Haematology
For red and white cell counts, haemoglobin estimation and derived parameters, collect blood in EDTA (purple top) tubes.
EDTA blood may not be suitable for differential white cell count and morphology if blood films are not made within 1 hour of blood collection.
Blood films
Fresh blood films should be made from EDTA blood immediately after collection. They should then be air dried.
Leucocytes degenerate when blood stands for a few hours.
Use dry slides, free of dirt and grease. Avoid contamination when preparing blood films.
Preparation of blood films
- Use a glass slide as the spreader The spreading edge must be smooth (i.e. no chips out of it) and clean. Spreaders can be re-used if cleaned and dried after each use.
- Place a small drop of blood (thoroughly but gently mixed) in the centre of the slide about 1 cm from the end. Grasp the spreader with thumb and middle finger using the index finger to put light pressure on the spreader.
- Place the spreader beyond the drop and at 45° to the slide. Draw it back until it touches the drop and the blood spreads evenly across the slide almost to the edges.
- Quickly and smoothly push the spreader right to the end of the slide at the 45° angle.
- Wave the slide quickly in the air to dry it. Label at the thick end with the owner's name and animal ID (if necessary) using a lead pencil.
Storage and Despatch of Specimens
Blood should be kept chilled, not frozen, whilst being held prior to despatch and during transport to the laboratory. Blood should be submitted to the laboratory chilled in insulated containers. Avoid contact between the blood sample and icebricks.
NB.
Do not chill blood films or expose them to formalin vapour.
Blood films can be submitted in the same container as chilled specimens, provided the blood films are securely packed and well wrapped for insulation against chilling.