lump on back

Question
hi my male guinea pig who is 1 1/2 years old has a big dark red lump in between his shoulder there is no hair there it doesnt siim to be annoying him he is eating and drinking but it does concern me, i have a further 4 they are fine they dont have it.

Answer
Hello,
personally I would get the lump checked out by a vet to make sure it's not a tumor. If he's eating and drinking normally it could be some sort of tumor or bump. If your guinea pig is eating and drinking normally then I don't think it's a real emergency, but if you are able to take your guinea pig to a vet and confirm what it is that would give you a peace of mind.