PM Change

Question 0

What is the definition of algor mortis?

Answer 0

Cooling of the body after death (time of death)

Question 1

What should happen as soon as possible when cadavers are submitted?

Answer 1

They should be refrigerated especially if they are ruminants or horses (large amounts of abdominal viscera). Freezing should be avoided as the formation of ice crystals damages the tissue and hampers histological interpretation.

Question 2

What is PM clotting of blood?

Answer 2

Blood coagulation in vessels- differentiate from ante mortem thrombi

Question 3

What is hypostatic congestion?

Answer 3

The effect of gravity- seen in lungs and kidneys

Question 4

What is Pseudomelanosis?

Answer 4

Green/black discolouration due to conversion of iron to iron sulphide by GI bacteria.

Question 5

What is biliary imbibition?

Answer 5

Pigment imbibed into any organs that are in contact with it e.g. GIT

Question 6

What is emphysema?

Answer 6

Invasion by gas producing bacteria.

Question 7

What is rigour mortis and how does it form?

Answer 7

Begins 2-4hrs after death, it is the rigidity of skeletal muscles.
There is a burst of metabolic activity as substrates are depleted on cessation of circulation= decrease in pH, oxygen and ATP.
Ca efflux from SR= shortening of mm fibres.
Head and neck affected first then the extremities.

Question 8

When should rigour mortis disappear and what can influence its onset?

Answer 8

As putrefaction begins (1-2days), should have completely disappeared after 72hrs.
Low glycogen= quick
high temp=faster onset
pH- higher in pyrexic animals so slower progression.

Question 9

What is autolysis?

Answer 9

Release of intracellular enzymes that results in self digestion of tissues. It results in changes in the cytoplasm and nucleus that resemble those seen in necrosis, but there is no associated inflammatory response (differentiate by this!)

Question 10

How does the rate of autolysis differ?

Answer 10

Mucosa of the stomach and intestine are very rapid whereas muscle and skin retain their structure for much longer. Bacterial involvement = rapid.

Question 11

How does putrefaction occur?

Answer 11

When dead tissue is invaded by anaerobic organisms such as Clostridia- the tissue turns green/brown due to haemoglobin breakdown and formation of hydrogen sulphide.

Question 12

What are agonal changes?

Answer 12

They occur around the time of death due to irreversible circulatory failure that leads to congestion in the vessels.

Question 13

What do agonal changes look like?

Answer 13

Exaggerated in the lung- hypostatic pooling of blood in dependant sites. The spleen is particularly susceptible to congestion after barbituate euthanasia- this also shows crystals in the endocardium.

Can also be regurgitation of GI contents being in the alveoli or airways- GI intussusception.

Question 14

What types of lesions can resemble neoplasia?

Answer 14

Nodular Hyperplasia- (inc. in number of cells), occurs when hyperplastic nodules of tissue develop in organs- multiple nodules of well-differentiated cells within a tissue.

Inflammatory lesions- can resemble neoplasia due in influx of inflammatory cells, combined fibrosis and reactive hyperplasia.

Question 15

How can neoplasia be both a significant and insignificant finding?

Answer 15

If it is as a result of age, and is in a location that has room for expansion e.g. abdominal cavity and on the spleen. If it is in the spinal chord, where there is no potential space for expansion then it will be significant.

Question 16

What are 3 examples of age-related changes?

Answer 16

Bones, joints an CT lose flexibility and become rigid.
Wear and tear to joints
Splenic siderofibrosis- yellow, dry encrustations on the capsule= local haemorrhage with subsequent deposits of Fe, Ca and fibrosis.

Question 17

What changes can be seen in the lungs?

Answer 17

Anthracosis- polluted areas= inhaled carbon particles are phagocytosed by alveolar macrophages which become visible as multiple black foci in the lung tissue. The medulla of the trachebronchial lymphnode may also be black.

Question 18

What changes can be seen in the vasculature?

Answer 18

Arteriosclerosis- common but incidental finding. Degeneration and proliferation in the arterial wall results in a loss of elasticity and hardening- obvious at branches of arteries.

Atherosclerosis- not common in animals except dogs with hyperthyroidism and hypercholesterolaemia- walls are thickened due to accumulation of cholesterol.

Question 19

What drug associated changes can be seen?

Answer 19

1) local reaction- jugular v can be purple and swollen
2) Barbituate crystals
3) Splenomegaly- engorged with blood

Question 20

What can steroids do that shows up PM?

Answer 20

Steroid-induced hepatopathy- glucocorticoids induce the enzyme glycogen synthetase leading to increased storage of glycogen within hepatocytes- often the midzonal areas are affected and 10x normal size.