Physical effects

• Mechanical effects

• High and low temperature

• Narrow temperature zone

• Less sensitive to too low

• Electricity

• Radiant energy - irradiations

• Climate and weather

• Local effect of burning

– Burning (combustio)

– Categorized by the severity of the lesions

• C. erythematosa (1st)

• C. bullosa (2nd)

• C. escharotica (3rd)

• Carbonization (4th)

– Radiant heat, hot liquid, steam, gas, solid

substances (live coal, melted metal)

• General effect - hyperthermia

6. High temperature

as cause of disease

complete depth

partial depth (epidermis)

Degree of burn is influenced…• … by the temperature

• … by the duration

• … by the quality of substance• paraffin – water

• 60 °C – 50-52 °C

• … by the extension of burn

• … age of the animal

Effect can be

– external (skin) or internal (trachea, esophagus)

Inhalation burns

• Destruction of airways and lungs– mucous membrane of nasal and oral cavity, upper

respiratory system

– gasses soluble in water form acids or base and cause edema

• chloride, sulphur dioxide, ammonia

• swelling, inflammation

– pneumonitis (nitrogen oxide)• in 24-48 hours

• secondary infections – loss of epithel– Pseudomonas aeruginosa, Staph. aureus, candida

Appearance of the burns

• C. erythematosa (1st degree)

– hyperaemic area, vasodilatation, edema

• C. bullosa (2nd degree)

– vesication, denaturation of proteins, pain

• C. escharotica (3rd degree)

– coagulation necrosis of the tissues, hemostasis, thrombosis, pale, insensible

• Carbonization (4th degree)

– tissues are charred

General effects

• Circulatory disturbance, shock … (immediate)– edema (permeability of the blood vessels)

– pain, hypovolaemia, hyperkalaemia, autointoxication

• Necrosis, enzymatic lysis of proteins– increased local osmotic pressure

• Hemoconcentration, desiccation

• Degeneration of parenchymal organs– catabolic enzimes continue to work

– liver, kidney, heart, bone marrow! (anaemia)

• Hyperkalaemia (potassium released from the cells)– 2nd day: oliguria, anuria (degeneration of tubular cells)

– 3rd day: polyuria (later no water retention ability)

• Toxaemia

General effects of burningnecrosis

degeneration /from 1. day/ hyperkalaemia

(heart, liver, kidney, bone marrow)

heart failure

poliuria /from 3. day/

autointoxication /from 7. day/ oliguria /for 2 days/

anaemia /from 7. day/

Hyperthermia

• Extremely increased internal temperature of the body

• Hyperthermia (failure of physical heat regulation)

– High (and humid) environmental temperature

– High own heat production (pyrogens)

– Heat loss is inhibited

• Consequences

– damage of vasomotor centrum, low blood pressure, spastic muscle

contractions, kidney insufficiency, hyponatraemia…

• Pathologic findings– Quickly developing rigor mortis, incompletely clotted blood, early putrefaction

– hemostasis in internal organs, brain edema, meningeal hyperemia and

hemorrhages in the hypothalamus

• Heat stroke (> 43°C)

Lesions

• Heat spasms

– electrolyte loss (sweating)

• Heat distress

– most often seen, collapse

– failure of cardiovascular compensatory

mechanisms after hypovolemia

– usually solved by itself

• Heat stroke

– vasodilation, hemostasis, necrosis, DIC

Sunstroke - Insolation

• Infrared (ultraviolet?) radiation of sunshine

– Longlasting or strong impact of sunshine

– Vasodilatatio in the skin of the head

– Vasodilatatio in the collateral brain vessels,

hyperemia

– Brain and meningeal edema – death

– Rare in animals (haircoat!)

7., Low temperature as cause of disease

• Local effects– Contraction of vessels, local ischaemia

• Metabolic and waste products (lactic acid, histamin)

• Irregular vasodilatation! - hemostasis

– Frostbite (congelatio)• C. erythematosa (1st) – bluish-red, swollen

• C. bullosa (2nd) – vesication, edema

• C. escharotica (3rd) – necrosis

• C. gangrenosa (4th) – gangrene

– Not only at freezing point - wet, windy surroundings!

• Piglet with diarrhea, protruding body parts (ears, tail, testicles)

• General effects– Gangrenous lesions, necrosis

• Toxaemia

http://blogs.scripps.com/kshb/weather/archives/nov 15 frostbite.html

Hypothermia

• Failure of the heat regulation – around 35oC

– Weather (cold, windy, wet…)

– Exhausted, starving animals

• Predisposing factors (diarrhoea, bleeding…)

• 27-30 oC: vital functions come to standstill

• 20-25 oC: death

• Endangered species: pig, rabbit, dog

• Brown fatty tissue: great metabolic activity!!!

Defence mechanisms

• Against falling body temperature

– Contraction of muscles

• Shivering

– Vasoconstriction in the skin

– Increased metabolism

• Labile glycogen reserves are used up

– Shallow and quick respiration

Baby pig disease• Acute hypoglycemia of the newborn pigs

– Fatal if untreated

– Cold, starvation

• In newborn or young animals

– Heat regulation is not perfect

– Body surface is relatively large

Topics

• Irradiations and electricity (also

lightning) as cause of disease

• Inadequate oxygen and water supply

• Inadequate nutrient supply. Starvation

8., Irradiations and electricity

as cause of disease

Electricity as cause of disease

• Touching/biting a wire or hit by lightning (bolt)

• Electric shock – death: electrocution

• Animal effect – the effect on the animals

• Influencing factors:

– current intensity, voltage, duration, earthing

– resistence of the body (skin, wet ground)

• The higher the voltage the less the resistance!!!

