Exam 1: Morphologic Appearance of Postmortem Changes Flashcards
true or false: autolysis is the degradation of cells by enzymes not normally present in the tissues and occurs pre-mortem
FALSE: self-digestion/degradation from NORMAL cell enzymes POST-MORTEM;
occurs after somatic cell death
What causes somatic cell death?
Total diffuse hypoxia
In what organs will autolysis occur more quickly? why?
GI tract, pancreas, gall bladder, kidney, liver
because they have more enzymes
Cool environment and refrigeration can delay autolysis except where? why?
the forestomach in ruminants (the rumen); the equine cecum and ascending colon;
these organs have a large number of microbes and ingesta will continue to undergo fermentation even after death (in addition to autolysis)
Why isn’t freezing a carcass recommended?
Now you have to determine:
- Changes caused from freezing/artifacts
- changes caused by the actual lesions
- changes caused by autolysis
What is rigor mortis? When does it occur?
stiffening of muscles after death.
Occurs 1-6 hours after death and lasts for 1-2 days
What should you do if an animal has been dead for 8 hours and rigor has not set in?
DO NOT PERFORM A NECROPSY; likely anthrax – look for bacillus in blood from a clip of the ear or tail
True or false: animals with more stress (or a fever) will have a faster onset of rigor mortis?
True
What is Algor Mortis?
Cooling of the body after death. For animals time of death can be determined using a hole in the skull. However, temperature is affected by wool, environment and other factors
How does bacillus anthracis prevent rigor?
the bacteria produces cAMP which inhibits muscle stiffening and relaxes the muscles
What is livor mortis?
the same this as hypostatic congestion. Gravity pulls blood to the lowest point after death. This will cause a variation in color, particularly in bilobed organs like the lungs. It will also show which side the animal was lying on when it died.
What is this a picture of?
Livor Mortis aka hypostatic congestion
Where do we expect to see a lot of post mortem clotting
in the heart
You see a blood clot that is dry and dull in color and firmly attached to the vesell wall. What type of clot is this?
Pre mortem blood clot
You see a blood clot in the heart that is very shiny and slips out easily, it is in the perfect shape of the vessel it was in. You also notice that it has different colored components in a layered appearance. Is this a pre or postmortem clot?
Post mortem clot – chicken clot
What type of clot is this?
pre mortem clot (thromboemboli or muralthrombi)
What type of clot is this?
Post mortem clot
What is hemoglobin imbibition? Where is it expected to be found?
Red staining of tissues, especially heart arteries and veins. Will also penetrate adjacent tissues.
What change is present in this tissue?
Hemoglobin imbibition
What change is present in this image?
Hemoglobin imbibition
When hemoglobin imbibition is present in fat, what type of autolysis is it?
Advanced autolysis
You are doing a necropsy on an animal and notice lots of reddened areas in the tissues. However, the level of autolysis in the animal is very mild. What is happening?
The reddening was caused by a pre-mortem change, possibly erythrolysis
What is bile imbibition?
yellow staining of tissue adjacent to bile (near the gall bladder or the small intestine).
How can you distinguish Bile Imbibition from Icterus?
Icterus causes a diffuse yellow staining of mucosa. Bile imbibition will only affect areas adjacent to the bile
What is shown in this picture? Is it a normal post mortem finding?
Bile imbibition. Yes but it may also be a premortem change (not as common)
What is shown in this picture? How do we know that this is not peritonitis?
Bile Imbibition:
yellow loops of intestin, distended loops indicating autolysis along with other color changes indicating hemoglobin imbibition
Is bloating a normal post mortem change?
Yes
How can you tell the difference betwen ruminal tympanny and post mortem bloating?
In ruminal tympanny there MAY be a bloat line – white line caused by congestion and blockage of blood flow.
there is not bloat line in a post mortem bloat
What is shown here?
Bloat line indicating tympanny (pre-mortem bloat)
What causes clouding of the lens?
cold temperatures of the carcass – refrigeration. Makes it difficult to differentiate from cataracts so use age of animal to help diagnose them
Cats 10+, Dogs 7-8
What is pseudomelanosis? Where do we expect to find it?
greenish black discoloration of tissues post mortem;
found in areas in contact with the gut (kidney, liver, spleen, gut wall) – becomes more advanced with more autolysis (may eventually get to lungs)
What is the discoloration shown here?
pseudomelanosis. note that there is not a definitive line but rather a gradation of black discoloration
What is the black discoloration shown here?
pseudomelanosis. Notice the friable edges of the spleen indicating autolysis
What changes are shown here?
hemoglobin imbibition, bile imbibition and pseudomelanosis indicating autolysis
