suffering suffering how do we know if an animal is suffering?

63
SUFFERING SUFFERING How do we know if an animal is suffering? How do we know if an animal is suffering?

Upload: angelica-lindsey

Post on 18-Dec-2015

245 views

Category:

Documents


3 download

TRANSCRIPT

Page 1: SUFFERING SUFFERING How do we know if an animal is suffering?

SUFFERINGSUFFERINGHow do we know if an animal is suffering?How do we know if an animal is suffering?

Page 2: SUFFERING SUFFERING How do we know if an animal is suffering?

Evidence in mammals:Evidence in mammals:

Same CNS response to painful stimuliSame CNS response to painful stimuliin thalamusin thalamus

Same neural anatomy to perceive painSame neural anatomy to perceive pain

Similar behavioral responsesSimilar behavioral responses

Similar physiological responsesSimilar physiological responses

Page 3: SUFFERING SUFFERING How do we know if an animal is suffering?
Page 4: SUFFERING SUFFERING How do we know if an animal is suffering?

SUFFERING: A wise range of unpleasant states, SUFFERING: A wise range of unpleasant states, including:including:

FearFearPainPainFrustrationFrustrationExhaustionExhaustionHungerHungerThirstThirst

Page 5: SUFFERING SUFFERING How do we know if an animal is suffering?

But what of gray areas?But what of gray areas?

Boredom?Boredom?Loneliness?Loneliness?A little hunger?A little hunger?A little thirst?A little thirst?

Page 6: SUFFERING SUFFERING How do we know if an animal is suffering?

Suffering vs. Suffering vs. Discomfort/UnpleasantnessDiscomfort/Unpleasantness

Page 7: SUFFERING SUFFERING How do we know if an animal is suffering?

Suffering vs. Discomfort/UnpleasantnessSuffering vs. Discomfort/Unpleasantness

INTENSITYINTENSITYPain can cause minor discomfort or Pain can cause minor discomfort or terrible sufferingterrible suffering

Page 8: SUFFERING SUFFERING How do we know if an animal is suffering?

Suffering vs. Discomfort/UnpleasantnessSuffering vs. Discomfort/Unpleasantness

INTENSITYINTENSITYEx: Pain can cause minor discomfort or Ex: Pain can cause minor discomfort or terrible sufferingterrible suffering

DURATIONDURATIONEx: Pain can last 1/4 of a second or for hoursEx: Pain can last 1/4 of a second or for hoursor days.or days.

Page 9: SUFFERING SUFFERING How do we know if an animal is suffering?

Suffering vs. Discomfort/UnpleasantnessSuffering vs. Discomfort/Unpleasantness

INTENSITYINTENSITYEx: Pain can cause minor discomfort or Ex: Pain can cause minor discomfort or terrible sufferingterrible suffering

DURATIONDURATIONEx: Pain can last 1/4 of a second or for hoursEx: Pain can last 1/4 of a second or for hoursor days.or days.

INDIVIDUAL/SPECIES DIFFERENCESINDIVIDUAL/SPECIES DIFFERENCESAny 2 individuals differ in what’s “painful” Any 2 individuals differ in what’s “painful”

Page 10: SUFFERING SUFFERING How do we know if an animal is suffering?

HOW DECIDE IF ANIMAL IS SUFFERING?HOW DECIDE IF ANIMAL IS SUFFERING?

I. PHYSIOLOGICAL I. PHYSIOLOGICAL TESTS -TESTS -

Comparative levelsComparative levelsof Cortisolof Cortisol

Page 11: SUFFERING SUFFERING How do we know if an animal is suffering?

HOW DECIDE IF ANIMAL IS SUFFERING?HOW DECIDE IF ANIMAL IS SUFFERING?

II. PHYSICAL HEALTHII. PHYSICAL HEALTH

Page 12: SUFFERING SUFFERING How do we know if an animal is suffering?

II. PHYSICAL HEALTHII. PHYSICAL HEALTH* * Most widely used indicator of sufferingMost widely used indicator of suffering

Doctor’s Without Borders FlyerDoctor’s Without Borders Flyer

Page 13: SUFFERING SUFFERING How do we know if an animal is suffering?

II. PHYSICAL HEALTHII. PHYSICAL HEALTH

* * Most widely used indicator of sufferingMost widely used indicator of suffering* Ill health, disease and injury most common cause * Ill health, disease and injury most common cause

of suffering in all species, including ours.of suffering in all species, including ours.

Page 14: SUFFERING SUFFERING How do we know if an animal is suffering?

