animal welfare

Animal welfare (Prof. Donald M. Broom, Cambridge): "the physical and psychological state of an animal as regards its attempt to cope with its environment."

Framework

Change in welfare → change in physiological states → physiological responses (measurable).
Change in welfare → activation of CNS → two response pathways:

  1. Autonomic Nervous Responses

  2. Neuroendocrine Responses

MODULE 6A: AUTONOMIC NERVOUS SYSTEM (ANS)

ANS = Sympathetic Adrenal Medullary system (SAM) + Parasympathetic Nervous System (PNS)

SAM Process

  • Central Nervous System → stimulates Adrenal Medulla (releases catecholamines, circulated) and innervates Heart (Sinoatrial node).

  • SAM effects:

    • ↑ Cardiac output: ↑ heart rate (tachycardia), ↑ cardiac muscle contraction

    • ↑ Blood to muscles: peripheral vasoconstriction, spleen contraction

    • ↑ Air intake: ↑ respiratory rate, bronchiole relaxation

PNS System

  • Regulates/counters SAM system.

  • Reduces cardiac output → ↓ heart rate (bradycardia) via heart (sinoatrial node).

Measurement of ANS

  • ANS response = acute measure; pathological changes = chronic measure.

  • Direct measures: Heart rate, catecholamine levels, respiratory rate, blood pressure.

  • Indirect measures: Adrenal habituation, adrenal enzymes.

Heart Rate

  • Indicates welfare at that point in time.

  • ↑ HR = tachycardia (active response); ↓ HR = bradycardia (passive response).

  • Example: Sheep HR ↑45 bpm with strange person; ↑79 bpm with strange person + dog (Baldock & Sibly, 1990).

  • Example: Rodent HR ↓ when disturbed by threatening visual cue or sudden noise (Hofer, 1970).

  • Arrhythmias = chronic welfare indicator: repeated restraint → arrhythmias in squirrel monkeys (Corley et al., 1973); repeated noise/threat → arrhythmias in rats (Hofer, 1970).

  • Measurement methods & invasiveness/restrictiveness/disturbance:

    • Direct (stethoscope): not invasive; restrictive; disturbing

    • Tethered (Polar monitor): not invasive; restrictive; not disturbing

    • Telemetry: invasive; not restrictive; not disturbing

    • Remote: not invasive; not restrictive; not disturbing

Blood Pressure

  • Measure of chronic welfare change.

  • Example: Aggression → ↑ BP in mice (Henry et al., 1975); daily immobilisation → ↑ BP in rats (Lamprecht et al., 1973).

  • Measurement methods:

    • Cuff (tail/ear/arm): not invasive; restrictive; disturbing

    • Catheterization (arterial): invasive; restrictive; not disturbing

    • Telemetry: invasive; not restrictive; not disturbing

Respiratory Rate

  • Assesses present state; easy to observe; closely correlated with heart rate.

  • Example: Lamb respiratory rate ↑ after tail docking and castration (Mellor & Murray, 1989).

Catecholamines

  • Examples: Rat catecholamines ↑ with cage door opening, handling/moving between cages, restraint (40-fold ↑) (Kvetnansky et al., 1978). Defeated male guinea pigs show significantly higher catecholamines than victors (Sachser & Lick, 1989).

  • Measurement methods:

    • Catheterization: invasive; restrictive; not disturbing

    • Urine: not invasive; not restrictive; disturbing

    • Autopsy: not invasive; not restrictive; not disturbing (post-mortem only)

Adrenal Habituation (indirect, chronic assessment)

  • Repeated stimulus → ↓ catecholamine to that stimulus (habituation) or ↑ catecholamine to other stimuli (sensitization).

  • Assessed by measuring levels continuously, before/after stressful period.

  • Example: Repeated rat restraint — day 27 vs. day 1: restraint-induced catecholamine ↓, but different stressor induces ↑ catecholamine (Konarska et al., 1989).

Adrenal Enzymes

  • Enzymes in catecholamine production/breakdown (measured post-mortem): Tyrosine hydroxylase (TH), Phenylethanolamine-N-methyl transferase (PNMT), Monoamine oxidase (MAO).

  • Example: Social stress in mice → ↑ TH, PNMT, MAO levels (Henry et al., 1971).

Vanillylmandelic Acid (VMA)

  • Metabolite of catecholamine breakdown; measured in blood or urine.