• Alternity current more dangerous than direct current!

• Medium amperage cause disturbances

– Brain – loss of consciousness, heart failure – cardiac arrest

Common Kestrel

(Falco tinnunculus)

Pathology

• Entry: current marks and arboreal patterns– m. arrector pili

• Cavity between str. corneum and str. spinosum

• Electrolytic effect (direct current)– Coagulation necrosis of tissues

• Metallisation – dispersed metallic particles

• Spastic contractions (nervus vagus)

• Mechanical changes – secondary shock wave– fractures of bones, ruptures…

HE. 200x

HE. 400x

HE. 100x

HE. 200x

HE. 100x

HE. 400x

Radiant energy• Electromagnetic rays

– Ultra-short waves (microwaves - warming)

– Infrared waves (warm surface radiations)• Capillary dilatation – increased metabolic pr.

– Visible rays (physiological effect)

– Ultraviolet rays (biological - path. effect!)• Endangered organs: eyes, skin (pigments in animals!)

• Cancerogen effect

• Photosensibilisation

– alkaloids (eg. photodynamic substances) in the food…

• Photochemical reactions (producing vitamin D)

• SUNLIGHT – dermatitis solaris

Radiant energy• Ionizing rays - positive or negative charges

– Effect: dose, ionization, penetrability

– Cosmic rays

– Particular radiations (alpha, beta, proton, neutron,

deuteron rays)

• Alpha: greatest ionizing ability – low penetrability

• Beta: lower ionizing ability – higher penetrability

– Electromagnetic rays (X- and gamma rays)

• ionizing ability – high penetrability: biological effect!!!

– Abnormal cell division

Irradiation sickness

• Phase I (initial phase – after 1-2 hours)– dizziness, vomiting, exhaution, anorexia, nervousness

– alopecia

• Phase II (latent phase) – 1-2 days without signs

• Phase III (sickness – after a week)– Bone marrow lesions: hemopoietic insufficiency

– No phagocytosis, no antibody production

• Phase IV (break down - 4-5 months after)– diarrhea, anemia, kidney & liver failures etc.

– malignant tumors

DEATH

Lesions• Lymphocytes

– lymphopenia, smaller lymphonodes

• Bone marrow

– hypoplasia

• Testicles, ovaries

– atrophia, fibrosis

• Lens

– opacity

• Skin

– ulcers, tumors

• Cartilage

– retarded growth, malformation of the legs

• Fetus

– developmental anomalies

Climate and weather

• Climate and weather have direct and indirect

effect on the diseases

– Condition predisposes for certain pathogens

• Meteoropathology

– Hot front, cold front

– is there any connection between fronts and diseases? -

outbreaks

• Colic in horses

• Erysipelas in pigs

External causes of diseases• Physical effects

• Chemical effects

• toxicosis

• Biological effects

• Infectious agents

• Virus, bacteria, fungi, prions, protozoa

• Inadequate supply

• Oxygen, water, nutrient

9., Inadequate oxygen and water

supply

Disturbances in oxygen supply

• Suffocation (asphyxia) – lack of air

• Hypoxaemia – insufficient saturation of the blood

– Hgb saturation decreased (O2 decreased, CO2 increased)

– Hgb is incompetent for oxygen change (CO poisoning, nitrit poisoning)

– Hgb amount is less (hemolysis, anaemia)

– Intracellular respiratory enzymes are inhibited (cyanide poisoning)

– Paralysis of respiratory and/or vasomotor center

– Mechanical obstacles in the circulation and/or breathing

• Obstruction, compression, pneumonia, pneumothorax, pressure, paralysis

• Hypoxia - insufficient saturation of the tissues

• Hypercapnia – increased CO2 level in the tissues

Pathology of the suffocation

• Dark, unclotted blood

• Petechial hemorrhages

– serosal membranes, larynx, trachea, heart

• Acute lung hyperemia and edema

• Acute dilation of the heart

• Acute emphysema

• Differentiate from septicaemia!

Unclotted blood

Dilated stomach

Stomach torsion

Disturbances in water supply

• Exsiccosis, dehydration

– Lack of water intake

• Fluid loss never stops – eg. evaporation

• Relatively high mineral content, pH shift

– Increased fluid loss

• Vomiting, diarrhea, perspiration

• Pathological changes:

skin, eyes, etc.

• Hyperhydratio (water toxicosis)

– Normal kidney

– Loss of minerals and electrolites

10., Inadequate nutrient

supply. Starvation.

Disturbances in nutrient supply

• Total starvation (Inanitio completa)– No food intake (energy, protein)

– 40-50 % of the body: death (Cachexia)

• Partial starvation, malnutrition (Inanitio incompleta)– Food supply is not adequate

– Deficiency diseases

• Obesity, overfeeding (Obesitas)– Surplus of feed or feed components

– Continuous or occasional (dilation and rupture of the stomach)

– Other causes (lack of movement, hormonal disorder)

Obesity

(obesitas)

Incomplete starvation, malnutrition

• Causes

– Feed

• Quantity or quality (ingredients)

– Normal feed, but

• Inadequate food uptake

• Pathological lesions of the digestive tract

• Digestion - Maldigestion

• Absorption - Malabsorption

• Deficiencies

– Increased need

• Consequence: deficiency diseases

Complete starvation• Age

– young more sensitive

• Causes

– Lack of nutrients

• First glycogen is used up, than fat, proteins

• Consequence: autointoxication

– increased fat and protein catabolism ketonaemia

Cachexia

Oedema cachecticum