Haematology 4

Question 1

PHYSIOLOGICAL RESPONSE

Answer 1

Mild mature neutrophilia, lymphocytosis +/- monocytosis.
Seen secondary to epinephrine (adrenaline) release.
Short lived (resolved after 30 minutes).
Seen in young animals (<1 year)

Question 2

STRESS RESPONSE

Answer 2

Stress leukogram.
Mild to marked mature neutrophilia (up to 2x more than upper reference), lymphopaenia (decreased lymphocytes), eosinopaenia (decreased eosinophils) +/- monocytosis.
Due to exogenous or endogenous corticosteroids.
Neutrophils from bone marrow storage pool and marginated pool move to circulating pool.
Lasts for ~24 hours, longer is steroid exposure is prolonged.

Question 3

INFLAMMATORY LEUKOGRAM

Answer 3

Mild to marked neutrophilia, lymphopaneia and monocytosis. 
Presence of LEFT SHIFT or TOXIC CHANGE. 
Magnitude of change depends on:
Duration
Severity of inflammation 
Nature of inflammation 
Species of animal

Question 4

LEFT SHIFT

Answer 4

If demand is high, immature leukocytes are released from the bone marrow.
Can be REGENERATIVE or DEGENERATIVE, or a LEUKAEMIOID REACTION.

Question 5

REGENERATIVE LEFT SHIFT

Answer 5

Neutrophilia with mainly mature neutrophils and some immature forms.

Question 6

DEGENERATIVE LEFT SHIFT

Answer 6

More immature than mature neutrophils are seen.

Neutrophil count may be normal, mildly raised, or reduced.

Question 7

LEUKAEMOID REACTION

Answer 7

Very HIGH neutrophil count seen, with left shift (immature forms released)

Question 8

TOXIC CHANGE

Answer 8

Seen in marked inflammation, especially bacterial infections and marked tissue necrosis.
Due to direct toxic effects on neutrophil progenitors and also due to immaturity of cells being released in to blood.

• Dohle bodies- dark, blue-grey inclusion bodies in neutrophils, though to be endoplasmic reticulum remnants.
• Increased cytoplasmic basophilia (RNA)
• Cytoplasmic vacuolation
• Toxic granulation
• Cell and nucleus swelling
• Giant neutrophils, ring forms (rare)

Question 9

SPECIES DIFFERENCES

Answer 9

Cats and dogs are capable of marked neutrophilias- more so than horses, which are more capable than ruminants.
cat/dog > horse > ruminant
-Ruminants typically see neutropaenia in the initial stages of inflammation.
-Horses may also see acute neutropaenia, ESPECIALLY in endotoxaemia- endotoxin stimulates margination of neutrophils.
-Peracute, severe, overwhelming inflammation can cause neutropaenias in cats and dogs- uncommon.

Question 10

NEUTROPHILIA

Answer 10

Increased number of circulating neutrophils.
Occurs with:
-Excitement- physiological (mild)
-Stress/corticosteroids (stress leukogram)
-Inflammation
-RARELY with granulocytic leukaemia.

Question 11

NEUTROPAENIA

Answer 11

DECREASED number of circulating neutrophils.
Cattle see transient neutropaenia with acute inflammation.
Other species:
-Severe overwhelming inflammation
-Toxic depression of bone marrow (eg. toxins/drugs, infectious agents, neoplasia or myelodysplastic syndromes)
-Immune mediated- rare, controversial.

These causes are clinically important- risk of infection.

Question 12

EOSINOPHILIA

Answer 12

Increased number of circulating eosinophils.
Occurs in response to IL-5 release from T cells and histamine release from Mast cells.
Seen most commonly in PARASITIC CONDITIONS and ALLERGY/HYPERSENSITIVITY.
-Paraneoplastic eosinophilia is uncommon- Mast cell disease, lymphoma, various other neoplasms (rare)

Question 13

EOSINOPAENIA

Answer 13

Decrease in circulating eosinophils.
Endogenous and exogenous steroids inhibit Mast cell granulation and neutralise histamine, thus decreasing IL-5 release and eosinophil release.
By itself, eosinopaenia is of little diagnostic significance.

Question 14

MONOCYTOSIS

Answer 14

Increase in circulating monocytes.

• Excitement/physiological- mild, mature.
• Stress/exogenous corticosteroids (dogs)
• Inflammation- marked
• Monocytic leukaemia- rare.

Question 15

MONOCYTOPAENIA

Answer 15

NOT RECOGNISED- reference interval is close to zero.

Question 16

LYMPHOCYTOSIS

Answer 16

Increase in circulating lymphocytes.

