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11.2 Normal Physiological Changes And Structural Variation

Abomasal mucosal reddening - this may be seen in animals that have recently eaten. It should not be misdiagnosed as gastritis unless accompanied by oedema, ulceration, fibrin or haemorrhage.

Abnormally shaped heart - goat hearts are very pointed compared to sheep and cattle.

Distended gall bladder - this often follows a period of not eating. The longer the period without food, the more watery the bile becomes.

Hepatic capsular fibrosis - large plaques of fibrous tissue on the surface of the liver not extending deeper than the capsule. These are thought to be resolved adhesions from a past bout of local peritonitis.

Endocardial fat - small foci of fat occur normally under the endocardium of the ventricles. They are quite shallow but may extend more deeply around the attachment of the moderator bands. It is more extensive in fatter animals. This is not myocardial scarring.

Enlarged mesenteric lymph nodes - the normally enlarged gut lymph nodes of young sheep and cattle may be mistaken for Johne's disease or as an indicator of parasitism.

Gastrointestinal mucus - thick mucus ranging in colour from white to yellow and brown may be loosely adherent to a normal looking underlying mucosa. It continues to be extruded normally from the mucous glands in the mucosa for up to an hour after death. This is not catarrhal inflammation.

Haemal nodes - haemal nodes are dark red, appearing similar to lymph nodes and only found in ruminants. They are lymphatic tissue with blood sinuses scattered in the peritoneal and thoracic cavities in the mediastinum and dorsal abdominal mesentery.

Melanosis - this is gray or black pigmentation of the meninges, brain parenchyma, kidney, adrenals, uterus, lungs, oesophagus, oral cavity, gastrointestinal mucosa, and intima of great vessels of the heart. It should not be confused with melanoma.

Omasal impaction - the omasum appears large and the contents are dry and compacted. This is a common finding in normal animals. It is rarely of diagnostic significance - a dry bible (omasum), however was regarded by some as key change in botulism.

Ossa cordis (heart bones) in cattle - two thin curved rings of bone may be present at the base of the aortic valve in the hearts of aged cattle. They are not abnormal ossification.

Pallor of the liver - this is a common finding in pregnant or lactating ruminants.

Pigmented lymph nodes - grey to black pigmentation of lymph nodes is a common incidental finding in older cattle, especially of the medulla of mesenteric lymph nodes. It is thought to be due to accumulation of lipofuscin.

Peyer's patches - these are large oval or linear, whitish raised plaque-like patches on the ileum and jejunum - they are aggregates of lymphoid follicles. They sometimes encompass the entire circumference.

Pleural fibrosis - large areas of pale connective tissue may appear on the dorsal surfaces of normal lungs.

Telangiectasis - also known as "plum pudding" liver, these are dark red, irregular but well circumscribed areas from pin-point to many centimetres in size, scattered throughout the liver. They are dilated, blood filled hepatic sinusiods and have no functional significance.

Tension lipidosis in the surface of the liver - Straight edged yellow patches extending from the liver surface into the parenchyma, associated with fatty change under adhesions or near mesenteric attachments. These are thought to be related to interference with local perfusion caused by localised pull on the liver capsule.

White body fat - the fat in sheep and goats is normally very white compared to cattle. The white fat in the coronary groove of the heart of sheep and goats is sometimes suspected to be abnormal by veterinarians more used to examining hearts of cattle.

Whitish plaques in oesophageal mucosa - this is a common finding in animals not eating for a while.