Veterinary Hematology- An introduction

Gittan Gröndahl, DVM, PhD

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B lo o d V o lum e in A n im a ls in % o f B o d y W e ig h t

5,4

5,6

6,5

6,5

6,5

6,5

6,7

6,7

7

7,2

7,3

8,2

8,5

8,8

10,5

10,5

0 2 4 6 8 10 12

Rabbit

P ig

C attle – cow

Goat

Horse – co ldblood

Sheep

Rat

M onkey

C at

Guinea pig

C attle – o lder calf

Hamster

M ouse

Dog

C attle – young calf

Horse – w armblood

What Is Blood, and How Much Blood Is There?

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2 3

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Red Blood Cells – The Oxygen Carriers

Hemoglobin

Erythropoeisis:rubriblast – prorubricyte – basophilic rubricyte – polychromic rubricyte – normochromic rubricyte – metarubricyte – reticulocyte – mature erythrocyte

100 h100 h

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Red Blood Cells – The Oxygen Carriers

Erythropoeitin (EPO)

Hypoxia

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Red Blood Cells – Measurements

Hematocrit / PCV

RBC

Hemoglobin

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Red Blood Cells – Physiological Alterations

HGBRBCHCT

growing animals...

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Red Blood Cells – Physiological Alterations

HGBRBCHCT

exercise, fear, stress...

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Red Blood Cells – Physiological Alterations

HGBRBCHCT

dehydration, shock, high altitude, chronic lung disease, anabolic steroids...

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Red Blood Cells – Physiological Alterations

HGBRBCHCT

anaemia, anaesthesia, sedation, late pregnancy...

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Red Blood Cells – Artefactual Alterations

HCT

hemolysis, too little blood,

extended storage in EDTA...

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Red Blood Cells – Regenerative Signs

Reticulocytes

If HCT <30% (dog) or <20% (cat) count reticulocytes

Not normally seen in horses, cattle, sheep, goats

0-5% in cats

2-4% in rat, mouse, guinea pig, rabbit

0-2% in dogs and swine

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Red Blood Cells – Regenerative Signs

Not even seen in regenerative anemia

in horses

Instead, macrocytes are released

RDW MCV

Reticulocytes –never in horses!

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Red Blood Cells – Regenerative Signs

Nucleated RBC

Polychromasia variable coloration

Anisocytosis greater variation in cell size, RDW

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Red Blood Cells – Regenerative Signs

Howell-Jolly bodies nuclear remnants

Basophilic punctuation

Macrocytosislarge cells, MCV

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So – What Is This?

African Gray Parrot RBC

Llama RBC

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Red Blood Cells – Number and size in mammals

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Red Blood Cells – Mean Cell Volume (MCV)

Macrocytosis - MCV Often in regenerative anemia

Microcytosis - MCV Often sign of iron deficiency,

such as chronic blood loss

Used in classification of anemias:

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Red Blood Cells – MCHC, Mean Cell HGB Concentration

(Hyperchromic - MCHC )Artefact!

Hypochromic - MCHC In acute and chronic blood loss,

hemolytic anemia or iron deficiency

Normochromic - MCHC normal

Used in classification of anemias:

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Blood Groups in Animals

All animals species have their specific blood group system.

Cross-matching!

1. Blood transfusions

2. Incompatibility between dam and offspring

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Anemia – Too Low Oxygen Carriage Capacity

Signs of anemia:

Pale in eye and mouthVigor and strength

Appetite Heart rate

Respiratory rate Laboured breath

Blood, bleedings, hematomas

Icterus

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1. Blood loss (regenerative anemia)

Coagulopathies

Gastrointestinal hemorrhage

Platelet disorders

Splenic rupture

Trauma/surgery

Anemia – General Causes

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Anemia – General Causes

2. Blood destruction / hemolysis (regenerative

anemia)

Fragmentation

Immune-mediated disease

Infections

Intrinsic RBC defects

Toxicities

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Anemia – General Causes

3. Decreased / ineffective production of RBC

(non-regenerative anemia)

Anemia of inflammatory disease

Aplastic or hypoplastic anemias

Metabolic or endocrine disease

Neoplastic disease

Nutritional deficiency anemias (e.g., iron, copper, folate, cobalt)