• Physiological (excitement)
• May occur in infectious disease during recovery, or in chronic disease.
• Post-vaccination finding in young animals.
• Lymphoid neoplasia.

Question 17

LYMPHOPAENIA

Answer 17

Deficiency in circulating lymphocytes.
Occurs in infections- VIRUSES, SEPTICAEMIA.
Stress- Endogenous or exogenous corticosteroids.
-Transient altered distribution of lymphocytes between blood and lymphoid tissue.

Question 18

NEOPLASIA OF THE HAEMATOPOIETIC SYSTEM

Answer 18

Haematopoietic neoplasia.

• Clonal proliferation of haematopoietic progenitor cells.
• Results from an accumulation of mutations.
• Sometimes specific agents are involved:
• RETROVIRUSES eg. FeLV, BLV, ALV
• HERPESVIRUSES eg. Marek’s disease, Burkitt’s lymphoma.

Tumour groups include- Leukaemia

• Plasma cell tumours
• Mast cell tumours
• Lymphoma
• Histiocytic disease

Question 19

LYMPHOMA

Answer 19

A SOLID tumour of lymphoid cells.

Can mestastasise, entering blood and then bone marrow.

Question 20

LYMPHOID LEUKAEMIA

Answer 20

Originates in bone marrow, then can pass to blood and tissues.
Cancer of the leukocytes; not a solid tumour.

Question 21

LYMPHOMA VS LEUKAEMIA

Answer 21

Can sometimes be difficult to differentiate between the two.

Question 22

CLASSIFICATION OF LEUKAEMIA

Answer 22

Can be classified by:
1. Degree of maturation of cells involved- acute or chronic. Mirrors clinical picture and progression of disease.

2. Presence or absence of neoplastic cells in the blood- if NO neoplastic cells are being released in to the blood, we have a SUBLEUKAEMIC leukaemia (aleukaemic).
3. Cell line involved- lymphoid or myeloid.

Question 23

LYMPHOID LEUKAEMIA

Answer 23

B cell or T cell abnormalities/increases.

Question 24

MYELOID LEUKAEMIA

Answer 24

From myeloid cell line:

• Erythroid
• Granulocytic
• Monocytic
• Megakaryocytic
• Mixed lineages can be seen.

Question 25

CONSEQUENCES OF LEUKAMIA

Answer 25

• MYELOPHTHISIS- replacement of bone marrow population with neoplastic vells.
• EMH- Extramedullary haematopoiesis.
• SPLENOMEGALY/HEPATOMEGALY
• HAEMODYNAMICS- if WBC count is very high, the blood is thicker, impairing blood flow through microvasculature.

Question 26

ACUTE LEUKAEMIA

Answer 26

• ACUTE UNDIFFERENTIATED LEUKAEMIA
• ACUTE LYMPHOBLASTIC LEUKAEMIA
• ACUTE MYELOID LEUKAEMIA

Can be seen at any age, but particularly seen in young animals.
Aggressive disease, present acutely; animal can be very sick.
Immature blast cells seen in circulation.
Most are thrombocytopaenic and anaemic, sometimes see pancytopaenia.

Question 27

CLINICAL SIGNS OF ACUTE LEUKAEMIA

Answer 27

• Lethargy, anorexia, weight loss
• Pyrexia, shifting limb lameness
• Bleeding from mouth/nose, melaena (black, tarry faeces indicating GI haemorrhage)
• Splenomegaly, hepatomegaly (cause pale mucous membranes)
• Mild generalised lymphadenopathy
• Petechiae, echymoses.

Question 28

CHRONIC LEUKAEMIA

Answer 28

• CHRONIC LYMPHOCYTIC LEUKAEMIA
• CHRONIC GRANULOCYTIC LEUKAEMIA
• POLYCTHAEMIA VERA
• ESSENTIAL THROMBOCYTHAEMIA
• Seen in older animals.
• Slower onset, progresses slowly.
• Can be asymptomatic.
• Neoplastic cells are well differentiated- they are mature in the circulation.
• Mild non regenerative anaemia may be seen, but generally other cell lines (RBCs) are unaffected.

Question 29

CLINICAL SIGNS OF CHRONIC LEUKAEMIA

Answer 29

May be none; the leukaemia could be an incidental finding on routine screening.

• Gradual weight loss
• Lethargy
• Mild splenomegaly/hepatomegaly.

Question 30

OTHER NEOPLASTIC CELLS IN THE CIRCULATION

Answer 30

Malignant histiocytes
Mast cells
etc. (see page 7, last slide)