Chytridiomycosis caused by Batrachochytrium dendrobatidis has caused the most catastrophic wildlife disease extinction event in recorded history, with welfare implications for billions of amphibians.
Chytrid fungus has created a wildlife welfare crisis of extraordinary scale. Amphibians dying from chytridiomycosis experience progressive physiological failure — the disruption of skin-mediated ion transport leads to cardiac arrhythmia and eventually cardiac arrest in a process that involves behavioral signs of distress for days to weeks before death. The welfare harm occurs across billions of individuals in wild populations and in captive collections where disease control failures cause mass mortality events. Captive amphibian collections maintained as insurance populations against extinction require careful disease management — preventing chytrid introduction into captive facilities is the most important welfare intervention, as treatment options are limited and stressful. Probiotic research offers a promising avenue for developing disease resistance in wild populations without requiring individual animal treatment.