1.2 Post-mortem change

Question 1

What 3 changes can be identified in a cadaver?

Answer 1

• lesions
• agonal change
• post mortem change

Question 2

lesions:

Answer 2

changes that are due to disease

Question 3

agonal change:

Answer 3

changes that may occur prior to health

Question 4

post mortem change:

Answer 4

changes occurring​ after death and before the cadaver is examined

Question 5

What are major post mortem changes​ due to?

Answer 5

Autolysis and putrefaction

Question 6

Autolysis:

Answer 6

action of the intrinsic enzyme system of the dead animal’s cells that results in self digestion

Question 7

Putrefaction:

Answer 7

degradation of tissue by invasion and post-mortem activity of certain micro-organisms

Question 8

during a post-mortem examination ​an enlarged spleen can indicate?

Answer 8

overdose

Question 9

Rigor Mortis

Answer 9

The contraction of muscles occurring after death
- starts in the heart (blood pushed out of left ventricle)
- contraction reverses as carcase antolyses

Question 10

How soon does rigor mortis commence and last?

Answer 10

Commences: 1-6 hours after death
Lasts: 1-2 days

Question 11

When rigor Mortis sets in what is affected first?

Answer 11

Head and neck are affected first then extremities

Question 12

What can accelerate rigor?

Answer 12

High environmental temperature or activity before death

Question 13

What animals often have stronger rigor?

Answer 13

Muscular animals like grey hounds and race horses, emaciated animals have weaker rigor

Question 14

Normal muscle contraction:

Answer 14

• Calcium is sequestered in the sarcoplasmic reticulum
• An action potential results in calcium being released into the cytoplasm, binding to
  troponin on the actin myofibril, which exposes the binding site for myosin and results in
  contraction of the sarcomere
• ATP is required to sequester calcium back in the sarcoplasmic reticulum, resulting in
  relaxation

Question 15

Mechanism of rigor Mortis:

Answer 15

• Reduced ATP availability after death leads to a build up of calcium in the cytoplasm and consequent muscle contraction that persists as myosin binds to actin
• Subsequent muscle relaxation is due to enzymatic digestion of actin-myosin cross-links

Question 16

Algor mortis:

Answer 16

• Cooling of a carcase to the temperature of the environment
• Aids in estimating the time of death
• Important in detective stories
• Practical importance in meat production ( carcass quickly chilled after death)

Question 17

Warm and flaccid carcase

Answer 17

Dead less than 3 hours

Question 18

Warm and stiff carcass

Answer 18

Dead for 3-8 hours

Question 19

Cold and stiff carcass

Answer 19

Dead for 8-36 hours

Question 20

Cold and flaccid carcase

Answer 20

Dead for more than 36 hours

Question 21

How does blood separate post-morten?

Answer 21

• upper plasma lager: transtuant, looks like chicken fat
• lower red blood all layer: intense red, resembles jelly

Question 22

What is the difference in post mortem clotting and thrombus formation?

Answer 22

Past mortem: no internal damage, easily removed
Thrombus: firmly attached, white interior, layered

Question 23

Hypostatic congestion: Livor mortis

Answer 23

• Blood seeps to the dependent portions of
  the body post-mortem
• The process starts in an hour of death and stabilises in 12 to 24 hours
• May be apparent externally in animals with little hair cover (pigs)
• Best appreciated in the dependent lung and kidney during dissection

Question 24

If an animal dies while lying on it’s right side what side will the blood he pulled to?

Answer 24

Right side - best appreciated in the dependent lung and kidney during dissection

Question 25

Post Mortem imbibition of blood:

Answer 25

Within hours of death haemoglobin released by lysed erythrocytes stains blood vessel walls and adjacent tissues - foetuses which are dead for a few days prior to expulsion are usually diffusely red with imbibition - blood in right ventricle diffusely stains the endocardium - in cases where there has been a haemolytic crisis, staining of tissues occurs early after death

Question 26

Where is post mortemimbibition of blood best appreciated?

Answer 26

best appreciated on surface vessels of organs such as the intestine

Question 27

Probably the most common obscurer, of lesions in post-mottem exams

Answer 27

Post Morten imposition of blood

Question 28

What animals lack a gall bladder?

Answer 28

Horses and rabbits

Question 29

Post Morten imbibition of bile pigments:

Answer 29

- Starts within hours of death - Bile in the gall bladder penetrates the wall and stains adjacent tissue yellowish and then greenish brown - Staining involves the local liver, omentum and gastrointestinal tract

Question 30

Gaseous distension of the alimentary tract:

Answer 30

- bacterial fermentation producing gas in the alimentary tract continues after death - may be surface pallor of adjacent organs due to the pressure of this distension squeezing blood out of this adjacent tissue - abdominal viscera may be pale in comparison to thoracic viscera ** gas rises: distended loops may be pale and lower loops hypostatically congested (not to be confused with inflammation)

Question 31

What is antolysis caused by?

Answer 31

lysosomal and other enzymes liberated as cells die

Question 32

Antolysis characteristics:

Answer 32

particularly marked in the gut and associated glands such as the pancreas that are enzyme-rich • grossly tissue is uniformly paler and softer than normal • the cut surface may exude fluid or be greasy • cut surface tends to be greasy

Question 33

Will tissue that is antolysed have a host as the change is post mortem?

Answer 33

No host

Question 34

Putrefaction

Answer 34

-Most putrefactive bacteria are anaerobes and include Clostridium spp. that are numerous in the large intestine -proteins, fats and carbohydrates in the body substances are attacked by enzymes produced by these putrefactive bacteria, and are broken down peptides, amino acids and other compounds, including:

Question 35

Putrefaction: hydrogen sulphide causes

Answer 35

Foul smell

Question 36

Putrefaction: ferrous sulphide causes:

Answer 36

Green or black discoloration (pseudomelanosis)

Question 37

Benefits of post mortem examination:

Answer 37

- Confirms or refutes the clinical diagnosis, thereby improving differential diagnosis - Provides a diagnosis where no clinical diagnosis was possible e. g. in cases of sudden or apparent sudden death - In failure of treatment, it provides a reason why it may have failed - Aids diagnosis of group or herd problems - Records findings for further use e. g. disease surveys in various populations, legal actions, etc.. - Provides material for further examination e. g. histopathology, bacteriology, virology, toxicology

Question 38

When not to do a post mortem examination?

Answer 38

Personal safety is paramount In some cases of zoonotic disease (e.g. anthrax or rabies) post mortem examination is hazardous, especially if performed without appropriate personal protective equipment (PPE) in field conditions