Pigs have no interest in, or perception of, real estate. If instead we mean ‘territory’ when we say pigs are more aggressive indoors than out, this also doesn’t really make sense. A pet pig’s territory would, in fact, be wherever he eats, sleeps and spends his days. This could be inside or outside. If it were actual territorial aggression, there would be no difference in aggression levels between indoor and outdoor pigs—wherever their home, or territory, is would be the site of the same level of aggression. Pigs don’t magically have some sense that a house is worth more than a yard in terms of resource guarding. A pig doesn’t go, “oh, well, I live outside, and this lame yard isn’t really worth fighting anyone over. If I was in that HOUSE though, oh man, that is prime real estate and I’d be willing to fight over that…”
Lets consider instead that you are the pig… a room is essentially a dimly lit, enclosed space (remember that you already have bad eyesight); it’s cramped, there are walls and a ceiling that prevent you from fleeing danger easily; there are obstacles (furniture) all over that you could become entangled in if you tried to flee too (not to mention, if the pig doesn’t have continual access to a doggie door, he KNOWS he is trapped). Now consider that perhaps we have guests over, and now there are a lot of strange, scary people in a tight space in the house, and guess what, everyone wants to visit with the pig, because, "hey, it’s a pig! Living in the house! Haha, awesome!" So now, all these scary people are converging on, and towering over, this pig. This heightens the pigs’ fear response already... now add in that this pig likely has already ruled out flight as a possible means to avoid the scary situation, and that leaves fighting, that is, fear-based aggression—barking, snapping and then possibly biting — as the pig’s only option to deal with this frightening situation.
So here's where it gets interesting… once the pig snaps or bites, we are told that the pig is trying to show dominance, and so we punish the pig, maybe we even put the pig outside. At a minimum, we have reinforced to the pig that yes, he should have been frightened (he was feeling fearful and then got punished!). On top of that, we have ALSO reinforced to your pig that his fear-based response of snapping and biting got him thrown outside, away from the scary things! Perfect! We might think that we are punishing the pig, but the pig has learned the EXACT opposite lesson! “Biting gets me put outside, AWAY from the scary things! It saved me!” Next time this pig is in the same situation, he will be quick to use his newfound skill (biting) to achieve his goal of getting moved away from the thing he is afraid of.
Misinterpreting emotions and behaviors can lead to a lifetime of frustration, fear and misery, both for a pig and his people. If your pig is exhibiting problem behaviors, contact a certified behaviorist to help decode the underlying emotions and to develop a scientifically-sound plan of action to help solve the problem.
Be sure to check out Decoding Problem Behaviors for more information.