IF DISEASE AND INJURY CAUSES SUFFERING,IF DISEASE AND INJURY CAUSES SUFFERING,DOES THE LACK OF IT INSURE WELL-BEING?DOES THE LACK OF IT INSURE WELL-BEING?

* Intensity of injury not always equivalent to* Intensity of injury not always equivalent tothe amount of suffering.the amount of suffering.

De Waal De Waal 19961996

Page 15: SUFFERING SUFFERING How do we know if an animal is suffering?

IF DISEASE AND INJURY CAUSES SUFFERING,IF DISEASE AND INJURY CAUSES SUFFERING,DOES THE LACK OF IT INSURE WELL-BEING?DOES THE LACK OF IT INSURE WELL-BEING?

* Intensity of injury not always equivalent to* Intensity of injury not always equivalent tothe amount of suffering.the amount of suffering.

* Can’t always equate physical health/productivity* Can’t always equate physical health/productivitywith well-being because:with well-being because:

Page 16: SUFFERING SUFFERING How do we know if an animal is suffering?

IF DISEASE AND INJURY CAUSES SUFFERING,IF DISEASE AND INJURY CAUSES SUFFERING,DOES THE LACK OF IT INSURE WELL-BEING?DOES THE LACK OF IT INSURE WELL-BEING?

> Productivity is a feature of a group> Productivity is a feature of a group> How measure productivity? > How measure productivity?

Ex: Rapid weight gain of Ex: Rapid weight gain of commercial chickens, commercial chickens, who may suffer from who may suffer from arthritis. arthritis.

Page 17: SUFFERING SUFFERING How do we know if an animal is suffering?

IF DISEASE AND INJURY CAUSES SUFFERING,IF DISEASE AND INJURY CAUSES SUFFERING,DOES THE LACK OF IT INSURE WELL-BEING?DOES THE LACK OF IT INSURE WELL-BEING?

> Productivity is a feature of a group> Productivity is a feature of a group> How measure productivity? > How measure productivity?

Ex: Deletion of geneEx: Deletion of genein roosters that detectsin roosters that detectsLordosis Lordosis

More breast meat;More breast meat;Females attackedFemales attackedand killed.and killed.

Page 18: SUFFERING SUFFERING How do we know if an animal is suffering?

Health is NOT enough to eliminate potentialHealth is NOT enough to eliminate potentialof suffering, but is the first thing to consider.of suffering, but is the first thing to consider.

Page 19: SUFFERING SUFFERING How do we know if an animal is suffering?

III. COMPARE WITH ‘NATURAL LIFE’III. COMPARE WITH ‘NATURAL LIFE’

Page 20: SUFFERING SUFFERING How do we know if an animal is suffering?

III. COMPARE WITH ‘NATURAL LIFE’III. COMPARE WITH ‘NATURAL LIFE’

1) 1) Are domestic/captive animals comparable Are domestic/captive animals comparable to wild versions?to wild versions?

* May be genetically different* May be genetically different

((Larger difference between egg layers Larger difference between egg layers and broiler chickens than between domestic chickensand broiler chickens than between domestic chickens and Jungle fowl.)and Jungle fowl.)

Page 21: SUFFERING SUFFERING How do we know if an animal is suffering?

Average # eggs Average # eggs laid/yearlaid/year

Red JunglefowlRed Junglefowl 62/year 62/year

White LeghornsWhite Leghorns 181/year181/year

Page 22: SUFFERING SUFFERING How do we know if an animal is suffering?

III. COMPARE WITH ‘NATURAL LIFE’III. COMPARE WITH ‘NATURAL LIFE’

1) 1) Are domestic/captive animals comparable Are domestic/captive animals comparable to wild versions?to wild versions?

* May be different due to experience* May be different due to experience

Page 23: SUFFERING SUFFERING How do we know if an animal is suffering?

III. COMPARE WITH ‘NATURAL LIFE’III. COMPARE WITH ‘NATURAL LIFE’

2) How do we know that animals suffer if they 2) How do we know that animals suffer if they can’t behave ‘naturally?’ can’t behave ‘naturally?’

Page 24: SUFFERING SUFFERING How do we know if an animal is suffering?

Anti-predator behavior in mixed flocks ofAnti-predator behavior in mixed flocks ofpasserines (song birds).passerines (song birds).

* Scan environment for predators less if* Scan environment for predators less ifin mixed flocks (more eyes), morein mixed flocks (more eyes), moretime to feed.time to feed.

