Presentation on theme: "Pain: Abolishing a Necessary Evil Donald C. Lay Jr. Research Leader Livestock Behavior Research Unit Agricultural Research Unit, USDA West Lafayette IN,"— Presentation transcript:
Pain: Abolishing a Necessary Evil Donald C. Lay Jr. Research Leader Livestock Behavior Research Unit Agricultural Research Unit, USDA West Lafayette IN, on Purdue University Campus
Livestock Behavior Research Unit Mission (Agricultural Research Service-USDA) to develop scientific measures of animal welfare that will allow an objective evaluation of animal agricultural practices to improve existing practices and invent new practices that can enhance animal welfare and increase animal productivity
Publications on “Farm Animal Welfare” (18,521, Science Direct)
Mounting Regulation, Policy, Standards and Assessments Tyson Announcement, Jan. 8 th, 2014 – Stop the use of Blunt Force Trauma – Eliminate or reduce pain from tail docking and castration Producer Groups and External On-Farm Assessment Programs
Skin Dorsal gray horn (Spinal cord) Reticular formation (Brain stem) Thalamus (Diencephalon) Somatosensory (Cortex) A, C -fibers Injury Skin A-, C-fibers Cheng, 2005; Modified from Neuroscience Exploring the brain, 2001 Pain Pain in Humans A-thickly myelinated = fast C – unmyelinated = slow, polymodal
Cheng, 2005 Pain Mediators
Function of Pain Adaptive evolutionary strategy to protect the body. – Early warning system. – Allows animals to learn what not to do. – The more intense the pain, the greater the threat. Non-adaptive pain. – Pain that persists after trauma is healed. – Neuromas and other neuropathic pain
CIPA and HSAN Congenital insensitivity to pain with anhidrosis Hereditary Sensory and autonomic neuropathy Never feel the stick of a needle Never feel a cut or a burn Never feel hunger Never feel uncomfortable in a chair
Pain is Necessary! Babies gnaw their fingers bloody Poke their eye so hard as to cause abrasions Lean on hot surfaces to cause 3 rd degree burns Most die before 3 years of age Cause of death – Heat stroke – Dehydration – Fever – Blood poisoning
Pain is difficult to measure Pain has both physiological and psychological components. Animals cannot communicate verbally regarding their sensory and emotional experience. Pain can be overridden with other feelings, such as fear, fighting, and feeding motivation …. Pain is also affected by multiple factors, such as genetic strain, age, production status; environments, and lesion and lesion size.
Neuroanatomy associated with pain in chickens Sensory receptors Lunam, 2005 In humans: Mechanical nociceptors Thermal nociceptors Chemical nociceptors In chickens: Herbst corpuscles and Grandry’s corpuscles Free Nerve endings
Behavioral and physiological studies There are similar behavioral and physiological changes in response to injury between chickens and mammals (Cheng, 2005; Kuenzel, 2007). Pharmacological studies Pain killers (analgesics) can reduce pain in both chickens and humans. (Gentle, 1991; Glatz et al., 1992; Paul-Murphy & Ludders, 2001).
Conclusions Chickens can feel pain. Chickens feel pain in a similar manner to that in mammals.
Definition of pain in animals In animals Pain is an aversive sensory and emotional experience by the animal in response to damage or a threat to the integrity of its tissues (Molony & Kent, 1997; Robertson, 2002; Vinuela-Fernandz et al., 2007 ) In humans Pain is an unpleasant sensory and emotional experience associated with actual or potential tissue damage (Merskey and Bogduk, 1994)
Pain can be recognized and assessed indirectly Physical parameters Body score (body injury) Growth rate Physiological parameters Neurotransmitters Neuropeptides Behavioral parameters General behavior (eating, drinking) Guarding behavior (protect injured areas)
Neuroma Trigeminal ganglia Beak Normal nerve fibers Regrowth Neuroma Degenerating of neuroma Neuromas may increase pain sensitivity --- chronic pain SomaFibersTerminals Ending of beak stump (post-trimming) Tissue Scar Targets Target
Neuromas Histological characteristics A neuroma is a tangled mass of a damaged (cut) axon terminal inside the injured area. Consists of unmyelinated fibers, and then becomes myelinated fibers (A-fibers) Physiological characteristics A source of substantial ectopic firing (spontaneous pain) Increase pain sensitivity
Analgesics are Beneficial Coetzee et al., 2012 Bulls castrated without analgesic (meloxicam) show a greater incidence of Bovine Respiratory Disease
Why not just use analgesics? They would need to be: 1)readily available and registered for use 2)easy to administer 3)quick and long acting 4)have short withdrawal periods 5)show return on investment Only 1 approved anti-inflammatory in the U.S. for swine and cattle; a few for cattle and swine in E.U. and U.K. Schwartzkopf-Genswein et al., 2012
Cannibalism will Increase in Prevalence with More Space a c N. intramand. N. ophthal. med. C
Lay et al., 2010
Infrared trimmed Control Heated blade trimmed Does Beak Trimming Cause Pain? Funded by AFRI
Control Hot Blade trimmed Infrared trimmed Drinking Behavior During Warm Water Pain Test Infrared Beak trimming has been adopted by the United Egg Producers, 2010 Five Weeks Later!
