'Ventilation Shutdown': The Gruesome Last Resort for Bird Flu-Infected Farms
Chickens stand in their cages at a farm near Stuart, Iowa. Photo by Charlie Neibergall/AP


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'Ventilation Shutdown': The Gruesome Last Resort for Bird Flu-Infected Farms

In a ventilation shutdown, the air systems in a chicken house are turned off, causing the birds to slowly overheat and suffocate.

Bird flu is terrible way for a chicken to go. Once infected with the highly pathogenic avian influenza virus (HPAI), a chicken's eyes and head will swell, it will bleed from its nostrils, lose the ability to walk, get diarrhea, struggle to breathe, and eventually die.

But in preparation for a possible second wave of the insidious viral outbreak that ravaged more than 200 commercial US farms this spring, the US Department of Agriculture is proposing another terrible death sentence for these birds: shutting off the air and slowly cooking them alive.


"It's not a very pleasant death. In fact, it can be pretty horrible," Dr. Michael Blackwell, the senior director of veterinary policy for the Humane Society of the United States, told me over the phone.

As the temperatures start to dip across the Midwest, we're at risk of a second wave of the deadly bird flu that swept the country earlier this year. The USDA is preparing for the worst, and that includes approving a controversial method for euthanizing infected birds called ventilation shutdown, where the air systems in a chicken house are turned off, causing the birds to slowly overheat and suffocate. This method is to be used only as a last resort, but may be required at larger, industrial facilities in order to comply with the USDA's decision to impose a 24-hour window for euthanizing birds once the virus has been detected.

But the Humane Society and other animal welfare groups aren't convinced this 24 hour rule is necessary to prevent the spread of the disease, especially when it may require the suffering of thousands of animals.

When a bird is infected with HPAI, it excretes the virus in its feces and from other bodily fluids (like the bird equivalent of snot). Outbreaks are usually linked back to wild waterfowl, which can carry the disease but usually aren't affected by it. Researchers aren't yet sure how HPAI spread earlier this year, but it's a hearty virus that can travel into farms via insects, rodents, clothing, shoes, equipment, egg cases, vehicles, and possibly even through the air. It's rare that the virus infects humans, but we can definitely carry it on us.


It's these multiple vectors that has Blackwell and others questioning what good the 24-hour rule will do to stop the spread of the disease. In fact, the USDA's own reports indicate factors like people and equipment traveling between farms, not having hard surfaces around barns that are easy to disinfect, and not disposing of dead birds far enough away contributed to the spread of the virus earlier this year. Why not focus more on preventing the virus from spreading to healthy chickens rather than rushing to meet an arbitrary 24 hour deadline to kill the chickens already infected?

"Containment is what's really key once the virus appears," Blackwell said. "If due diligence is given to all of the things that go into containing that virus, there's no reason to try to meet a 24-hour goal."

The USDA is trying to avoid the devastation caused by the outbreak earlier this year. Between December of last year and June 2015, 7.5 million turkeys and 42.1 million chickens in the US had to be euthanized due to HPAI, according to USDA stats. Those deaths meant a market loss of approximately $1.6 billion, and the USDA says the outbreak cost taxpayers $950 million. Multiple governors declared states of emergency. It was chaos.

HPAI is most likely to occur during the winter, especially between January and March, and the USDA is looking at all options for preventing or containing a second outbreak. The agency has done a lot of things to prepare, such as helping farmers review and improve their biosecurity—measures put in place to prevent viruses, bacteria, and parasites from getting into livestock facilities. It's ramped up the disease surveillance in wild birds, which carry but usually aren't affected by the virus. And it's instituted this 24-hour window for "depopulating" (i.e. euthanizing) chicken flocks once the virus is detected at a farm.


HPAI is unequivocally a death sentence for chickens: once the virus is detected, the entire flock will die. If the farmers don't kill them, the disease eventually will.

"A major lesson learned during the this year's avian influenza outbreak is that one key to defeating the disease is speed," Lyndsay Cole, a spokesperson for the USDA's Animal and Plant Health Inspection Service (APHIS), told me via email. "Scientific and epidemiological studies show that this 24-hour window is critical to speed disease response activities and reduce the amount of virus in the environment, helping to protect nearby poultry operations from infection and limit the unnecessary loss of animals."

To kill infected birds quickly, most facilities use either carbon dioxide gassing or a spray foam (kind of like the stuff that comes out of a fire extinguisher) that suffocates the birds. All of the birds killed earlier this year were euthanized using one of these two methods. Though neither are the most pleasant way to go, Blackwell told me the HSUS takes less issue with the foam and gassing options because they kill individual birds fairly quickly, compared to ventilation shutdown.

"This is just another indictment on this intensive farming model."

But considering the unfathomable size of some factory farms—one processor in Iowa houses 5.3 million birds, for example—foam might be too slow and inefficient of an option for some producers if the virus strikes again. The foam has to be applied to completely cover each chicken in order to euthanize them, and when you have giant barns filled with battery cages stacked on top of one another, that's no easy feat. That's when ventilation shutdown would come into play.


Without ventilation systems running, the temperature inside chicken houses can slowly rise to 122 degrees Fahrenheit. As the environment heats up, the chickens' internal organs start to fail, and they suffocate in a process that can take anywhere from 20 minutes to several hours, according to Blackwell. They're virtually cooked alive.

So why not avoid this gruesome death and just quarantine infected birds? According to the USDA, chickens shed large quantities of the virus very quickly, and the longer facilities wait to depopulate the flock, the harder it becomes to control the spread. Though the USDA concedes that biosecurity is paramount to stopping the spread of the disease, quickly euthanizing infected birds makes this much easier to achieve.

"Even with strict and well-enforced biosecurity measures, the raw amount of infectious material makes effective biosecurity in the midst of a response effort extremely challenging," the USDA wrote in its decision. "The amount of virus produced by infected birds is significant; the more virus that exists, the harder it is to control and contain the outbreak."

Cole told me approving ventilation shutdown wasn't a decision that was made lightly, and that it will only be approved on a case-by-case basis if absolutely necessary. She also wrote that, compared to the death the infected birds would suffer from the disease itself, it can actually be a more humane option. It highlights how dire the situation can become in the midst of the bird flu outbreak, and ultimately the decision on how best to kill thousands of birds is never an easy one.

Still, as Blackwell pointed out, the outbreak and the response to it also highlights how dysfunctional the industrial farming system can be.

"It has put these animals in an inhumane situation all the way to the point where you have to quickly kill them," Blackwell said. "If they were free-range, these challenges would not be the same. This is just another indictment on this intensive farming model."