Note many domestic animals less Note many domestic animals less alert than wild conspecifics - alert than wild conspecifics - less to fear?less to fear?

Page 25: SUFFERING SUFFERING How do we know if an animal is suffering?

Do pigs ‘need’ to wallow in mud?Do pigs ‘need’ to wallow in mud?

Only wallow if hot - if cool enough,Only wallow if hot - if cool enough,pigs avoid mud.pigs avoid mud.

Page 26: SUFFERING SUFFERING How do we know if an animal is suffering?

Sheep graze over 100’s of acres in areas of Sheep graze over 100’s of acres in areas of poor pasture, but if provided food and water, poor pasture, but if provided food and water, they stay in the same area for months.they stay in the same area for months.

Page 27: SUFFERING SUFFERING How do we know if an animal is suffering?
Page 28: SUFFERING SUFFERING How do we know if an animal is suffering?

Cloud VideoCloud Video

Page 29: SUFFERING SUFFERING How do we know if an animal is suffering?

Not enough to know animal is living a Not enough to know animal is living a ‘‘natural’ life to know that they aren’t natural’ life to know that they aren’t suffering.suffering.

Page 30: SUFFERING SUFFERING How do we know if an animal is suffering?

IV. BEHAVIORAL OBSERVATIONSIV. BEHAVIORAL OBSERVATIONS

1) Any behavioral signs 1) Any behavioral signs of suffering?of suffering?

Page 31: SUFFERING SUFFERING How do we know if an animal is suffering?

Gritsai 2004Gritsai 2004

Studied responses of cockroaches to Studied responses of cockroaches to morphinemorphine

~ Control subjects put on hotplate ~ Control subjects put on hotplate with no morphinewith no morphine

~ Exper’l subjects given morphine, ~ Exper’l subjects given morphine, put on hot plateput on hot plate

RES: Exper’l subjects spent signif’ly RES: Exper’l subjects spent signif’ly less time on plateless time on plate

Similar response seen in crickets.Similar response seen in crickets.

Page 32: SUFFERING SUFFERING How do we know if an animal is suffering?

Gritsai 2004Gritsai 2004

Studied responses of cockroaches to morphineStudied responses of cockroaches to morphine~ Control subjects put on hotplate with no morphine~ Control subjects put on hotplate with no morphine~ Exper’l subjects given morphine, put on hot plate~ Exper’l subjects given morphine, put on hot plate

RES: Exper’l subjects spent signif’ly less time on plateRES: Exper’l subjects spent signif’ly less time on plate

Bergamo 1992Bergamo 1992

Injected crabs with morphine, struck eye stalks.Injected crabs with morphine, struck eye stalks.~ Injected of morphine produced dose dependent decrease~ Injected of morphine produced dose dependent decreasein the crab’s defensive response.in the crab’s defensive response.

Page 33: SUFFERING SUFFERING How do we know if an animal is suffering?

Conflicting Views:Conflicting Views:

Farstad 2005Farstad 2005

Norway project on pain response inNorway project on pain response inlobsters, crabs and fish.lobsters, crabs and fish.

Argued evidence that these groupsArgued evidence that these groupsare incapable of experiencing pain.are incapable of experiencing pain.

Page 34: SUFFERING SUFFERING How do we know if an animal is suffering?

IV. BEHAVIORAL OBSERVATIONSIV. BEHAVIORAL OBSERVATIONS

1) Any behavioral signs of suffering?1) Any behavioral signs of suffering?

2) Experiment to find more subtle signs: 2) Experiment to find more subtle signs: (Ex: Cats trained to push lever for food reward.(Ex: Cats trained to push lever for food reward.Added blast of air as consequence of pushingAdded blast of air as consequence of pushinglever. Cats paced back and forth)lever. Cats paced back and forth)

Page 35: SUFFERING SUFFERING How do we know if an animal is suffering?

Displacement BehaviorDisplacement Behavior

A behavior performed due to the inability to A behavior performed due to the inability to perform/inhibition of the desired behavior. perform/inhibition of the desired behavior.

““To take the place of” -- To take the place of” -- A different behaviorA different behavior

Ex: Ex: (Person wants to yell at boss, instead chews on fingernails)(Person wants to yell at boss, instead chews on fingernails)

Page 36: SUFFERING SUFFERING How do we know if an animal is suffering?

