Blood Sample Collection
Introduction
When collecting blood samples, fill tubes containing anticoagulant to the fill line and mix gently immediately after collection. Vacutainers can be used for large animal blood sample collection, and a needle and syringe for small animals. The jugular vein is the preferred collection site using a wide bore needle to prevent haemolysis of the blood from using excessive suction during collection. The cephalic and saphenous veins are alternative venipuncture sites. Ensure the venipuncture site is clean and swabbed, wear gloves and ensure you have adequate restraint prior to collecting a blood sample.
Always label your sample tubes with permanent marker immediately with the animal's details and the date and time of collection. Serum samples can be processed by allowing the blood to clot in an upright position and removing the serum from the tube prior to sending the sample for analysis to avoid haemolysis (bursting of the red blood cells into the serum) during transit. A more ideal method of serum separation is to centrifuge the sample -balance the centrifuge by adding a tube filled with the same volume of fluid in the opposite well in the centrifuge for safety.
The following table is a guide to the sample type required for some specific laboratory tests - seek guidance from your processing laboratory for confirmation of sample requirements, which can vary depending on the equipment used to analyse the sample.
| Test Required | Sample Required | Comments |
|---|---|---|
| Haematology | EDTA | Mix gently immediately after collection |
| Biochemistry | Serum | Centrifuge after permitting sufficient clotting time (min 2 hours) |
| Fibrinogen | Citrate | Mix gently immediately after collection |
| SAA | Serum | Needs to be processed quickly as the half life is very short |
| Electrolytes | Heparin | Mix gently immediately after collection |
| Glucose | Fluoride oxalate | Can use fresh whole blood if tested immediately |
| Insulin | Serum | Fasting sample required |
| Prothrombin clotting time | Citrate | A normal sample is required for comparison |
| Progesterone | Serum | |
| Oestrone Sulphate | Serum | |
| Testosterone | Serum | Request Testosterone before Inhibin for GCTs |
| IgG | Serum | Measurement techniques vary so check sample requirements |
| ACTH | EDTA plasma | Freeze plasma as soon after collection as poss (max 2 hours) |
| Selenium | Heparin/Serum | Send Heparin for deficiency testing, serum for toxicity testing. |
| Zinc | Serum | Avoid using tubes with a rubber bung |
| Drugs testing | Serum or Heparin | Send to HFL |
| Virus Titres e.g. EHV | Serum | Take 2 samples 14 days apart (freeze 1st) |
| Tapeworm ELISA | Serum | |
| Fractional Excretion test | Serum and urine | Collect both samples simultaneously if possible and do not permit
food or fluids until both are collected |