Veterolegal aspects of death may be defined as a complete and persistent cessation of respiration and circulation called somatic death and death of the tissue, molecular death.
Death is classified as somatic or systemic and molecular. Somatic and systemic death is that state of the body in which there is complete loss of sensibility and ability to move and complete cessation of the functions of the brain, heart and lungs, the so-called ”tripod of life”, which maintain life and health. Molecular death means the death of the tissues and cells individually, which takes place some time after the stoppage of the vital functions, and is accompanied by cooling of the body, the temperature of which is reduced to an equilibrium with the external world.
Manner of Death
- Coma
- Syncope
- Asphyxia or Anoxia
(1) Coma
- Traumatic injury brain by accidental collision fall from height animal interaction or a weapon.
- Cerebral haemorrhage, thrombosis, embolism, tumours, abscess and other inflammatory conditions of the brain. Spontaneous cerebral haemorrhage observed in cows at parturition.
- Coenurus cerebralis-(Gid, Sturdy, Staggers)-Sheep and Cattle.
- Poisoning: Eg-bromides, carbon monoxide, zinc phosphide, barbiturates etc.
- Uremia and heat stroke.
Causes of death:
- Natural (or)
- Accidental death.
Three primary modes of death:
- Coma
- Syncope
- Asphyxia
Death may occur due to the combined effects of coma and asphyxia.
Coma is:
- Loss of consciousness.
- May be partial or complete.
- May be transitory lasting for a few minutes or may continue for some days or until the death takes place.
Symptoms
- Sudden onset of unconscious.
- Dilatation of pupil.
- Unconscious with as without transient convulsions.
- Absence of papillary light reflexes.
- Slow and irregular respiration.
- Slow pulse.
- Bleeding form nose and ears.
- Involuntary passing of urine and faces.
- Hemiplegia or paralysis of individual cranial nerves.
(2) Syncope
- Circulatory failure.
- Acute and progressive failure of the peripheral circulation is known as shock.
- Shock is “stagnant hypoxia”.
Haemorrhagic shock
- Common cause of shock in animals. Upto 20% blood loss animal can tolerate.
- Hypovalemic before reinfusion.
- Normovalemic-after reinfusion.
Traumatic shock
- Depressed state of vital function that results from severe traumatic injury.
- Two kinds of traumatic shock.
- Primary or immediate.
- Secondary or delayed-due to loss of plasma occurred few hours after injury.
- Primary shock:
- Overwhelming of vital centres in the medulla by nerve impulse originating in the injured area and conveyed to CNS.
- Death with in few minutes from vasomotor collapse in primary shock.
Septic shock
- Fatal infection by pyogenic organisms following an injury if animal survives immediate complication of shock and haemorrhage.
- Suppurative pathogenic bacteria
- Rupture of intestines.
- Injury to gastro intestinal tract.
- Reticulo endothelial system of a shocked animal-not having capability of detoxifying the bacterial toxins.
- Endotoxin produces peripheral circulatory failure (exact mechanism in not known).
Thermal shock
- Exposure to extreme degree of heat or cold,
- It is are characterized by progressive hypovalemia,
- Haemoconcentration and
- Circulatory failure.
Anaphylactic shock
- Is an immunologic phenomenon.
- Occurred between sensitized body cells and specific antigens.
Symptoms
- Coldness of the skin.
- Subnormal temperature.
- Rapid and shallow respiration.
- Pulse is faint while rate is high.
- Pale / cyanotic mucous membranes.
- Reduced amplitude of heart sounds.
- Dilated pupil and lacrimation.
- Muscular weakness and recumbency.
- Oliguria and increased thirst.
- Veins are difficult to rise.
Post mortem appearance
- Injury to skull.
- Brain and its membranes are congested.
- Blood in the cranial cavity.
- Right heart full and left empty.
- Tumour, cyst or abscess in the cranial cavity.
(3) Asphyxia or Anoxia
Interference with the oxygen interchange in lungs and at tissue level.
Etiology
Either natural or traumatic causes.
Mechanic obstruction
- Nasal granuloma.
- Oedema of larynx.
- Acute cellulitis of the throat.
- Peripharyngeal cellulitis, and oedema.
- Laryngeal obstruction.
- Tumour / abscess etc.
- Anaphylatic reactions following injection of foreign proteins or serum-fatal asphyxia.
- Paralysis of respiratory nerves, muscles or respiratory centre form injury or disease or poisoning.
- Disease of lungs or pulmonary circulation failure (lung disease, pleural effusion, pneumothorax, pulmonary embolism, collapse of the lung due to penetrating wounds of thorax and circulatory disturbance of the lung.
