I am sorry for your loss.
Could you give us more information please -
How old are they all?
Have you put them all on neutral territory together for the bonding process?
If you have, then what is actually happening?
How big is the cage they are to live in? For four sows it needs to be a 6x2 c&c or a cage measuring 210x60cm
You say one day they are ok, the next they aren’t - Bonding is a one time event seen through to conclusion on one day.
You put them all in a neutral territory bonding pen for several hours and see if they accept each other and start to form a bond and hierarchy. If they do and are ok together after a few hours in the bonding pen, then they move to the cage together. It will then take about two weeks of then permanently being together for them to fully form the relationship. You do not separate them after the initial bonding pen meeting if all goes well. You will see dominance but that is not the same as fighting.
If they don’t accept each other and can’t form a bond while in the bonding pen or if things fail during the first two weeks of permanently being together, then the bonding will not work and they need to live in two separate pairs in two separate cages permanently.
You can’t make them bond - they are either compatible or they arent. If you have bought the new pair then as you don’t know they are going to be compatible with your current pair, then having a plan b for living separately is needed.
If you have tried to put them on neutral territory and they are actually fighting, then please do not put them together again. A fight means they don’t like each other and unfortunately. will never bond.
If you havent yet put them on neutral territory and they have only ever met between a divider, then that isn’t really a clear indicator of what sill happen when you do actually put them on neutral territory - you will see territorial behaviours between a divider and not actual fighting.
If you a have simply removed the divider between the cages and allowed them piggies to wander into each others half of the cages, then that will be seen as a territory invasion and will cause fights.
Bonding two separate pairs is not always straight forward because of the character matches between the piggies. If the new pair are younger than your original pair, then acceptance can be easier to achieve but there is no guarantee. As there can only be one dominant piggy in a herd, it means one of the dominant piggy in of one of the pairs has to step down and lose their position as dominant piggy but they aren’t usually willing to do that and that is why it can fail.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics
Adding More Guinea Pigs Or Merging Pairs – What Works And What Not?
Dominance Behaviours In Guinea Pigs
