogenous corticosteroid hormones. Corticosteroids cause increased survival time of neutrophils by reducing adherence and emigration of neutrophils from the blood.

156
Q

How does Inflammatory Disease induce neutrophilia?

A

Inflammation causes an increased demand for neutrophils, which induces bone marrow to release stored mature neutrophils and increase production of neutrophils then release them

157
Q

If there are not enough neutrophils in the storage pool to meet demand, what might the bone marrow do?

A

Release immature neutrophils from the maturation pool - referred to as a left shift. May be accompanied by neutropenia if demand is too overwhelming.

158
Q

What is Neutropenia?

A

A decrease in the neutrophil count in the blood. May lead to an increased risk of infection.

159
Q

How does increased neutrophil use lead to neutropenia?

A

The increased tissue demand for neutrophils may cause the number of neutrophils leaving the blood toe exceed the number of mature neutrophils entering the blood from storage, causing a net result of neutropenia

160
Q

Why does inflammatory neutropenia occur more in ruminants than other species?

A

Occurs most commonly in ruminants and horses as they have a smaller storage pool of neutrophils in the bone marrow

161
Q

What might cause decreased neutrophil production?

A

Decreased production from the bone marrow may be caused certain infectious agents or bone marrow toxins

162
Q

How might increased neutrophil destruction occur?

A

Immune mediated neutropenia - anti-neutrophil antibodies bind to neutrophils and initiate their destruction

163
Q

What is sequestration neutropenia?

A

Neutropenia that is due to an increase in the proportion of neutrophils in the marginal pool. Occurs in anaphylactic shock and in response to endotoxemia.

164
Q

Describe the morphological appearance of mature lymphocytes

A

Usually smaller than a neutrophil and have a large round nucleus with a small rim of blue cytoplasm

165
Q

Describe the morphological appearance of reactive lymphocytes

A

They may be larger than a neutrophil and have slightly more abundant deep blue cytoplasm than a mature lymphocyte

166
Q

Describe the morphological appearance of lymphoblasts

A

Immature lymphocytes that are larger than a neutrophil and have a distinct nucleus

167
Q

Describe the morphological appearance of Large Granular Lymphocytes

A

Larger and have more of a cytoplasm in comparison to mature lymphocytes

168
Q

What is the function of B-Lymphocytes?

A

When they are stimulated by exposure to specific antigens they differentiate into plasma cells and produce antibodies

169
Q

What is the function of T-Lymphocytes?

A

They are cytotoxic for many virus-infected cells, tumour cells and parasites, but also regulate B-lymphocyte function

170
Q

Where do stem cells for B and T lymphocytes originate, and where do they migrate?

A

Stem Cells for B and T Lymphocytes originate in the bone marrow but during foetal development there is migration of T and B-lymphocyte precursors to the Thymus

171
Q

Where are T-cells produced?

A

Either in the thymus or thymic-dependent areas of the spleen and lymph nodes

172
Q

Where are B-Cells produced?

A

In peripheral lymphoid organs, but in different areas than T-lymphocytes

173
Q

What is lymphocytosis?

A

An increased number of circulating lymphocytes

174
Q

What is Physiological Lymphocytosis?

A

Occurs in health animals and is in association with fear or excitement. The absolute count may be markedly increased

175
Q

How does Chronic Infection cause Lymphocytosis?

A

It may cause lymphocytosis due to antigenic stimulation of T-cells but there is some disagreement surrounding this

176
Q

How does Lymphoid Leukaemia cause Lymphocytosis?

A

Lymphoid leukaemia is associated with the presence of circulating neoplastic lymphocytes

177
Q

What is Lymphopenia?

A

A decrease in the number of lymphocytes in circulation, most commonly seen due to corticosteroids and less commonly due to viral infection

178
Q

Describe the appearance of Monocytes

A

Tend to be larger than a neutrophil, with darker blue cytoplasm that often contains vacuoles. Nuclei can vary in shape

179
Q

What is the function of Monocytes?

A

Phagocytosis (Macrophage)

180
Q

How does inflammation cause Monocytosis?

A

May be seen in acute or chronic inflammation due to high demand for phagocytes, even more so if necrotic debris is present

181
Q

What medicines may cause monocytosis?

