Flashcards in Terminology and Cell ID Deck (22):
Immediately before death
1. Passive congestion
2. Pulmonary oedema
3. Pulmonary alveolar emphysema
4. Stomach contents in oesophagus/trachea, due to regurgitation and aspiration.
Due to drug used. Crystal formation in serosa and endothelium.
POST MORTEM CHANGES
Occur after death. Breakdown of cells and tissues.
WHAT CAUSES POST MORTEM CHANGES?
1. Autolysis of cells from respiratory failure. Proteolysis by lysosomal enzymes.
2. Bacterial growth (partly physiological bacteria)
EXTENT OF POST MORTEM CHANGES?
1. Tissue of origin
2. Temperature at death.
3. Fleece/fur thickness.
4. Bacterial flora.
5. Interval between death and necropsy.
Rigidity, seen 1-6 hours after death, lasts for 1-2 days. Muscles are contracted.
Starts in HEART.
Spreads to HEAD AND NECK MUSCLES, then to EXTEMITITES.
More pronounced in muscular animals.
Excitement accelerates onset.
May fail to develop if animal is extremely malnourished, due to insufficient energy stores in muscles- Myofibres do not contract. Heart remains full of blood.
1. Corneal opacity- Reduced turgor
2.Gas formation in liver and gut (spongy appearance of liver)
3. Softening of liver, kidney, pancreas
4. Drying of tissue surfaces.
Mucosa of rumen, reticulum, omasum.
'Hairslip'- Loss of hair.
-Dark red- Due to hypostatic congestion (blood settling)
-Diffuse reddish stain- Serosa, intima, serosal fluids- Due to haemoglobin imbibition (displacement). Hb moves in to tissues from blood.
-Greenish-yellow due to bile staining tissues near gall bladder.
-Green-black- Hydrogen sulphide from bowel organisms and sulfmethaemoglobin (from Hb)
Post mortem clots are rubbery and homogenous, forming perfect casts of the vessels they are in.
CURRANT JELLY CLOT
Red blue, contains red blood cells
CHICKEN FAT CLOT
Clear yellow, serum clot. Not just in chicken!
AUTOLYSIS plus PUTREFACTION
Tissue breakdown due to lack of oxygen. Minimised by chilling.
Generalised, advanced decomposition of viscera.
*Clostridial myositis can look similar, but it is localised to affected muscles. Putrefaction happens EVERYWHERE.
A structure or appearance that is not natural but is due to man made manipulation
Causes crystallisation and cell disruption- artefacts
Causes artefacts- Backbleeding in to thorax if angle of knife is incorrect.
Inhalation in to lungs if trachea is nicked.
CORRECT BLEEDING- Jugular veins and carotid arteries should be severed simultaneously.
Artefacts- Multiple pinpoint haemorrhages in lungs, muscle, heart and other organs. In sheep and pigs, caused by electrical stunning.
Can be localised in an organ (ie. on one part of that organ), or diffuse (all over organ)
Can be an artefact (also seen as a post mortem change) due to terminal gasping- Especially in old thin cows.