Chytrid fungus has caused the most devastating loss of vertebrate biodiversity in recorded history, causing mass die-offs and individual animal suffering globally.
Chytrid fungus welfare harm operates through a mechanism that is both ecologically catastrophic and individually painful. Infected amphibians lose the ability to regulate sodium and potassium across their skin, leading to heart failure through electrolyte imbalance. Behavioral changes in infected animals — lethargy, abnormal posturing, reduced avoidance — suggest a distressing dying process. The global scale of suffering across hundreds of species represents one of the largest wildlife welfare emergencies in modern times, driven largely by global trade in amphibians that spread the pathogen.