guinea behaviour

Question
Our two male guinea pigs are 9 month old brothers and have always got on well (although the larger of the 2 was always the 'leader').
The larger one has been biting the back of the smaller one, chasing him around the hutch and the smaller one keeps makes a funny noise.
Do you know what is wrong, will we have to seperate them?
Thanks
PS I don't know if this is relevant but they were traumatised last week when our little sisters got them out and played with them!


Answer
Hi Ben and Oliver!

Unfortunately male piggies are very territorial, and problems like this are very common. Males can get along well for a long time, then start hurting each other.

The older one may be bullying the younger one to assert his dominance, as the younger one may have tried to challenge him. Or he could be doing this because his hormones have just gotten to a very high level (this happens at about 9 months-1 year normally,) and this is he reason for his bullying.

All I can advise is that you keep an eye on them - this phase of biting may stop after a while. However, if it gets very bad, where he is injuring the other piggy more and more, and they're fighting, then seperate them, as they will no longer live together peacefully (this often  happens with males, and is normally to do with 'pecking order').

I dont think your sisters getting them out would have caused this behaviour, unless your sisters own female piggies. If they do, then the smell ofthe females on their hands would have triggered the aggresive behaviour (again, to do with male dominance).

I hope I was able to help,

Jo