Over 150,000,000 pigs are raised in factory farms and killed for food each year. Pigs are well documented to be exceptionally intelligent animals with cognitive abilities comparable to dogs or some primates. On industrial farms, many piglets are born to mothers in gestation crates, cages that confine the sow so restrictively that she cannot turn around. After piglets are born, many farms clip their front teeth and tails and castrate males without pain relief. The pigs are then raised in windowless warehouses. Though pigs can live upwards of a decade, most are sent to slaughter at around four or five months old.