Hen Behavior is Positive but …… Keel Bone Fractures 46 % to 90 % have fractures Nicol et al, 2010
Effect of Analgesic on Perching Behavior of Hens with Keel Bone Fractures Latency to land First two bars are hens with and without analgesic that do not have fractures. The second two bars are hens with and without analgesic that do have fractures. Nasr et al, 2012
Routine Piglet Processing Soon after birth, piglets undergo processing procedures, which are likely sources of stress: - Teeth resection - Tail docking - Identification - Iron administration - Castration For each process, there is a choice of methods Marchant-Forde et al., 2009 Funded by the National Pork Board
Objectives To evaluate stress responses evoked by two alternative methods performed singly: – Teeth (TR) – clip vs. grind – Tails (TD) – cold clip vs. hot clip – Identification (ID) – ear notch vs. ear tag – Iron (FE) – injection vs. oral paste – Castration (CA) – cords cut vs. cords torn
Results To evaluate stress responses evoked by two alternative methods performed singly: – Teeth (TR) – clip vs. grind – Tails (TD) – cold clip vs. hot clip – Identification (ID) – ear notch vs. ear tag – Iron (FE) – injection vs. oral paste – Castration (CA) – cords cut vs. cords torn = worse
Conclusions Carried out singly, we can identify which method has least impact on piglet welfare Carried out together, it’s much less clear The key combination is accuracy and speed
Piglet Aversion to Euthanasia Gases 90% Carbon Dioxide or 70:30 mixtures of: Nitrogen:Carbon Dioxide Nitrous Oxide:Carbon Dioxide Nitrous Oxide:Oxygen Rault et al., 2012, in press Funded by the National Pork Board
Euthanasia: Stress and Death Two-Step Procedure Gas treatmentCO 2 N 2 /CO 2 N 2 O/CO 2 N 2 O/O 2 p-value Transfer from treatment to CO 2 chamber (seconds) 2.9 ± 0.3 a 6.4 ± 0.6 b 6.7 ± 1.0 b 14.7 ± 2.1 c Time to death after transfer (seconds) 7.8 ± ± ± ± Total procedure duration (seconds) 10.8 ± 1.3 a 13.9 ± 1.2 a 11.3 ± 1.4 a 24.0 ± 3.0 b Rault et al., 2012
EEG and Euthanasia Carbon Dioxide Nitrous Oxide
Lameness in Sows Exercised sows will have: – An increase in bone density and an increase in muscular weight compared to control sows – An increase in osteoblastic activity and a decrease in osteoclastic activity compared to control sows – Improved condition of joints and hooves compared to control sows
Lameness in Sows will Likely Increase with Increase Movement Loose housing of Sows will likely acerbate this problem as the increase in movement will provide opportunity for torn cartilage to worsen.
Tail Docking Practice in Dairy Cows Introduced in 1990s in New Zealand to combat Leptospirosis
DOCKED INTACT Behaviors Recorded: Tail Swing, Weight Shift, Foot Stomp, Tail Curve Eicher et al., 2000 Are Docked Tails more Sensitive to Heat and Cold?
Bottom Line: Docking causes pain, but less pain in adult cows. Docked cows have more flies and avoidance behaviors. Docked tails show signs of neuromas (possibly painful). Docking doesn’t decrease somatic cell counts.
Conclusions Life without pain doesn’t exist. We recognize that animals feel pain. Our responsibility is to alleviate or minimize pain. We support future efforts to develop management tools to minimize pain and create alternative practices that alleviate pain.
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