evening all....what would cause a young guinea pig to lose weight? i have here a 4 month old boy who seems to have lost quite a bit of weight recently, he lives with his three brothers and they are all 3 times bigger than he is, he is too light to register his weight on my normal scales so shall be investing in some new kitchen scales on monday. he is eating fine his poops are fine, but his back bone is beginning to stick out and you can see physically he's losing condition? (he doesnt look as 'healthy' as the other three) any ideas before i toddle off to the vets on monday with him(gonna get him checked over any how incase its a teeth problem but as he's eating fine i cant see it being that?)