Decision-making Flashcards
What is the difference between “risk” & “hazard” & give examples in the veterinary context.
Risk - probability of an event and the consequences of this event
Hazard- a substance, organism or action that has the potential to lead to an adverse event.
Example:
Poultry kept in outdoors come in contact with wild birds.
RISK: Becoming infected with avian influenza and the consequences of it.
HAZARD: Wild birds may carry pathogens which may also infect domesticated birds.
What is a “decision” in the context of epidemiology & public health?
A choice or judgement as to future action, reached after consideration.
What are the components of RATIONAL decision-making?
Decision-making model
Aim at making logically sound decisions
This is so retarded.
What are the six elements of decision models?
- Define the problem eg., BVD causes disease/BVD vaccine costs money
- Define alternative solutions eg., vaccinate vs. not vaccinate & improve biosecurity
- Define assessment criteria - eg., economic, welfare
- Collect information, evaluation - eg. cost of the vaccine, risk of BVD introduction
- Select alternative
- ** Implementation**
What are the steps in risk management?
Collect risk information
Make a decision
Implement the decision
Review the decision
Monitor the risk
Collect risk information etc.
What is risk assessment?
A structured, systematic and complete collection
and interpretation of all available evidence
What are two key elements considered in risk assessment?
- Probability of occurrence of an event
- Consequences of an event
Ie., Ask the questions:
What is the problem? (define the problem)
What can go wrong?
How likely is it to go wrong?
What are the consequences if it goes wrong?
What is risk communication?
The exchange of facts and opinions on risk between individuals and groups affected by risk and risk management.
What is a scenario analysis?
A systematic comparison of outcomes of a set of scenarios (alternatives).
What are the hazards for food safety?
Biological:
Bacteria, Viruses, Parasites, Prions
Chemical:
Vet Meds, Farm Products (fertillizer, insecticides), Environmental Contaminants (eg., Dioxin)
Physical:
Glass, Wire, Vaccine Puncture
What is the upper ilmit for somatic cell count in cow’s milk for EU?
400,000 cells/mL (>3 months geometric mean) is EU-wide upper legal limit for SCC in milk destined for liquid market.
What are the considerations in assessing animal welfare problems (W)?
W = NIDC
N = number or animals affected: incidence or prevalence
I = Intensity of suffering
D = Duration of suffering
C = Capacity of animal to suffer
What are two key requirements of farm-animal problems that qualify them as welfare issues?
- They are avoidable
- They depend on the farming system and the standard of management
Eg.
- Production disorders in dairy cows
- Handling problems in beef cattle
- Pneumonia in pigs
- Dehydration in runt broilers
- Foot-pad dermatitis in broilers
- Cold stress in sheep after shearing
- Transport stress in sheep
What are some examples of UNAVOIDABLE welfare issues?

• Leg disorders in broilers
• Shearing stress in sheep
• Tail docking lambs
• Deprivations in caged layer hens
In gait scoring, what is the score for a bird with no gait abnormalities?
0
Zero
Feet under its legs
Can balance on one leg
Can walk backwards if necessary
What is meant by a bird rated with Gait Score 1?
It has a slight defect that is not easily defined.
It may have a large stride (not easily recognised) that results in uneven-ness in gait.
What is mean when a chicken is rated with Gait Score 2?
It has a definite defect but it doesn’t stop the bird from getting about to compete for water, food or space.
Eg. It could be slightly lame in one leg.
What is wrong with a bird with a Gait Score of 3?
It has an obvious defect that affects its ability to move. For example, it might have a limp, an unsteady strut or a severe splaying of one leg.
A Gait Score 3 bird prefers to sit down when not moving.
Three is a sitter.
What is wrong with a Gait Score 4 bird?
It has a severe gait defect.
It can still walk, but with difficulty, and only when it’s forced to move or strongly motivated. It usually squats down at the first opportunity.
Acceleration, maneuvreability & speed are all severely affected.
Four is a squatter.
What is wrong with a Gait Score 5 bird?
It is incapable of sustained walking.
It is the saddest looking bird in Neville’s video.
What are the main leg/foot pathologies that affect broilers?
Which are assumed to be painful?
PAINFUL:
Osteomyelitis
Spondylolisthesis
Inflammatory joint disorders such as:
Synovitis
Tenosynovitis
MAYBE PAINFUL:
Tibial dyschondroplasia
PROBABLY NOT PAINFUL:
Tibia and femur rotation
What is Osteomyelitis?
