Daniela Castillo

Photo by Lori Fusaro

Dr. Daniela Castillo, a practitioner in Southern California, is shown with her cat, Valito, whom she adopted from a shelter after performing a thoracic limb amputation on him. Today, she reports, he's faster than her four-legged felines.

I have been reluctant to raise the subject of ventilation shutdown — a technique used in crisis situations for mass killing livestock through heatstroke — because I have seen conversations become adversarial and even hostile, resulting in a fracturing of the veterinary profession. But this topic is so important that I cannot be silent. I hope we can discuss it and avoid personal attacks by focusing on solutions.

A bit of background about me: I graduated from a heavy production animal university in Mexico and now practice in California. As a Latina veterinarian, I have had clients ask to see a white doctor instead of me. Even professional colleagues have made comments to me about how immigrants are causing problems and should go back to Mexico. My personal experiences have made me sympathetic toward the animals who are vulnerable to the biases of those in power. I see how this mentality of dominance and lack of compassion is destructive to our relationships with other humans, other species and the natural environment.

I realize I am part of a system that believes we, as the dominant species, can treat animals — whom we know are conscious and feel pain — as units of production instead of unique, sentient individuals. This belief is brought into stark focus by the issue of ventilation shutdown, or VSD, a method of killing animals on farms en masse by shutting down the ventilation system to induce heatstroke and eventual death. VSD alone is generally recognized as inadequate to the task, and therefore is usually combined with measures such as added heat and humidity to hasten death, a practice referred to as "ventilation shutdown plus," or VSD+.

Tolerance of VSD+ by some in the profession not only calls into question whether we adequately prioritize animals' welfare and consider their suffering as we use them for our benefit, but also whether we prioritize the mental health of colleagues involved in their care and that of the workers who are forced to inflict such suffering under veterinary authority.

The issue of VSD+ came to the fore in 2020 when COVID-19 illnesses and exposures among workers caused shutdowns in slaughterhouses and meatpacking facilities, resulting in a backlog of animals intended for slaughter. VSD+ was used to cull large numbers of pigs, both because of financial pressures and because overcrowding would cause severe welfare issues. How many pigs were killed this way is unclear, but a letter from the National Pork Producers Council suggests it could have been up to 10 million animals. The American Veterinary Medical Association's Guidelines for the Depopulation of Animals: 2019 Edition allow the use of VSD+ as a last resort. The guidelines classify VSD alone as "not recommended" but VSD plus heat and/or carbon dioxide is "permitted in constrained circumstances" for poultry and pigs.

The idea that those in power have the right to exploit the more vulnerable is embedded in our profession and society. It also affects our science by influencing whose perspectives are centered in the questions we ask. A recent article in the Journal of the American Veterinary Medical Association, "A case study of ventilation shutdown with the addition of high temperature and humidity for depopulation of pigs," describes in detail how 243,016 pigs came to be killed through VSD+ in Iowa between April and June 2020. The authors conclude: "Efficacy exceeded AVMA recommendations for the use of VSD+ (> 95% mortality rate in < 1 hour). Findings could potentially guide the use of this method for mass depopulation in the event of a foreign animal disease outbreak or severe market disruption in the future."

I was gratified to read letters to the editor responding to that article that presented differing opinions. The letters — one from Dr. Gwendolen Reyes-Illg and another from Drs. Jim Reynolds, José Peralta and Beth Boynton — politely refute the claim that the article's data shows AVMA guidelines were met. The correspondents also discuss the pathophysiology of heatstroke and the suffering of pigs. They propose possible alternatives and advocate changes and preparations to ensure VSD+ is never used again. Many of us agree.

In a response to the letters (appearing on the second and third pages of this pdf reprinted with permission from JAVMA), the authors of the case study make the valid point that implementing VSD+ "was an excruciating decision for many veterinarians involved in the process." There is no doubt in my mind that deciding how to kill one's healthy patients in unprecedented numbers caused moral anguish for all involved. The mental health impact on veterinary colleagues should be considered a One Health crisis. Mental illness stemming from the brutality of our food system should be considered as much of a threat as a zoonotic respiratory or gastrointestinal outbreak.

