Ventilation Shutdown Is One of the Cruelest Ways to Kill Animals
From The Observatory
Source: The Humane League
The least humane way of culling poultry and pigs has become increasingly common.
This article was produced by Earth • Food • Life, a project of the Independent Media Institute.
“Ventilation Shutdown Is One of the Cruelest Ways to Kill Animals” by Michael Windsor is licensed by the Observatory under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License (CC BY-NC-SA 4.0).
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Introduction
Ventilation shutdown plus (VSD+) is an incredibly inhumane method of killing lots of animals at once by shutting off the air supply and driving up temperatures, causing organ failure and suffocation. It must stop.
Surging temperatures from heat pumped into an airless shed leave animals trapped inside, making it increasingly challenging for them to breathe. Eventually, after enduring hours of suffering, these animals suffocate and die in agony. This scenario is real, and the results are intentional. VSD+ is a brutal method of putting an entire flock—or herd—of animals to death all at once.
No animal should ever endure hours of suffering to die in extreme heat. However, in 2022, millions of chickens were killed through this horrific practice due to the avian influenza, or bird flu, which reemerged in bird populations across the United States, including the earlier outbreak in 2020. According to the U.S. Department of Agriculture, between February 2022 and August 2024, 100.71 million poultry were affected in the United States, including both commercially raised and backyard flocks. To stop the highly infectious virus from spreading, poultry farmers began culling entire flocks of chickens and turkeys raised to produce eggs or meat, meaning millions of birds were put to death using VSD+.
Inhumane Killing: Ventilation Shutdown and Ventilation Shutdown Plus
VSD+ is a process in which barns or sheds, where chickens or other animals live, are closed tightly, ventilation is sealed, fans are turned off, and heat, steam, or gas is turned on. As the temperature inside the building soars above 100 degrees Fahrenheit, the animals inside die from suffocation, heat stroke, and organ failure. This process occurs over long hours, where animals are essentially baked alive.
Ventilation shutdown (VSD) is the process of shutting off ventilation, allowing temperatures inside a building to rise or fall naturally. Ventilation shutdown plus (VSD+) is a specific method of depopulation that involves shutting off ventilation and pumping in heat or carbon dioxide.
It would be criminal to deliberately allow a pet to die through forced heat and suffocation. Therefore, it is unacceptable to allow farm animals to perish in this way. This thought process has led veterinarians to demand that the American Veterinary Medical Association (AVMA) reclassify VSD+ as “not recommended.”
There’s a problematic loophole in which the AVMA approves VSD+ for culling chickens and pigs in “constrained circumstances.” This method of slaughter is anything but humane, as animals die in a long and painful fashion from VSD+. This raises the question: Why is VSD+ happening in the first place? The answer has everything to do with the rampant spread of disease on factory farms.
Disease Spreads Quickly on Factory Farms
When animals are packed together, diseases can spread rapidly. This can also occur within crowds of people—close proximity increases the likelihood of transmitting the disease. Think of the way COVID-19 quickly spread in nursing homes, or of how the Black Death claimed the lives of more than 50 percent of a crowded city’s inhabitants.
A whopping 94 percent of animals raised for food (or to provide products like milk and eggs) live on factory farms, where crowding and unsanitary conditions are rampant. Due to this, factory farms can become breeding grounds for infectious diseases to emerge, spread, and travel from animals to humans.
Germs that jump from animals to humans are known as zoonotic diseases. While COVID-19 brought the connection between infectious disease and animal cruelty into the spotlight, other illnesses remain of great concern. The sad truth is that the threat of zoonotic disease isn’t going away. A United Nations report suggests we may see an increase in zoonotic diseases due to unsustainable farming practices, climate change, and wildlife exploitation.
The validity of this theory is reflected in the avian influenza outbreak that began in 2020. Avian influenza, also known as bird flu, is a contagious respiratory disease that spreads through direct contact with infected birds. It can also spread through contact with contaminated water, feed, equipment, or materials. Chickens raised on factory farms make up nearly 90 percent of all land animals raised for food in the U.S., and they suffer incredible abuse. Living in cramped, filthy sheds with thousands of other birds, even a single sick chicken can quickly lead to a sick flock.
Bird flu travels fast in crowded factory farms—but it’s worth remembering that factory farms are crowded because our broken food system prioritizes scale and profit. The spread of bird flu is a symptom of industrialized animal agriculture. When a few chickens in a large flock contract avian influenza, the response is to euthanize the affected birds through depopulation.
Animal Depopulation
Animal depopulation is a term for killing large numbers of animals all at once—namely, pigs, cows, or chickens. Depopulation generally happens in response to a crisis and should only ever occur on rare occasions when a humane method of slaughter, like euthanasia, is not possible.
Unfortunately, the American Veterinary Medical Association (AVMA) currently approves depopulation methods like VSD+ in “constrained circumstances.” This has been interpreted as a go-ahead in response to events such as the surplus of pigs during the COVID-19 pandemic or the avian influenza outbreak that occurred in 2022. In both cases, farmers turned to VSD+ to kill vast numbers of pigs (during COVID-19) and chickens (during avian influenza), allowing countless herds and flocks to die slowly and painfully in unbearable heat. Of the 95 million birds depopulated between February 2022 and July 2024, most were killed in gas chambers, by firefighter foam, or with VSD+.
Pigs and Chickens: The Main Victims
To date, poultry (primarily chickens and sometimes turkeys) and pigs are most commonly culled through ventilation shutdown plus (VSD+). VSD+ has been most widely used in response to crises affecting pigs and chickens, but the practice is now on the rise. In 2023, the Department of Agriculture paid poultry farmers more than half a billion dollars in compensation for birds culled after being infected with the H5N1 strain–compensation that was only paid for culled birds, not those that died of the infection.
While this strategy may have helped slow the spread of the virus, it did nothing to incentivize system change. Instead, it encouraged farmers to persist in business practices that aggravated the infections (housing animals in overcrowded, stressful, and unsanitary conditions) while simultaneously awarding them for exceptionally cruel depopulation practices such as VSD+.
A research group at North Carolina State University received a grant from the U.S. Poultry and Egg Association to validate VSD+ as a method for culling chickens. After that single industry-funded study was published, the American Veterinary Medical Association (AVMA) listed ventilation shutdown plus as “permitted in constrained circumstances,” which the poultry industry interprets as “veterinary approved.”
Since then, VSD+ has become increasingly prevalent and is now being practiced at unprecedented rates. During 2022, when the virus began infecting commercial birds in large numbers in the United States, VSD+ became the preferred method of killing millions of chickens nationwide.
When slaughterhouses closed during the COVID-19 pandemic, factory farming led to what the industry considered a surplus of pigs. To address this, farmers turned to VSD+, eradicating entire herds of pigs by forcing them to swelter to death. It’s time to demand change, starting with asking the AVMA to revoke its endorsement of VSD+ through petitions and awareness campaigns.
Working to End VSD+
Despite the blatant cruelty of VSD+, the AVMA continues to endorse the practice—an endorsement based on one poultry industry-funded study. It’s time for that to change.
Veterinarians are trusted partners in the care of all animals, regardless of species, and veterinarians joined together to call on the AVMA to rescind VSD+ and help prevent more animals from being killed in this manner. It is essential, now and in the future, to send a powerful message that it’s time to stop the suffering and horrific slaughter of millions of animals.
