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Animal welfare during pandemics and natural disasters


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Caring during crisis: Animal welfare during pandemics andnatural disastersHumane killing of animals for diseasecontrol purposes.

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Animal welfare during pandemics and natural disasters

  1. 1. Caring during crisis:animal welfare during pandemics andnatural disastersHumane killing of animals for diseasecontrol purposesMohan Raj BVSc MVSc PhDDepartment of Clinical Veterinary ScienceUniversity of BristolLangford BS40 5DU,
  2. 2. Disease outbreaks
  3. 3. Intensions of humane killing ofanimals for disease control purposes• Protecting human health• Eliminating suffering in diseased animals• Preventing suffering in susceptible animals• Maintaining healthy national heard or flock• Sustaining or gaining disease free status andeconomic advantage over competitors
  4. 4. Physiological basis of stunning /killingStunning methods induce a pathological brain state that isincompatible with the persistence of consciousness andsensibilityStunning methods should induce immediate loss ofconsciousness without causing animals avoidable painand distress- animals should remain unconsciousness until deathoccurs through slaughter, destruction of brain, etcKilling methods should induce immediate death withoutcausing animals avoidable pain and distress- hence preferred during outbreaks of diseases
  5. 5. Scientific reports and guidelinesAmerican Veterinary Medical Association(AVMA) Food Safety Authority (EFSA) Organisation for Animal Health (OIE)
  6. 6. Methods (1)• Free bullet (rifles, handguns and shotguns) -large animals• Penetrating or non-penetrating captive bolt -large animals• Manual blow to head - neonates• Neck dislocation / decapitation - poultryspecies• Electrical stunning / killing - all animalsincluding poultry
  7. 7. Methods (2)• Gas mixtures – pigs, lamb and poultry• Lethal injection of anaesthetics - all animalsincluding poultry• Maceration – newly hatched chicks /unconscious poultry• Anaesthetics in feed or water - poultry andother birds followed by killing• Exposure to gas mixture followed bymaceration• Foam with inert gases – poultry
  8. 8. Method selection criteriaIncludes• Nature of disease (e.g. notifiable, zoonotic) ordisaster• Location of farm• Species, number, size and age of animals• Operators’ health and safety• Availability of resources and expertise• Biosecurity• Cost and efficacy of method
  9. 9. Existing threat of a pandemic• Highly pathogenic avian influenza (HPAI)• H5 and H7 strains known to infect humans• Persistence of disease in birds remains to be apotential global threat to human health• Previous flue outbreaks caused death in millions ofpeople– 1918 Spanish influenza – 40 to 50 m– 1957 Asian influenza – 2 m– 1968 Hong Kong influenza – 1 m
  10. 10. Sources of HPAI infectionPoultryDirect contact with– Infected birds– Respiratory secretions from infected birds– Faeces of infected birdsHumansExposure to infected birds, their faeces or dust or soilcontaminated with faeces
  11. 11. Minimising human exposureVentilation shut down as a killing method– No human contact with live or dead infected birds orinfected materials– Lung ventilation of birds seriously compromised due to AI,and therefore, shutting down the ventilation of house maynot be a serious welfare concern?Humane Slaughter Association (UK)“This method raises considerable welfare concerns and theHSA looks to all concerned to take every step to avoid thissituation ever arising”
  12. 12. Previous experience2003 AI outbreak in the Netherlands (example)30 million birds were slaughtered within 3 km radius1242 commercial farms8000 hobby / back yard flocksRevealed pros and cons of various killing methodsGerritzen et al (2006) Veterinary Record, 159: 39-42
  13. 13. Limitations of established methods• Manual catching and handling can be distressing topoultry, may cause injury• Lethal injection, captive bolt guns and electricalmethods need manual handling and severe restraint ofbirds• Mobile electrical water bath system failed to kill allthe birds, need slaughter to ensure death• Shooting with captive bolts, neck dislocation anddecapitation and slaughter causes blood spillage –biosecurity hazard
  14. 14. Gas mixturesCarbon dioxide has been used in,Skips and waste binsModified Atmosphere Killing (MAK) CartsContainers
  15. 15. Skips and bins in useCourtesy: Dr. Pam Hullinger, California, USA
  16. 16. Waste bins
  17. 17. Concerns with skips and bins• Throwing batches of live birds into skips andbins could compromise bird welfare• Birds may die due to compression andsuffocation by other birds• Labour intensive• Potential health and safety hazard when usedin confined spaces
  18. 18. Containerised gas killing system• Gas tight steel container• Transport module full of birds loaded and then gassupplied• Welding gas mixture – 80% argon and 20% carbondioxide – least aversive to poultry– Sandilands et al. (2006) Proceedings of the 40th InternationalCongress of the ISAE, University of Bristol, August 8th – 12th 2006.• 2% residual oxygen for ducks and geese• 5% residual oxygen for chickens and turkeys• Operating procedures and training DVD
  19. 19. Container in use
  20. 20. Manual or mechanical emptying ofcontainers• Used on three farms inNorfolk LPAI outbreak withabout 48,700 birds killed inless than 48 hours• Used for East Lothian NDVoutbreak for 12745 birds(partridge, quail, pheasantchicken)• Throughput of 4000 perhour achieved with safeoperation and humane kill
  21. 21. Whole house gassing with CO2• Moderate sealing ofventilation needed• Minimum 45% CO2 in air• 2 minutes exposureadequate to kill birds• Takes about 10 minutes tofill a UK poultry house• House emptied 1 hour aftergassing• Very steep learning curveover the last 2 years
