ANBI 411.3 Lecture Notes - Lecture 7: Mcdonaldland, Livestock Dehorning, Neuroma
20 Jun 2018
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Lecture 7: Animal welfare Pain, Injury, and Disease
Freedom from pain, injury and disease- by prevention or rapid diagnosis and treatment
Occurrence of pain in farm animals:
- Accidental injury
- Husbandry practices
- Surgical procedures
- Disease
Pain (nociception) is an unpleasant sensory or emotional experience associated with actual or
potential tissue damage, or described in terms of such damage
- Causes: Thermal, mechanical, chemical
- Deep pain: In bones joints, tendons
- Visceral pain: in soft tissue
- Cutaneous pain: superficial
- Acute or chronic
Elements of nociception:
Same process in animals and humans:
- Reception: activation of pain receptors
oA and C fibers
- Transmission: along spinal cord to sensory cortex and to reflexive motor neurons
oCan be a difference in speed
C fibers are a slower pain
A fibers are sudden reaction
- Perception: within CNS
oBrain is where you perceive what is going on
- Response: withdraw, vocalize, orient
Gateway control in spinal cord: controls the amount of pain transferred to the pain receptors,
you don’t react badly to pain every time
- Chronic pain is where this mechanism come in to play
Historical perspective:
- Animal pain was not recognized at all
- Recognition of significance of pain in animals has been slow
- Philosophical dualism: Descartes- body vs. mind
- Anthropomorphism criticized
- Lack of clear indications or appropriate therapies or animals
- Outdated views- example: pain is “protective”
oThey use to think that pain is protective mechanism and helps you to identify a
problem but not thought as a problem to the animal itself
- Recently: major changes in companion animal practice
oStarting to gain acceptance in food animal production
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oBut fewer drugs approved- must be food approved, documented withdrawal
times
Assessment of pain:
- Humans: self-report
- Animals: hard to assess, especially in prey species
- Different species of animas can have different behaviors in response to pain
- Behavior:
oAcute: response of withdrawal, vocalization, and orientation
oChronic: response of immobility, posture and quiet/ isolation- “sickness
behavior”
- Measure response to analgesics, and anesthetics
oCan study how much pain is there and if there is pain in the animal
- Physiology: look at cortisol and prostaglandins in the blood
-Grimace scale: is a method of assessing the occurrence or severity of pain
experienced by non-human animals according to objective and blinded scoring of
facial expressions, as is done routinely for the measurement of pain in non-verbal
humans.
oUsed in humans and rodents
- Assessment of pain is complex:
oSensory dimension
oAffective state dimension
oHypersensitivity due to chronic conditions
Pain treatment:
-Anesthetics
oLoss of sensation/feeding- local vs. general
oInduction/excitement/general anesthesia
oProblem: farm animals have a problem of how we can use it, are people certified
to use it, its not an over the counter drug
-Analgesics
oLoss of pain
oOpioids: endorphins (endogenous morphine-like compounds)
oNSAIDS- non steroidal anti-inflammatory drugs
oBlock arachidonic acid cascade and prostaglandin formation
Examples: meloxicam, ketoproden, aspirin
Analgesic, anti-pyretic, anti-inflammatory
-Sedatives
oReduced responsiveness
oOpioids are generally sedatives
Painful procedures:
- Cattle:
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