  • VMA levels correlate with self-reported stress in humans (Brantley et al., 1988).

Limitations of ANS Measures

  1. Other factors causing changes: activity, metabolism, timing of sample.

  2. Disturbance due to measurement: human presence, handling, restraint, sampling method.

  3. Individual differences: high/low responders (rats — Livezey et al., 1985); dominance status (tree shrews — von Holst, 1986); sex (rats — Livezey et al., 1985).

Conclusions (6A)

  • ANS response = acute measure; chronic change = chronic measure.

  • Direct: Heart rate, blood pressure, respiratory rate, catecholamines. Indirect: adrenal habituation, enzymes, metabolites.

  • ANS measures are limited — care required in assessment.

MODULE 6B: NEUROENDOCRINE SYSTEM (NS)

A welfare change affects three sub-divisions:

  1. Hypothalamic-Pituitary-Adrenal axis (HPA)

  2. Anterior Pituitary

  3. Posterior Pituitary

HPA Axis

  • Major mediator of endocrine responses; mobilises energy stores for physical response.

  • Mediates responses to stress, sexual activity, courtship, food arrival.

  • HPA Cascade: Stimulus → Hypothalamus → CRH → Anterior Pituitary Gland → ACTH → Adrenal Cortex → Glucocorticoids → Liver.

  • HPA characteristics: Not as immediate as SAM; acute welfare measure. Plasma glucocorticoids elevate 2–10 min after stimulation; can stay elevated for hours depending on stimulus severity.

Glucocorticoids (GCCs) — species-dependent

  • Cortisol: humans, pigs, monkeys.

  • Corticosterone: rats, mice, other rodents.

  • Useful acute direct measure.

  • Example 1: Cortisol ↑ in lambs after tail-docking, castration (Mellor & Murray, 1989).

  • Example 2: Corticosterone in rats after aggressive encounter — victor: initial ↑ then ↓; loser: initial ↑, remains elevated (Henry & Stephens, 1977).

  • Measurement methods:

    • Plasma: invasive; restrictive/not restrictive; disturbing/not disturbing (mixed)

    • Saliva: not invasive; not restrictive; disturbing

    • Urine: not invasive; not restrictive; not disturbing

    • Feces: not invasive; not restrictive; not disturbing

    • Analysis techniques: ELISA, HPLC, competitive protein binding assay, radioimmunoassay.

Chronic Welfare Assessment (indirect HPA)

  • Sensitisation of HPA: via ACTH challenge test.

  • Brain glucocorticoid receptor levels: hippocampus and amygdala.

  • ACTH challenge test: ACTH administered, resulting glucocorticoid levels measured. Long-term overcrowding → higher cortisol response than controls in dairy cows (Friend et al., 1977).

  • Brain glucocorticoid receptors: post-mortem test; brain samples exposed to radio-labelled glucocorticoids; ↓ receptor levels in rats with prolonged handling/disturbance (Wadham, 1997).

Limitations of HPA

  1. Individual differences: early experience (rats — Levine et al., 1967); sex (rats — Livezey et al., 1985).

  2. Disturbance due to measurement: human presence, handling, restraint, sampling method.

  3. Other factors causing changes: species (New World Monkeys — Klostermann et al., 1986); metabolism; timing of sample.

Anterior Pituitary (AP)

Other hormones associated with welfare changes:

  • ACTH

  • Reproductive hormones: Prolactin, Luteinising hormone (LH), Follicle stimulating hormone (FSH)

ACTH

  • Acute measure — more rapid than glucocorticoids, short-lived.

  • Radioimmunoassay analysis; shows diurnal variation.

  • Example: ACTH ↑ in rhesus monkeys when confined and exposed to noise (Kalin et al., 1985).

Reproductive Hormones

  • Associated with other welfare-change measures.

  • Sensitivity order: Prolactin > LH > FSH.

  • Radioimmunoassay analysis; acute measures rise quickly and remain elevated for hours.

  • Examples: Prolactin ↑ with handling/blood sampling in rats (Gärtner et al., 1980); LH ↑ in rats with novel environment/restraint (Briski & Sylvester, 1987); FSH ↑ in rats when cage moved short distance (Gärtner et al., 1980).

  • Limitations:

    • Sample timing: Prolactin = diurnal; LH = pulsatile.

    • Sex: females > males.

    • Stage of oestrus: Prolactin (pro-oestrus > dioestrus); FSH (pre-ovulatory > ovulatory).