A

Corticosteroids

182
Q

Describe the appearance of Eosinophils

A

They have a multi-lobed nucleus and almost colourless to pale blue cytoplasm with prominent pink granules, shape varies by species

183
Q

What is the function of Eosinophils?

A

They are involved in hypersensitivity and allergic reactions and defense against parasites

184
Q

Why might eosinopenia be clinically insignificant?

A

Eosinophil concentrations in healthy animals are typically low, and some lab reference ranges have them down as ‘zero’.

185
Q

Describe the appearance of Basophils

A

Contain variable purple staining granules within their cytoplasm

186
Q

What is a ‘Stress Leukogram’?

A

A change in leukocyte count due to increased endogenous or administration of exogenous glucocorticoids

187
Q

What are the classic components of a stress leukogram?

A
  1. Mature Neutrophilia 2. Lymphopenia 3. Eosinopenia 4. Monocytosis
188
Q

What is characteristic of Bovine Leukocyte Adhesion Deficiency?

A

Characterised by stunted growth and recurrent infections including: Pneumonia, Ulcerative Stomatitis and Periodontitis and Enteritis and Eventually leads to death

189
Q

Describe the pathogenesis of Leukocyte Adhesion deficiencies

A

The lack of a glycoprotein essential for normal neutrophil-endothelial cell adherence and emigration prevents neutrophils from leaving the blood and attacking infectious agents.

190
Q

What breeds does Canine Leukocyte Adhesion Deficiency affect?

A

Irish and Red-White Settlers

191
Q

What are the clinical signs of Canine Leukocyte Adhesion Deficiency?

A

Gingivitis, Lymphadenopathy and Skeletal Lesions resembling metaphyseal osteopathy

192
Q

What is Pelger-Huet Anomaly?

A

An uncommon condition where an animal fails to make segmented neutrophils, eosinophils and basophils

193
Q

What are the two main types of Haematopoietic Neoplasia?

A

Myeloproliferative disorders and Lymphoproliferative disorders

194
Q

What type of neoplasia are grouped into Myeloproliferative disorders?

A

Neoplasia of all the non-lymphoid cells in blood, such as RBCs, granulocytes, monocytes and megakaryocytes

195
Q

What type of neoplasia are grouped into Lymphoproliferative disorders?

A

All neoplasia of lymphoid origin

196
Q

How are haematopoietic neoplasia classified?

A

Most common neoplasms are classified by cell types and can also be based on cell maturity

197
Q

Describe cell maturity of Acute (Lymphoblastic) Leukaemia

A

Immature blast cells - short clinical course if not treated (days to weeks)

198
Q

Describe the cell maturity of Chronic (Lymphocytic) Leukaemia

A

More mature cells - long clinical course (months to years)

199
Q

How are haematopoietic neoplasia classified?

A
  1. Classified via Light Microscopy (Cell Type) 2. Immunocytochemistry (Special stains for enzymes/compounds in cells) 3. Immunophenotyping (Surface antigen recognition)
200
Q

What does lymphoid leukaemia refer to?

A

Lymphoid malignancies where neoplastic lymphocytes are in the bone marrow and in most cases, also the peripheral blood

201
Q

How is Acute Lymphoblastic Leukaemia characterised?

A

By the presence of large, immature and poorly differentiated lymphoblasts in the bone marrow, usually in circulation

202
Q

What might be the CBC findings in cases of Acute Lymphoblastic Leukaemia?

A

May include lymphocytosis (especially immature blast lymphoid cells), anaemia and thrombocytopenia

203
Q

What are clinical signs of Acute Lymphoblastic Leukaemia related to?

A

To the decrease in other haematogenous cells due to replacement of the bone marrow with neoplastic lymphoid tissue, or infiltration of organs with lymphoid cells

204
Q

What is the prognosis for patients with Acute Lymphoblastic Leukaemia?

A

Poor - with a limited survival time

205
Q

Describe the lymphocytes seen in Chronic Lymphocytic Leukaemia

A

They are small and well-differentiated - however, the magnitude of lymphocytosis is usually greater

206
Q

How is diagnosis of Chronic Lymphocytic Leukaemia made?

A

Usually made based on significant lymphocytosis and an increased portion of lymphocytes in the bone marrow

207
Q

What is a Lymphoma?

A

Lymphoid neoplasia that originates in the tissues and may progress to leukaemia

208
Q

What is Lymphoma classification usually based on?

