2 year old guineas started fighting

[Hellebollis]

we have 3 two year old guinea pigs, who have been getting along fine until recently. one has become aggressive, and teeth chattering and chasing the smaller of the three. its upsetting because they all used to get along well together. They have a cage in the house, a run in the garden, and a paddling pool as an indoor run. They get plenty of cuddles and attention, and are fine with human contact, its just between the two. The 3rd piggie seems to get along with either. any suggestions? is it possible that the aggressive one is coming into season, she is a couple of months older than the other two (we lost her original companion, so got 2 new ones)

 

[Niki]

It is certainly possible she's come into season & therefore moody. I'm assuming the one she's chasing is in good health as this may also be a reason for her change in behaviour - an ill piggy in the wild would draw attention to the rest & would be ostracised from the group.

Is she doing it in the cage only or everywhere?