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GeneralGeneral pathologypathology

Postmortem changes

Mechanical effects

PostmortemPostmortem changeschanges

• Physico-chemical changes

– independent (!) from the fatal disease

– take place immediately or shortly afterdeath

– progress in a fairly orderly fashion

– strongly influenced by unpredictableendogenous and environmental factors

• Estimating the time of death

• Separating from the real lesions!

CoolingCooling offoff –– algoralgor mortismortis

• No metabolic process

– no heat production = thermo-equalization

• Depends on

– Hair, subcutanous fat tissue

– Temperature of the surroundings

– Zone (tropical, temperate)

• Increased PM temperature

– Overtemperature (heat stroke, septicaemia)

– Spastic muscle contraction (tetanus, strychnine or

DiNitroOrtoCrezol poisoning )

SubcutaneousSubcutaneous

fatfat tissuetissue

In dogs

usually 1°C/hour

PalePale colourcolour -- ppallorallor mortismortis

• Blood is settling to lower parts of the

animal

– Skin and mucous membranes are pale

– Contraction of the small blood vessels

• Not easy to recognize in animals

– Hair and pigmentation!

• Not an infallible sign of death

– anaemia!

DesiccationDesiccation

exsiccatioexsiccatio postmortalispostmortalis

• Due to evaporation

• Skin

– nasal plate,rostralplate

• Mucous membranes

• Cornea

• Also inalive animal

– necrotized skin

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MumificationMumification

- complete dehydration

of the tissues

- dry heat and/or air current

- desert, chimney

- Function of the

putrefactive bacteria

is also hampered

SoakingSoaking

maceratiomaceratio

• Skin, organs filled

with fluid

• Foetuses

– aseptic autolysis

• Carcasses staying in

the water

• Also in living animals

– flows on the skin!

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DischargeDischarge StiffnessStiffness -- RigorRigor mortismortis

• Occurs in all the three kind of muscles

– Voluntary and involuntary muscles

• Nysten’s rule

– first investigation in 1811

• Skeletal muscles

– 2-4 hours the beginning

– 5-8 hours becomes general

– 24-48 hours starts to disappear

– 48-60 passes off

RigorRigor mortismortis

• Heart muscle

– Standstill in diastole – looks like systole

– Develops fast (30 minutes)

– Lasts for 1 day

• Smooth muscles

– Quick process (10-15 min.)

– Lasts for 1 – 4 hours

• intestines, arteries, spleen

OnsetOnset andand durationduration ofof RMRM

• Rapid and short– High environmental and/or inner temperature

– Prolonged muscular activity

– Young and elder animals

– Septicaemia, wasting diseases

• Delayed– Asphyxial death (notably by carbon monoxide

poisoning)

– Severe hemorrhage, cold surroundings

• Fails to develop– In case of degenerative muscle changes

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DevelopmentDevelopment ofof stiffnessstiffness

• N: ATP inhibits the activation of the linkage betweenthe actin and myosin

• Muscle tissue becomes anoxic after death– Oxygen dependent processes cease

– Ca ++-pump stops, Ca++ reaches the sarcoplasm

– Level of ATP is maintained by anaerobic glycolysis

• Increased amount of pyruvic and lactic acid

• Myosin-ATP-ase liberates energy

– Muscle glycogen becomes depleted

– Cellular pH drops to 6 - COAGULATION of actomyosin

– Level of ATP falls below critical level

RAPID RIGOR

• Irreversible development of those linkage– Resolved by the autolysis

StiffnessStiffness -- rigorrigor mortismortis

PostmortemPostmortem clotclot

CruorCruor postmortalispostmortalis• Dark red, smooth, fleshy

with glistening surface

• Not attached to the intima!

• Trombocytolysis– cruor sanguinis – red clot

– crusta lardacea – chicken fat clot

• After death blood clots in

15-30 minutes

– Heart, large blood vessels

• No clotting in small blood

vessels - fibrinolysin

BloodBlood clotclot

inin thethe heartheart

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PM PM bloodblood sedimentationsedimentation, , lividitylividity

• postmortem hypostasis

• Effect of gravity on the blood fluid – in 1 hour!

– Also in the organs (lungs, kidney …)

• livores mortis

PM spots

dark purple

• Changing

position

– Special

pattern

ImbibitionImbibition

• Discoloration

• Forms:

• From the blood

– hemoglobin – aorta !

