Postmortem changes • Physico-chemical changes – independent (!) from the fatal disease – take place immediately or shortly after death 4. Postmortem changes – progress in a fairly orderly fashion – strongly influenced by unpredictable endogenous and environmental factors General pathology • Estimating the time of death • Separating from the real lesions! Cooling off – algor mortis Subcutaneou • No metabolic process s fat tissue – no heat production = thermo-equalization In dogs usually 1°C/hour • 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 ) Pale colour - pallor mortis Desiccation - exsiccatio postmortalis • Blood is settling to lower parts of the • Due to evaporation animal • Skin – Skin and mucous membranes are pale – nasal plate,rostral – Contraction of the small blood vessels plate • Not easy to recognize in animals • Mucous membranes – Hair and pigmentation! • Cornea • Not an infallible sign of death – anaemia! • Also in alive animal – necrotized skin 1 Mumification Mumified dog in a tree - complete dehydration of the tissues - dry heat and/or air current - desert, chimney - Function of the putrefactive bacteria is also hampered http://www.newsweek.com/photos-strange-phenomenon-left-dog-stuck-tree-almost-60-years-without-rotting- 784863 Mumified dog in a tree Soaking maceratio • Skin, organs filled with fluid • Foetuses – aseptic autolysis • Carcasses staying in the water • Also in living animals http://www.newsweek.com/photos-strange-phenomenon-left-dog-stuck-tree-almost-60-years-without-rotting- 784863 – flows on the skin! 2 Discharge Stiffness - Rigor mortis Rigor mortis • Occurs in all the three kind of muscles • Heart muscle – Voluntary and involuntary muscles – Standstill in diastole – looks like systole • Nysten’s rule – Develops fast (30 minutes) – first investigation in 1811 – Lasts for 1 day • Skeletal muscles • Smooth muscles – 2-4 hours the beginning – Quick process (10-15 minutes) – 5-8 hours becomes general – Lasts for 1 – 4 hours – 24-48 hours starts to disappear • intestines, arteries, spleen – 48-60 passes off 3 Onset and duration of RM Stiffness - rigor mortis • 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 Postmortem clot Cruor postmortalis • 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 Blood clot in the heart 4 PM blood sedimentation, lividity • 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 Imbibition • Discoloration • Forms: • From the blood – hemoglobin – aorta ! – 24 hours - permeable • From the gall bladder – bile pigment imbibition 5 Self softening Autolysis Autolysis • normal • Autolytic ferments of the cell in the cytoplasm – endogenous enzymes • autolysed • Autodigestio (self digestion) – Gastromalatia • Gastric juice – Oesophagomalatia Postmortem destruction - putrefaction • 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 Rate of putrefaction • Rapid – Obese (retaining the body heat) – Warm environmental temperature – Hyperemic organs – Widespread infection – Injuries (portals of entry) – Oedematous tissues • Slow – Lean – Exsanguination (dehydration) 6 Emphysema postmortalis hepatis Postmortal tympany Honey-comb pattern 7 Sulph-hemoglobin Reaction of Hb (hemoglobin) plus H2S (hydrogen-sulphid) greyish-green, paling off on air Pseudomelanosis • H2S + Fe (from Hb) • Iron-sulphide 8 PM Wax - Adipocere Adipocere • Saponification • In wet, clayey soil • Fatty acids and Ca++ • Form soaps, impregnate soft organs • Sweetish odour Post mortem changes Topics • Cooling off – algor mortis • Pale color – pallor mortis • 5. Traumas and their consequences • Desiccation – exsiccatio postmortalis • 6. High temperature as cause of disease • Soaking – maceratio postmortalis • 7. Low temperature as cause of disease • Stiffness – rigor mortis • Postmortem clot – cruor postmortalis • 8. Irradiations and electricity (also • PM blood sedimentation – hypostasis postmortalis lightning) as cause of disease – Livores mortis • 9. Inadequate oxygen and water supply • Discoloration - imbibition • Selfsoftening – autolysis (selfdigestion – autodigestion) • 10. Inadequate nutrient supply. Starvation • Postmortem decomposition – putrefaction • Grave wax - adipocere General aetiology Causes of the cellular damage • Stimuli from the