Animal Health and Disease (Infectious and Non-Infectious)
Splitting the domain
Infectious disease covers bacteria, viruses, fungi, and parasites, plus the principles of transmission, incubation, carrier states, and control (biosecurity, vaccination, quarantine). Non-infectious disease covers nutritional, metabolic, toxic, genetic, and neoplastic conditions.
Infectious disease concepts
- Transmission routes: direct, aerosol, faecal–oral, vector-borne, vertical.
- Control: vaccination types (live vs inactivated), herd immunity, biosecurity, isolation, disinfection.
- Notifiable diseases: recognition and reporting obligations matter for public health.
- Zoonoses: e.g., brucellosis, rabies, salmonellosis.
Non-infectious disease concepts
- Metabolic: ketosis, hypocalcaemia, rumen acidosis - linked to production and diet.
- Deficiency: minerals (e.g., selenium, copper), vitamins.
- Genetic and congenital conditions.
- Neoplasia recognition and basic classification.
Traps
Questions often present a clinical sign list and ask for the most likely diagnosis - check species, age, and diet first. Another trap is confusing notifiable with merely contagious: not all contagious diseases are notifiable, and not all notifiable are contagious. Also, do not assume infectious cause for herd-level problems; nutritional and management causes are common.
Worked example
A dairy herd with sudden drop in milk yield, subclinical rumen pH fall, and laminitis: think rumen acidosis (dietary/management) before infectious disease. Ask: was the ration changed?
Study approach
Create a disease matrix: agent, species, signs, transmission, control, zoonotic status.