Physiological Indicators Flashcards
True or false
Behavioural changes happen before physiological welfare indicators
True
Behavioural changes happen before physiological welfare indicators however we still need physiological indicators because of what 4 things?
1) It’s essential to have an additional set of welfare indicators that can be used to assess welfare
2) Physiological indicators provide a different perspective than behavioural measures
3) Some limitations are seen with behavioural measures, but there are also limitations with physiological ones
4) physiology, neurology and behaviour are interrelated
Give some examples of physiological indicators
Cardiovascular and respiratory measurements Hormones Neurotransmitters Biochemical parameters Immune function Pheromones and secretions Gene expression Organ/tissue composition and pathology Anatomical indicators
Define homeostasis
Homeostasis = It’s the dynamic maintenance of a constraint internal environment within the body
Constraint = a limitation or restriction
The body's internal environment remains generally fairly constant despite significant changes in the environment
This is due to the body's dynamic internal maintenance mechanisms
Any challenge to an individual’s homeostasis is known as what?
Stress
Any challenge to an individual’s homeostasis is known as stress
What is the physiological definition of stress?
Physiological stress = response of the body to a demand that tends to disturb homeostasis
Due to the definition of physiological stress what 3 things can be said about it?
Stress responses are an adaptive mechanism
Stress responses are innate to the individual
Stress responses promote survival
How does stress responses promote survival?
Stress hormones are usually catabolic hormones
Catabolic hormones break down other molecules to release energy
Stress hormones break down molecules to release the energy needed at that time to perform an action necessary for the individual to survive
An example of this would be generating energy to run from a predator
What are stress hormones?
Stress hormones are an adaptive mechanism to generate energy to allow the animal to perform an action that ensures it’s survival in a stressful situation
What is the hypothalamic-pituitary-adrenal axis known as?
HPA Axis
The hypothalamic-pituitary-adrenal axis is a feedback loop responsible for what?
Promoting/controling stress responses
The hypothalamic-pituitary-adrenal axis is a feedback loop responsible for promoting/controlling stress responses
How does the HPA axis work?
First a signal is sent to the anterior pituitary lobe
Then the signal causes the anterior pituitary lobe to produce adrenocorticotropic hormones (ACTH)
Then the ACTH hormones travel to the adrenal cortex
ACTH then triggers the adrenal cortex to produce glucocorticoids
The glucocorticoids then travel through the blood to produce negative feedback once they reach either the hypothalamus or the posterior pituitary lobe
This then stops the stress response
What are glucocorticoids referred to as?
Stress hormones
Glucocorticoids are referred to as stress hormones
True or false
Different species produce different types of glucocorticoids
True
Give examples of different glucocorticoids produced by different species
Cortisol is produced by:
- humans
- ruminants
- most mammals
Corticosterone is produced by:
- birds
- rodents
- reptiles
Where are glucocorticoids produced?
Adrenal cortex’s medulla
Glucocorticoids are produced in the adrenal cortex’s medulla
What is the adrenal cortex’s medulla responsible for producing?
Glucocorticoids
Adrenaline
Noradrenaline
What types of hormone are glucocorticoids?
Glucocorticoids are steroid hormones
Glucocorticoids are also catabolic hormones
True or false
Glucocorticoids are at a constant level within an individual
False
Glucocorticoids levels show constant variation within the individual
How can you measure glucocorticoids?
From the:
- Blood
- Metabolites in:
- faeces
- urine
- Saliva
- Hair
- Milk
Where are glucocorticoids released into?
The blood
What kind of action is the effect on the body after the glucocorticoid hormones are released into the bloodstream?
Delayed action
The effect on the body after the glucocorticoid hormones are released into the bloodstream is a delayed action
What are the 3 benefits of having access to the Hypothalamic-pituitary-adrenal axis activity?
1) Glucocorticoids help us to deal with stress, as it maintains a steady state of fuel to the body
2) Glucocorticoids help to deal with stress invoking situations by helping to:
- Conserve glucose and energy molecules
- Elevate or stabilise glucose concentrations depending on the individuals need in a given situation
- Mobilise protein and lipid reserves
- Conserve salts and water
- have anti-inflammatory effects
3) Glucocorticoids are responsible for returning the body to a normal pre-stress state
This helps return the body to a normal homeostatic state
What are the 5 disadvantages of HPA activity as a welfare indicator?
There are only a limited number of steroid hormones in the brain, meaning that once the glucocorticoid brain receptors are saturated the excess glucocorticoids remain in the bloodstream
Due to this the excess glucocorticoids will travel around the body and bind to steriod receptors on other organs causing damage
Glucocorticoids maintain the organism in an alert state
Glucocorticoids have anti-inflammatory properties that slow down healing
Glucocorticoids suppress the immune system leaving the organism open to infection and disease
Glucocorticoids can also suppress the reproductive system
Due to these negative effects we can use glucocorticoids as a welfare indicator
What are glucocorticoids used to assess?
