Blood Smear Examination Quiz

Clinical Haematology 1 & Introduction to Task

• The session is part of a course called "AGEP 2; Animal Systems and Professional Life 2"
• The lecturer is Emi Barker, a veterinary specialist in small animal internal medicine
• She holds degrees in BSc (Hons), BVSc (Hons), PhD, PGCertTLHE, and DipECVIM-CA, and is a Fellow of the Royal College of Veterinary Surgeons (FRCVS)
• She is a recognised expert and European Veterinary Specialist
• The course material is available on the University of Bristol website
• Use the Turning Point mobile application to participate (session ID: EmiB)
• The website eClinPath (https://eclinpath.co.m) is an online textbook for veterinary clinical pathology.

Intended Learning Outcomes

• Understand the laboratory assessment of erythrocytes
• Recognize common red blood cell (RBC) abnormalities, including terminology and clinical significance.
• Be aware of auxiliary diagnostic tests used in assessing RBC abnormalities, such as those related to evaluating platelets and white blood cells.

Haematology

• Haematology is the scientific study of blood and the tissues that produce or form blood.
• The series of lectures/notes will focus primarily on canine and feline species, but other species will be noted where appropriate.

Red Blood Cell Production

• Erythropoiesis (RBC production) is typically within the bone marrow, particularly in the medullary cavity of larger bones.
• Erythropoietin (EPO) stimulates RBC production.
• The stages of production include pluripotent hematopoietic stem cells, proerythroblast, erythroblast, reticulocyte, and erythrocyte. This process takes 5-7 days.
• Mature erythrocytes circulate for 1-2 days, or 70 days, or 110 days, or 145 days depending on the species.

RBC Structure

• RBCs are biconcave disks; this increases surface area for oxygen diffusion.
• They are flexible for passing through small vessels.
• They contain haemoglobin, a metalloprotein that carries oxygen.
• Mammals have anucleate (no nucleus) RBCs.
• Senescent (aging) RBCs are removed by the spleen.

Sample Collection for Haematology

• EDTA tubes are commonly used for blood sample collection related to haematology.
• Other options include: citrate, Heparin, Oxalate fluoride, or Serum / clot.

Red Blood Cell Parameters

• Haemoglobin, haematocrit, red blood cells (RBCs), mean cell volume (MCV), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC), platelets, and white blood cell (WBC) parameters provide measurements and ranges.

Artefacts

• Clots, platelet clumps, macroplatelets, cell agglutination (RBC and leukocytes), nucleated RBCs, Heinz bodies, and lipemia can influence and skew results.

Evaluating RBC

• Packed cell volume (PCV) is the percentage of red cells in a blood sample.
• Manual technique, by centrifugation, is a method to determine PCV.
• Additional parameters that can be evaluated from a blood sample include haematocrit, RBC mass, and indices (RBC indices to provide further analyses).

Evaluating Platelets

• Platelet counts have a typical range for different species/animals.
• Macrothrombocytes may skew results and falsely appear low.

Evaluating White Blood Cells (WBCs)

• Various white blood cell types (band neutrophils, neutrophils, lymphocytes, monocytes, eosinophils, and basophils) are measured and have specific ranges.
• Macrothrombocytes (large platelets) may cause a falsely low platelet count during analyses.

Blood Smear Examination

• Stain the slide with a dye like modified Wright's then use oil immersion microscope.
• Begin examining from the feathered edge of the slide, and then move to the monolayer/battlements, and later to the lateral edge of the smear.
• Examination looks for platelet clumps, atypical cells, RBC morphology and for platelets estimation. Also, WBC count, morphology and 100-cell differential.

Normal RBC Parameters

• Normocytes and normochromic cells are considered normal cells.

Anisocytosis and Polychromasia

• Anisocytosis describes variation in cell size (macrocytosis/microcytosis).
• Polychromasia, the variability in cell color, is linked to immature RBC presence and indicates regeneration. This is seen in larger and bluer cells (polychromatophils).

Macrocytes and Microcytes

• Macrocytes and microcytes are abnormal RBC sizes, sometimes associated with regeneration or other conditions, like FeLV, familial macrocytosis, etc.

Nucleated Red Blood Cells (nRBCs) and Howell-Jolly Bodies

• nRBCs are red blood cells with nuclei, often associated with regeneration, lead poisoning, splenic disease, or bone marrow disease.
• Howell-Jolly bodies are nuclear remnants within RBCs and can also indicate regeneration.

Species Differences in Nucleated RBC

• Birds and reptiles, and horses, and donkeys and lagomorphs/rodents are normal species with nucleated RBCs.
• Sheep and cattle do not typically have nucleated RBCs.

Hypochromasia

• Hypochromasia indicates a lower than usual level of haemoglobin in RBCs.
• It commonly occurs in iron-deficiency anaemia, and some farm animals and copper deficiency is also a potential cause.
• It's often associated with poikilocytosis (abnormal RBC shapes) and microcytosis (small RBCs).

Schistocytes

• Schistocytes are fragmented RBCs, indicative of shear injury.
• Potential causes include vascular neoplasia, disseminated intravascular coagulopathy, and iron-deficiency anaemia.

Acanthocytes, Keratocytes, and Blister Cells

• Acanthocytes have irregular projections; they might be present in liver disease, lipid disorders, and shear injury.
• Keratocytes are abnormalities in RBC shape, and are linked to shear injury.
• Blister cells also indicate shear injury to RBCs.

Echinocytes

• Echinocytes (crenated RBCs) are common artefacts, but if present alongside other shear-related changes, they might indicate a true condition.

Spherocytes and Ghost Cells

• Spherocytes are small, round RBCs and often occur with certain anemias, such as immune hemolytic anemia.
• Ghost cells are empty RBCs.

Red Blood Cell Oxidative Injury

• Heinz bodies are inclusions in RBCs from oxidized hemoglobin and are present in some animal species, especially cats, horses and dogs.
• Oxidative injuries are sometimes caused by toxicity or disease.

Codocytes

• Codocytes (target cells) are a frequent, but non-specific, finding in blood smears.
• They are related to regenerative anemia or hypochromia (low hemoglobin).

Inclusion Bodies

• Inclusion bodies are small, abnormal structures within cells.

Infectious Agents

• Possible infectious agents: Anaplasma spp, Babesia spp., Dirofilaria spp., Ehrlichia spp. and Leishmania spp.

Task - Intended Learning Outcomes

• These intended learning outcomes focus on applying established knowledge, recognizing normal and abnormal haematology results, interpreting haematology data to understand likely causes, suggesting extra tests and applying basic principles to predict relevant findings.

Must Do Tasks

• Online Blackboard tasks
• Case studies, clinical haematology, will be examined and presented on Blackboard.
• Specific due dates and times to complete each section are included in these instructions.

Additional Information

• The course will have review sessions and other available support for further learning.
• Students can ask questions and provide feedback on padlet; specific queries can be sent to the instructor, by email.