Describe gross changes in necrotic tissue
- paler
- swollen
- malacia
And if animal survives injury…
- surrounding zone of inflammation
- +/- haemorrhage
What does the inflammatory process hope to achieve… ?
- removal of agent of disease
- neutralize/ dilute foreign material
- vascular changes allowing vasodilation & inc capillary permeability
- to transport of cells to site of damage
- repair of tissue
- regeneration of constituent cells, otherwise develops fibrous capsule (scar tissue)
Describe post mortem autolysis
after an animal dies, the speed death of it’s constituent cells will depend on
a) metabolic rate of tissue (brain dies early)
b) temperature of carcass hastens death (e.g. fever before death/ fatty carcass)
Clinically, what helps us differer post mortem autolysis from necrosis?
- early changes ARE similar
- history/ circumstances help
e. g. time death/ temp - gross appearance
e. g. PM autolysis doesn’t elicit immune response (inflammation)
Define autolysis
the destruction of cells or tissues by their own enzymes, especially those released by lysosomes.
What process is a major contributor to PM autolysis
Bacterial putrefaction (bacteria from e.g. gut invade organs close by)
Describe mechanisms & consequences of bacterial putrefaction
- bacteria from bacteria laden in situ surfaces invade (e.g. GIT)
- softening of tissue
- odour
- green/ black staining
- tissue sponginess & distended hollow organs due to gas
Hypostatic congestion and clotting in an artefact of PM. Describe.
blood pools in bottom parts of animal (as affected by gravity)
-can happen prior to death if animal can’t move
List some other PM artefacts
- bile staining
- haemoglobin inhibition= breakdown of RBC
- gas buildup
- barbituation crystal precipitation
How can we diagnose cell injury that happened before the animal died?
- Biopsy
2. Clinical biochemistry
How is clinical biochemistry a valuable tool?
damaged cell»_space; damaged membrane»_space; leaks»_space; subsequent chemicals (esp enzymes) can be found in blood
- tells us which tissue affected & to what extent
- however must be significant cell damage at one point in time
- can reflect organ disfunction
- only tells us which organ/ cell was dysfunctional, NOT the cause
Example of a diagnostic enzyme contributing to a PM artefact in skeletal muscle cells?
creatine kinases (CK)
Example of a diagnostic enzyme contributing to a PM artefact in liver cells?
- alamine transferases (ALT) in DOG/CAT
- glutamate dehydrogenases (DH) in HORSE/COW
** these are due to hepatic lipidosis
Example of a diagnostic enzyme contributing to a PM artefact in pancreatic cells?
- lipase
- amylase
can enzymes tell us if the pathological process was reversible/ irreversible?
nope
BUT their concentrations can tell us the extent of necrosis
