Page 588 - The Veterinary Laboratory and Field Manual 3rd Edition

Necropsy guidelines 525

Figure A2.12 Pluck, sheep, the trachea is on the Figure A2.13 Aorta, sheep. Haemoglobin imbibi-
left side of the picture (†). Hypostatic congestion. tion. The aorta has been opened longitudinally to
Note the left lung is diffusely dark red and right lung expose the endothelial surface which is discoloured
is diffusely pale pink. In this case it appears that the by feathered areas of pale red discolouration. This
body was placed on the left side after death and represents post-mortem haemoglobin imbibition
blood has pooled by gravity in the dependent lung. in which pigment has leached from vessels into
This should be differentiated from inflammation or adjacent tissue. In this case the pattern of imbibi-
congestion by gently palpating the lungs to detect a tion follows the vasa vasorum in the wall of the
change in texture which is a feature of a true lesion. aorta from which haemoglobin pigment has origi-
See also Plate 51. Photo: courtesy of Mr R. Irvine, nated. This should be differentiated from true
University of Glasgow, UK. haemorrhage. Note in this case the pale red colour,
feathered appearance following course of blood
tiated from true congestion or inflammation. vessels, and the bland appearance of affected tis-
Striking lateralization with one lung affected and sue which is unremarkable apart from the colour
the other unaffected, particularly if it is known change. See also Online figure 7. Photo courtesy of
on which side the animal has been placed after Mr R. Irvine, University of Glasgow, UK.
death is consistent with post-mortem change.
Hypostatic congestion will also not affect the haemorrhage. Haemoglobin imbibition occurs
texture of the lung whereas inflammation or around blood vessels and so will often have a
haemorrhage in the lung will result in increased dendritic or ramifying pattern or be homog-
firmness of the affected tissue. When occurring enous and bland with no other alterations in
in the skin or subcutis reddening often has a appearance of the tissue (Figure A2.13). True
very sharp, straight line of demarcation between haemorrhage appears as multiple pinpoint areas
affected and unaffected tissue which is highly of reddening (petechiae), larger splashing areas
unusual in genuine cutaneous congestion. of haemorrhage (ecchymoses) or as paint-brush
areas of reddening. Affected tissues may also be
swollen or distorted by accumulated blood.
Haemoglobin imbibition

Haemoglobin pigment will slowly diffuse from bile imbibition
blood vessels after death giving a pale red,
feathered appearance to tissues. This must be Bile pigment can leach from the gall bladder
differentiated from true petechial or ecchymotic or proximal duodenum resulting in orange or

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