Aggression Looking for advice for my guinea pig lunging at others

[Moxchi]

Hello!

Backstory:
I have a 4 Guinea Pigs: George, Rosie, Kuro and Sophie.

Kuro and Sophie are the daughters of George and Rosie.
Before George was neutered, the girls all lived together.
Things were harmonious until when the babies were 2 months old.
Kuro was the dominant of the two sisters until Sophie gained confidence and
started to push her around. Sophie would often chase Kuro but Kuro never fought back.
She would always run away and hide.

When I attempted to bond George after he was neutered, all went well except Kuro fought back towards Sophie and started behaving extremely aggressively towards George.
I separated Kuro and the other three bonded perfectly.

From that day, Kuro would start lunging at the bars whenever George came near.
She bit him through the bars but he never retaliated. From day 1, he has never given her
any reason to be aggressive towards him. He is very passive and had remained calm and stayed passive even when she kept nipping at him.

Kuro now lives with Rosie, Sophie with George.
Kuro went into heat and suddenly was less aggressive towards George since then.
But she occasionally lunges at the bars towards Sophie.

Other than this, she does not display any other aggressive behavior. She is really docile
and gets frightened very easily. The vet has checked for cysts, she is very healthy.

If anyone has advice, I would really appreciate it.

Thank you very much!

 

[bpatters]

How large is the cage? Lack of space is a major cause of guinea pig aggression.

If they're living relative peacefully in two cages, that may be the best you can hope for. While some larger groups of pigs, usually sows, live together with no problems, the chances of one territorial pig being in the bunch increases with the size of the herd.