A

Distinction between viral and sporadic forms and on the distritubitional features as well as cytology

209
Q

What are the anatomical forms of feline lymphoma?

A

Multicentric, Alimentary, Thymic and can involve the bone marrow or a leukaemic form

210
Q

Describe the characteristics of Sporadic feline lymphoma

A

Majority of these lymphomas affect middle aged to older cats. The alimentary form is the most common, but multicentric and thymic forms also occur.

211
Q

Describe the characteristics of Retrovirus Associated Lymphoma

A

Lymphoma can arise from infection with feline leukaemia virus and to a lesser extent FIV. Affects young cats and the multicentric and thymic forms are most common

212
Q

What are the main forms of Canine Lymphoma?

A

Multicentric, Alimentary, Thymic and Skin.

213
Q

What clinical signs may arise as a result of canine lymphoma?

A

Hypercalcaemia of malignancy, as well as PU/UD, lethargy and anorexia secondary to the hypercalcaemia.

214
Q

Describe the characteristics associated with General Sporadic Bovine Lymphoma

A

Not associated with BLV infection and usually occurs in animals less than 3 years of age

215
Q

Describe the characteristics associated with the Calf of Juvenile form of Sporadic Bovine Lymphoma

A

Usually multicentric and generalised lymph node involvement, and frequent infiltration of the bone marrow, liver and kidney

216
Q

Describe the characteristics associated with the Thymic form of Sporadic Bovine Lymphoma

A

Occurs primarily in cattle less than 2 years of age and is characterised by massive enlargement of the thymus leading to swelling of the ventral neck

217
Q

Describe the characteristics associated with the Cutaneous form of Sporadic Bovine Lymphoma

A

Characterised by multiple nodules in the skin of cattle 1-3 years of age. The nodules may ulcerate and regress - but infiltration of internal viscera eventually causes death

218
Q

Describe the General Characteristics associated with Viral Lymphoma

A

Enzootic bovine leucosis is a multicentric form of lymphoma affecting adult cattle caused by bovine leukaemia virus (BLV)

219
Q

Where does BLV persist and how is it transmitted?

A

Persists in lymphocytes and is transmitted horizontally by blood transfer via insects or dehorning, rectal palpation ad vaccination

220
Q

What happens to most cattle that get infected with BLV?

A

They become asymptomatic carriers and ~30% develop a persistent lymphocytosis which may last for several eyars

221
Q

What is Marek’s disease?

A

Lymphoma of birds caused by avian herpes - occurs in young birds usually less than 16 weeks of age and is prevented by vaccinating one-day old birds

222
Q

What is Lymphoid Leukosis?

A

Occurs in older birds, usually greater than 22 weeks of age, and is caused by a retrovirus

223
Q

Where does Plasma Cell Myeloma tend to occur?

A

Most often in bones engaged in haematopoiesis, causing multiple osteolytic lesions especially in the vertebrae and ribs

224
Q

What is a fairly consist finding of Plasma cell neoplasia?

A

Hyperglobulinaemia, usually with a sharp, monoclonal spike observed in the gamme region of an electrophoretogram (“monoclonal gammopathy”)

225
Q

In terms of antibody production, what may occur from Plasma Cell Myeloma?

A

In some cases, production of excessive quantities of high molecular weight IgM and IgA causes serum hyperviscosity

226
Q

Why might a bleeding disorder arise from Plasma Cell Myeloma?

A

Secondary to high molecular antibodies as these proteins may interfere with platelet aggregation and the function of certain clotting factors

227
Q

A diagnosis of plasma cell myeloma can be made based on what criteria?

A
  1. Radiographic evidence of osteolytic lesions 2. Neoplastic plasma cells in bone marrow aspirates 3. Monoclonal gammopathy 4. Bence-Jones proteinuria
228
Q

What is cutaneous plasmacytoma?

A

Usually a well circumscribed tumour often seen on the digits or head, composed of a moderate to abundant number of fairly well differentiated plasma cells - good prognosis, treated via surgical exicision.

229
Q

What is the incidence of Myeloproliferative Disorders?

A

Myeoloproliferative diseases are fairly rare. When they occur it is most commonly in cats.

230
Q

What is lymphadenomegaly?

A

Enlargement of lymph nodes

231
Q

What might cause enlargement of lymph nodes?

