This program will discuss POSTMORTEM CHANGE - the changes due to autolysis. This cow was "STRUCK BY LIGHTNING" and now has POST MORTEM BLOAT and RIGOR MORTIS

Let's start with a story...

The MORTIS family
Once upon a time there were three brothers.  They were all members of the MORTIS family.
Algor was the coolest (check out the hat!!!).
Livor was the lazy son - he gravitated to the lowest spot.
Rigor was oldest and best known - he was rigid and inflexible.
*Kudos if you can tell me the real names of these three brothers!!!  

ALGOR MORTIS - the temperature of death

The white lenses seen in these eyes are an artifact of cold, but not algor mortis. 

When an animal is placed in a cold room or cooler, the lenses become opaque - thus these are not cataracts.

Algor mortis is COOLING of the body.  After death, the body temperature declines to the environmental temperature.  The rate of cooling depends upon the ambient temperature, body fat, and amount of hair or wool covering the animal.

LIVOR MORTIS - the color of death  
Livor mortis is defined in Dorland's dictionary as "discoloration appearing on dependent parts of the body after death, as a result of cessation of circulation, stagnation of blood, and settling of the blood by gravity, called also POSTMORTEM LIVIDITY".
How do you explain the pattern on this pig's side?
This is the carcass of an aborted lamb. Is this an example of livor mortis?
Portions of organs may be more red (or blue) than other portions. Is this livor mortis?
Do you see the differences in this sheep's lung lobes?

This visual illustrates the mechanism of HYPOSTATIC CONGESTION. Note gravity pulls blood to dependent portions of the vascular bed resulting in pooling of blood in the most ventral areas.

Note this would not occur if clotting was present or the animal was exsanguinated (bled out).

RIGOR MORTIS - the stiffness of death
There are two postmortem changes visible in this cow - do you see them?
What is rigor mortis?  
RIGOR MORTIS is defined by Dorland as "the stiffening of a dead body, accompanying the depletion of adenosine triphosphate in the muscle fibers". ATP is necessary to "unlock" the contraction units in myofibers. If ATP is depleted, the contraction units remain locked and the body is stiff or "in rigor". Rigor is usually complete by 6 to 8 hours after death and may last 1 to 2 days. The times are variable depending on environmental conditions and carcass conditions.
Why are the legs stiff and straight?
Can you think of differences in contraction of other muscles during rigor?  
This is a diseased heart, but it illustrates the difference in contraction during rigor mortis between the left and right ventricles.

Which ventricle contracts most during rigor mortis?

Intraventricular blood in the right side but not the left side of the heart can be an indicator of rigor mortis. Why is that?
What if a clot is found in the left ventricle?
Let us now consider the details of the mechanism of rigor mortis.

Lightning may kill cattle during a thunderstorm... in a few hours, muscle rigidity (RIGOR MORTIS) is seen (has "set in").

What is the pathogenesis for this muscle contraction?

What happens in rigor mortis?

Let's see if you understand some of the principles of rigor mortis.

1. Which of these moose (mooses? meese?) would be in rigor mortis earliest after death? The cow or the calf?


2. Rigor mortis ends as AUTOLYSIS advances.  What is the mechanism?

Okay, that was the quiz.  Now on to more postmortem changes »