Posterior Pituitary (PP)

  • Oxytocin associated with welfare changes; species differences:

    • Restraint in rats = 5–10-fold ↑.

    • Confinement + noise in rhesus monkeys = ↓ for 30 minutes.

Other Measures (neuroendocrine + ANS effects)

  • Temperature, opioid levels, organ pathology.

Body Temperature

  • Changes in other physiological systems (e.g., adrenal activity) → changes in core body temperature = acute welfare measure.

  • Example: Rat body temperature ↑ induced by storms/unfamiliar people (Georgiev, 1978); ↓ body temperature in defeated tree shrews (von Holst, 1986).

  • Measurement methods:

    • Direct (thermometer — mouth, ear, rectal): measures core temp; not invasive; restrictive; disturbing.

    • Telemetry (internal): measures core temp; invasive; not restrictive; not disturbing.

    • Thermo-imaging (skin): does not measure core temp; not invasive; not restrictive; not disturbing.

Organ Pathology

  • Chronic welfare changes → wide variety of pathologies, mostly measured post-mortem.

  • Pathologies include: adrenal hypertrophy, kidney lesions, myocardial lesions, atherosclerosis.

  • Examples: Social instability in female rat groups → adrenal hypertrophy (Haller et al., 1999); subordinate mice show kidney lesions in presence of dominant animals (Henry & Stephens-Larson, 1985); myocardial lesions with longer restraint periods in pigs (Wutzen et al., 1987).

Opioids

  • Three types: Endorphins, Enkephalins, Dynorphins.

  • Functions: stress-induced analgesia, control hormone release.

  • Measurement: Blood (invasive, restrictive, disturbing); Blood receptors (not invasive, not restrictive, not disturbing).

  • Examples: ↑ plasma β-endorphin in lambs during castration, tail docking, mulesing (Shutt et al., 1987); tethered sows show higher opioid receptor density than group-housed sows (Zanella et al., 1992).

Conclusions (6B)

  • Neuroendocrine system provides acute and chronic welfare measures.

  • ANS responses measurable directly and indirectly.

  • NS measures are limited — care required in assessment.

  • Other physiological responses (temperature, opioid levels, organ pathology) can also assess welfare.

MODULE 7A: Introduction & Behavioral Indicators in Welfare Science

Learning Objectives: Understand factors that influence animal behavior; identify how behavioral indicators contribute to understanding animal welfare.

Introduction

  • Behavior is useful in welfare studies because it indicates how animals feel through: choices the animal makes, and reaction to a variety of stimuli.

  • Behavior assessments are often used as indicators of welfare.

  • Animal welfare scientists use behavioral indicators to identify what's important to animals and to recognize poor welfare or good welfare.

What is Animal Behavior?

  • The choices an animal makes as a result of analyzing environmental stimuli (often many).

  • Influenced by: experience, physiological status (e.g., age, pregnancy), innate responses (e.g., species, breed).

Five Categories of Behavioral Indicators in Welfare Science:

  1. Behavior Observation

    • Observe time allocation in natural environment vs. record behavior in restricted environment.

    • Examples: Open/outdoor environment — 60 different behaviors in blue-breasted quail; complex sexual, parental, anti-predator behaviors in domestic hens. Restricted/housed environment — broiler chickens showed 11–19 behaviors (different studies); caged hens showed 18 behaviors.

    • Result: Very limited behavior in restricted environment.

    • Conclusion: Welfare is compromised by restricted environment.

    • Limitation: Doesn't tell us whether particular restrictions matter to the animal — other methods developed.

  2. Choices

    • Offer the animal a variety of options and let it choose.

    • Example: Hens given access to bean bag (BB) and flat floor (FF) nests; choices recorded over 16 egg-layings. Birds favored bean bags: Glances 0.66 (BB) vs 0.25 (FF); Examinations 0.72 vs 0.28; Entries 0.81 vs 0.15.

    • Result: Hens prefer nests with loose material manipulable by body/feet.

    • Conclusion: Animals choose plenty of space, comfortable bedding, control over environment, and interaction with others.

    • Limitation: Shows preference but not whether welfare suffers if the preference isn't met.

  3. Work an Animal Will Do to Gain What It Needs

    • Animal works for rewards (food, dust bath); amount of work = importance of reward.