  22. 22. Evolution of gas injection system• 32 mm internaldiameter• Tip cut at 30degree angle to theground• Mounted on atrolley - secured toavoid recoil
  23. 23. WHG – lance position for deep litter1.5 meters from groundCO2 slurry directed towards ceilingUses heat in headspaceBirds excluded for 20 meters
  24. 24. WHG – deep litterBird dispersalbefore gassingBird clumping insmall amountafter gassingBarrier excludedbirds, someclumping seenaround barrier
  25. 25. WHG battery cage9000 end-of-lay hens4 tiers, each 60 cageslong8 rows of cages
  26. 26. WHG – battery cage - lance position
  27. 27. Pros and cons of WHG with CO2• Minimal contact with birds and faeces, improvedbiosecurity• Gas administration made simple and quick• Lethal concentration achieved rapidly• Delayed rigor onset in carcasses helps depopulationfrom cages• Extremely low temperature (-78.5oC)– Triple point (solid, liquid and gas)– Heat produced in the house may be adequate to avoid frostbite or cold burn– Difficult to estimate or predict heat production / loss, varyaccording to housing and husbandry conditions
  28. 28. Other methods of CO2 admin intohouses• Dry ice blocks• Crushed dry ice• Delivered from cylinders– No serious bird welfare concerns with thesemethods
  29. 29. WHG with nitrogenCourtesy: Camilla Andersen, Denmark
  30. 30. Pros and cons of nitrogen• Cheap and readily available in large quantities• Non-aversive to poultry• Easy to vaporise using ambient temperature• 2% residual oxygen achieved in one trial• Birds killed within 20 minutes from start• Extremely low temperature (-196oC) of liquidnitrogen• Only gaseous form should enter houses• Air-to-air vaporisers are also available– for details
  31. 31. Carbon monoxide• Has been used in Europe, especially Belgium, forwhole house gassing• Remains to be a choice• 1.5 to 2.0% in air can kill poultry• Not readily available• Explosive at 12.5% in air– Presence of fire brigade essential• Health and safety hazard• Limited availability
  32. 32. Cyanide• Has been used in Europe for killing poultry in houses• Kills poultry in less than 10 minutes• Convulsions may occur in conscious poultry– Convulsive dose less than required to inducing loss ofconsciousness?• Health and safety hazard• Adverse public opinion of the method• Rapid rigor development hinders depopulation fromcages
  33. 33. Inhalation anaestheticshalothane in a jam jar & fish tank aerator asvaporiser• Can be used incontainers or houses• Humane• Potential health andsafety andenvironmental hazard• Costs
  34. 34. Fire fighting foam (USA)“Researchers and commercial poultry companiesrecently established that non-toxic water-based foamwith a certain bubble size presents a practical,effective, and humane method for mass depopulation.Foam of the right bubble size creates an occlusion inthe trachea of birds, causing a rapid onset ofhypoxia. The foam that blankets the broiler houseinduces physical hypoxia—the same cause of deathas the approved method using carbon dioxide gas(CO2)”.–
  35. 35. Foam Vs CO2• Exposure to carbon dioxide does not rely onhypoxia– 40% carbon dioxide in air with 15% residualoxygen and 45% nitrogen works as well as amixture of 50% carbon dioxide, 20% oxygen and30% nitrogen• Occlusion does not occur during exposure tocarbon dioxide or other gas mixture
  36. 36. Welfare concerns• Occlusion of trachea = suffocation• Suffocation = physical separation of the upperrespiratory tract from atmospheric air– Drowning– Chocking– Strangulation– Clamping nostrils or smothering• Death by suffocation is prohibited / ethicallyunacceptable?
  37. 37. Fire fighting foam (UK)
  38. 38. UK trials with FFF• Air, carbon dioxide or nitrogen was used• Carbon dioxide filled foam contained 100% but foamfailed to raise due to the denser than air gas• Nitrogen filled foam contained 100% nitrogen (0%oxygen) and foam raised well due to lighter than airgas• Nitrogen vaporised without difficulty• Carbon dioxide difficult to vaporise – frozen pipes• Decided to pursue nitrogen in dry foam
  39. 39. Foam maker & Perspex boxMohan Raj, Gordon Hickman and Colin Smith
  40. 40. Foam made with shampoo & airFoam filled Perspex box rapidlyBobbles burst due to bird movementBird survived with large air pocketsObservation ended after 5 minutes
  41. 41. Foam made with shampoo & nitrogenFoam filled the Perspex box within seconds
  42. 42. Foam made with shampoo & nitrogenOxygen level dropped to less than 1% in the boxBird started to show anoxic convulsionsFoam depleted
  43. 43. Post mortem examinationTiny amount of pin-head-sized bubbles found in larynxand one centimetre into upper tracheaAnte-mortem occlusion or post-mortem entry?
  44. 44. Promising resultsNeed research and development to• Ensure the foam is robust to hold gas and fillhouses to required width, length and height,but• Remain fragile enough so that bird movementbreaks bubbles and release nitrogen• Study bird reaction to foam / welfareimplications?
  45. 45. Overdose of anaesthetic in feed andwater• Alpha-chloralose has been tested– 3 to 6% recommended– Very bitter in taste– Birds need to consume lethal dose in one feedingor drinking bout– Fasting (24 h) may force birds to consume– Need a killing method, e.g. containerised gassing• Ideal for sedating all birds, including wild,under all conditions
  46. 46. Summary opinion• Whole house and containerised gassingmethods are feasible and better thanconventional methods– Generic operating procedures and protocols exist• Dry foam created using nitrogen is feasible butfurther research and development is urgentlyneeded• International resources could be pooled for thiscommon cause?
  47. 47. Thank youAcknowledgementsCamilla Andersen, Danish Veterinary and FoodAdministration, DenmarkLotta Berg, Swedish Animal Welfare Agency, SwedenGordon Hickman, Animal Health, UKDavid Pritchard, Defra, UK