pathology

test selection

strategic and cost effective

send multiple samples for quality control

BM cell selection controls

* EPO → erythropoeisis


* Thrombopoietin → platelets
* CSF → Granulocytes and macrophage

Regulations of erythropoiesis

Hypoxia → HIF-1 → EPO → erythropoiesis → RBC formation → normoxia → reduced EPO

Locations of erythropoiesis

liver and spleen

immature reserves in BM

Haemolysis

destruction of RBCs

Extravascular haemolysis

normal, occurs in macrophage

Steps of Extravascular haemolysis

1. phagocytosed
2. Globin → recycled a.a
3. Heme → release iron → bilirubin
4. Fe → trans on transferrin to BM → erythropoiesis
5. Bilirubin stored → haemosiderin or excreted in bile

Intravascular haemolysis

suggests disease, occurs in blood vessels

stages of intravascular haemolysis

1. lysed → Hb in blood
2. Globin dimers bind to Hpt
3. Hb-Hpt → liver
4. broken down → Fe and bilirubin
5. Excess Hb in plasma → kidney → haemoglobinuria

Packed cell volume (PCV)

percentage of blood composed of RBCs

indicates: anaemia or erythrocytosis

Haematocritt (HCT)

proportion of blood composed of RBCs

Complete Blood count (CBC)

evaluation of all cells in blood

Haemoglobin (Hb)

conc of Hb per L of whole blood

Indicates: O2 carrying capacity

RBC

no. of RBCs x10^12/L

WBC

no. WBCs x10^9/L

Mean cell volume (MCV)

ave size of RBC

Indicates: macrocytosis or microcytosis

Causes of macrocytosis

* IMHA
* reticulocytosis
* FeLV
* poodles

Causes of Microcytosis

* iron deficiency
* Liver Disease
* Akitas

Mean corpuscular haemoglobin (MCH)

amount of Hb per ave RBC

Mean corpuscular haemoglobin conc (MCHC)

conc Hb per L of RBCs

Indicates: Hypochromasia and Hyperchromasia

causes of Hypochromasia

* iron deficiency
* reticulocytosis

causes of Hyperchromasia

* haemolysis
* heinz bodies
* marked spherocytosis
* lipamias

Nucleated RBCs (nRBCs)

immature RBCs with nucleus

Platelets (PLT)

no. platelets x10^9/L

Reticulocytes

no. immature RBCs in circulation

Indicates: polychromatophil, blue dots

Causes: BM regen

Polychromatophils

large blue cells

causes: regenerative anaemia

Poikilocytosis

abnormal shaped RBCs

Cause: no specific

Acanthocytes

irregular projections- few

**causes**:

cats- hepatic lipidosis

dogs- haemangiosacroma, Fe deficiency

Echinocytes

multiple short, evenly spaced, uniform projections

**CAUSES:**

Common: crenation, EDTA, cats

Uncommon: renal dis, lymphoma, chemo, post-exercise in horses, rattlesnake bite

Schistocytes

fragmented RBCs

**CAUSES:**

Intravascular trauma- DIC-fibrin strands, neoplasia, non-laminar flow

Weak cells- Fe defciency

Keranocytes

Helmet/ blister cells

CAUSES: iron deficiency, DIC-fibrin strands, haemangiosarcoma

Spherocytes

small, dark staining, lack central pallor

Causes: partial phagocytosis by macro, IMHA

Eccentrocytes

Hb shifted to side, lack central pallor

CAUSES: oxi. damage, conjunc. with heinz bodies

Codoctes/ Leptocyte

excessive membrane folding, ring of pallor

Causes: inc. EDTA, var. disorders

Heinz bodies

clumps of denatured Hb, blebs on edge (blue with NMB)

CAUSES: oxi. damage, DM, hyperthyroidism, lymphoma

Howell-jolly bodies

small purple dots

CAUSES: retained nucli, regen anaemia, chronic steroid therapy, red. splenic function

Metarubicytes

nucleated RBC

CAUSES: regen. anaemia, non-func spleen, haemagiosacroma, lead toxicity, increased corticosteroids

siderocytes

Iron cytoplasmic inclusions

CAUSES: taranaki anaemia, lead toxicity

Rouleaux

linear stacking

CAUSES: inc. plasma p, hyperfibrinogenemia, hyperglobinaemia

Agglutination

irregular clumps

CAUSES: ag-Ab complexes → IMHA

Relative Erythrocytosis

red. plasma vol. due to dehydration and endotoxaemia

Physiological Erythrocytosis

transient increase in RBC mass

* splenic contraction, adrenaline mediated
* normal plasma p.

