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CO₂ Stunning in Pigs Awareness

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Understanding the Practice

In modern commercial slaughter systems, most pigs are stunned before slaughter.

One of the most widely used methods globally — including in Australia — is carbon dioxide (CO₂) gas stunning.

This process involves:

  • placing pigs into a chamber or gondola

  • lowering them into high concentrations of CO₂ gas (typically 70–90%)

  • rendering them unconscious before slaughter

This method is commonly used because it allows pigs to be handled in groups and supports large-scale processing.

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Why This Practice Is Being Questioned

While CO₂ stunning is widely used, it has become a significant focus of animal welfare concern and advocacy.

Research and welfare bodies have identified that:

  • CO₂ gas is highly aversive to pigs

  • it can cause:

    • breathlessness

    • irritation to eyes and airways

    • distress behaviours such as gasping and attempts to escape

  • pigs may remain conscious for a period before losing awareness

Scientific and policy reviews have concluded that this method can cause avoidable pain and distress prior to unconsciousness

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Current Industry Position

Despite concerns, CO₂ stunning remains widely used because:

  • it is efficient for large-scale operations

  • alternatives are still being researched and are not yet widely implemented

  • regulatory systems currently allow its use

In Australia, it is estimated that the majority of pigs are stunned using CO₂

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What Is Being Advocated For

Animal welfare organisations and researchers are calling for:

  • phasing out CO₂ stunning

  • development of more humane alternatives, such as:

    • inert gases (argon, nitrogen)

    • improved electrical stunning systems

  • improved monitoring (e.g. CCTV in slaughter facilities)

  • stronger regulatory oversight

In 2025, a government advisory body recommended that the industry move toward replacing CO₂ with more humane methods within a defined timeframe

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Current Campaigns & Petitions

 Global Campaign

End CO₂ Pig Slaughter (Active Campaign)
Run by Compassion in World Farming

  • Calls for governments to phase out CO₂ stunning

  • Encourages public support for humane alternatives

  • Based on findings that pigs can remain conscious for up to 60 seconds while distressed

 Visit: https://action.ciwf.org.uk/page/95747/action/1

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 Australia Campaign Awareness

Ban Gas Chambers for Pigs
Run by Farm Transparency Project

  • Highlights use of CO₂ gas chambers in Australian facilities

  • Advocacy focus:

    • banning gas stunning

    • increasing transparency

    • regulatory reform

 Visit: https://www.farmtransparency.org/campaigns/gas-chambers

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 Australia Petition

Pigs Without Borders Campaign
Run by Animal Liberation

  • Calls for:

    • stronger animal welfare protections

    • review of intensive pig farming practices

    • improved regulation and transparency

 Visit: https://www.al.org.au/pigs-without-borders/petition

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 Recent Petition Activity (Status Update)

  • Over 22,000+ signatures were submitted to government calling for a phase-out of CO₂ stunning 

  • Government advisory bodies have acknowledged welfare concerns

  • Policy discussions and consultations are ongoing (as of 2025)

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Organisations & Further Information

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A Balanced Perspective

It is important to recognise:

  • Stunning is used to reduce suffering compared to unstunned slaughter

  • CO₂ remains widely used due to practicality and scale

  • There is growing global agreement that improvements are needed

This is an evolving area, with ongoing research, industry change, and public discussion.

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Why This Awareness Matters

This topic is often highlighted because:

  • it occurs on a large global scale

  • the welfare concerns occur prior to unconsciousness

  • there is increasing recognition that more humane alternatives may be possible

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This page is offered as a space for awareness.

If this topic resonates with you, you may wish to explore the resources and initiatives above.

If it does not, that is completely okay.

Awareness is not about judgement — but about understanding the systems we are part of, and choosing how we respond, if at all.

Expanding Awareness: Pig Welfare Across the Industry

 

While many people are becoming aware of CO₂ stunning practices, this is only one part of a much larger system. Pigs may experience stress, discomfort, or suffering at multiple stages of their lives—from breeding and housing, through transport, and ultimately at slaughter.

Understanding the full picture allows for more informed choices, deeper compassion, and meaningful advocacy.