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Platelets – The Sealers and Healers

First line of defense in damage to vessels

cow

cat

Important in inflammation and wound healing

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Platelets – Thrombocytopenia – PLT

Production Destruction

Consumption

Caused by:

Signs, if PLT <20-50 x 109/L:

HematomasBleedings

dog

horse

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Platelets – Thrombocytopenia – PLT

Certain medications

(antibiotics, NSAID,

hormones)

Some infections (FIV, FeLV,

BVDV, EIA, Ehrlichia etc)

Hemolytic anemia

DIC – Disseminated

intravascular coagulation

Vaccination

Malignant cells

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Platelets – Thrombocytopenia – PLT

Platelet aggregates

False Low PLT Caused by:

Platelets and fibrin clumps

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Platelets – Thrombocytosis – PLT

Surgery or trauma

Chronic bleedingsAcute/chronic infections or inflammatory

conditions

Cushing’s disease

Corticosteroid therapy

Myeloproliferative

disorders

Caused by:

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White Blood Cells – The defence troops

Defence

Cleaning up

Inflammatory reactions

Signalling system:

Cytokines

Receptors

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White Blood Cells – The defence troops

First line of defence

Phagocytosis

Toxic proteinsParasites

Allergic reactions

Allergic reactionsHistamin,

heparin

InterplayPhagocytosis

AntibodiesCell destruction

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White Blood Cells – Physiological Alterations

breed,

sex...

WBC/

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White Blood Cells – Physiological Alterations

exercise, stress,

excitation...

young animals.

..

late pregnancy, feeding...

WBC

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White Blood Cells – Artefactual Alterations

WBC

extended storage...

Cells from very sick Cells from very sick animals animals

are the most sensitiveare the most sensitive

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Granulocytes – Neutrophils

White, small pink granules

White/pink, no granules,

”knobby” nuclei

White, small stronger pink granules

White, no granules

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Granulocytes – Band Neutrophils

Regenerative left shift

Neutrophilia with >1,0 x 109/L of Bands for dogs and cats

>0,3 x 109/ L of Bands for horses and cattle

Bands = Left Shift

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Granulocytes – Band Neutrophils

Degenerative left shift

Normal or Low WBC count with significant left shift

or Band neutrophils ~ Segmented neutrophils

(with any WBC count)

Bands = Left Shift

Poor

Prognosis!

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Granulocytes – Toxic Neutrophils

Segmented, normal

Segmented with toxic change

Band, normalBand with toxic change

Basophilic discoloration, foaming, Döhle bodies, toxic granules

Guarded

Prognosis!

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Granulocytes – Eosinophils

Very large globular orange

granules

Small rod-shaped orange granules

Many small round orange granules

Marked variation within and between

individual dogs

Gray, no granules, vacuoles

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Granulocytes – Basophils

Small deep purple granules.

Low numbers.

Small oval granules, pale lavender. Rare.

No granules, ribbon-like nucleus,

gray-lavender. Rare.

Small deep purple granules. Low numbers.

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Lymphocytes

Slightly larger

Small, dense chromatin

Small, dense chromatin

Quite variable

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Lymphocytes -Reactive and Granular

Larger, coarse chromatin, deep blue cytoplasm

Associated with immune response

Small pink granules

Reactive lymphocytes

Granular lymphocytes

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Monocytes

Extremely variable in appearance in all animals

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Avian Hemogram

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Dogs’ Hemogram

Stress (cortico-steroids)

WBC

Neutro

No left shift

Lymph

Eos

Mono

Excitement (adrenaline = epinephrine)

Not so much change

All cells ()

Inflammation

WBC

Left shift if >1 x 109/L bands

Neutro (10-30)

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Cats’ Hemogram

Stress (cortico-steroids)

WBC

Neutro

No left shift

Lymph N/

Eos

Excitement (adrenaline = epinephrine)

Common reaction

Lymph

Inflammation

WBC (25-40)

Left shift if >1 x 109/L bands

Neutro

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Horses’ Hemogram

Stress (cortico-steroids)

WBC (-20)

