Pain: Abolishing a Necessary Evil

1. 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

2. 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

3. Publications on “Farm Animal Welfare”(18,521, Science Direct)

4. Mounting Regulation, Policy, Standards and Assessments • Tyson Announcement, Jan. 8th, 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

5. Pain in Humans Somatosensory (Cortex) Injury Thalamus (Diencephalon) Reticular formation (Brain stem) Skin Skin A, C -fibers Dorsal gray horn (Spinal cord) A-, C-fibers A-thickly myelinated = fast C – unmyelinated = slow, polymodal Cheng, 2005; Modified from Neuroscience Exploring the brain, 2001

6. Pain Mediators Cheng, 2005

7. 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

8. CIPA and HSANCongenital insensitivity to pain with anhidrosisHereditary 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

9. Pain is Necessary! • Babies gnaw their fingers bloody • Poke their eye so hard as to cause abrasions • Lean on hot surfaces to cause 3rd degree burns • Most die before 3 years of age • Cause of death • Heat stroke • Dehydration • Fever • Blood poisoning

10. 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.

11. Neuroanatomy associated with pain in chickens Sensory receptors • In humans: • Mechanical nociceptors • Thermal nociceptors • Chemical nociceptors • In chickens: • Herbst corpuscles and • Grandry’s corpuscles • Free Nerve endings Lunam, 2005

12. 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).

13. Conclusions • Chickens can feel pain. • Chickens feel pain in a similar manner to that in mammals.

14. Definition of pain in animals In animals • Pain is an aversive sensoryand 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)

15. 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)

16. Targets Tissue Scar Neuroma Trigeminal ganglia Beak Soma Fibers Terminals Normal nerve fibers Regrowth Neuroma Degenerating of neuroma Target Ending of beak stump (post-trimming) Neuromas may increase pain sensitivity --- chronic pain

17. 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

18. Painful Situations in Agriculture • Controllable • Beak Trimming • Castration • Tail docking • Branding • Uncontrollable • Birth • Accidents • Injury

19. Analgesics are Beneficial Bulls castrated without analgesic (meloxicam) show a greater incidence of Bovine Respiratory Disease Coetzee et al., 2012

20. Why not just use analgesics? They would need to be: • readily available and registered for use • easy to administer • quick and long acting • have short withdrawal periods • 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

21. Cannibalism will Increase in Prevalence with More Space N. ophthal. med. c C a N. intramand.

22. Predicted Levels of Behavioral Expression+none or incomplete, ++low, +++moderate, and ++++full or high Lay et al., 2010

23. Infrared trimmed Does Beak Trimming Cause Pain? Funded by AFRI Heated blade trimmed Control

24. Drinking Behavior During Warm Water Pain Test Five Weeks Later! Control Hot Blade trimmed Infrared trimmed Infrared Beak trimming has been adopted by the United Egg Producers, 2010

25. Hen Behavior is Positive but ……Keel Bone Fractures • 46 % to 90 % have fractures Nicol et al, 2010

26. Effect of Analgesic on Perching Behavior of Hens with Keel Bone Fractures 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. Latency to land Nasr et al, 2012

27. 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 Funded by the National Pork Board Marchant-Forde et al., 2009

28. 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

29. 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

30. 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 Conclusions

31. Piglet Aversion to Euthanasia Gases 90% Carbon Dioxide or 70:30 mixtures of: Nitrogen:Carbon Dioxide Nitrous Oxide:Carbon Dioxide Nitrous Oxide:Oxygen Funded by the National Pork Board Rault et al., 2012, in press

32. Euthanasia: Stress and DeathTwo-Step Procedure Rault et al., 2012

33. EEG and Euthanasia Carbon Dioxide Nitrous Oxide

34. 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

35. 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.

36. Tail Docking Practice in Dairy Cows Introduced in 1990s in New Zealand to combat Leptospirosis

37. Are Docked Tails more Sensitive to Heat and Cold? DOCKED INTACT Behaviors Recorded: Tail Swing, Weight Shift, Foot Stomp, Tail Curve Eicher et al., 2000

38. 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.

39. 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.

40. Thank You ARS-USDA Meeting Tomorrow’s Challenges Today