A good standard of welfare not only benefits the birds—results obtained from
well-cared for birds will be more biologically meaningful.
9.2.5Blood sampling
Blood samples can be collected from one of three veins—the right jugular vein
(the left jugular vein is small), the ulnar (wing) vein, and the medial metatarsal
vein (leg). The right jugular is a large vessel alongside the trachea. It is clearly visi-
ble beneath the skin after the overlying feathers have been parted (plucking is not
normally necessary). The feathers can be dampened with surgical spirit. A thumb
can be used to apply light pressure to the vein—this prevents it from moving and
causes the vein to swell slightly. Blood is withdrawn into a syringe. Use the small-
est gauge needle compatible with syringe size and blood volume (i.e. 25G for
small birds). Apply light pressure on cotton wool to the venepuncture site as the
needle is withdrawn. This prevents further blood loss and helps to prevent the for-
mation of hematoma. Carefully remove the cotton wool to avoid disrupting the
newly formed clot and ensure that bleeding has ceased. The ulnar vein can be seen
as it passes over the ventral side of the elbow. In this case, plucking some feathers
may improve visibility. Again, light pressure applied to the vein proximal to the
elbow causes the vein to swell slightly. With larger birds, a syringe can be used to
collect blood. With smaller birds (100 g) an alternative approach is to prick the
vein with a needle and to collect blood into micro-hematocrit capillary tubes as it
emerges onto the skin surface. Pressure applied to cotton wool again prevents
excessive bleeding and hematoma formation. The medial metatarsal vein is only
appropriate for large birds (1 kg). For further details see Morton et al. (1993).
Blood can be kept in one of three ways. If whole blood is required, for example,
for DNA extraction, clotting can be prevented by prior treatment of the syringe
or capillary tube, and the storage vessel, with an anti-coagulant such as heparin.
Similarly, if plasma is required, again an anti-coagulant should be used, and the
sample then needs to be centrifuged to precipitate the erythrocytes. Plasma can be
aspirated with a pipette and stored. Alternatively, the sample can be stored as
serum. In this case, no anti-coagulant is used, the sample is allowed to form a clot,
which will then contract. After a few hours, the sample is centrifuged and serum
can be aspirated and stored. The difference between plasma and serum is that the
latter does not contain fibrinogen, which can be an advantage in some procedures.
The volume of blood taken should be the minimum required. In the United
Kingdom the Home Office guidelines suggest that the maximum volume
removed in any 28-day period is 15% of total blood volume. The blood volume
of birds is approximately 7 ml per 100 g body weight. This equates to 1 ml of
blood per 28-day period for a 100 g bird. Ideally, a single sample should not
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