Inflammation of the bone caused by a pyogenic organism.
In poultry the infection is usually acquired through the navel in the hatchery, and involves a Staphylococcus aureus.
Painful.
The physeal region becomes pitted with foci of osteomyelitis and in advanced cases the physes are soft and fragile. In cases which pass meat inspection at the processing plant, femurs softened through osteomyelitis (and other conditions causing femoral head necrosis) are a problem for outlets such as KFC because automatic deboning equipment leaves bone splinters behind in the thigh meat which is subsequently sold as a breaded ‘boneless’ product.
What is Spondylolisthesis?
Displacement of one vertebra over another.
Painful.
What is synovitis?
Inflammation of the synovial membrane.
Pitting, inflammation and erosion of the acetabulum from Staphylococcus aureus.
Inflammatory joint disease.
Painful.
What is Tenosynovitis?
Inflammation of a tendon sheath. Inflammatory joint disease.
Painful.
What is Tibial dyschondroplasia?
Abnormal growth or differentiation of tibial cartilage with the formation of a cartilaginous body in the shaft at and below the epiphysis. It can lead to softening and deformity of the proximal head of the tibia, and this in turn can cause angulation of the leg distal to the defect.
Maybe painful.
What are rotated long bones, such as femur rotation or tibial rotation?
Axial rotation of the bone usually near the diaphysis. This also leads to angulation of the legs.
Probably not painful.
What is the definition of opportunity cost in the vet-client context?
The sacrifice of alternatives in production (or consumption) of a good.
What is productivity of an enterprise?
The efficiency of conversion of inputs to outputs
How would you calculate productivity of an enterprise?
Productivity =
Total value of outputs per unit of time / Total value of inputs per unit of time
Can also use:
Production per animal per unit time
or
Production per hectare per unit time
What framework do economists use to make farm-animal welfare decisions?
Marginal cost-benefit analysis - the marginal costs or benefits incurred or accrued after a change is implememented.
What are the factors involved in partial-budget analysis?
Costs:
New Costs (investment)
Revenue Forgone (opportunity cost)
Benefits:
Saved Costs
New Revenue
What is decision-tree analysis?
Decision Tree is a flow-chart like structure in which internal node represents test on an attribute, each branch represents outcome of test and each leaf node represents class label (decision taken after computing all attributes).
A path from root to leaf represents classification rules.
In decision analysis a decision tree and the closely related influence diagram is used as a visual and analytical decision support tool, where the expected values (or expected utility) of competing alternatives are calculated.
A decision tree consists of 3 types of nodes:
- *Decision nodes** - commonly represented by squares
- *Chance nodes** - represented by circles
- *End nodes** - represented by triangles
Decision trees are commonly used in operations research, specifically in decision analysis, to help identify a strategy most likely to reach a goal.
What must be taken into account in a Disease Impact Assessment?
A DIA looks at Direct & Indirect Impacts:
Direct:
Refers to the impact caused by the disease. Includes visible & invisible losses due to the disease.
Indirect:
Refers to impact caused by human reaction/intervention to the disease. Includes additional costs & revenue foregone.
What are examples of the VISIBLE LOSSES due to the DIRECT IMPACT of the disease in a DIA?
Dead animals
Thin animals
Animals poorly developed
Low returns
Poor quality products
What are examples of INVISIBLE LOSSES due to the DIRECT IMPACT of disease in a DIA?
Fertility problems
Change in herd structure
Delay in the sale of animals and products
Public health costs
High prices for livestock and livestock products
What are examples of ADDITIONAL COSTS due to the INDIRECT IMPACT of disease (human intervention) in a DIA?
Medicines
Vaccines
Time
Treatment of products
What are examples of REVENUE FOREGONE due to INDIRECT IMPACT of a disease (human intervention) in a DIA?
Access to better markets denied
Sub-optimal use of technology (?)
After doing an disease-impact assessment, which compares costs associated with disease against costs associated with human intervention, how would you conclude that investment in treatment is worthwhile?
You would say an investment was worthwhile if avoidable losses are greater than costs of a change in disease status.
What is ranked as the highest priority pathogen in terms of public health impacts?
Campylobacter spp. spp from poultry meat & environmental contamination by farm animals
Followed by Salmonella from chicken eggs.
Followed by Listeria.