Stress and pain induced distress
Glucocorticoids are used in the assessment of stress and pain induced distress
Glucocorticoids are the most widely used assessment indicator of stress and pain induced distress
Why are glucocorticoids used in the assessment of stress and pain induced distress?
This is because glucocorticoid hormones are 1 of the easiest measures you can get non-invasively
What do glucocorticoids measure?
Glucocorticoids measure arousal rather than valence
Because glucocorticoid measure arousal rather than valence you need to do what 2 things in your welfare assessment?
1) Rule out interfering factors
2) Use another indicator to determine valence alongside glucocorticoids
Because glucocorticoid measure arousal rather than valence you need to do what 2 things in your welfare assessment?
1) Rule out interfering factors
2) Use another indicator to determine valence alongside glucocorticoids
What is important about species differences when it comes to glucocorticoids?
Across species the type of glucocorticoids varies and so do the glucocorticoid metabolites
Each species also varies in how the glucocorticoid metabolites are excreted and the proportion of glucocorticoid metabolites in each excretion type also varies
This is important to note when designing your experiments
What are fault bars/stress bars?
Fault bars/stress bars are a bar going across each feather of unusual colour/continuity compared to the rest of the feathers
It’s where a stressor effected all the feathers development at the same time causing a difference in feather continuity for all feathers that’s easy to see
How are fault bars/stress bars created?
Fault bars/stress bars are created by a stressor causing muscles around the feather follicle to constrict
This alters the feather follicles function altering the feathers development
What kind of stressors can cause fault bars/stress bars?
Human handling of the birds
Predation attempts on the birds
Where were fault bars/stress bars first seen and what where they applied to?
Fault bars/stress bars were first seen in wild birds and are now being applied to captive/domesticated birds to measure there welfare
What does research suggest fault bars/stress bars are a indicator of?
Acute stress
Research so far suggests that fault bars/stress bars in feathers are reasonable indicators of acute stress rather than chronic stress
What are 2 methods of measuring the HPA axis without measuring glucocorticoids?
In birds you can look for fault bars/stress bars
Actually get the adrenal glands and compare the adrenal glands proportional make up of its medulla vs cortex
What would you expect to see if you actually got the adrenal glands and compared the adrenal glands proportional make up of its medulla vs cortex to measure the HPA axis activity?
If the adrenal glands medulla is really large then the adrenal gland is hypertrophic
Hypertrophic = exhibiting hypertrophy (enlargement or overgrowth of an organ or part of the body due to size of the constituent cells)
The adrenal gland would be hypertrophic if the adrenal gland is overproducing glucocorticoids due to a stressor
What is adrenal glands hypertrophism a measure of?
Adrenal gland hypertrophism is more a measure of chronic stress
In specific circumstances what can chronic stress do to organs used by the immune system?
In some specific situations chronic stress can cause organs used by the immune system to shrink due to glucocorticoid damage
This has been seen to be more of a curved relationship than a linear relationship so this method should be used with caution
What does chronic stress do to reactions to stress?
Chronic stress can make animals generally unresponsive to stress but when the animal responds to the stress they overreact
Why might an animal be unresponsive to chronic stress?
They’re always tense
They’re always apathetic
Apathetic = showing or feeling no interest, enthusiasm or concern
Because chronic stress can make animals generally unresponsive to stress but when the animal responds they overreact,
Why does this makes measuring chronic stress difficult?
This can make measuring chronic stress difficult since sometimes stressed animals have lower baseline levels of glucocorticoids if they’re apathetic
Chronic stress and early life experiences can affect how the body responds to glucocorticoids
Early life experiences only apply to this if there was a severe traumatic event or chronic stress in youth
Due to chronic stress causing lower baseline levels of glucocorticoids, when using glucocorticoids as an indicator of chronic stress you need to compare it with another chronic stress indicator like what?
Looking for pathologies of relevant organs like:
Enlarged adrenal glands
Stomach ulceration
Comparing adrenocorticotropic hormone to cortisol concentrations can indicate altered responsiveness of the HPA axis
What 3 things do you need to know about a physiological indicator?
1) The physiology of the indicators production and their feedback loop
2) If they’re better for acute or chronic stress measurements
3) What their validation for being a welfare indicator is
Give examples of other physiological indicators other than glucocorticoids and the HPA axis
Oxytocin Prolactin Creatine kinase Vasopressin Urea Serum osmolality and haematocrit Immunoglobulin A (IgA) Telomere
How can oxytocin be used as a physiological indicator?
Oxytocin is used as both a hormone and neurotransmitter in the body
Due to its different uses you need to be aware of what it’s function is from your chosen sampling area to know what welfare indicator it is for
Oxytocin may indicate positive welfare and can be assayed in blood or urine
What can prolactin do?
Prolactin increases under certain kinds of stress and can impair reproduction
What does creatine kinase indicate?
High concentrations of creatine kinase in blood and urine can indicate muscle damage and over exertion
What does vasopressin indicate?
