Lecture 8 Flashcards
Occurrence of pain in domestic animals?
◼ Accidental injury (slip)
◼ Husbandry practices (tail docking)
◼ Surgical procedures
◼ Disease
What is pain?
is an unpleasant sensory or emotional experience associated with actual or potential tissue damage (first person)
What is Nociception?
is the neural mechanisms that result in
pain (third person- can be observed)
causes of Pain (‘nociception’)?
Causes: thermal, mechanical, chemical, sickness
◼ Deep pain- in bones, joints, tendons (arthritis)
◼ Visceral pain- in soft tissue (Hard to locate)
◼ Cutaneous pain- superficial (sharp- poked with a needle)
◼ Acute or Chronic
What is the Process of Nociception?
◼ Reception- activation of pain receptors
(Aδ and C nerve fibres)
◼ Transmission- along spinal cord to sensory cortex & to reflexive motor neurons
◼ Perception- within CNS
◼ Response- (acute pain) withdraw**,
vocalize, orient
How do you assess pain?
◼ In Humans: self-report- “that hurts!!”
◼ In Animals: hard to assess (prey animals are good at hiding pain so they don’t get eaten)
◼ Measure behaviour-
◼ acute response: withdrawal,
vocalization, and orientation
◼ chronic response: immobility, posture
and isolation, AKA ‘Sickness behaviour’
◼ Measure response- to analgesics, anaesthetics
◼ Measure physiology- cortisol, prostaglandins
◼ Force plate- weight bearing, lameness assessment
◼ Grimace scale
What pain treatments are there?
Anaesthesia/Anaesthetics
◼ Loss of sensation/feeling
◼ Local- specific area Eg. Lidocaine
◼ General: Induction/Excitement/General
anaesthesia
Analgesia/Analgesics
◼ Loss of pain
◼ Opioids- endorphins (endogenous
morphine-like compounds)
◼ NSAIDs- non-steroidal anti-
inflammatory drugs
◼ block arachidonic acid cascade and
prostaglandin formation
◼ Analgesic, anti-pyretic, and anti-
inflammatory effects
◼ Examples: Meloxicam, Ketoprofen,
Aspirin
Sedative
◼ Reduced responsiveness- e.g. Ketamine, Azaperone (Stresnil)
What are painful processes?
Cattle
◼ dehorning, castration, branding, tail-
docking
Pigs
◼ castration, teeth-clipping, tail-docking,
ear notching
Sheep
◼ castration, tail-docking, mulesing
Poultry
◼ Beak treatment, claw trimming/removal,
dubbing
Deer
◼ antler removal
Why is Castration & dehorning in cattle done?
◼ Prices for unprocessed (green) calves
are much reduced
◼ Animals safer, easier to handle
◼ Younger animals are easier to process
and suffer less setback
◼ reduce aggression
◼ But, entire males grow faster! (this is a downfall)
Disbudding in calves
Horn buds removed at 4-8 weeks
3 Methods:
◼ Electrical or butane iron, Caustic paste or Gouging
◼ Pain response- all methods: behavioural changes and elevated cortisol levels for ~4 hours
◼ Gouging has more rapid cortisol response than electric iron
◼ Local anaesthetic block- recommended for surgical pain, then post-op analgesia
Dehorning in cattle
◼ Dehorning of mature animals affects
weight gain
◼ Dehorning on entrance to feedlot
reduced performance by 300 g/d for
first two weeks
◼ Effect on growth was significant over the 106 day feedlot period
What are the beef codes and recommendations for dehorning cattle?
Beef Code Requirements:
◼ Competent personnel
◼ Disbud early (2-3 months)
◼ Since Jan 2016- use of pain control required after horn bud attachment
Beef Code Recommendations:
◼ Do not process calves at weaning time
◼ Select/breed for polled trait
Castration in Cattle
◼ Physical (surgical, burdizzo, elastrator,
banding), chemical and hormonal methods
◼ Younger age: easier for producer & animal (easier to handle)
◼ Surgical castration induces higher
cortisol response than elastrator or burdizzo
What are alternatives to castration?
Immuno castration
vasectomy
hormone suppressants
sexed semen
Castration- Beef vs Dairy
Dairy code: pain control required at all ages
Beef code: pain control required for bulls older than 6 months
This might be do to practicality
Why is Castration in Pigs done?
Main reason is boar taint- an
unpleasant smell and taste
◼ meat from boars can contain elevated
levels of skatole and androstenone
Secondary reason- reduce mounting
and aggressive behaviours
Castration in Pigs
◼ Surgical and immuno-chemical
◼ Improvest (anti-GnRH vaccine)
◼ Surgical: at 2-7 days
◼ Young animals recover more quickly
Code Requirements:
◼ Local anesthetic & analgesic- required for pigs over 10 days of age
◼ As of July 1, 2016, castration performed atany age must be done with analgesics
Beak treatment in Hens
Mechanical methods (hot blade)
◼ Dramatic reductions in eating, preening immediately after trimming when performed at later ages
Infrared beak-trimming
◼ Significant reduction in pain responses
Acceptability of Painful Procedures?
◼ The general public is unaware of most
procedures and the use of anesthetics
◼ Alternative practices are available - sometimes reluctance to move away from
painful practices
◼ Codes of practice promote phase-in of
pain control and use of alternatives
What is lameness?
A significant welfare issue-
◼ Reduced performance in broilers
◼ Improved through genetic selection
◼ Major reason for production losses and
culling in dairy cattle and sows
◼ Reduced welfare due to chronic pain
Lameness assessment
Subjective and objective measures:
Gait scoring
◼ Subjective measure- observer ranking
◼ Developed for poultry, pigs and cattle
◼ Typically a 0 – 5 scale: 0= no signs, 5= the animal cannot walk
Accelerometers, Kinematics, Force plate
◼ Objective measures- device recording
Lameness & self medication
Lame and non-lame broilers were given
feeds with and without analgesic (Danbury, 2000)
◼ Lame birds preferred the drug-treated feed
◼ Gait scores improved, performance increased
Conclusions:
◼ 1. Pain is present
◼ 2. Bird cognition: associated feed with painreduction: = self-medication
Reducing lameness
Lameness can be reduced by:
◼ genetic selection, flooring/bedding,
exercise and nutrition
Is a major welfare issue- focus of much
research in poultry, cattle and pigs
◼ Eg. Rubber mats, hoof care, pain control
What is Euthanasia
◼ Greek- Eu= ‘good’ + thanatos =‘death’
◼ Important for welfare- End suffering
Choose methods based on: human safety, animal welfare, practicality, animal age and location
◼ Gunshot or captive bolt gun
◼ Blunt force trauma- manual or device
◼ Anesthetic overdose (veterinary oversight)
Immediate confirmation of death
◼ Follow-up if needed (e.g., bleed or pithing)
Euthanasia- oversight
Research and CCAC: euthanasia plan
(humane intervention point: HIP) required for all research protocols (AREB)
Packing plants and AMA audits:
◼ Effective stunning
◼ Immediate insensibility and death
◼ Zero returns to sensibility
Special circumstances- CFIA:
◼ E.g., Disease outbreaks- mass euthanasia
