Post-Mortem Changes

1.      Algor mortis:

•      Algor mortis refers to the cooling down of the body after death.

•      The rate of heat dissipation from the body is 3̊C in 1^st hour and subsequently 1̊C per hour upto reaching the ambient temperature.

•      Cooling down of the body is due to absence of blood supply.

•      It is affected by the temperature prior to death, size of body, dehydration, obesity, body position, hair coat, humidity, wind, cover and water immersion.

2. Hypostatic congestion:

•      It is deposition of blood in the dependent portions of the body after death due to the gravitational force.

•      Livor mortis is the hypostatic congestion in the subcutaneous tissue.

•      It usually appears 30 minutes to 2 hours after death.

3. rigor-mortis

4. Post-mortem clot:

•      It appers 25-30 minutes after death within the heart and large blood vessel, e.g., aorta.

•      It is shiny, gelatinous, rubbery, dark-red in colour and not attached to the endothelium.

5. Post-mortem autolysis:

It is the destruction of cells of tissue through the action of their own lysosomal enzymes (mainly cathepsine) after the death.

Four Indications of post-mortem autolysis:

1.      Imbibition of blood: Release and spread of haemoglobin to the tissue surrounding the blood vessels and reddening.

2.      Imbibition of bile: Release and spread of bile to liver and the tissue surrounding the gall bladder give them greenish yellow in colour.

3.      Pseudomelanosis: Dark green or blackish discolouration of abdominal viscera after death by blood pigments.

After death, iron (Fe) frees from haemoglobin that is released from RBCs due to autolysis.

Hydrogen sulfide gas (H₂S) is produced after the invasion of saprophytic bacteria in dead tissue.

Fe+H₂S→FeS (Ferrous sulfide, dark green/blackish in colour)

Within the dead tissue, iron reacts with hydrogen sulfide gas to form ferrous sulfide that gives the tissue the blackish colour, the false impression of melanin deposition.

The condition is first discovered in the colon of horse (pseudomelanosis coli).

       4. Desquamation of the digestive epithelia: The epithelial layer of the digestive tract is desquamated due to cellular destruction.

Post mortem autolysis is observed in adrenal medulla, epithelium of gall bladder, digestive epithelium, nervous tissue, connective, other tissue/ organs and lastly the enamel sequentially.

6. Post-mortem tympanites:

•      Accumulation of excessive gas produced by the airborne saprophytic bacteria in gastrointestinal tract especially in the rumen after the death of animal is known as post-mortem tympanites.

7. Post-mortem emphysema:

•      Accumulation of excessive gas produced by the airborne saprophytic bacteria in the tissue especially in the lungs after the death of animal is known as post-mortem emphysema.

8. Post-mortem displacement:

•      Displacement of internal organs especially the digestive organs after death is known as post-mortem displacement.

•      This may occur due to either handling of carcass or tympanites.

9. Post-mortem rupture:

•      Rupture of different viscera especially the viscera of GIT after death is known as post-mortem rupture.

•      This may occur due to either handling of carcass or tympanites.

10. Post-mortem decomposition and putrefaction:

•      Decomposition is the process by which organic substances are broken down into a much simpler forms of matter.

•      Decomposition begins at the moment of death, caused by two factors: autolysis and heterolysis, and putrefaction, the breakdown of tissues by bacteria.

•      Decomposition is followed by putrefaction.

•      Bad odours comes from the decomposed tissue.