Page 574 - The Veterinary Laboratory and Field Manual 3rd Edition

Necropsy guidelines 511

glistening with very little material adherent Special techniques
to it.
• Mucosal associated lymphoid tissues (MALT) Removing the brain
is most abundant in the distal jejunum and
ileum and is also present in the more proxi- • Remove the head by disarticulating at the
mal small intestine, cecum, and colon. They atlanto-occipital joint.
appear as plaque-like or multinodular thick- • If available, it is strongly advised to secure
enings on the anti-mesenteric side of the the skull in a head vice. If not available have
intestine. an assistant stabilize the skull while the work
• Several important diseases in ruminants is completed.
including bovine viral diarrhoea virus/muco- • Make a full thickness incision in the skin
sal disease, malignant catarrhal fever and overlying the poll and frontal bone and skin
salmonellosis will cause prominent lesions the head to, and remove, the ears.
in MALT. It is therefore very important that • De-flesh the occipital and parietal bones by
when sampling for both histopathology and cutting away the masseter muscles bilaterally.
ancillary testing that these areas are identi- • Using a saw make two slightly divergent cuts
fied and sampled. in the occipital bone running craniolaterally
• In ruminants open the cecum and spiral colon just inside the occipital condyles (Figure A2.3).
and examine contents and mucosa. • Using the saw make a transverse cut across
• Identify mesenteric lymph nodes: incise and the frontal bone just caudal to the zygomatic
examine the cut surface. process of the frontal bone (Figure A2.4).
• Now make two sagittal cuts bilaterally
through the occipital, parietal, and frontal
Sampling bones joining up the cuts in the occipital
bone and frontal bones (Figure A2.4).
Formalin:

• Take 2–3 cm long sections of opened intes-
tine and colon directly into formalin. Do not
touch or brush the mucosal surface as this
will damage the delicate villous structures
and hinder histological examination.
• Take a cross section of lymph node includ-
ing the capsular surface, cortex, medulla and
hilus.

Fresh-frozen:

• Tie off 2–3 cm sections of jejunum, ileum, Figure A2.2 Bovine cerebral cortex. Note mul-
and spiral colon with string and excise. tifocal areas of slightly raised, red areas within
• Several mesenteric nodes should be saved meninges and extending into the cortical grey mat-
frozen. ter corresponding to areas of ischaemic infarction
as a result of bacterial vasculitis. See also Plate 45.
Photo: courtesy of C. MacGowan, University of
Calgary, Canada.

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