cut or infection?

Question
i have two female guinea pigs, about 6 months old. i was stroking one of them earlier when i noticed a lump on her back and when i moved back her fur there was quite a large cut where there was no skin but i haven't noticed it bleeding before. it is about 1cm square. she is acting ok apart form this apart form she keeps making squeaky hiccup like noises. neither guinea pig has had any problems before. what do you recommend i do?

Answer
Hi Jo.  I would suggest you check both your guinea pigs' hair.  Cuts can arise from a pig scratching itself caused by a skin upset such as parasites, skin infection or sensitivity.  Mites are very common for guinea pigs.  A guinea pig with an infestation of mites (which you can not visibly see) typically scratches its itchy skin which can in turn make the hair shed and create dandruff like flakes.  If this is what is upsetting your guinea pig then it is wise to treat both pigs.  I would recommend you see your vet for the correct treatment for the severity of the condition.
I hope this helps.