Tail docking is performed to prevent tail biting and cannibalism among pigs. Tail docking should be performed as early as possible, but by 14 days of age.
Teeth clipping is performed as necessary to prevent trauma to the sow's teats and snouts of other piglets (due to the presence of sharp canine teeth at birth). Farms may minimize the need for clipping piglets' teeth altogether by not cross fostering between litters.
The AVMA recommends the use of procedures and practices that reduce or eliminate pain, including the use of approved or AMDUCA-permissible clinically effective medications whenever possible.
Extralabel Drug Use and AMDUCA (FAQ)
2015 American Veterinary Medical Association