This means you can use "it" or "they" to refer to a pig.
* "It" is the most common pronoun used for a single pig, regardless of its sex.
* "They" is used when referring to multiple pigs, regardless of their sex.
However, if you know the sex of the pig, you can use the appropriate pronoun:
* "He" for a male pig (boar)
* "She" for a female pig (sow)
Ultimately, the gender of the pronoun you choose depends on the context and the information you have about the pig(s) in question.