I know none of this is going to be the news you wanted but it is important for you to get the correct advice.
The Pet shop has not given you the correct advice. I can’t tell you the amount of times we see people come here saying pets at home said three/four boars together is ok, sold a cage (which probably isnt appropriate) but now they’re fighting. They are then left dealing with the aftermath of the fall out and stressed piggies.
It may only be humping for now, which is a dominance behaviour and how they size up to each other so is always going to happen, but it’s the fact that the chances of them making it work long term are pretty much zero.
Add in the fact they are hormonal teenagers and you’ve got a recipe for disaster I’m afraid.
(The best chance (still not great chance though) of having a boar quartet is with boars who are at least 5 years old and no longer subject to hormones and who have also chosen each other).
The bonding could either fail immediately when acceptance doesn’t occur. It could fail within the two week post bonding period when they are attempting to sort out the fine details of their hierarchy, or it could fail months (sometimes many months) down the line - basically you would need to constantly be on standby for it to happen.
They find it too hard to get a working hierarchy when there is more than two piggies.
There needs to be one dominant and one submissive in each pairing. When adding in a third or fourth etc piggy you are inevitably going to end up with more than one dominant (because there is currently a dominant in each of your pairs) and then that is when the problems will start when they aren’t prepared to back down and lose position.
Our advice (and you will see plenty of posts on here on this subject dealing with boar trios and quartets) is to leave them in two pairs while you can and not risk the issues.
If you wish to try it, then of course go ahead but do so with caution, with the expectation that things won’t work and therefore with a plan you can immediately implement to deal with the fight (separation with oven gloves so you don’t get hurt, plus the potential for the piggies needing vet treatment for any injuries) and with a living plan you can immediately implement for separate cages. You must make sure that
1. You introduce the correct way. All four piggies must be put in a totally neutral territory bonding pen with no hides, nothing belonging to either pair. Just add hay and water.
Putting the cages together (or one cage in the run) and opening them, so they can then run into each others territory is not correct and is likely to cause invasion problems.
You are going to see all kinds of dominance behaviours, but if you intend on trying a quartet you have to just leave them to do it and only step in when a fight occurs (and never try to put them together again if a fight happens).
2. Should they get past acceptance and after several hours/overnight in neutral territory to be in a position to be moved to their permanent cage, the cage you plan to have them live in is
at least 4 metres by 1 metre in size. Anything less won’t provide enough territory per pig and can exacerbate the risk of space related issues. Bigger than that is better.
There is no single commercial cage that will be big enough to house four boars (there aren’t any commercial indoor cages that are big enough to house two boars - if you bought a cage from pets at home for them then I can be pretty sure it isn’t big enough for even two boars and it certainly won’t be big enough for all four) so you will have to make it yourself, use c&c grids to make a cage to meet the size needed or join multiple commercial cages together.
3. That all hides (only added into the main cage, never in the bonding pen) have two doors. Don’t use any single exit hides as it increases the risk of one getting trapped by the other and a fight breaking out inside a hide.
That there are multiple of everything in the cage - at least four hides, four water bottles, four hay piles.
Don’t use bowls or hay racks as they increase the risk of food hogging.
(The multiple of everything, hides with multiple doors etc goes even for a pair of boars)
These steps won’t make them get on but not introducing them properly, not providing enough space or resources will certainly cause problems in an unstable grouping such as a quartet.
Also and importantly that you are prepared to split them up.
You may be able to get them back into two pairs after a fall out (it may not be the original pairs though) but it may also be any combination - a pair and two singles or at worst all four as singles and therefore you would need to prepare for needing anything up to four separate cages.
We do sadly have an active member on here who was told by pets at home that four would be ok. They, of course, were not and they did end up with four single boars.
If you decide to keep them as pairs or following a quartet fall out you are still able to make a pair, then a pair need a cage of 180x60cm or a 5x2 c&c (an absolute minimum of 150x60cm but for a lot of teen pairs that isn’t big enough), (again, there aren’t any commercial indoor cages that are big enough for a boar pair). A single needs a minimum of 120x60cm or a 3x2 c&c.
Therefore, if a cage you have been sold for a pair is smaller than 180x60cm then they will need to be replaced (otherwise the pair could have space related issues and still fall out.
In addition to the guides (green links) I added in my previous post, I also attach the bonding guide here.
This guide explains how to carry out a bonding correctly.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics
There is also this guide about dealing with teen boars
Boars: Teenage, Bullying, Fighting, Fall-outs And What Next?