A

May occur either due to neoplasia or inflammation

232
Q

What is necessary for a definitive diagnosis involving lymphadenomegaly?

A

By sampling the node, either by fine needle aspirate for cytology, or by biopsy for histology is usually necessary

233
Q

In terms of neoplasia, what can cause enlarged lymph nodes?

A

Primary (Lymphoma) or Secondary (Tumours metastatic to the lymph nodes) can cause enlarged lymph nodes

234
Q

What are the two instances of inflammation of lymph nodes?

A

Hyperplasia and lymphadenitis

235
Q

What might enlargement of lymph nodes due to inflammation be due to?

A

Increased numbers of any of the various cells of the inflammatory response (neutrophils, eosinophils etc.)

236
Q

What causes Lymphoid hyperplasia?

A

An antigenic response to disease outside the lymph node - either localised or less commonly systemic

237
Q

In response to antigen, what do lymph nodes do?

A

Lymphoid follicles enlarge and increase due to B-cell prolfieration, which produce plasma cells. T-cells in paracortical areas also increase.

238
Q

What is Lymphadenitis?

A

Refers to the situation where the lymph node itself is inflamed and often occurs due to subsequent infection of the node draining an infected site. Often painful on palpation

239
Q

If Eosinophils and Mast cells are present within an inflamed lymph node, what type of infection is likely the cause?

A

May indicate a parasitic infection

240
Q

If Macrophage cells are present within an inflamed lymph node, what type of infection is likely the cause?

A

May be present in chronic stages of many diseases, including TB

241
Q

What is Caseous Lymphadenitis?

A

A chronic, suppurative lymphadenitis caused by Corynebacterium pseudotuberculosis. Mainly affects sheep and goats.

242
Q

What is the pathogenesis of Caseous Lymphadenitis?

A

In sheep, bacteria enter through the skin wounds, the wound becomes infected, and the infection spreads to the regional lymph nodes.

243
Q

What are the gross lesions of caseous lymphadenitis?

A

Onion-like appearance on cross-section

244
Q

What is the usual route of infection for Tuberculosis?

A

Via inhalation of infected aerosol droplets leading to respiratory tract infection. GIT or cutaneous exposures occur but are less common.

245
Q

What are the general gross lesions caused by Tuberculosis in cattle?

A

The classic lesions are multiple pale caseous and often calcified nodules (granulomas or chronic granulomatous lymphadenitis)

246
Q

What are the gross lesions seen in deer and possums affected by TB?

A

Node lesions are often much more suppurative

247
Q

What might cause bloody splenomegaly?

A

Congestion, Hyperaemia or a combination of the two (acute septicaemias)

248
Q

What are examples of congestion that may cause bloody Splenomegaly

A

Barbiturates, GDV, Acute Haemolytic anaemia

249
Q

In terms of barbituates, what effects do these have on the spleen?

A

Cause congestion as they cause relaxation of smooth muscle in the splenic trabeculae and the sinusoids in the red pulp fill with blood

250
Q

What generally causes Splenomegaly?

A

Most commonly due to cellular proliferations (typically neoplasia) or increased phagocytosis

251
Q

What is the spleen frequently involved in when it comes to neoplasia type?

A

Lymphoma

252
Q

For an animal with lymphoma - describe their spleen

A

Uniformly enlarged and meaty due to diffuse infiltration with tumour cells - occasionally will present as multiple pale tan or cream-coloured nodules

253
Q

In cats, besides lymphoma, what can also cause splenic enlargement in terms of neoplasia?

A

Mastocytosis (Mast Cell Tumour)

254
Q

How can chronic haemolytic anaemia influence the spleen?

A

The red pulp macrophages often proliferate to phagocytose erythrocytes. Chronic phagocytosis of erythrocytes containing blood parasites also results in meaty splenomegaly.

255
Q

What are the main differentials for bloody splenic nodules?

A

Haematomas, neoplasia (hemangiosarcomas and hemangiomas) and nodular hyperplasia

256
Q

What is the spleen a predilection site for in dogs (with regards to neoplasia)?

A

Hemangiosarcomas and haemangiomas - these are tumours of vascular endothelial origin

257
Q

What dogs are hemangiosarcomas relatively common in?

A

Older dogs and large breeds, particularly German Shepherd Dogs and Golden retrievers

258
Q

What happens when a splenic hemangiosarcoma ruptures?

