Haematology - Erythrocyte Morphology

RBCs

Normal Canine and |Feline Erythrocyte Morphology

• Anucleated

• Circular

• Biconcave in shape

• Pink with a small area of central pallor

• Size difference - Canine are slightly larger than feline

The most commonly seen morphological changes include:

• Crenation

• Schistocytes (resulting from Haemolysis)

• Anisocytosis

• Hypo and polychromasia

• Autoagglutination

• Rouleaux formation

• Intracellular inclusions - Howell-Jolly Bodies, Heinz bodies, Babesia

Crenation looks like .. 

Distorted, shrivelled and spikey appearance due to an osmotic shift causing it to shrivel 

Crenation - known as .. 

Echinocyte or Burr cells 

When does crenation occur? And what is it the result from?

• Occurs when there is a disruption in the cells ability to maintain its ionic state

• Commonly resulting from inappropriate blood sampling, handling, storage and testing techniques e.g. use of aged blood sample, EDTA tubes that have not been sufficiently filled

Why might crenation occur from EDTA tubes not being filled sufficiently enough?

Too much anticoagulant can cause the osmotic change and causes the liquid in the cells to be drawn out

What is a Schistocyte? 

A fragmented RBC that is a result of cell haemolysis (bursting of the cells) 

What does a Schistocyte look like?

The cell swells and eventually burst 

Which patients are Schistocytes seen?

Patients with immune mediated haemolytic anaemia (IMHA) - body starts to attack its own blood cells 

What is the cause of a Schistocyte?

Inappropriate blood sample, handling, storage and testing techniques

What do Platelets (thrombocytes) look like?

Round/spindle shaped fragments of cytoplasm with no nucleus

What is Anisocytosis?

Where a patient has either larger than or smaller than normal RBCs

What are the subsections of Anisocytosis? And what do they mean?

• Macrocytosis - Larger than normal RBCs

• Microcytosis - Smaller than normal RBCs

Common causes of Anisocytosis ..

• Regenerative anemia (In dogs)

• Immune-mediated haemolytic anemia (IMHA)