How Pigs Are Killed: Slaughter, Welfare & the Ethics Behind It

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Ever wondered about the journey of pigs from farm to table?

It’s unsettling but essential to understand the reality behind pig farming and slaughter.

This article uncovers how pigs are killed, the ethical and environmental costs, and why it matters to anyone who cares about animals, the planet, or their food choices.

How are pigs killed?

Pigs typically go through two critical phases before slaughter: handling/movement and the killing itself.

The most common methods for slaughtering pigs are electrical stunning, gas stunning, and stunning using a captive bolt pistol to shoot the animals directly into the brain.

1. Electrical stunning

• Head-only: Reversible unconsciousness. It involves two electrodes placed on either side of the head. Pigs may regain consciousness in ~30 seconds.
• Head-to-body: It can cause different complications and adversely affect the end product, so rarely used due to potential quality issues..

The effectiveness of electrical stunning depends on factors like the pig’s weight, skin thickness, wetness, hair length, and age.

If not done ‘properly’, it causes pain without immediate death. (source – page 77) 

2. Gas (CO₂) stunning

• Gas stunning typically uses 80–90% carbon dioxide and is one of the most common methods.
• Pigs begin to lose consciousness between 20 and 40 seconds after exposure starts. (1)
• Before unconsciousness, pigs suffer from fear, intense respiratory distress, air hunger, and pain.
• Exposure causes hyperventilation and a strong sensation of suffocation.
• Scientific studies show CO₂ stunning is neither immediate nor painless.
• The method does not eliminate avoidable suffering.
• These factors raise serious concerns about the welfare of pigs during gas stunning.

3. Penetrative captive bolt

• A bolt is fired into the pig’s brain to cause unconsciousness and death.
• Effectiveness relies on accurate placement; misfires require repeated shots, causing significant suffering.
• Captive-bolt stunning is difficult because even a slight misangle can fail to cause instant unconsciousness, and older or larger pigs may have a forehead bone that blocks the bolt from penetrating effectively.
• That means the pig won’t die immediately, and a second shot is required. 

Common slaughtering methods around the world

• Europe: Electrical stunning (head-only and head-body) and gas stunning (carbon dioxide gas and inert gas mixtures)  
• Australia: group gassing, where pigs are transferred into a gas chamber and gassed to death
• The US: captive bolt pistol/gunshot, electrical, or gas stunning
• The UK: gas and electrical stunning

Key facts

• Pigs are typically aggressively restrained before slaughter, causing extreme stress and fear.
• Stunning methods vary – some cause both unconsciousness and death, while others only induce unconsciousness.
• Stunning is always followed by a killing method, such as bleeding (slitting the throat) or pithing (destroying brain tissue). (1)
• If stunning is ineffective or the pig regains consciousness, bleeding causes intense pain, suffering, and fear.

Environmental impact of pig farming

Pig farming isn’t just inhumane, it also poses serious environmental risks:

• Manure pollution: Pig farms produce vast amounts of manure, which can release excessive nutrients into the environment. While small amounts may fertilize soil, overapplication leads to soil and water degradation. Manure often carries pathogens, heavy metals, and bacteria that pollute nearby air and water sources.
• Air pollution: Malodors and airborne particles from large-scale operations reduce air quality, causing stress and respiratory problems for local populations.
• Public health risks: Waste from pig farms is frequently spread into surrounding communities, increasing the risk of respiratory issues, infections, and even cancer in nearby residents.
• Contribution to climate change: Animal agriculture, including feed crops and transportation, contributes 14-18% of all GHG emissions (1, 2, 3) – more than all forms of transport combined (cars, planes, ships, etc.).
• Greenhouse gas emissions: Pork production emits approximately 12.1 kg CO₂-equivalents per kg of meat, making it one of the most environmentally damaging meats. In contrast:
  – Tofu: 2.2 kg CO₂e
  – Rice: 2.7 kg CO₂e
  – Potatoes: 2.9 kg CO₂e
  – Beans: 2 kg CO₂e
  – Lentils: 0.9 kg CO₂e

Source: Environmental working group

To find out more about the harmful effects of animal agriculture, read my article on 8 environmental benefits of reducing meat consumption.

Source: Environmental Working Group Meat Eaters Guide: Methodology 2011, page 23

Pig intelligence: Smarter than you think

Pigs aren’t just “farm animals” – they’re incredibly smart, emotional, and social beings. In fact, they rank among the most intelligent animals on the planet. Here’s why:

• Cognitive skills: Some studies suggest pigs can outperform dogs in certain problem-solving tasks. They can play video games with joysticks, recognize symbols, and even learn their names just like your pet at home.
• Self-awareness: Pigs have been shown to recognize themselves in mirrors – a rare ability that only a handful of animals possess. Passing this “mirror test” suggests they have a level of self-awareness once thought to be unique to humans and a few primates.
• Social intelligence: Pigs form close-knit relationships and hierarchies within groups. They can distinguish between individual pigs and humans, remember past interactions, and even show empathy-like behaviors when companions are distressed.
  Pigs form strong connections with other pigs – and with humans. They’re curious and affectionate, and they thrive in environments where they can explore, root around, and interact.
• Emotional beings: Like dogs, pigs feel fear, joy, grief, and affection. They can get lonely, bored, or stressed when confined or isolated, but they also play, cuddle, and show excitement. They even console each other when one is upset.
  

Treating pigs as products rather than living beings ignores a growing body of scientific evidence about their rich inner lives. When subjected to standard industry practices, such as confinement, separation from offspring, and brutal slaughter methods, their capacity for fear, stress, and suffering makes the process even more ethically troubling.

