Guinea pig suddenly being aggressive

[BooksChocolateAndSleep]

Hi all, we have two female guinea pigs (sisters) who are 9 months old and have been with us since October. They have always got on ok with just the odd grumbling at each other and one has always been a bit bossier (will take food from the other etc).

Tonight however the other one has gone a bit crazy! She is clearly very agitated and is frequently attacking the other, mounting her head and making her squeal. She just will not leave her alone and is chasing her around the cage. When we hold her she normally just sits but she was just crawling all over me and just wouldn't sit still, we have put her back in the cage and after terrorising the other for a bit she is now laying down but outside of her house where she normally chills out..

Anyone have any ideas? They were out in the garden earlier but only ate grass and she had been eating hay etc..

TIA.

[nicky2512]

Unfortunately we had something similar with our two girls at a similar age.
Sadly turned out piggy one had an ovarian cyst and didn’t come through the surgery.
Hopefully it’s not anything like that but that was our experience.

[BooksChocolateAndSleep]

Oh I hope that there isn't anything majorly wrong with her. We ended up leaving them last night as I didn't have anywhere else to put one of them, I woke up at 3am and they were quiet. This morning they are rumbling at each other but no aggression from the crazy one and she seems really tired 🙁 Going to keep an eye on them today and see how it goes, really hoping it was just a mad moment and they don't need separating.

[fantastaballs]

I breed Guineas. You need two food bowls at opposite ends of the cage, two water bottles, two hides etc. How big is your cage? I would never recommend less than 4ftx2ft for space (all on one level) for two girls and I really do feel that 5x2 is a C much better size. If they draw blood then they need to be separated on a permanent basis. A lot of people just use the CC cages and put a divide down the middle so they still see each other but can't hurt each other.

[twointhemorning]

With female piggies it could be hormonal, maybe an ovarian cyst, so good to get her checked by a vet.

Sometimes piggies do get cross and fed up with one another. We had 2 boars who had to go on a long car journey together. On arrival in at our destination we put them in their run. The normally submissive one was really pissed off at dominant one and kept trying to attack him every time he came near. He was so cross for about 24 hours then calmed down. They travelled separately after that incident, but we didn't keep them separate in their c&c cage.

[LavishLavender]

I'm so sorry to hear this. :( When guinea pigs with a previously strong bond, have a falling out, it's incredibly stressful for everyone! It is best to take her to a cavy savvy vet, just in case she is acting out because of a health issue (sometimes when they are in pain they can become aggressive with other guinea pigs). I found this article to be quite helpful when my piggies were fighting: kaveecage.net/blogs/kavee-c-and-c-cage-fleece-liner-guinea-pig/all-you-need-to-know-about-guinea-pig-fights

[ATowelAndAPotato]

We have this with one of ours. When I checked her over, she also had sore nipples, and was starting to lose hair on her sides.
The vet said it was hormonal, possibly a cyst, but that GP’s rarely do well in surgery.
We were given some cream for her nipples which are looking a lot better, and she seems less grumpy as well, vet said she was not in any pain so we are managing with the cream for now. Female GP’s have a hormonal cycle too although a bit shorter than human, so we know that every ~3 weeks she will have a grumpy day or two, but other than that she is much better.
Definitely worth getting her checked over.