Increased concentrations of vasopressin can indicate nausea
What can urea indicate?
Urea can indicate protein catabolism following food deprivation
What does haematocrit mean?
Haematocrit = the ratio of the volume of red blood cells to the total volume of blood
What does serum osmolality mean?
Serum osmolality = a serum osmolality test measures the amount of chemicals dissolved in the liquid part (serum) of the blood
What can IgA indicate?
Low levels of IgA in the blood or saliva can indicate stress and immunosuppression
What can inflammatory cytokines indicate?
Inflammatory cytokines are produced by inflammatory cells
They can tell us the stress state of the animal
Also increased levels of cytokines have also been related to pain
What is telomere length used as a measure of?
Telomere length is used to measure cumulative stress in an individual
Why was telomere length posed as a animal welfare indicator?
Telomere attrition is accelerated by stress
Telomere length predicts future health in humans and non-human animals
What shortens telomere length?
Stress
Highly rewarding activities
Chronic recreational drug use is an example
High stocking densities
What are the 2 main problems with skeletal indicators?
1) You have to kill the animal to look at its skeleton
2) You have to wait until the animal dies naturally to do a postmortem to access the skeleton
True or false
Bone structure and fractures have been posed as a welfare indicator of you compare fractures with housing
True
Give an example of bone fractures used as a welfare indicator
You can compare keel bone fractures with poultry housing systems
More keel bone fractures could be a sign of bad welfare because:
- Keel bone fractures cause pain
- Keel bone fractures could be due to poor cage/enclosure design
The birds will break their keel bone due to crashing into elements of their housing
True or false
Another type of skeletal welfare indicator is fluctuating asymmetry of bilateral bone structures
True
How can fluctuating asymmetry of bilateral bone structure be used as a welfare indicator for early developmental stress?
Bilateral bone structures would normally develop to look exactly the same as eachother
However stress can lead to 1 side/bone structure being stunted or developing weirdly meaning that the bilateral bone structures won’t develop into identical bone structures
The nervous system is split into what 2 systems?
Central Nervous System
Peripheral Nervous System
The Peripheral Nervous System is divided into what 2 systems?
Somatic Nervous System
Autonomic Nervous System
What does the Autonomic Nervous System control?
The Autonomic Nervous System controls vital bodily functions and is therefore largely beyond conscious control
The Autonomic Nervous System is a autonomic system, what does this mean?
The Autonomic Nervous System is self-regulating
The Autonomic Nervous System can be divided into what 2 systems?
Sympathetic Nervous System
Parasympathetic Nervous System
What responses does the Sympathetic Nervous System control?
The Sympathetic Nervous System controls an individuals fight or flight responses
What responses does the Parasympathetic Nervous System control?
The Parasympathetic Nervous System controls the rest and digest responses
The Parasympathetic Nervous System is responsible for slowing heart rate, digestion, and gastric gland control
Within a situation with an extreme stimulus the fight or flight response will trigger the activation of what system?
Sympathetic Medullary System
Within a situation with an extreme stimulus the fight or flight response will trigger the activation of the Sympathetic Medullary System
Within a situation with an extreme stimulus the fight or flight response will trigger the activation of what system?
Sympathetic Medullary System
Within a situation with an extreme stimulus the fight or flight response will trigger the activation of the Sympathetic Medullary System
What does the activation of the Sympathetic Medullary System stimulate the release of?
Adrenaline
Noradrenaline
They are secreted from the adrenal glands medulla
Give examples of measurable changes to the body that adrenaline and noradrenaline create
Elevated heart rate Elevated blood pressure Vasoconstriction Pupil dilation Dilation of bronchioles Elevated glucose metabolism Inhibition of intestinal motility and secretions
What is the Sympathetic Medullary System also known as?
SAM = Sympathetic Medullary System
True or false
Another way to measure Sympathetic Medullary System activation is to use thermal imaging to detect differences in an animals internal temperature
True
How would you use thermal imaging to see Sympathetic Medullary System activation?
Temperature varies between body regions
An example is that changes in eye temperature has been validated in being able to show us affects of analgesics and negative valence stimulation
You can then use this to compare different welfare states and different methods of management/husbandry of the animal
Another example is that you can use thermal imaging alongside behavioural measures to assess welfare
You can look at heat stress to see if a cage/housing is appropriate
You can then look at behavioural measures like:
- panting
- eating frequency
- postural changes
Then you’d compare the behavioural data with the thermal data to see how well the animals can dissipate heat
What are the 3 general problems with physiological indicators?
Sympathetic Medullary System (SAM) measures may be related to non-stress factors
Glucocorticoids are affected by multiple factors not just stress and so there levels naturally fluctuate
Due to this when designing an experiment you need to control for the other factors to ensure the data is useable
Physiological measurements alone may not be sufficient indicators of stress or reduced welfare
Due to this you always need multiple indicators and to be aware of what they can and can’t do
