Cattle, sheep, and pigs are prey animals that hide signs of pain and illness — making welfare assessment difficult and meaning suffering often goes unrecognised and untreated.
A cow showing severe lameness is in significant pain — yet stoic behaviour means animals may work through considerable discomfort before welfare issues are obvious to casual observers. Training and systematic scoring dramatically improve detection. The welfare cost of undertreated pain in millions of farm animals is enormous and substantially reducible with better monitoring.