Behaviour and Disease

Question 1

What is the detailed description, list or inventory of all the different kinds of behaviour or activity of a species called?

Answer 1

An Ethogram!

Question 2

What are extensively used by veterinarians to aid in diagnosis?

Answer 2

Changes in behaviour, activity or posture

Question 3

Why does behaviour have an important role in diagnosing disease?

Answer 3

• Many diseases initially present as behaviour changes or problems

Question 4

Before diagnosing a primary behaviour problem and initiating behavioural therapy, what must be ruled out?

Answer 4

Medical differentials

Question 5

Why might disease pathogens be adapted to cause behavioural changes in their host?

Answer 5

To increase chance of transmission

Ex. rabies spread great bc it causes biting behaviour

Question 6

What type of ‘state’ is sickness?

Answer 6

A motivational state

Motivation states are states that cause animals to behave in a certain way

Question 7

What other motivational states does sickness compete with?

Answer 7

• hunger, exploration, reproduction, learning
• sickness often overwhelms or co-opts other motivational states

Question 8

What is the “Acute-Phase Response” to cytokines?

Answer 8

• fever
• inappetance
• increased sleep
• postural changes
• reduced motion, grooming
• isolation from others

Question 9

What are the short term advantages and long term disadvantages of adaptive cytokine responses?

Answer 9

Short term advantages:
- energy saving
- promotion of body defense mechanisms

Long term disadvantages:
- burning through a lot of energy maintaining the “acute-phase response”

Question 10

How does the immune system influence behaviour?

Answer 10

Just as the brain uses humoral and neural paths to affect the immune system, the immune system uses humoral and neural paths to affect the brain and influence behaviour

Question 11

Why might have acute phase responses evolved?

Answer 11

As strategies for addressing extreme threats to survival of a group, population, or species

Question 12

Why is there a reduced likelihood of clinical signs being expressed in unfamiliar environments? Why do some animals look okay when the vet arrives?

Answer 12

Expression of sickness behaviour is context-dependent which reduces likelihood of clinical signs being expressed in unfamiliar environments.

• behavioural responses may be more readily expressed in familiar environments and amongst familiar conspecifics

Question 13

How are welfare and disease linked?

Answer 13

• disease will often cause poor welfare
• poor welfare, resulting from a wide variety of different external causes, may make disease more likely, often by initiating immunosuppression

Question 14

What is the definition of stress?

Answer 14

An environmental effect on an individual that overtaxes its control systems and results in adverse consequences and, eventually, reduced fitness

Question 15

What are 4 responses to stress?

Answer 15

1. brain activity (reduced or focused)
2. adrenal and other physiological responses (humoral or neural)
3. immunological suppression (down regulation of immunity)
4. behavioural changes

Question 16

What is the stress response?

Answer 16

• stressors affect the BRAIN
• hypothalamus responds and releases CRH
• CRH acts on the anterior pituitary to release ACTH
• ACTH acts on the adrenal cortex to release cortisol
• Cortisol acts as a negative feedback loop to the hypothalamus and anterior pituitary

Question 17

What are responsible for causing sickness behaviour?

Answer 17

Proteins (i.e. cytokines) secreted by activated macrophages

Cytokines transmit messages from the immune system to the brain via humoral and neural pathways

Question 18

How can sickness behaviour generally be described? What is its impact?

Answer 18

A well-organized adaptive response of the host animal that may enhance disease resistance and facilitate recover, or avoid transmission within the population

Question 19

Think back to the case study, what types of questions were asked?

Answer 19

Generating a “History” and “Signalment” (aka signs animal is showing that may signal what systems are involved

Question 20

What role does behaviour have in diagnosing disease?

Answer 20

Changes in behaviour, activity or posture brought about by disease are extensively used by veterinarians to aid in diagnosis.
- Many diseases initially present as behaviour changes or behaviour problems
- Medical differentials must be ruled out before diagnosing a primary behaviour problem and initiating behavioural therapy

Question 21

What is ‘sickness behaviour’?

Answer 21

Sickness behaviour is a motivational state. Behavioural priorities are re-organized in sick animals.

Question 22

Why does behaviour change when an infection or other illness occurs?

Answer 22

Disease pathogens may be adapted to cause (or avoid causing) behavioural changes in their hosts that will increase the chance of transmission.

Sickness is a motivational state that competes with other motivational states such as: hunger, exploration, reproduction, learning.

Question 23

How does the brain know the rest of the body is sick?

Answer 23

The adaptive cytokine responses. The immune system uses humoral and neural paths to affect the brain and influence behaviour.

The animal is infected by the pathogen. Cytokines secreted by activated macrophages go to the brain to signal information. The brain translates this info and signals new behaviours with the goal that it won’t spread the infectious pathogen aka causes sickness behaviour.

Question 24

What are behavioural changes due to cytokine response?

Answer 24

Increased sleep, postural changes, reduced motion (grooming), isolation from others

Acute phase responses may have evolved as strategies for addressing extreme threats to survival of a group, population, or species. But for individual animals behavioural and inflammatory acute-phase responses during illness can make the animals “sicker” and impair prognosis, particularly for neonatal animals.

Question 25

What is evoked behaviour?

Answer 25

An animal’s response to standard stimuli

Question 26

What are some examples of uses of behaviour for disease diagnosis?

Answer 26

1. Daily routines (eating, elimination, grooming)
   - illness may influence the pattern of behaviour shown by animals in a 24hr period
   - the normal behaviour pattern needs to be established before alterations to the pattern by a parameter like pain can be confirmed
2. Evoked behaviour
3. Response to analgesic treatment