Chytridiomycosis caused by Batrachochytrium dendrobatidis has driven the most significant vertebrate extinction event in modern history, with profound welfare implications for affected amphibian populations.
Chytridiomycosis causes individual amphibians to die slowly through progressive skin dysfunction. The electrolyte imbalances that result from disrupted skin osmotic function cause lethargy, loss of righting response, and ultimately cardiac arrest over a period of days to weeks. This is a welfare crisis operating at species level — millions of individual animals dying from this disease in affected populations. The welfare implications of conservation responses including captive assurance colonies raise questions about the quality of life of animals in captive breeding programs maintained primarily as genetic reserves. Probiotic treatments that could protect wild populations offer both conservation and welfare benefits by preventing disease-related suffering in situ.