Chytrid fungus has driven the largest mass extinction event in vertebrate history, killing hundreds of amphibian species. The welfare of billions of individual amphibians dying from chytridiomycosis represents a catastrophic ongoing crisis.
Chytrid disease welfare encompasses both the suffering of individual frogs dying from the disease and the population-level extinction crisis affecting hundreds of species. Individual frogs dying from chytridiomycosis experience progressive skin dysfunction causing electrolyte imbalance, cardiac arrhythmia, and death. The scale of individual deaths is enormous: with millions of frogs potentially dying daily at peak epidemic spread, this represents one of the largest ongoing wildlife welfare crises in history. The extinction of species also has ecosystem welfare implications as insect prey of frogs accumulates without predation, affecting downstream species. Captive insurance programmes save species from extinction while creating the welfare challenges of long-term captivity for animals that may live their entire lives in biosecure facilities without the possibility of wild return.