Background: I have two guinea pigs, Penny and Rosie (both female, both around 3 years old, neither spayed). I got Penny in May of 2017, and she was a single until January 2018 when I got Rosie. (My vet told me to give Penny a few months to get used to me before adopting a second pig, so I waited until the semester break.) They've never been super close friends (they seem to have different ideas of what counts as enough personal space), but they're civil, and I know how important it is for guinea pigs to have cage mates.

Overall, their squabbles have been very minor: Rosie gets in Penny's space, Penny snaps at Rosie, and Rosie backs off for a while. But for the past few days I've seen a lot of squabbling that looks like an introduction all over again. They chase each other in tight circles; Penny snaps at Rosie repeatedly, and Rosie refuses to budge. There's a lot of teeth-chattering from Penny and angry rumbling from Rosie. All this happens two or three times a day and lasts several minutes each time. So far there hasn't been any real fighting.

My questions are: Is there a risk that Penny and Rosie will need to be separated? How closely do I need to watch them? And why is this happening now, when they've lived together for almost two years without any problems?

1 Answer 1


First step if your animals change behavior is a visit at the vet. Pain makes one aggressive, so it is a good idea to let exclude pain as reason by the vet.

You do not explain how your little ones live. So I have to assume a lot... Please comment, to give more details :)

Maybe they stay most of the time in their cage of approx. 1 x 0.5 metres. Imagine you were to live in one room with a second person your whole time. Eating, sleeping and toilet. The second person could be your best friend. But after short or long time, you would have trouble with this person.

To avoid this, you could learn to look at guinea pigs more like you would do at cats than like fish. They like to explore, run and hide.

You could inform yourself about other forms of living space for them. I have seen a lots of examples with places to hide and space to run. One was an old wardrobe with wire and plexiglas as doors and 3-4 floors. Another was on top of the dressers.

A second area to inform yourself about could be using fleece as substrate instead of straw and wood shavings. It is less dusty, so you could have more open space for the piggies.

So your guinea pigs have enough space to hide if they do not wish contact. Regardless they are aggressive to each other.

Aggression is caused by unclear dominance hierarchy. As you described, both of them had an hierarchy in history. But now it changes. Maybe the "boss" gets "weak", or the other one gets "impertinent". (Again here the hint for a visit at the vet.)

I do not know methods to avoid this in general. It is a normal event in relation development. But you could look for good circumstances, so they do not hurt each other too hard. For example, there should be no dead ends where one could trap the other. The houses need two doors and the pigs' furniture should not stay on the wall. There have to be some space to run around it.

Such struggles could last for some weeks, so you need to be patient. Only if one is constantly hunted and bitten by the other or is not allowed to get food, you have to separate them.

I read about some good changes in female guinea pig groups caused by adding a neutered male. Maybe this is an option for you.

So the answer is: "No, you do not have to separate them, you have some options you could try before."

I'm looking forward to read more questions about the themes you and your piggies are interested in :)

  • My pigs have a 2x4 C&C cage with fleece bedding, two hideys, and two or three chew toys (I change the hideys and chew toys each week when I change the bedding). I live in a house that doesn't normally allow pets (my guinea pigs are my emotional support animals, so they're protected under the Fair Housing Act), so I unfortunately can't let them roam very often. I have eight housemates, but they have their own rooms and keep to themselves. The pigs' cage is right next to my bed, and I spend most of my time in my room, so they get lots of attention. I hope this helps. :)
    – Annapox
    Dec 1, 2019 at 21:52
  • Wow! I am positive impressed :) please excuse my prejudice. Dec 2, 2019 at 13:02
  • No worries, I completely understand. I know most guinea pig people don't do their research. And thank you for your answer. The pigs seem to have calmed down and are back to the very minor arguments rather than the several-minute standoffs; I'm hoping one of them was just in a bad mood, but I'll keep my eyes open for more aggression or other signs of illness. :)
    – Annapox
    Dec 2, 2019 at 16:05

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