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Transport: Stress, Injury & Exhaustion

 

Transport is widely recognised as one of the most stressful periods in a pig’s life.

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Key welfare concerns include:

  • Handling stress: Loading and unloading can involve fear, rough handling, and unfamiliar environments

  • Mixing unfamiliar pigs: This often leads to fighting and injury

  • Temperature extremes: Pigs are highly sensitive to heat and can suffer heat stress or dehydration

  • Long journeys: Associated with fatigue, hunger, thirst, and motion stress

  • Overcrowding: Restricts movement and increases injury risk

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Scientific assessments have identified multiple welfare risks during transport, including:

  • Heat stress

  • Injuries

  • Prolonged hunger and thirst

  • Restricted movement

  • Sensory overload and fear

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Research also shows pigs can experience:

  • Elevated stress hormones

  • Increased heart rate

  • Weight loss and dehydration

  • Even mortality during transport (in some cases)

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More information:

EFSA Pig Transport Welfare Summary

Australian Pig Transport Guidelines

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Breeding & Housing: Confinement and Restriction

 

Modern pig production systems can include practices that raise welfare concerns, particularly around breeding sows.

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Common issues raised by welfare organisations:

  • Farrowing crates:
    Mother pigs (sows) are often confined in narrow metal enclosures during and after giving birth

    • Prevents turning around

    • Limits natural maternal behaviour

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  • Lack of enrichment:
    Pigs are intelligent and curious animals, yet environments may lack stimulation

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  • Restricted movement:
    Limited ability to walk, root, or explore

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  • Injury and untreated illness:
    In some systems, injuries or illness may go unnoticed or untreated

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Animal welfare standards emphasise that pigs require:

  • Freedom of movement

  • Social interaction

  • Ability to express natural behaviours

  • Protection from distress and injury

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More Information

Victorian Pig Welfare Standards & Guidelines (PDF)

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Slaughter Conditions: Stress in Final Stages

 

The final stage of a pig’s life can involve multiple stress points:

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Before slaughter:

  • Holding in unfamiliar environments (lairage)

  • Exposure to noise, smells, and other distressed animals

  • Continued effects of transport stress

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Stunning and slaughter:

  • CO₂ stunning is widely debated (See separate page)

  • Concerns include:

    • Panic and distress before unconsciousness

    • Handling methods leading into stunning systems

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Research highlights that:

  • The entire slaughter process—including transport and handling—can be highly stressful

  • Welfare outcomes depend heavily on staff training, handling methods, and facility conditions

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Recent reporting in Australia has also raised concerns about:

  • Injuries and lameness on arrival

  • Delays in inspection after transport

  • Emergency euthanasia due to welfare issues

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More Information

Pigs Suffering in Factory Farming - FOUR PAWS in Australia - Animal Welfare Organisation

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Why This Matters

 

Pigs are widely recognised as:

  • Highly intelligent

  • Social and emotionally responsive

  • Capable of experiencing fear, stress, and comfort

When multiple stressors are combined—housing, transport, and slaughter—the cumulative impact on welfare can be significant.

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Take Action: Petitions & Advocacy

 

If you feel called to support change, here are current advocacy pathways and petitions focused on pig welfare. Petitions in this space change frequently. If a link is no longer active, searching terms such as *‘pig welfare petition’, ‘ban farrowing crates’, or ‘pig slaughter reform petition’ on platforms like Change.org will show current campaigns.:

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Australia & International Campaigns​

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Improve transport conditions and journey limits

Sign the Petition | Pigs Without Borders — Animal Liberation | Compassion without compromise

World Animal Protection – Farm Animal Welfare Campaigns

Stop Cruel Live Animal Transport | FOUR PAWS

Ban or phase out farrowing crates

Petition · Ban Sow Stalls and Farrowing Crates in Australia – End Legalised Cruelty - Australia · Change.org

Petition · Ban Farrowing Crates and Sow Stalls in Western Australia - Australia · Change.org

Petition · Ban Farrowing Crates - Let Mother Pigs Care for Their Babies - United States · Change.org

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​When people understand what pigs may experience, where welfare challenges exist & how systems can improve…it creates space for more conscious choices, compassionate conversations, and meaningful change.

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