    • Example: Sow experiment — layout with straw area, feed area, water, separated by lockable swing-door panels. Entries recorded: Low work (1 press): Food 21.4, Straw 17. High work (150 presses, 2 days before farrowing): Food 11.4, Straw 2.6. High work (150 presses, 1 day before farrowing): Food 17, Straw 16.4.

    • Result: Sow's motivation to nest-build is very strong on the last day of pregnancy.

    • Conclusion: Animals work hardest for food rewards, but other motivations (e.g., nesting) can become very strong at certain production-cycle times.

  4. Work an Animal Will Do to Escape Unpleasant Stimuli

    • Measures how hard an animal works to avoid stress/pain.

    • Example: Sheep clearing a raceway under 4 conditions — Free Run (fastest, ~0–20s, flat), Restraint, Wired-up, Full Electro Immobilisation (slowest, up to ~400s) — times increase with trial number for restrained groups but stay low for free-run.

    • Result: Useful for measuring short-term stressors, NOT chronic suffering.

    • Caution: These tests cause suffering.

  5. Deviations from Normal Behaviour

    • Stereotypies — repetitive abnormal behaviors; more time spent in stereotypy = poorer welfare (Very Good = occasional stereotypy from minor frustration; mid = 5% of active time; Very Poor = 40% of active time).

    • Example: Wild giraffe — much locomotion, no stereotypies, variation in time budgets across sites. Zoo giraffe — little locomotion, all show stereotypies (especially at night); one zoo recorded stereotypic behavior >60% of nights.

    • Conclusion: Abnormal behavior patterns most common in barren, unstimulating environments.

  6. Interaction with Humans

    • Animals learn by experience; associate humans with pleasure or with pain/fear.

    • Example: Variation in pig stockmen — negative interaction % rises across 0–30+ stockpeople (chart shows increasing trend). Variation in pigs' fear of stockmen across Australian farms — time to interact ranges from ~160s down to ~80s across different farms.

Comparison: Behavioral vs. Physiological Measures

Advantages

Disadvantages

Easier/less invasive

Interpretation is difficult

Requires less equipment

Some consider it less rigorous

Can be done away from the lab

Conclusion (7A): Observation of animal behavior tells us a lot about choices and their importance to the animal.

MODULE 7B: The 'Normal' Animal & Indicators of Poor Welfare

Learning Objectives: Recognize and interpret behavioral indicators of animal welfare; learn to identify possible causes of abnormal behavior.

Behavioral Indicators of the 'Normal' Animal:

  • Alertness

  • Curiosity

  • Range of activities

  • Interaction with other members of the herd/flock

  • Interaction with humans/aversion to humans

  • Play

  • Behavior is also influenced by species, age, breed, and sex.

  • The experienced stockman can recognize these normal patterns.

Behavioral Indicators of Poor Welfare (6 categories):

  1. Limited Range of Activity — may affect individuals or whole groups:

    • Restricted space (intensive farming/lab housing)

    • Close tethering

    • Lameness

    • Increased lying time (due to lameness, disease, obesity, weakness)

    • Lame animals suffer: in pain; don't interact normally with herd; often thin (can't move to feed); may suffer urine scalding or sores from prolonged lying.

    • Increased lying time causes: weakness (chronic starvation), disease (exhaustion/collapse), obesity (important issue in pets).

  2. Panting and/or Sweating — caused by: heat stress, fever, overcrowding, fear.

    • Identify cause via: ambient temperature, stocking density, clinical examination for disease signs.

  3. Huddling or Shivering

    • Cold: doesn't usually affect most animals except in extreme environments; often affects very young animals; more likely if wet/chilled by wind or if young animals haven't been fed.

    • Fear (also a cause).

  4. Depression (behavioral indicator, illustrated via donkey example).

  5. Abnormal Fear or Aggression Towards Humans

    • 'Normal' depends on species, breed, and previous contact with humans; dairy cows frequently handled should not fear people.

    • Abnormal fear/aggression may indicate previous cruelty (animals learn from experience).

    • Negative Tactile Interactions example: Negative interactions of 15–30 seconds daily → pigs less willing to approach stationary humans; positive interactions → more willing to approach.

    • Pig Interaction with Stockman (Gonyou et al., 1986): Time to interact — Negative (~140s, longest), None (~50s), Positive (~30s, shortest).

  6. Stereotypies and Other Behavioural Abnormalities.

Conclusions (7B):

  • Animal behavior tells us a great deal about welfare.

  • If behavior indicates poor welfare, we must investigate causes and identify potential solutions.