This document discusses the post-mortem changes that occur in animal bodies after death. It describes 13 post-mortem changes including: rigor mortis, algor mortis, livor mortis, postmortem clotting of blood, imbibition with hemoglobin, pseudomelanosis, imbibition with bile, postmortem emphysema, rupture of organs and tissues, displacement of organs, post mortem softening or autolysis, and putrefaction. Several factors can influence the onset and progression of these post-mortem changes including nutritional status, environmental temperature, and cause of death.

1. Post-mortem changes
1. Rigor-mortis: It is the shortening and contraction of muscles that
occur after death, resulting stiffness and immobilization of the body.
Rigor –mortis usually appears 1 to 8 hours after death and passed off
in 24-48hrs.It starts from the anterior portion (head, neck, trunk, and
limbs) of the body and progresses in a posteriordirection.Rigor mortis
disappears in the same order it appeared (head, neck, trunk, and
limbs). Several factors influence the onset of rigor-mortis. These
factors are:

2. 1. Nutritional status of the animals:. Well-fed animals have large
glycogen reserve, and may show a delay in onset of rigor-mortis.
While in emaciated and cachectic animals, it appears quickly.
2. Environmental and body temperature of the cadaver: Its appearance
is faster in high environmental temperatures (summer season) and
retarded by low temperatures (winter season)
3. Cause of death: Rigor mortis will appear faster in animal that died
due to violent exercise (racing, fighting, or struggling), or when
violent muscular contractions have occurred as in tetanus or strychnine
poisoning. Animal that died due to septicemia, rigor- mortis may not
develop at all.

3. 2. Algor Mortis: Gradual cooling of the animal body after death and it
is associated with fall in ATP.
3. Livor mortis: is the accumulation of blood in the ventral portion of
organs and the entire carcass due to the influence of gravity.This
gravitational setting of blood and body fluids results intense reddish
coloration of the organ and tissue at the down side of the cadaver.
4. Postmortem clotting of blood: It is the coagulation of blood in
blood vessels after death. In dead animals the endothelial cells begin to
degenerate and liberate thromboplastin which then clots the blood
within the heart, arteries, and veins.

4. 5. Imbibition with hemoglobin: Pinkish to reddish coloration
imparted to tissue due to thelysis of red blood cells.
6. Pseudomelanosis: It is the appearance of grey, green, or black
pigment in the tissues after death. Hydrogen sulphide produced during
putrefaction combines with the iron to form iron sulphide, a black
pigment. The concentration of this pigment and its combination with
other tissue pigments result in a variety of shades of green, grey, and
black.
7. Imbibition with bile: It is the golden yellow colouration of tissue
following seepage of the bile.
8. Postmortem emphysema: It is the accumulation of gas in tissues
as the result of bacterial fermentation.

5. 9. Rupture of organs and tissues: It occurs when gases
produced cause progressive distension of body structures until
they burst. This usually occurs in stomach, intestine,
diaphragm, and ventral abdominal wall.
11. Displacement of organs: It occurs when the dead animal
is rolled over or moved. The intestine is usually displaced.
This must be differentiated from ante-mortem malposition of
the viscera (volvulus and torsion).

6. 12. Post mortem softening or Autolysis: Autolysis is the digestion of
tissues by their own cellular enzymes. This may be easily observed on
liver and kidney. When tissue is fixed in formalin or alcohol, cellular
enzymes are inactivated by them and autolysis is prevented.
13. Putrefaction: It is the decomposition of tissues by enzymes of
saprophytic bacteria. After death, bacteria from the digestive tract and
body surfaces invade, multiply and eventually digest the tissuewith their
enzymes.