- Strangulation in the closure of the air passages by eternal pressure on the neck which prevents the ingress or egress of air during respiration. Crossing of the halter of two bulbs tied close together.
- Inhalation of irrespirable gases eg. CO, Hydrogen sulphide, sulphur dioxide, nitrous oxide and chlorine.
Symptoms
- Four stages:
- Dyspnoea: accumulation of CO2 in blood affect respiratory centre-Rapid & shallow respiration, rapid pulse and cyanosis.
- Convulsions: clonic convulsion then tonic, ophisthotonus spasm, pupil dilated, heart rate slows.
- Apnoea: unconsciousness.
- Final stage: respiratory paralysis heart may beat.
Postmortem Appearance
- Protruded tongue.
- Frothy blood stained fluid in nostrils.
- Congested conjuctiva.
- Laryngeal and tracheal mucosa congested.
- Lungs engorged and oedematous (frothy, dark, coloured blood, exudates).
- Petechial haemorhage of pleura, pericardium, myocardium, endocardium and sometime of brain.
- Cavities of right side heart are engorged with dark coloured, imperfectly clotted blood.
- Left heart are comparatively empty.
- Congestion of abdominal viscera.
- Congested brain and excess serous fluid in the lateral ventricles.
- Cranial sinuses filled with dark-coloured blood.
- Blood dark in colour mostly fluid in the large veins.
- Microscopically lung tissue shows marked dilatation of both the capillaries and veins.
- Signs of severe injuries.
- Generalized visceral congestion.
- Oedema of lungs.
- Dark red fluid blood.
- Petechial haemorrhages.
Examination of Blood Stains
Important in veterolegal cases:
- Blood stains present or not / which species of animal the blood belongs. E.g. Mammals, birds, fish or
- reptiles.
- Done by chemical examiner.
- Exact location of stains to be noted
- Stains form person and animals are best removed with a piece of filter paper soaked in NS and allowed to contact and remove and dry it.
- Garments and weapons allowed to dry and wrapped and packed with out unnecessary handling.
- Liquid stains are taken in test tubes with the help of dropper. Test tube placed in Ice box.
- Blood soaked soil sent in glass container walls and flours-digging and sent in a container.
- Stain can be scrapped up by knife.
- Physical
- Chemical
- Microscopical
- Spectroscopic
- Serological
Physical examination
- Foreign bodies like hairs and fibres.
- Colour, position, shape and size of blood stain and relationship with surrounding to be recorded.
- Examined by naked eye or simple lens.
Various shapes of stains:
- Blood streak: venous blood.
- Parts of blood of irregular shape: abundant haemorrhage.
- Circular stains: drop of blood falls on horizontal surface from a small height.
- Ova stains: drop of blood hitting vertical or oblique surfaces.
- Splashes or line shaped stain are usually- projection of arterial blood
- Smears: blood wiped off.
Chemical examination
Benzidine test:
- Press piece filter paper over stain.
- Add few drops of 10% benzidine sol in glacial acetic acid.
- Add few drops of fresh, acti 3% hydrogen peroxide.
- Green or blue colour positive.
- Sensibility-1: 200,000.
- Not specific for blood.
- Most oxidising agents like permanganate, chromates, bichromates etc.
- Give strong reaction with our addition of H2O2.
- Positive result big pas, secretion of throat and nose by plant juices, by commercial formalin, fly excretion.
Phenolphthalein test:
Solution preparation:
- Phenolphthalein-18 ml.
- Sodium hydroxide-20 pm.
- Distilled water-200ml
- Mix phenolphthalein and sodium hydroxide in distilled water and boil it under a reflux condenser.
- Add 20gm of granulated Zinc (20 to 30 mesh) while boiling.
- Boiling continued until solution become colorless.
Procedure:
- 1 to 2 ml of saline suspension of blood stain in a test tube.
- Boil it for ½ minutes to destroy any oxidases.
- Cool it and add 5 drops of phenolphthalein reagent and followed by some drops of 3% H2O2.
- Pink colour develop in position cases.
- Colour lasts no longer the 3 mts.
- Sensitivity 1:1,000,000.
- Not specific for blood.
- Direct oxidising compound copper, potassium ferricyanide and nickel-positive reaction.
Leucomalachite green test:
Reagent:
- Acetic acid-100ml.
- Distilled water-150ml.
- Add one drop of the reagent on the stained filter paper.
- Lease it for 10 seconds.
- one drop of H2O2.
- Green colour develops-if blood.
- More sensitivity-not commonly used.