Here's why:
* Anatomy: Fetal pigs, like adult pigs, have four limbs designed for walking on all fours.
* Evolution: Pigs are mammals, and mammals evolved from quadrupedal ancestors.
* Development: While fetal pigs may not be able to walk yet, their skeletal structure is already set up for quadrupedal locomotion.
Even though a fetal pig might not be walking around, its body is developing to eventually be able to walk on all fours.