Chytrid fungus has caused the greatest vertebrate biodiversity crisis in recorded history. Individual amphibians infected with the disease experience prolonged suffering before death.
Amphibians infected by chytrid fungus experience progressive skin disease that impairs the cutaneous gas exchange and osmotic regulation they depend on for survival. The disease causes cardiac arrest as electrolyte imbalances accumulate — death takes days to weeks. Individual frogs experience discomfort, lethargy, and increasingly compromised physiological function during this period. The individual welfare harm multiplied across the millions of individuals affected in population crashes represents one of the most significant welfare tragedies in wild animal history.