Re-directed BehaviorRe-directed Behavior

The same behavioral action directed toward The same behavioral action directed toward a different target than originally intended.a different target than originally intended.The same behaviorThe same behavior

Ex: Ex: (Cat redirects aggression toward house mate when sees(Cat redirects aggression toward house mate when seesintruder cat in yard)intruder cat in yard)

Page 37: SUFFERING SUFFERING How do we know if an animal is suffering?

IV. BEHAVIORAL OBSERVATIONSIV. BEHAVIORAL OBSERVATIONS

1) Any behavioral signs of suffering?1) Any behavioral signs of suffering?

2) Experiment to find more subtle signs.2) Experiment to find more subtle signs.

3) Look for abnormal, persistent actions:3) Look for abnormal, persistent actions:Ex: feather plucking, self-mutilation,Ex: feather plucking, self-mutilation,STEREOTYPIES STEREOTYPIES

Page 38: SUFFERING SUFFERING How do we know if an animal is suffering?

STEREOTYPIES:STEREOTYPIES:

Cause release of endorphins likeCause release of endorphins likeserotonin and dopamine that can serotonin and dopamine that can act as internal opiates.act as internal opiates.

(careful though - note behavior of Red Deer)(careful though - note behavior of Red Deer)

Page 39: SUFFERING SUFFERING How do we know if an animal is suffering?

V. CHOICE EXPERIMENTSV. CHOICE EXPERIMENTS

Spencer: “Pleasure and pain are evolutionarilySpencer: “Pleasure and pain are evolutionarilyconstructive responses.”constructive responses.”

Animals move toward pleasureAnimals move toward pleasureAnimals move away from painAnimals move away from pain

Page 40: SUFFERING SUFFERING How do we know if an animal is suffering?

PREFERENCE TESTS:PREFERENCE TESTS:Choice between 2 (or more) conditionsChoice between 2 (or more) conditions

Ex: Brambell Committee andEx: Brambell Committee and size of wire in chicken cages.size of wire in chicken cages.

Page 41: SUFFERING SUFFERING How do we know if an animal is suffering?

Ex 2: Ex 2:

Sheep given choice to move into Sheep given choice to move into squeeze cage or electrical device.squeeze cage or electrical device.

Page 42: SUFFERING SUFFERING How do we know if an animal is suffering?

Ex 3: Taught pigs to control theirEx 3: Taught pigs to control theirenvironmental temperature inside the environmental temperature inside the facility.facility.

Pigs chose temperature Pigs chose temperature lower than had beenlower than had beenthought they wanted.thought they wanted.

Improved well-being. Improved well-being. Decreased costs.Decreased costs.

Page 43: SUFFERING SUFFERING How do we know if an animal is suffering?

BENEFITS TO CHOICE/PREFERENCE TESTSBENEFITS TO CHOICE/PREFERENCE TESTS

1) Animalcentric - ‘asks’ the animal what’s 1) Animalcentric - ‘asks’ the animal what’s important, avoids anthropocentrism.important, avoids anthropocentrism.

Page 44: SUFFERING SUFFERING How do we know if an animal is suffering?

BENEFITS TO CHOICE/PREFERENCE TESTSBENEFITS TO CHOICE/PREFERENCE TESTS

1) Animalcentric - ‘asks’ the animal what’s 1) Animalcentric - ‘asks’ the animal what’s important, avoids anthropocentrism.important, avoids anthropocentrism.

2) Some tests are relatively easy to do.2) Some tests are relatively easy to do.

Page 45: SUFFERING SUFFERING How do we know if an animal is suffering?

BENEFITS TO CHOICE/PREFERENCE TESTSBENEFITS TO CHOICE/PREFERENCE TESTS

1) Animalcentric - ‘asks’ the animal what’s 1) Animalcentric - ‘asks’ the animal what’s important, avoids anthropocentrism.important, avoids anthropocentrism.

2) Some tests are relatively easy to do.2) Some tests are relatively easy to do.

3) Answers can be very clear.3) Answers can be very clear.

Page 46: SUFFERING SUFFERING How do we know if an animal is suffering?

BENEFITS TO CHOICE/PREFERENCE TESTSBENEFITS TO CHOICE/PREFERENCE TESTS

1) Animalcentric - ‘asks’ the animal what’s 1) Animalcentric - ‘asks’ the animal what’s important, avoids anthropocentrism.important, avoids anthropocentrism.

2) Some tests are relatively easy to do.2) Some tests are relatively easy to do.

3) Answers can be very clear.3) Answers can be very clear.

4) Can get sense of strength of preference:4) Can get sense of strength of preference:How hard is the animal willing to work?How hard is the animal willing to work?

Page 47: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

Page 48: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.