Absolute Erythrocytosis

increased RBC mass

Primary erythroctosis

* independant of EPO
* Myeloproliferative disease = clonal expansion
* Polycythaemia vera +/- leukocytosis, thrombocytosis

Secondary Erythrocytosis

* response to increased EPO
* Hypoxic vs Innapropriate

Pathogenesis of Anaemia

1. inc haemolysis
2. haemorrhage
3. dec. RBC production

Regenerative anaemia

BM response

* visible in peripheral blood \~3-5d
* red. RBC mass → hypoxia → inc HPO → BM make RBC

Pre-Regenerative Anaemia

not enough time to see response

*

Non-Regenerative Anaemia

expected BM response not seen

Characteristics of Regenerative anaemia

* polychromia
* anisocytosis
* basophillic stippling
* metarubicytes

Haemolysis

* RBC destruction > erythropoiesis
* TP normal
* larger regen response

Features of Extravascular haemolysis

\-macrophage, liver, spleen, BM

* +/- hyperbilirubinaemia
* bilirubinaemia
* abnormal morphology
* postive coombs test
* splenomegaly

Features of Intravascular haemolysis

\-within circulation

* haemoglobinuria
* haemoglobinaemia
* +/- hyperbilirubinaemia
* +/- bilirubinaemia
* abnormal morphology
* postive coombs test
* anaemia and inc MCHC

IMHA

immune mediated RBC destruction due to:

* inflammatory response
* cytokines
* tissue damage → hypoxia

Mecahnisms of IMHA

Ab-Ag interactions → complement fixation → intravascular +/- extravascular destruction

Forms of IMHA

Primary- autoimmune/ idiopathic

secondary- infectious agents, neoplasia, drugs

General signs of IMHA

* pale mm
* dyspnoea
* tachycardia
* heart murmur
* lethary

Specific signs of IMHA

* Haemoglobinaemia
* Hyperbilirubinaemia
* splenomegaly
* +/- Hepatomegaly
* +/- fever

Strong Regenerative response (features)

* anisocytosis
* polychromasia
* reticulocytes
* +/- nRBCs
* Spherocytes
* Agglutination
* +/- leuk, left shift neutrophilia, thrombocytopenia, pos coombs test

Lab features of IMHA

1. strong regen response
2. spherocytosis
3. agglutination
4. coombs test

Iron deficient anaemia

caused by chronic blood loss, suckling animals

* initially regen → non-regen if persistent
* microcytic +/- hypochromic

Haemolytic Sporidesmin toxicity

Acute haemolytic crisis, toxins cause liver injury → photodynamic dermatitis

* anaemia
* haemoglobinuria
* lcterus

Leptospirosis

CAUSE: L interrogans varpoma in Young calves >> lambs and weaner deers

* anaemia
* haemoglobinuria
* icterus

Chronic copper toxicity

**Cause:** cu accumulates → sudden release from liver → acute haemolysis

* acute crisis
* haemoglobinaemia
* haemoglobinuria
* icterus
* heinz bodies
* h. mortality \~ 2-3d
* Cu in serum, liver and kidney

Blood parasites

1. immune medataed extravascu
2. intravascular haemolysis

**blood smear for diagnosis**

Brassica Redwater

* heinz bodies
* haemoglobinuria
* icterus
* death

Bovine Post-Part. Haemoglobinuria

low sporadic deaths 4 weeks post calving

hypophosphataemia → red. RBC glycolysis → red. ATP → increased fragility

* anaemia
* haemoglobinaemia
* h.g-uria

\

Non-Regenerative Anaemia

1. pancytopenia
2. RBC line decreased

Chronic renal failure

* severity correlates with renal damage
* reduced EPO produced by kidney

Lead toxicity

inhibits ribosomal RNA breakdown and heme synthesis

* mild normochromic, normocytic
* non-regenertaive
* basophilic stippling
* large no. metarubricytes

