Page 359 - The Veterinary Laboratory and Field Manual 3rd Edition

328 Susan C. Cork, Willy Schauwers and Roy Halliwell

Table 7.1 continued

Tests/indications Specimens Container* Stability and comments**
Electrolytes (Na, K, Cl), 5–7 ml clotted Dry glass container,
may alter in metabolic blood or 5 ml with i.e. red topped
and other physiological anti-coagulant vacutainer or Lithium
disorders (serum or plasma) heparin (green
topped)
Glucose 3 ml blood in Dry glass container Also use for samples collected for
grey-topped tube glucose tolerance studies
(calcium oxalate)
Calcium/low in milk 1–2 ml clotted Use dry glass Stable in blood at room
fever (see section 7.7) blood/serum (not container, acid washed temperature or 4°C for 3 h/stable
plasma) glass, well rinsed in serum for up to 72 h

Notes: *Plastic syringes may be used to collect samples but some types of plastic storage containers may contaminate the
samples. Check with the supplier. **For referral, try to send at least 1 ml of serum in a chilled container to reach the specialist
facility within 24 h. Make sure that the serum samples are correctly labelled and, where appropriate, send a case history with
the submission form. It is important to add the collection date. Referral laboratories may batch samples together for some tests.
Information collated from various sources.

Sample collection haemolysis during sample collection (see also
Chapter 5).
Serum versus plasma

The required sample for most biochemical tests Transport and processing
performed on blood is serum or heparinized If there is to be a delay in processing samples the
plasma. As mentioned before, submitting animal serum (or plasma) should be separated from the
health professionals should check what type of red blood cells as soon as possible after collec-
samples the laboratory recommends before col- tion. This will reduce the risk of haemolysis and
lecting the sample. deterioration of the sample, especially if samples
Definitions: Serum is the fluid that separates are going to be transported for long distances
from clotted whole blood (or from blood plasma) in the heat. The samples will keep best when
that is allowed to stand. Plasma is serum plus stored in glass containers in a cool place. If pos-
the proteins associated with clotting. Plasma is sible, it is good to set up a ‘cold chain’ especially
required for tests used to determine clotting times. if many samples need to be collected (that is,
Make sure that the animal(s) to be sampled for disease surveillance, health monitoring and
are appropriately restrained. This is to avoid trace element survey work). For small numbers
injury to the animal and to the handlers but of samples a cool box will be adequate as long
will also ensure a better-quality sample. Animal as fresh cold packs are available when needed.
health staff and technicians should gain expe-
rience in the best method of blood sample
collection from the species commonly kept in Storage and preservation
their region. When collecting blood, it is gener- In many cases serum samples will also be used
ally preferable to use the widest gauge needle for concurrent serological tests or will be stored
suitable for the size of the blood vessel to be in a serum bank for future reference. Samples
sampled because this will reduce the risk of that need to be kept for more than 2–3 days

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