– 24 hours - permeable

• From the gall bladder

– bile pigment imbibition

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SelfSelf softeningsoftening

AutolysisAutolysis

• Autolytic ferments

of the cell in the

cytoplasm

– endogenous enzymes

• Autodigestio

(self digestion)

– Gastromalatia• Gastric juice

– Oesophagomalatia

PostmortemPostmortem destructiondestruction -- putrefactionputrefaction

• Decomposition products

– Activity of saprogenic bacteria

• Suffocation supports the putrefaction

– blood remains liquid

• Intestine – v. portae – liver

• Dissolution into gases, liquids and salts

– Ptomaines (neurine, muscarine, putrescin)

– Gas production – stomach distension

• Under 5oC putrefaction stops

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RateRate ofof putrefactionputrefaction

• Rapid– Obese (retaining the body heat)

– Warm environmental temperature

– Hyperemic organs

– Widespread infection

– Injuries (portals of entry)

– Oedematous tissues

• Slow– Lean

– Exsanguination (dehydration)

EmphysemaEmphysema postmortalispostmortalis hepatishepatis

HoneyHoney--combcomb patternpatternPostmortal tympany

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SulphSulph--hemoglobinhemoglobin

Reaction of Hb (hemoglobin) plus H2S (hydrogen-sulphid)

greyish-green, paling off on air

PseudomelanosisPseudomelanosis

• H2S + Fe (from Hb)

• Iron-sulphide

PM PM WaxWax --

AdipocereAdipocere

• Saponification

• In wet,clayey soil

• Fatty acidsand Ca++

• Form soaps,impregnatesoft organs

• Sweetishodour

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AdipocereAdipocere PostPost mortemmortem changeschanges

• Cooling off – algor mortis

• Pale color – pallor mortis

• Desiccation – exsiccatio postmortalis

• Soaking – maceratio postmortalis

• Stiffness – rigor mortis

• Postmortem clot – cruor postmortalis

• PM blood sedimentation – hypostasis postmortalis– Livores mortis

• Discoloration - imbibition

• Selfsoftening – autolysis (selfdigestion – autodigestion)

• Postmortem decomposition – putrefaction

• Grave wax - adipocere

GeneralGeneral aetiologyaetiology

• Stimuli from the environment:

physiological

• External causes + internal conditions

• Causes of diseases

– Absolute – relative cause

– Monocausalis – pluricausalis» causa essentialis (dominating) – Clostridium perfringens D

» causa auxillaris (helping) – decreased motility

» causa occasionalis (occasional) – overfeeding

CausesCauses ofof thethe cellularcellular damagedamage

• External causes

– Physical

– Chemical

• Intoxications

– Biological

• Viruses, bacteria, fungi, protozoa

– Inadequate supplements (malnutrition)

• Internal conditions (predisposition)

PhysicalPhysical effectseffects

a. Mechanical effects

b. High and low temperature

c. Electricity

d. Radiant energy

e. Climate and weather

f. Inadequate supplements

TraumasTraumas

• Forms– Open wound or covered lesion

– Superficial (excoriatio) or deep (denudatio)

• Causes– force

– high, sudden pressure

– dilaceration• pulling, extension, torsion

– explosion (detonation)• Fragment cause wounds

• Pressure changes tear or rupture of the tissues

– Ultrasound• Pseudocavitation, heat production

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LuxationLuxationDislocationDislocation

FormsForms ofof thethe woundswounds ((vulnusvulnus))

• On the surface (open w.)– abrasion (v. abrasum)

– contusion (v. contusum)

– incision and cut(v. scissum et caesum)

– puncture (v. punctum)

– laceration (v. lacerum)

– bite (v. morsum)

– gun-shot (v. sclopetarium)

• Inside the body– Bleeding (haemorrhagia)

– Split (ruptura)

– Perforation (TRP)

– Trituration(conquassatio)

– Compression

– Covered lesionssometimes withoutouter signs on thesurface!– SURGICAL WOUND !!!

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BleedingBleeding inin thethe brainbrain tissuetissue RuptureRupture

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TriturationTrituration SequelaeSequelae ofof traumatictraumatic effectseffects

• Local effects

– Lesions

– Tissue damage

– Portal of entry!

• General effects

– General effect of a localinfection

• tetanus, gas-phlegmone

– Loss of blood

• Bleeding out

– Functional disturbances

• fractures, luxations

– Embolism

• fat, bone marrow

– Traumatic shock

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BleedingBleeding,,

haemothoraxhaemothorax

LossLoss ofof functionfunction

LesionsLesions inin thethe tissuestissues

• Microscopical

– Fibrillary ruptures

• Macroscopical

– Ruptures (ruptura)

– Fractures (fractura)

– Luxation (luxatio)

– Fissure

– Concussion (commotio)

– brain, spinal cord, bone marrow – bony capsule!!!

Locus minoris

resistenciae

- sick animals

- bad condition

- nutritive problems

FractureFracture

• open (fr. aperta) or covered (fr. optecta)

• special appaerance

– Infraction - bone fracture marked by a smallline that shows up in X-ray examination

– newborns, metabolic disorders, tumors

• Minor trauma can cause it

– strenght of the bone decreases

– cachectic animal

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Hematome Hyperemia

TumorTumor

VitalVital

reactionreaction

• Did it happen in life?

• Edges of the wound

– Hemorrhages at the surrounding tissues

– After soaking it disappears!