environment: physiological • External causes (causae efficientes) • External causes + internal conditions – Physical • Causes of diseases – Chemical – Absolute – relative cause • Intoxications – Monocausalis – pluricausalis – Biological » causa essentialis (dominating) – Clostr. perfringens D • Viruses, bacteria, fungi, protozoa » causa auxillaris (helping) – decreased motility – Inadequate supplements (malnutrition) » causa occasionalis (occasional) – overfeeding – enterotoxaemia in sheep • Internal conditions (predisposition) – pneumomycosis in newly hatched chicks – causae predisponibiles 9 Physical effects 5. Traumas and their consequences • Forms a. Mechanical effects – Open wound or covered lesion – Superficial (excoriatio) or deep (denudatio) b. High and low temperature • Causes – force, high sudden pressure c. Electricity – tension (stretching) d. Radiant energy – torsion • dilaceratio, pulling, extension e. Climate and weather – penetration into tissues – explosion (detonation) • fragment cause wounds • pressure changes tear or rupture of the tissues – ultrasound • pseudocavitatio, heat production Luxation Consequences • depend on – causing agent – strength of conjunction – type of organ or tissue • soft tissues • bones, head Forms of the wounds (vulnus) • On soft tissues (open w.) • Inside the body – abrasion (v. abrasum) – bleeding (haemorrhagia) – contusion (v. contusum) – split (ruptura) – laceration (v. lacerum) – perforation (TRP) – incision and cut – trituration (crumbling) (v. scissum et caesum) (conquassatio) – puncture (v. punctum) – compression • penetration, perforation • gun-shot (v. sclopetarium) – Covered lesions – bite (v. morsum) sometimes without outer signs on the surface! – SURGICAL WOUND !!! 10 11 Bleeding in the brain tissue Rupture Trituration Sequelae of traumatic effects • Local effects • General effects – Lesions – General effect of a local infection – Tissue damage • tetanus, gas-phlegmone – Port of entry! – Loss of blood • Bleeding out – Functional disturbances • fractures, luxations – Embolism • fat, bone marrow – Traumatic shock 12 Bleeding, haemothorax Loss of function Lesions in the tissues • Microscopical disruption of the – Fibrillary ruptures Achilles tendon • Macroscopical – Ruptures (ruptura) Locus minoris resistenciae – Fractures (fractura) - sick animals – Luxation (luxatio) - bad condition – Fissure - dietetical problems – Concussion (commotio) – brain, spinal cord, bone marrow – bony capsule!!! – not always seen with naked eyes 13 Dislocation of the broken ends Fracture • open (fr. aperta) or covered (fr. optecta) • special appaerance – Infraction - bone fracture marked by a small line that shows up in X-ray examination – newborns, metabolic disorders, tumors • Minor trauma can cause it – strenght of the bone decreases (rarefied) – cachectic animal Vital reaction • Did it happen in life? • Edges of the wound – Hemorrhages at the surrounding tissues – After soaking it disappears! 6. High temperature Physical effects as cause of disease • Mechanical effects • Local effect of burning • High and low temperature – Burning (combustio) • Narrow temperature zone – Categorized by the severity of the lesions • Less sensitive to too low • C. erythematosa (1st) partial depth (epidermis) • C. bullosa (2nd) • C. escharotica (3rd) • Electricity complete depth • Radiant energy - irradiations • Carbonization (4th) – Radiant heat, hot liquid, steam, gas, solid • Climate and weather substances (live coal, melted metal) • General effect - hyperthermia 14 Degree of burn is influenced… Inhalation burns • … by the temperature • … by the duration • Destruction of airways and lungs • … by the quality of substance – mucous membrane of nasal and oral cavity, upper respiratory system • paraffin – water – gasses soluble in water form acids or base and cause • 60 °C – 50-52 °C edema • … by the extension of burn • chloride, sulphur dioxide, ammonia • … age of the animal • swelling, inflammation – pneumonitis (nitrogen oxide) • in 24-48 hours Effect can be • secondary infections – loss of epithel – external (skin) or internal (trachea, esophagus) – Pseudomonas aeruginosa, Staph. aureus, candida Appearance of the burns • C. erythematosa (1st degree) – hyperaemic area,