The Rise of Heatstroke as a Method of Depopulating Pigs and Poultry: Implications for the US Veterinary Profession

Abstract

Depopulation of food-producing animals is becoming increasingly common in response to both disease outbreaks and supply chain disruptions. In 2019, the American Veterinary Medical Association released depopulation guidelines classifying certain heatstroke-based killing methods as “permitted in constrained circumstances”, when circumstances of the emergency constrain reasonable implementation of “preferred” methods. Since then, tens of millions of birds and pigs have been killed by such methods, termed ventilation shutdown (VSD) Plus Heat and VSD Plus High Temperature and Humidity. While no research using validated measures of animal welfare assessment has been performed on these methods, their pathophysiology suggests that animals are likely to experience pain, anxiety, nausea, and heat distress prior to loss of consciousness. Heatstroke-based methods may result in prolonged suffering and often do not achieve 100% mortality. Potential and available alternative depopulation methods are briefly reviewed. The veterinary profession’s ethical obligation to protect animal welfare in the context of depopulations is discussed.

Incidence and risk factors of heat‐related illness in dogs from New South Wales, Australia (1997–2017)

“…In dogs, Heat Related Illness (HRI) is a progressive condition, resulting from an imbalance between heat generation and heat dissipation, which occurs when core body temperature exceeds homeostatic limits 8 . Heat stress occurs when the ambient temperature exceeds an animal's thermoneutral zone 9 . The most severe form of HRI is heat stroke 10 .…”

“…8 Heat stress occurs when the ambient temperature exceeds an animal's thermoneutral zone. 9 The most severe form of HRI is heat stroke. 10 Hyperthermia leads to direct cellular injury.…”