Page 49: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.3) Methods can skew the results.3) Methods can skew the results.

Page 50: SUFFERING SUFFERING How do we know if an animal is suffering?

WireWireFloorFloor

LitterLitterFloorFloor

Hughes and Flooring Preference TestHughes and Flooring Preference Test

IF SUMMED TIME ON WIRE VS LITTER, HENS MOVED FREELY: IF SUMMED TIME ON WIRE VS LITTER, HENS MOVED FREELY: NO DIFFERENCENO DIFFERENCE

SUMMED # OF CHOICES FOR WIRE VS. LITTER, HENS KEPT WHERE CHOSE FOR SUMMED # OF CHOICES FOR WIRE VS. LITTER, HENS KEPT WHERE CHOSE FOR 2 HOURS: 2 HOURS:

PREFERRED LITTERPREFERRED LITTER

3) Methods can skew the results.3) Methods can skew the results.

Page 51: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.3) Methods can skew the results.3) Methods can skew the results.4) Effect of experience.4) Effect of experience.

Page 52: SUFFERING SUFFERING How do we know if an animal is suffering?

BatteryBatteryCagesCagesGardenGarden

Allowed to make choice between cages or garden.Allowed to make choice between cages or garden.Kept in chosen area for five minutes.Kept in chosen area for five minutes.Repeated 24 times (look for increase over time in choice if animalRepeated 24 times (look for increase over time in choice if animal

has a preference.)has a preference.)

DawkinsDawkins

StarStartt

Page 53: SUFFERING SUFFERING How do we know if an animal is suffering?

2) Effect of Experience2) Effect of Experience

BatteryBatteryCagesCagesGardenGarden

IMMEDIATE PREFERENCE FOR GARDEN IF FAMILIARIMMEDIATE PREFERENCE FOR GARDEN IF FAMILIAR

IMMEDIATE PREFRENCE FOR BATTERY IF FAMILIARIMMEDIATE PREFRENCE FOR BATTERY IF FAMILIAR

GARDEN ULTIMATE PREFERENCE FOR BOTHGARDEN ULTIMATE PREFERENCE FOR BOTH

Dawkins experiment on Dawkins experiment on chickenschickens

StarStartt

Page 54: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

Page 55: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.

Page 56: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.3) Methods can skew the results.3) Methods can skew the results.

Page 57: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.3) Methods can skew the results.3) Methods can skew the results.4) Effect of experience.4) Effect of experience.

Page 58: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.3) Methods can skew the results.3) Methods can skew the results.4) Effect of experience.4) Effect of experience.5) Animals don’t always choose what’s good5) Animals don’t always choose what’s good

for them.for them.

Page 59: SUFFERING SUFFERING How do we know if an animal is suffering?

DISADVANTAGES TO CHOICE TESTSDISADVANTAGES TO CHOICE TESTS

1) Preference is not an indicator of suffering.1) Preference is not an indicator of suffering.(Coke or Pepsi?)(Coke or Pepsi?)

2) Short-term preference vs. long-term one.2) Short-term preference vs. long-term one.3) Methods can skew the results.3) Methods can skew the results.4) Effect of experience.4) Effect of experience.5) Animals don’t always choose what’s good5) Animals don’t always choose what’s good

for them.for them.6) What if choice between two evils?6) What if choice between two evils?

Page 60: SUFFERING SUFFERING How do we know if an animal is suffering?

VI. ANALOGIES WITH OURSELVESVI. ANALOGIES WITH OURSELVES

1) Compare their behavior with ours1) Compare their behavior with ours(If animal screams and cries,(If animal screams and cries,it might mean it is suffering.)it might mean it is suffering.)

2) Imagine yourself in the animal’s2) Imagine yourself in the animal’ssituation (How would YOU feelsituation (How would YOU feelif you had to eat feces?) if you had to eat feces?)

Page 61: SUFFERING SUFFERING How do we know if an animal is suffering?

SUMMARY:SUMMARY:No one method is enough to evaluate No one method is enough to evaluate suffering in many cases.suffering in many cases.

We must integrate:We must integrate:

PhysiologyPhysiologyHealthHealthKnowledge of EthologyKnowledge of EthologyObservations of BehaviorObservations of BehaviorChoice TestsChoice TestsAnalogies with ourselves IF animalcentric Analogies with ourselves IF animalcentric

Page 62: SUFFERING SUFFERING How do we know if an animal is suffering?
Page 63: SUFFERING SUFFERING How do we know if an animal is suffering?