I, too, have suffered from anxiety and depression stemming from living in a disconnected society in need of kindness toward fellow humans as well as animals, while struggling to navigate a profession lacking diversity and inclusion. So I feel a great deal of concern for the livestock veterinarians who, in this instance, had to square the compassion they feel for animals with their role in a system that prioritizes production efficiency and corporate profits.

The authors of the case study point out that "10% of swine veterinarians have thought about suicide and 23% have reported needing mental health counseling." This potential impact on our colleagues alone is enough of a reason for us to join together to ask the AVMA to reclassify VSD+ as a "not recommended" form of depopulation. The renowned animal behaviorist Temple Grandin and others have pointed out that if we prepare now, future use of VSD+ is avoidable.

Recommendations from Grandin and others in the animal welfare field include ensuring government and corporate veterinary stockpiles include equipment for more humane depopulation methods, ones that cause instantaneous loss of consciousness, such as gunshot, captive bolts and mobile electrocution units; converting slaughterhouses to production of whole carcasses rather than cuts of meat, which would require far fewer workers; and decreasing stocking densities to avoid the rapid onset of severe animal welfare problems when supply chains are disrupted.

The study authors, rather than recognizing that the emotional distress of swine veterinarians arises from the trauma of overseeing VSD+ itself, place the blame on veterinarians who criticize the technique. They state: "[W]e need to acknowledge how criticism from peers may have unintended negative consequences on our colleagues. We must rally behind those involved, beginning with acknowledging the strain and negative mental health effects experienced by many veterinarians involved with these events."

While I agree we must support our colleagues by showing compassion to them, we should not dampen scientific discourse in the process. Open professional dialogue and transparency lead to advancements in science and ethics. I am concerned that lack of transparency and silencing of critical perspectives related to animal agriculture prevent progress and perpetuate the systems of oppression in place that benefit only those in power.

The authors imply that critical letters to the editor are inappropriate, stating that "criticism from friends, family, and colleagues directly impacts the distress level experienced by veterinarians involved in difficult decision-making. The anguish in this decision-making may be compounded when individuals are judged by those who lack understanding."

Understanding comes from open communication. None of the letter-writers judged any individuals; they sought only to increase understanding of the issue by critically evaluating the study, reminding readers of the experience of the pigs, and suggesting a different path in the future. The idea that professional inquiry into published research should not continue for fear of causing more emotional distress is, whether intended or not, a limit on scientific advancement.

I am a member of the founding committee of Veterinarians Against Ventilation Shutdown and also part of Our Honor, a nonprofit that hopes to spread compassion within our profession. On Oct. 26, Our Honor sent a letter to the AVMA and its Panel on Animal Depopulation, which considers science and data on depopulation methods, including VSD+. So far, we have not received a response. Therefore, we have published it as an open letter, to which other veterinarians and animal professionals have signed on. Please sign on if you see fit.

Our profession should support livestock veterinarians in raising awareness about the mental health impacts of this industry as well as the animal welfare implications. We know animals have rich emotional lives, and humans have a duty to protect the conscious individuals at our mercy — especially since we are responsible for bringing them into existence. I hope that our profession can find the courage and strength to speak up for the major changes that are necessary in our food production systems.

The reputation of our profession as caring advocates for animals is at stake.

About the author: Daniela Castillo was born and raised in Oaxaca, Mexico. She graduated as valedictorian of her class in 2008 with a veterinary medicine degree from Universidad Veracruzana. After completing a one-year internship in a government-funded zoo in Veracruz City, Dr. Castillo went on to earn a master's degree in wildlife conservation at Macquarie University in Sydney, Australia. In 2011, she started volunteering at St. Francis Wildlife Association, a wildlife rehabilitation center in Quincy, Florida, eventually becoming a licensed wildlife rehabilitator and director of the organization. In 2016, Dr. Castillo became licensed to practice in California. Currently, she works as a shelter veterinarian for several nonprofit organizations and owns a mobile practice.