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September 15, 2021

HOD recommends depopulation policy sent to expert panel for further consideration

Methods for depopulating swine, poultry in the spotlight after being used last year
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Two methods of depopulating chickens or pigs listed in AVMA guidelines have come under scrutiny in the past year.

During 2020, meat processing plants experienced substantial employee shortages because of COVID-19, with unprecedented declines in processing capacity nationwide. As a result, farmers were forced to hold animals longer than planned, leading to overcrowding and resulting in animals becoming too big for housing and processing facilities. After alternatives for marketing were exhausted, some meat processing companies used either ventilation shutdown or what is called VSD plus to quickly depopulate animals.

In reaction, a group of AVMA members submitted a late resolution by petition to the AVMA House of Delegates for the regular winter session in January. That resolution asked that the AVMA classify all forms of ventilation shutdown—VSD and VSD plus—as “not recommended” for poultry and pigs within the “AVMA Guidelines for the Depopulation of Animals: 2019 Edition.”

AVMA HOD vote to refer resolution on VSD
The AVMA House of Delegates voted to refer a resolution on reclassifying ventilation shutdown methods as not recommended to the AVMA Board of Directors for consideration by the Panel on Depopulation. (Photo by R. Scott Nolen)

Delegates opted not to consider the resolution in January because it was submitted late, but took it under consideration during the regular annual session, held July 29-30 in Chicago. Ultimately, 99.1% of the HOD voted to refer the resolution to the AVMA Board of Directors with a recommendation to refer the proposal to the AVMA Panel on Depopulation for consideration.

The panel consists of more than 60 subject matter experts and continuously reviews new research on approaches to depopulation. If, based on its review of that research, the panel decides to make any updates, AVMA members are given a chance to review and comment on those changes before the document is finalized.

According to the depopulation guidelines, VSD is a method of depopulation that involves closing the facility, shutting inlets, and turning off the fans associated with the ventilation system. VSD is not listed in the AVMA guidelines as an option for pigs and is “not recommended” for poultry.

According to background materials for the resolution, VSD plus incorporates components such as heat, humidity, and carbon dioxide, in addition to shutting down the ventilation system, to cause the death of pigs or poultry. VSD plus is listed as a “permitted in constrained circumstances” method for depopulating swine and poultry and should only be used in emergencies after preferred methods have been contemplated and ruled out, according to the guidelines.

Last year, the COVID-19 pandemic caused disruptions in the food supply that affected swine and poultry markets.

“While alternate strategies were sought first, some producers and companies made the decision to depopulate animals in response to these market disruptions,” according to the background materials for the resolution.

The depopulation guidance is extremely important for veterinarians who provide input into these decisions, said Dr. Gail Golab, chief veterinary officer for the AVMA.

“The amount of deliberation and care taken in developing these guidance documents is what has provided their validity not only here, but internationally,” she said to a reference committee of the HOD.

At the same time, according to the background materials, the AVMA acknowledges that it is not a regulatory body and “has no authority over depopulation decisions made by producers, the companies with which they are affiliated, or by state or federal agencies. ... Nor does the AVMA oversee depopulation when it is being conducted.”

Animals should not be depopulated unless required by a serious emergency—such as a zoonotic or pandemic disease like COVID-19—and all other reasonable alternatives to managing the affected animals have been explored and been found to not be viable, according to the background materials.

Specifically regarding VSD plus, the method should be applied with a scientifically validated protocol and with strict engineering process control that causes greater than 95% mortality in less than an hour.

Dr. Cia Johnson, who provides staff support to the Panel on Depopulation and is director of the AVMA Animal Welfare Division, said data in a manuscript that appears in the Aug. 15 issue of JAVMA suggest producers at a swine facility in Iowa were able to achieve that standard.

Dr. Bill Williams, Iowa alternate delegate, said to the HOD reference committee: “The veterinarians making these choices made no small effort to come to that conclusion that VSD plus was the last effective, available, and efficient type of option. I can tell you those people were permanently affected by that decision.”

Dr. Michael Zager, Georgia delegate, said to the committee that state veterinarians from Georgia and South Carolina told him they would prefer to have these depopulation methods as options when necessary.

“We have African swine fever in the Dominican Republic. There’s avian influenza,” he said. “There are going to be times when this is needed, like it or not.”

Read the resolution (PDF) on reclassifying ventilation shutdown and methods as not recommended.