Understanding who pigs are, and not just what they’re used for, challenges us to rethink our relationship with them.

FAQ

Why are pigs boiled alive?

There are many cases in which pigs are being boiled alive. That type of violation continues to occur, as there is not enough supervision and fines.

It can happen because many animals are not stunned according to procedures, mainly due to time constraints. (sources at the end)

Do pigs cry and suffer when slaughtered?

Much research exists showing that pigs are highly intelligent animals that feel pain similar to humans. They are sentient beings, and they suffer and feel pain. Research shows that pigs cry, squeal, and vocalize when they sense pain. 

How long do pigs live before slaughter?

Factory farm pigs are sent for slaughter after just six months of their life. The average life span of pigs is 10-15 years when they live their natural life.

Can we humanely kill a pig? 

No. The word humane is often misunderstood to mean “without pain or suffering,” but even the most controlled slaughter methods involve fear, stress, and often significant pain.

Humane means showing compassion or kindness – concepts fundamentally incompatible with killing a sentient being that wants to live. Calling slaughter “humane” is, by definition, an oxymoron.

Conclusion

Pigs are sentient, smart animals that we treat horribly, just to satisfy our sensory pleasure. The truth is, we can survive and thrive without killing and eating pigs.

There are now innovative, delicious alternatives that can satisfy any craving, without having to kill a sentient being for the sake of a 10-minute meal

More and more people are becoming aware that killing animals is unnecessary; they are open and brave enough to change their old habits. 

If you are interested in reducing your meat consumption, you can follow my step-by-step beginner’s guide on transitioning to a 100% plant-based diet.

Do you have any questions or comments? Feel free to start a friendly conversation in the comment section below.

Sources:

Pigs slaughtering:

Pig slaughter (Wikipedia)

Panel on Animal Health and Welfare (2020). Welfare of pigs at slaughter. DOI:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447914/

Panel on Animal Health and Welfare (2020). Welfare of pigs during killing for purposes other than slaughter. DOI:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7372489/

Slaughtering methods:

Europe: 

Mia Scott (2018). The humane slaughter of pigs in the EU. DOI: https://www.researchgate.net/publication/328710482_The_humane_slaughter_of_pigs_in_the_EU

Australia: 

https://animalsaustralia.org/features/not-so-humane-slaughter/#:~:text=Because%20pigs%20are%20highly%20intelligent,are%20now%20killed%20this%20way.

Aussie Pigs: https://www.aussiepigs.com/documents/Pig%20slaughter%20video%20Broom.pdf

The US: 

National Agriculture Library. Humane Methods of Slaughter Act: https://www.nal.usda.gov/awic/humane-methods-slaughter-act

(2020). Animals and animal products. Chapter iii - Food safety and inspection service, Department of agriculture: https://www.animallaw.info/administrative/us-slaughter-humane-slaughter-livestock-regulations 

The UK:

Animal Welfare Team (2019). Results of the 2018 FSA Survey into Slaughter Methods in England and Wales. DOI: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/778588/slaughter-method-survey-2018.pdf

Captive bolt (Slaughter Factfile): https://www.rspca.org.uk/adviceandwelfare/farm/slaughter/factfile

Meat processing: By-products: https://www.britannica.com/technology/meat-processing/By-products 

Humane Slaughter Association - Pigs: https://www.hsa.org.uk/positioning/pigs#:~:text=The%20site%20for%20stunning%20pigs,the%20forehead%20(Figure%2018). 

The lifespan of pigs:

Pig Transport and Slaughter: https://www.peta.org/issues/animals-used-for-food/factory-farming/pigs/pig-transport-slaughter/#:~:text=When%20allowed%20to%20live%20out,just%20six%20months%20of%20life.

Effects on the environment: 

Animal protection and health - Pigs and environment: http://www.fao.org/ag/againfo/themes/en/pigs/Environment.html#:~:text=The%20main%20direct%20environmental%20impact,related%20to%20the%20manure%20produced.&text=High%2Ddensity%20pig%20production%20can,eventually%20accumulate%20in%20the%20soil. 

Environmental impact of pig farming (Wikipedia): https://en.wikipedia.org/wiki/Environmental_impact_of_pig_farming 

Steve Wing (2013). Air Pollution from Industrial Swine Operations and Blood Pressure of Neighboring Residents. DOI: https://ehp.niehs.nih.gov/doi/10.1289/ehp.1205109 

Environmental Working Group Meat Eaters Guide: Methodology 2011: https://static.ewg.org/reports/2011/meateaters/pdf/methodology_ewg_meat_eaters_guide_to_health_and_climate_2011.pdf 

Heather Browning (2020). Is Humane Slaughter Possible? DOI: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7278393/#:~:text=The%20RSPCA%20(Royal%20Society%20for,humane%20slaughter%20describe%20it%20as 

Giampiero Grossi (2018). Livestock and climate change: impact of livestock on climate and mitigation strategies. DOI: https://academic.oup.com/af/article/9/1/69/5173494  

Elena Lara de la Casa (2017). Intensive pig farming: Ethical considerations. DOI: https://www.researchgate.net/publication/322837792_Intensive_pig_farming_Ethical_considerations 

Pigs being boiled alive:

https://www.iamexpat.nl/expat-info/dutch-expat-news/pigs-boiled-alive-dutch-slaughterhouses 

https://www.dutchnews.nl/news/2020/06/pigs-still-boiled-alive-despite-promises-to-eradicate-practice-varkens-in-nood/ 

https://www.kinderworld.org/videos/meat-industry/pig-slaughterhouse/