I have 3 boar guinea pigs who, until a few days ago had been happy as can be living together for nearly a year (they are just over 1 year old). Sadly, a few days ago when I went to feed them I noticed one had what looked like a nasty bite under his eye, and scratches on his back. Interestingly, it was the one who had always seemed the dominant guinea pig, but now the other two seem to have turned on him. I have separated him, and the other 2 seem very happy living together without him. I did try to reintroduce him by putting them all out into the grass run, as I thought this might feel neutral. However, the boar who is being picked on seemed very frightened and the other 2 were kind of chasing him so I removed him. As soon as I did so, the other 2 went back to grazing happily. I'm going to have to separate them aren't it? It's such a shame because after 1 year together I thought it was safe to assume they'd be alright!