Pain in broiler chickens is common, often chronic, and frequently unrecognised due to the limited behavioural repertoire chickens use to express pain and the industrial scale at which they are housed, making validated assessment tools critical.
Pain is arguably the most widespread welfare problem in broiler production, yet it remains systematically underrecognised. Chickens that cannot walk without difficulty — gait score 3 or above — are in pain, but they do not cry out or display obvious distress because predator-avoidance instincts suppress such displays. The welfare implication is that enormous numbers of chickens spend a significant portion of their short lives in chronic pain from lameness and contact lesions, without any pain relief being administered. The most direct welfare intervention is reducing lameness through slower growth rates, better litter management, and lower stocking densities. Where lameness occurs, early culling of severely affected individuals prevents prolonged suffering.