2. The universe of natural law
Greeks thought-disease was the
result of derangement of four
humours of the body
Four humours were associated with
four properties (heat,moisture,
dryness and cold) and with four
elements (air, earth, water and fire)
3. The universe of natural law
Diseases were considered to be caused
by external forces, including climatic
and geological changes
The word 'malaria' literally means 'bad
air' and hints at the 19th century belief
that the disease was caused by stale air.
The Greek idea of disease was
susceptible to scientific investigation
4. Contagion
Idea-diseases can be transmitted from
one animal to another has its ubiquitous
origins
The Romans believed that disease could
be spread by airborne seeds
The primitive Hindus associated sick
rats with human plague, the first
suggestion of a zoonosis.
5. Germ Theory of Diseases
Main advances-identification of
microbes as causes of infectious
diseases (19th century)
Louis Pasteur's investigation of anthrax
& rabies
Robert Koch's discovery of bacteria
causing TB & cholera firmly established
microbiology (downfall-miasmatic
theory)
6. Miasmatic Theory Of Disease
Miasmatic theory of disease-
such as cholera were caused
by a miasma (ancient
Greek:"pollution"), a noxious
form of "bad air"
7. Microbes as cause of infection
The set of postulates formulated by
Koch to define causal agents-used to
identify many microbial diseases since
those early days of bacteriology
Viruses discovered in late 19th century
(1892) Iwanowsky demonstrated that
tobacco mosaic disease could be
transmitted by sap (filterable agent)
8. Movement for change
Veterinary medicine has
experienced five stable periods
and revolutions up to the
middle of the 20th century
relating to disease control
9. The first period: until the first century AD
Initial domestication of animals
brought man into close contact with
animals and therefore with their
diseases
Humoral pathology developed and the
miasmatic theory of cause evolved.
Slaughter became preventive strategies
10. The second period: the first century
AD until 1762
Veterinarians specialized in equine
medicine and surgery, reflecting the
importance and value of horses
11. The third period: 1762-1884
The animal plagues, especially those of cattle, became
particularly common in Europe with the introduction
of rinderpest from Asia
Public concern, highlighted by the rinderpest outbreak
of 1865 was responsible for the establishment of the
British State Veterinary Service
By the mid-19th century, disinfection was also being
applied to control the disease
12. The fourth period: 1884-1960
Treatment of disease was based on laboratory
diagnosis involving isolation of agents and
identification of lesions followed by Therapy
The discovery of disease vectors facilitated prevention
by vector control
13. The fourth period: 1884-1960
Many infectious diseases were
either effectively controlled
/eradicated using new techniques
of the microbial revolution and
older techniques including
quarantine, importation
restrictions, slaughter and hygiene
14. The fifth period
The animal-health problems and anomalies stimulated
a change in attitude towards disease causality and
control
15. The fifth period
Veterinary services Veterinarians
practicing in the livestock sector
continue to control and treat disease in
individual animals.
Developments in molecular biology are
improving diagnostic procedures
16. New control strategies
Two major strategies: the
structured recording of
information on disease
Analysis of dis. in populations
Surveillance & monitoring:
intensive investigation of
particular diseases
17. Recent trends
Veterinary services : Control and treat disease individual animal
Improving diagnostic procedures
New opportunities for vaccine production systems
Multification nature of many disease necessitates modification
of the environment of the animal and management practices.
Food animals-reduced levels of production
Diseases assessed in terms of suboptimal health, manifested by
decreased herd performance
Select suitable ‘performance indicators’ (e.g., ‘calving to
conception interval’) herd that miss the targets.
Performance-related diagnosis.
Veterinarian, involved in husbandry, management and nutrition.
Veterinarian’s evolving role in animal production.
Investigations of specific animal health problems of complex
cause, such as mastitis.
18. Food Quality
Area of concern (Vet. public health) is food quality
Guaranteeing wholesomeness of food at the abattoir,
and addresses all levels of the production chain.
Establishment of quality assurance programs on the
farm, using techniques such as HACCP (Hazard
Analysis Critical Control Points), in focus from quality
control of food throughout the production.
Quantitative evaluation of the risk of transmission of
infection throughout the chain
19. Animal welfare
Obvious aspects of animal welfare are deliberate
physical abuse (non-accidental injury) and
neglect; surgical mutilation (tail docking of dogs)
Welfare in livestock production systems is often
evaluated in the context of the ‘five freedoms’
freedom from hunger and thirst;
freedom from discomfort;
freedom from pain, injury and disease;
freedom from fear and distress.
20. National & international disease
reporting
Improved disease reporting systems at the national &
international level in the prevention of spread of infectious
agents form one country to another.
Residues need to be identified and eliminated-pesticides and
hormones, antibiotic residues
Free internal market in the European Union, and global goals to
liberalize international trade through the World Trade
Organization (WTO)
highlighting the requirement for comprehensive disease
reporting
Established organizations, such as the Office International des
Epizooties (OIE), are modifying their goals and reporting
techniques, taking account of these new requirements.
21. What Is a "Herd Health"
Herd health plans are designed by herd veterinarian
and producer to reduce disease incidence, provide
effective diagnosis and treatment protocols, and
improve productivity
Herd health Includes:
Routine visits by veterinarian at specific times of
year
Training of employees
Health and production records
Economic analysis of decisions
22. Herd health
Herd health is a key driver of profitability in today’s
production environment.
Maintaining health is extremely challenging,
particularly as management systems become more
intensive and profit margins are squeezed.
Disease robs profits and productivity by reducing
growth, increasing deads, lightweights and culls, and
adding drug and vaccine costs.
A healthy and robust immune system protects profits
and animal welfare by minimizing the incidence and
effects of disease