Taranaki anaemia

associated with Mg deficiency

* poor condition and red. milk prod
* inc. nRBCs and siderocytes
* peris prussian blue staining

Inflammation mediated

* most common
* mild non-regen
* nomocytic/ normochromic
* chronic disease
* cytokine suppression of erythropoiesis

Granulopoiesis

* BM
* EMH inc. demand → spleen, liver, LN
* differentiation by cytokines

Bone marrow pools

1. dividing
2. maturation
3. storage

neutrophil features

* phagocytosis and destruction by lysosomal enzymes
* get smaller as they mature
* multilobed and segemented

Pools of neutrophils

1. Bone marrow
2. circulating / blood
3. tissues

Neutrophillia

1. physiological response
2. corticosteroid response
3. inflammation
4. Leukaemia

Physiological neutrophilia

* fight/flight response
* mild leukocytosis
* pseudoneutrophilia
* young animals
* transient \~30mins

Corticosteroid response

mature neutrophilia

* red. margination and migration therfore inc. in circulation
* inc. release from BM
* within \~8hrs, lasts 3d
* Magnitude: Dog>cat>horse/ox
* stress response

Inflammatory Neutrophilia

* increase demand
* released in BM
* left shift - can be marked

Neutropenia

1. increased use
2. reduced production
3. increased destruction
4. sequestration

Reduced production

\-granulocytic hyperplasia

**-stem cell damage:**

* infection
* toxicity
* myelophthisis
* congential

Sequestration

* pseudoneutropenia
* tranient
* CAUSES: anaphylaxis, endotoxaemia

Eosinophilia

1. hypersenstivity
2. parasitism
3. other- leukaemia, hypereosinophillic syndrome, idiopathic

Causes of Eosinopenia

* inc. corticosteroid levels
* acute inflammation

Lymphocytosis

1. Physiological
2. Chronic inflammation
3. Neoplasia (lymphoid leukaemia)
4. Other (BLV, addisons)

Lymphopenia

1. Corticosteroid induced
2. Acute viral infection
3. Dec. Lymphopoiesis
4. Loss, sequestration, LN blockage

Monocytosis

1. Inflammation
2. Corticosteroid excess

Stress Leukogram

cause: Inc. endo/exo corticosteroids

**Leukocyte changes:**

* mature neutrophilia
* lymphopenia
* Eosinopenia
* Monocytosis

Leukogram

* total WBC count

Blood smear

* essential
* low power
* 40x assessment
* no. and types

Disorders

1. **BLAD and CLAD** (62 integrin deficiency)
2. **Canine Cyclic Neutropenia** (stem cell defect)
3. **Canine Granulocytopathies** (weimers, irsish setter)
4. **Hereditary Neutropenia** (boarder collies)

Neoplasia classifications

1. Cell type
2. Cell maturity (acute v chronic)
3. Numbers (leukaemic, subleukaemic, aleukaemic)

Myeloproliferative neoplasia

* all non-lymphoid blood cells
* BM origin
* spleen and liver infiltrated
* anaemia, neutropenia, thrombocytopenia

Lymphoproliferative neoplasia

1. lymphoid leukaemia
2. plasma cell neoplasia
3. lymphoma

1. Lymphoid leukaemia

* BM origin
* cells in circulation → spreads to tissues
* acute or chronic

2. Plasma cell neoplasia

1. plasma cell myeloma
2. cutaneous plasmacytoma

Plasma cell myeloma

tumour of B-lymphocytes with poor prognosis

* hyperglobinaemia
* lytic bone lesions
* neoplastic plasma cells in BM
* Bence Jones protein in urine
* +/- hypercalcaemia
* myelopthisic- anaemia, leukopenia,thrombo
* hyper-viscosity syndrome

Cutaneous Plasmacytoma

* extramedullary plasmacytomas
* solitary skin mass with good prognosis

3. Lymphoma

* solid tissue form in LN
* Classified by distribution, architecture and cell type