A

It bleeds into the peritoneal cavity and affected dogs may present ina state of collapse w/ tachycardia, very pale mucous membranes and abdominal distension due to haemoabdomen

259
Q

Why is the prognosis for Haemangiosarcomas poor?

A

It is poor as metastasis to the liver or other sites within the peritoneal cavity is common - Metastases are often visible within the abdomen as multiple dark, red, bloody nodules of varying size

260
Q

Where might haematomas develop?

A

In areas of nodular hyperplasia or neoplasia occur after trauma - often are multiple, large, dark red splenic masses

261
Q

What is the presence of splenic nodules that have a firmer consistency most commonly caused by?

A

Nodular hyperplasia or neoplasia (particularly lymphoma or histiocytic sarcoma)

262
Q

Describe the lesions seen by nodular hyperplasia

A

Nodules may be single or multiple, red to grey-white in colour and up to 3cm in diameter

263
Q

What effect does thymic lymphoma have on the thymus?

A

The thymus is usually massively enlarged by neoplastic lymphocytes and often displaces the trachea, heart and lungs dorsally

264
Q

How can you diagnose Thymic Lymphoma?

A

Can be achieved in the live animal by fine needle aspiration cytology of the mediastinal mass after detection via ultrasonography or radiography

265
Q

Describe the characteristics of a Thymoma

A

It is a primary neoplasm of the thymus and contains varying proportions of both thymic epithelial cells and small, non-neoplastic lymphocytes.

266
Q

How do you diagnose a Thymoma?

A

Fine needle aspirates of thymoma reveal a mix of small lymphocytes, thymic epithelial cells and variable numbers of mast cells, plasma cells and macrophage

267
Q

What are the 5 main events of Haemostasis?

A
  1. Transient Vasoconstriction 2. Platelet plug formation 3. Coagulation cascade 4. Clot Breakdown/Removal 5. Repair of the damaged vessel
268
Q

What is involved in transient vasoconstriction?

A

A local reflex which temporarily minimises blood loss and decreases the surface area of the defect

269
Q

What is involved in Platelet Plug Formation?

A

Endothelial injury which exposes collagen, and platelets stick to the collagen to become activated

270
Q

What is involved in the Coagulation Cascade?

A

A series of clotting factors are activated, resulting in the production of fibrin the stabilises the primary platelet plug

271
Q

What is primary haemostasis?

A

When tissue injury occurs, primary haemostasis is activated. The outcome of which is the formation of a platelet plug at the site of blood vessel injury

272
Q

What are the 3 main components of primary haemostasis?

A

Platelets, Von Willebrand’s Factor and the Blood Vessel Wall

273
Q

What happens immediately after tissue injury and why?

A

Vasoconstriction of the affected vessel occurs to minimise further blood loss and decrease the size of the defect that needs to be plugged and repaired

274
Q

How does Von Willebrand’s factor work?

A

When damage occurs, platelets adhere to the exposed subendothelial collagen. von Willebrand’s factor can aid platelet adhesion by forming a bridge between the platelet and the collagen

275
Q

After adhesion of platelets to collagen, what follows?

A

Platelets become activated and release their granules, which contain a number of proteins involved in coagulation and factors involved in wound healing

276
Q

How do the protein mediators released by platelets help with healing/coagulatyion?

A

They stimulate the platelet to change shape and aggregate, and form a dense plug

277
Q

In terms of a blood smear, why is it useful to look out for platelet clumps?

A

Clumps indicate the presence of enough platelets to provide adequate primary haemostasis

278
Q

What is involved in Buccal mucosal bleeding time tests?

A

A small incision using a surgicutt is made into the buccal mucosa and the time taken for bleeding to stop is measured

279
Q

What is the normal BMBT for a dog, and what can a longer time indicate?

A

Normal time is <4 mins, average being 2.5 minutes. Prolonged BMBT indicates thrombocytopenia, decreased platelet function, vessel wall defects or von Willebrand’s disease

280
Q

What are the 2 causes of artefactual thrombocytopenia?

A
  1. An Artefact of sample collection, preparation or analysis 2. Greyhounds and Shiba Inus have lower platelet counts than other breeds
281
Q

How might analysis of platelets be misinterpreted when using an analyser?

