Why Vets Are Saying Enough Is Enough to Ventilation Shutdown During the Avian Flu Crisis
As highly pathogenic avian influenza continues to rip through poultry operations across the United States, veterinarians are facing an uncomfortable reality. Disease control is essential, but how flocks are depopulated is becoming one of the most divisive animal welfare debates the profession has seen in years. Under the USDA stamping out policy, poultry flocks presumed positive for avian influenza are to be depopulated within 24 to 48 hours. On paper, this rapid response limits viral spread. In practice, the methods used to achieve that goal are drawing sharp criticism from veterinarians across sectors.
How Ventilation Shutdown Became the Default
A 2022 analysis found that Ventilation Shutdown Plus, commonly called VSD+, quickly became the most frequently used depopulation method for large poultry flocks. The process involves sealing poultry houses, adding supplemental heat, and allowing birds to die from hyperthermia over the course of several hours. Producers often turn to the AVMA Guidelines for the Depopulation of Animals when selecting depopulation methods during disease outbreaks. These guidelines, developed in part through USDA funding, directly influence federal policy. They also determine eligibility for USDA indemnity payments that compensate producers for animals lost during outbreaks. Critics argue that this financial and regulatory framework has unintentionally encouraged the use of methods that prioritize speed and cost over animal welfare.
Dr Crystal Heath, executive director of the veterinary advocacy organization Our Honor, emphasizes a distinction many veterinarians feel has been blurred. Depopulation is not euthanasia. Euthanasia refers to the humane ending of life to relieve suffering. In many avian influenza responses, birds are not clinically ill at the time they are killed, and some depopulation methods do not meet humane standards. Heath and others argue that the current guidelines allow VSD+ under constrained circumstances without clearly defining what those circumstances actually are. As a result, operations may default to VSD+ rather than investing in more humane alternatives.
The Profession Speaks Up
Veterinary discomfort with VSD+ is not fringe. A Veterinary Information Network poll of more than 3,000 veterinarians found that only 1.1 percent believed VSD+ was an ethical and humane depopulation method. Financial data has further fueled the debate. Our Honor has compiled USDA indemnity payment records tied to avian influenza depopulation. Jennie O Turkey Store reportedly received around $120 million after using VSD+ on some flocks. Hickman’s Egg Ranch in Arizona is estimated to have received over $100 million. Many veterinarians see this as a system that rewards corporations while failing animals.
Ellensburg, Washington veterinarian Dr Erin Zamzow has criticized the current framework for enabling large companies to avoid investing in less cruel technologies. She and others point to nitrogen gas and high expansion nitrogen foam as alternatives that render birds unconscious within minutes, with death following shortly after. Compared to hours of heat stress, these methods are widely viewed as significantly more humane.
Documents obtained through Freedom of Information Act requests by Our Honor indicate that VSD+ continues to be used regularly, despite being designated for constrained circumstances. This ongoing reliance has led some veterinarians to question whether the designation has any real meaning in the field. San Francisco veterinarian Dr Moni Ramirez has described the continued classification of VSD+ as permissible as a moral failure that conflicts with the veterinary oath to protect animal welfare.
A Shift in Guidelines or Just New Language
The AVMA released a draft of a new edition of the depopulation guidelines last year and opened a comment period for members. The updated draft replaces labels like preferred and not recommended with a tiered system. Tier 1 methods are described as highest priority and preferred whenever possible. Tier 2 methods may be used when circumstances limit access to Tier 1 options. Tier 3 methods have limited or conflicting evidence regarding animal welfare.
In the draft, VSD+ appears as a Tier 2 method for poultry and a Tier 3 method for pigs. Critics argue that this restructuring may obscure welfare concerns rather than resolve them. Heath and other advocates are calling for VSD+ to be clearly listed as not recommended for all species. The AVMA is expected to release the next edition of the Guidelines for the Depopulation of Animals in January. For veterinary professionals, this moment represents more than a policy update. It is a test of whether the profession will assert animal welfare as a non negotiable standard, even during crisis response. As avian influenza continues to challenge food systems and animal health infrastructure, many veterinarians are making it clear that how animals die matters just as much as stopping disease spread.
