41 Reflect the abdominal wall ventrally to expose the abdomen. This approach will help
avoid puncturing abdominal viscera. Cut the right diaphragm along its outer margin and observe if the lungs collapse. Failure
of the lungs to collapse indicates lung disease. Cut along the right side rib cage as far dorsally and ventrally as possible with rib cutters
to expose the thoracic viscera leaving first rib intact to serve as a hinge. The forward reflected rack of ribs will serve as a table to examine the heart and lungs if required.
If heat stroke is suspected, measure the temperature of the heart, liver and pelvic muscle mass at this point using a deep probe thermometer.
Reflect the tongue and larynx caudally to expose the oropharynx cutting the joints or bones of hyoid apparatus with rib cutters to free the larynx.
Major dissection is now completed. The next steps involve a systematic process of examination, description and sample collection.
Figure 6.2: Major dissection steps to expose body cavities and viscera
6.3.4 Second step — step back
• Place sampling equipment and containers, voice recorder and digital cameras within easy reach.
• Carefully overview the visible organs. In particular note any adhesions or displacements, the distribution and extent of any lesions and any abnormalities of size, shape, surface,
sound, smell, colour, contour, consistency and content. • Check the body cavities and pericardial sac for abnormal collection of fluids.
6.3.5 Third step — examining and sampling the abdomen
As a general guide, it is best to open hollow viscera after solid viscera have been sampled to avoid contamination.
• Palpate the duodenum, jejenum, ileum, caecum, colon and rectum along their length.
42 The ileum, caecum and colon can be fanned out over the abdomen and lumbar region
for closer systematic inspection. Reddening of intestines alone does not mean that enteritis or enterotoxaemia is present.
Simple postmortem change can cause this. Thickening of the intestinal wall, watery or bloody contents and enlarged, oedematous
draining lymph nodes will be present to some degree in enteritis. • Examine the omentum and mesenteries including mesenteric lymph nodes, hemisecting
at least three lymph nodes to examine cut surfaces. • Find and expose the pancreas embedded in the mesentery adjacent to the duodenum
and collect samples if required. • Cut the attachments of the small and large intestines to the carcass and remove,
thereby exposing the forestomachs, bladder and kidneys. • Check the diaphragm for adhesions before palpating the forestomachs rumen,
reticulum, omasum and abomasums, spleen, liver and duodenum before cutting their attachments to the carcass allowing these to be rolled together from the abdomen and
away from the carcass.
Make handholds of the oesophageal groove and stabs in the rumen wall to pull on. Using the orifice of the oesophageal groove as a handhold also serves to stop it leaking
fluid.
• Roll the forestomachs so that the spleen and liver are on top, out of the manure. • Inspect the reticulum and diaphragmatic surface of the liver for adhesions.
• Palpate and slice the spleen in situ. • Palpate the liver before dicing each lobe and examining cut surfaces. If required, collect
samples of liver for histology a sample from each lobe. • Incise the gall bladder to examine the mucosa and bile
• After the spleen, liver and gall bladder have been examined, layout the forestomachs for systematic examination and sampling.
• The lining and contents of rumen, reticulum, omasum and abomasum can be compared by incising along the ventral aspect of the abomasum and other forestomachs in one
continuous cut. Ventral mucosal surfaces are most likely to exhibit lesions and should be collected for
histological examination. Lifting of strips of the mucosa of the rumen and reticulum can look spectacular but is normal post mortem change and should not be mistaken for
rumenitis. Rumenitis is often only detectable microscopically.
Closely inspect the reticular contents for foreign bodies such as wire or poisons such as lead.
• Measure pH of rumen content with a test strip. Normal pH range is 5.5 -7. • Collect samples of the ventral walls of the rumen and reticulum if required.
• Cut the abomasum along its greater curvature through the pyloric valve into the
duodenum to expose the mucosa. • Examine the abomasal folds and duodenal mucosa collecting samples if required
43
6.3.6 Fourth step — examine the oral cavity and neck