A

Traumatic venepuncture activates platelets, causing them to clump. Analysers may incorrectly count small clumps as a single platelet, so it is necessary to examine the feathered edge of a blood smear

282
Q

What are the 4 reasons behind true ithrombocytopenia?

A
  1. Decreased platelet production 2. Increased platelet consumption 3. Increased platelet destruction 4. Platelet sequestration
283
Q

What might cause increased platelet consumption?

A

Trauma, Surgery, Rodenticide Toxicity and Neoplasia as well as Disseminated Intravascular coagulation

284
Q

What might cause platelet sequestration?

A

Splenomegaly (due to congestion or neoplasia)

285
Q

What is a main cause of increased platelet destruction?

A

Immune mediated thrombocytopenia, where the immune system forms antibodies to target platelets. Platelets are phagocytosed by macrophage in the spleen, liver and bone marrow

286
Q

What can cause secondary immune-mediated thrombocytopenia?

A

Certain viruses (measles) and drugs (antihistamines, sulphonamides, barbiturates) may adsorb onto platelet surfaces and induce production of antiplatelet antibodies

287
Q

What is Von Willebrand’s Factor?

A

A large protein produced mainly by megakaryocytes and endothelial cells, which acts to glue platelets to exposed subendothelial content.

288
Q

When does Von Willebrands disease occur?

A

When there is a decrease in the amount or function of vWF

289
Q

Describe the clinical signs of Von willebrands disease

A

May be negligable or cause severe types of bleeding

290
Q

Where is vWF antigen measured, and how are the samples collected?

A

vWF antigen can be measured in plasma. Blood is collected into a blue top sodium citrate tube, and plasma is separated immediately and frozen

291
Q

What is the outcome of Secondary Haemostasis?

A

The formation of fibrin to stabilise the initial platelet plug produced in primary haemostasis

292
Q

What induces the intrinsic pathway of secondary haemostasis?

A

Induced by interaction of clotting factors with negatively charged subendothelial surfaces - one factor activates the next, until the common pathway is activated by Factor X

293
Q

What induces the extrinsic pathway of secondary haemostasis?

A

Activated when tissue factor III is released from damaged cells and interacts with factor VII. The tissue factor V-II complex activates factor X.

294
Q

Describe what Factor X gets up to, as apart of the common pathway

A

Factor X binds to Factor V, and the activated Factor V converts prothrombin to thrombin

295
Q

And what does that cheeky thrombin do, after being activated by that sneaky, yet subtley sexy Factor X (more like factor seX)?

A

Thrombin converts fibrinogen to insoluble fibrin, which acts like a cement to stabilise the platelet plug - and also amplifies the clotting process

296
Q

How do you test clotting times via secondary haemostasis?

A
  1. Prothrombin Time (PT) 2. Activated Partial Thromboplastin Time (APTT)
297
Q

What does Prothrombin Time measure?

A

PT measures the time required for fibrin clot formation in citrated plasma after the addition of factor VII activator

298
Q

If prothrombin time is prolonged, what does this indicate?

A

A defect in either extrinsic or common pathways

299
Q

What does Activated Partial Thromboplastin Time measure?

A

APTT measures the time required for fibrin clot formation in citrated plasma after addition of a factor XII activator

300
Q

What does prolonged Activated Partial Thromboplastin Time indicate?

A

A defect in either intrinsic or common pathways

301
Q

What does Thrombin time measure?

A

The time required for fibrin clot formation in citrated plasma after the addition of thrombin - provides a measure of fibrinogen concentration

302
Q

What do disorders of secondary haemostasis tend to present as?

A

Large haemorrhages into body cavities and organ involvement

303
Q

What is required for activation of clotting factors II, VIII, IX and X?

A

Vitamin K

304
Q

How can Caumarin, chemical used in rat bait poison, compromise secondary haemostasis?

A

It inactivates vitamin K, so coagulation cannot be activated

305
Q

After ingestion of coumarin, how long before it starts to cause issues?

A

It takes several days for active vitamin K and active factor II, VII, IX and X to run out. Bleeding usually occurs 3-7 days after exposure.

306
Q

What are the factors that increase rat bait toxicity effects?

A
  1. High fat diet increases toxin absorption 2. Drugs that inhibit haemostasis in other ways (i.e. NSAIDs) 3. Disease that decrease absorptionof vitamin K
307
Q

What is the most useful test to monitor vitamin K treatment?