Neutro

No left shift

Lymph N/

Excitement (adrenaline = epinephrine)

Common reaction

WBC (12-15)

No left shift

Lymph (6-14)

Inflammation

WBC

Left shift if >0.3 x109/L bands

Neutro (10-20)

Severe infections:WBC ; Neutro ; degenerative left shift; toxic changes

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Cattles’ Hemogram

Stress (cortico-steroids)

WBC N/No left shift

Lymph Eos

Excitement (adrenaline = epinephrine)WBC (15-27)No left shiftLymph N

Inflammation

Acute:

WBC N/Marked left shift

(>0.3 x109/L bands)

Chronic:

WBC (20)

Neutro Left shift

Normally: Lymph# > Neutro#

so WBC DIFF is more important than WBC#!

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WBC- General Interpretation

•pathological conditions

•duration

•prognosis

Repeated analyses ->

Best for assessment of

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WBC- General Interpretation

•neutrophils

•mild left shift

•persistent eosinophils

Mild infection that the body can handle well

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WBC- General Interpretation

•neutrophils

•mild left shift

•lymphocytes

•eosinopenia

Moderate or severe infection

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WBC- General Interpretation

•immature neutrophils

•segmented neutrophils

Grave condition

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WBC- General Interpretation

•neutrophils

•no immature neutrophils

•lymphocytes

•eosinophils

Stress (e.g., severe disease, pain) or steroid influence

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WBC- General Interpretation

•monocytes

Chronic disease

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WBC- General Interpretation

•degenerative left shift

•falling lymphocyte numbers

•persistent lymphopenia

•persistent absence of eosinophils

Each of these signs = Unfavourable prognosis

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WBC- General Interpretation

•falling WBC count together with increase in lymphocyte and eosinophil

counts

•decreasing numbers of immature neutrophils

Each of these signs = Good prognostic signs,

convalescence

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Interpretation – Medonic histogram (dog)

Platelets/Thrombocytes (PLT)

Platelets and Red blood cells / Erythrocytes (RBC)

White blood cells/Leukocytes (WBC) divided into 3 populations – LYM, MID and GRAN

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Interpretation – Medonic histogram (cat)

Platelets/Thrombocytes (PLT) – typical for cat: low, flat curve with poor distinction from red cells = FD-flagPlatelets and Red blood cells/Erythrocytes (RBC)

White blood cells / Leukocytes (WBC) divided into 3 populations – LYM, MID and GRAN

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Interpretation – Medonic histogram (horse)

Platelets/Thrombocytes (PLT) – typical for horse: low, flat curve, relatively few platelets

Platelets and Red blood cells / Erythrocytes (RBC)

White blood cells / Leukocytes (WBC) divided into 3 populations – LYM, MID and GRAN

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Interpretation – Numerical values

Platelet parametersPlatelet count (PLT)

Mean platelet volume (MPV)

Plateletcrit (PCT)

Platelet distribution width (PDW)

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Interpretation – Numerical values

Red blood cell parametersHemoglobin (HGB)

Hematocrit (HCT = RBC x MCV)

Red blood cell count (RBC)

Mean red cell volume (MCV)

Mean cell hemoglobin concentration (MCHC = HGB/HCT)

Red cell distribution width (RDW)

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Interpretation – Numerical values

White blood cell parametersWhite blood cells count (WBC)

Lymphocytes (LYM, LYM%)

Granulocytes (GRAN, GRAN%)

Mid cells (MID, MID%)

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Why review a blood smear?

To identify among the white blood cells for example….Immature cellsToxic changesMonocytosisEosinophiliaBasophiliaMast cellsLeukemia (blast cells)

To identify among the red blood cells for example….AutoagglutinationEccentrocytesEchinocytesSpherocytesHeinz bodiesNucleated red blood cellsBlood parasites in or on erythrocytesParasites in plasma, e.g. microfilaria

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When should one review a blood smear?

If you routinely make a blood smear it will always be available ……

Blood samples that look very abnormal If WBC is lower or higher than normal,

especially if over 30x109/L If the absolute count of lymphocytes (LYM)

or mid cells (MID) is above normal If any parameter is outside normal range

together with an instrument flag Blood samples with signs of anemia