depends on the colour and personality
A male desexed Guinea Pig is called "Neutered", and a female desexed Guinea Pig is known as "Spayed".
A female guinea pig is called a sow, whether it is spayed or not.
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A male guinea pig can impregnate a female when it's only two months old. It should be separated from its mother and sisters by six weeks.
it really depends on the guinea pig, some get along fine with friends some don't
Yes and fast
you shoudl not put a hamster and a guinea pig in the same cage no matter what.
Yes!
No, not posible.
Actually rabbits an guinea pigs are fine together. But maybe the female guinea pig is felling lonely being the only kind in the cage. Or maybe its because the rabbit just doesn't like the guinea pig. If it's possible you can try getting another female guinea pig or separating the the guinea pig and rabbits.
call the vet
Jeffrey would be a lovely name for a male guinea pig, though you could call a female Jeffrey if you really wanted to.