A

Prothrombin Time (PT) - it is assessed 48h after suspected ingestion to determine if toxicity has occurred

308
Q

Define Disseminated Intavascular Coagulation

A

It is defined as a pathological of the coagulation system that leads to generalised intravascular clotting

309
Q

What does Disseminated Intavascular Coagulation result in?

A

Multiple thrombi forming in small vessels, leading to congestion, ischaemia and widespread tissue/capillary damage

310
Q

What does widespread tissue/capillary damage cause, secondary to DIC?

A

The release of more tissue factor from cells, activating clotting which sets up a cycle.

311
Q

What happens at the same time as coagulation during DIC?

A

Fibrinolysis is triggered, leading to the formation of plasmin and fibrin degradation products which are metabilised by the liver and can interefere w/ fibrin formation and platelet function

312
Q

What do dogs with acute DIC usually rpesent with?

A

Spontaneous bleeding, signs of anaemia and organ dysfunction due to microthrombosis

313
Q

What are some potential lab findings for DIC?

A
  1. Thrombocytopenia 2. Increased PT and APTT 3. Decreased Fibrinogen, with prolonged TT 4. Increased Fibrin degratation products 5. Schistocytes on blood smear
314
Q

What should you focus on in the blood smear?

A

The thin area of the smear (the monolayer), just before the feathered edge, where erythrocytes are not touching

315
Q

Why is it useful to look at the monolayer on a blood smear?

A

The erythrocytes and leukocytes are lying flat on the side and any morphological changes can be easily appreciated

316
Q

What should be noted about the feathered edge of the blood smear?

A

A scan of the feathered edge is important to check for the presence of large, abnormal cells in circulation which are more likely to be seen in this region

317
Q

What are the key focus points for each cell type to look out for in the blood smear?

A
  1. Platelet Number 2. WBC - Number, Proportion/Type 3. RBC - Number, Size, Shape, Colour
318
Q

What are some advantages of using cytology over histopathology?

A

Cytology is rapid, inexpensive, samples can be taken without anaesthesia and can evaluate the cellular component of effusions as well as solid tissue lesions

319
Q

What is the advantage to using histology over cytology?

A

Histology allows you to see architecture of the lesion and cytology is not ideal for assessing mesenchymal lesions like histology is

320
Q

Describe the requirements for a Fine Needle Aspirate

A

A 5-12mL syringe and a 22-25G needle long enough to reach the lesion

321
Q

Describe the first step of the Fine Needle Aspiration technique

A

After cleaning the overlying skin and clipping the hair, the mass is immobilised with one hand and the needle (attached to the syringe) is inserted into the mass

322
Q

Once the needle is inserted into the lesion during a Fine Needle Aspiration, what happens next?

A

The mass negative pressure is applied to the syringe while the needle is redirected, negative pressure is released and the needle is withdrawn.

323
Q

After releasing the negative pressure during a FNA, what happens next?

A

The needle is withdrawn, then detached and air is drawn into the syringe and the needle re-attached. The contents are then gently expressed onto a clean glass slide and smeared.

324
Q

Describe the non-aspiration technique of a Fine Needle Aspiration

A

The mass is imobilised with one hand and the needle alone (no syringe) is inserted to the mass then redirected several times. It’s then attached to an air filled syringe and the contents are put on the slide.

325
Q

Describe how to perform an impression smear

A

The sample is grasped with forceps and a freshly cut surface is touched several times on a clean paper towel, then several times on a slide, in a straight line

326
Q

Describe how you would perform a Scraping

A

When a cut surface of the lesion is blotted dry on a paper towel, then gently scraped with a new scalpel blade. Material is smeared by drawing the edge of the glass slide several times.

327
Q

Is oil and a coverslip required for Objective 4x?

A

No oil, No coverslip

328
Q

Is oil and a coverslip required for Objective 10x?

A

No oil, No coverslip

329
Q

Is oil and a coverslip required for Objective 40x?

A

Drop of oil is placed then coverslip - oil must not touch objective

330
Q

Is oil and a coverslip required for Objective 100x?

A

Remove coverslip - objective makes direct contact with oil

331
Q

Describe the CSI-TM approach

A
  1. Are there any useful cells present? 2. Is the staining adequate? 3. Inflammatory vs Non-inflammatory 4. What is the cell type present? 5. Is it Malignant or Benign?
332
Q

How will you check if there are any useful cells present?

A

Once the slide is stained and dried, scan the entire slide on lower power and look for non-haematogenous cells

333
Q

What are the contents of an adequately stained cytology smear?

A

Varying shades of pink and blues = if everything looks pink it is understained. There should be a clear differentiation between the cytoplasm and nucleus.

334
Q

What are the 3 types of neoplastic and hyperplastic lesions?

A
  1. Epithelial 2. Mesenchymal 3. Round cells
335
Q

Describe the distribution of Epithelial cells in cytology

A

They are cohesive and largely stick together so they are often seen in sheets or clsuters and occasionally arranged in acini.

336
Q

Describe the appearance of Epithelial cells in cytology

A

They are often very large with oval or round nuclei and abundant cytoplasm

337
Q

Describe the appearance of Mesenchymal cells

A

They are often described as spindle or fusiform cells, which typically have cytoplasmic tails extending in one or two directions - sometimes they can appear more plump with indistinct borders

338
Q

Describe the appearance of Round Cells

A

Generally small, circular cells with round or oval nuclei and distinct cytoplasmic borders

339
Q

What are the 6 types of round cells?

A
  1. Lymphocytes 2. Plasma Cells 3. Mast Cells 4. Histiocytes 5. TVT 6. Melanoma
340
Q

What are the advantages to doing an Ear Smear Examination?

A
  1. Allows more specific and appropriate treatment of the ear 2. Very inexpensive 3. Simple to examine
341
Q

What are possible structures seen in an Ear Smear Exam?

A
  1. Skin Cells (Squamous epithelial cells) 2. Yeast 3. Bacteria (cocci, rods) 4. Neutrophils
342
Q

How should Samples of body fluids be taken?

A

Aseptically with the site being clipped and surgically prepped. Aspirate sample using a sterile syringe and an 18-22G needle

343
Q

Following collection of a bodily fluid, what should be immediately done?

A

It should be placed in an EDTA tube, in order to prevent clot formation.

344
Q

When creating a smear using bodily fluids, how should this be done?

A

A small drop of fluid should be placed on the frosted end of the slide, and a smear made, with a similar technique to making a blood smear - 2-3 smears should be prepared as soon as possible after sample collection

345
Q

When assessing fluid, what should you take note of?

A
  1. Colour and turbidity before and after centrifuge 2. Total solid concentration with a refractometer 3. Cytological exam to estimate where there is low, moderate or high cellularity
346
Q

What are the 3 types of effusions?

A

Transudate, Modified Transudate and Exuate

347
Q

Describe the characteristics of a transudate

A

It is a fluid with low protein concentration and low nucleated cell counts. It is a non-inflammatory fluid.

348
Q

Describe the characteristics of a Modified Transudate

A

The fluid may initially be a transudate but becomes modified by the addition of protein or cells. A modified transudate as a moderate protein concentration and moderate number of cells.

349
Q

Describe the characteristics of Exudate

A

These fluids have high protein concentrations and high nucleated cell counts. They are turbid and white/yellow/pink in colour, and may clot on exposure to air due to high fibrinogen content.

350
Q

What are the two main groups of vacutainers?

A

Plain tubes that contain no anticoagulants, and Anticoagulated Tubes that contain various anticoagulants.

351
Q

What are red top vacutainers used for and are they anticoagulants?

A

No anticoagulant. Used for serum biochemistry and serum endocrine tests.

352
Q

What are purple top vacutainers used for and are they anticoagulants?

A

EDTA anticoagulant. Used for routine haematology.

353
Q

What are Grey top vacutainers used for and are they anticoagulants?

A

Potassium Oxalate/Sodium Fluoride anticoagulant. Used for glucose assessment.

354
Q

What are blue top vacutainers used for and are they anticoagulants?

A

Sodium citrate anticoagulant. Used for coagulation testing.

355
Q

What are green top vacutainers used for and are they anticoagulants?

A

Lithium heparin anticoagulant. Used for: Plasma and Haematology (interferes w/ WBC staining), Best for bird blood

356
Q

What is serum?

A

The noncellular portion of clotted blood

357
Q

What is plasma?

A

The non-cellular portion of unclotted blood

BVSc 2024 (1 decks)

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