Skin problems

Question
Hi there,
I have two female guinea pigs who will be 5 years old in June. I noticed recently that one of them seems to be losing a lot of fur on her chest and the tops of her front legs. I'm not sure when it started because she's quite a biter so I very rarely attempt to turn her over to look at her underside because I just get bitten and scratched. She has had a problem with the skin on her back for a few months where if you stroke her back towards her bottom a lot of her fur comes out and brings with it a sort of black dandruff. However she doesn't seem to be going bald where the fur comes out, her fur is shiny and soft and she doesnt scratch it. I bathed her a few days ago and the water was quickly full of ginger fur and black flakes.
Its quite odd because the other pig doesnt have this problem, she sheds now and then but she doesnt have the black flakes and it doesnt come out in clumps like her cage mate's does. They both get a lot of veggies and theyre indoor pigs so the room I keep them in is rarely too hot or cold.
I wonder if she might have some kind of fungal infection, I doubt it's lice as the other pig doesnt have this problem. I am considering trying a mild fungicidal shampoo on her but I wanted to ask someone's advice first! I'm wary of taking her to the vet unless I have no other choice because last time I took a guinea pig her age to the vet they put it to sleep straight away :(

Any input or advice you have would be greatly appreciated!

Answer
thats a tough one, and unusual, normally something like that i would assume it is mange or lice, but what you describe does not match that.

bathing her is a good idea, of course you cnanot do it too often, like dogs it is not good for a pig to be washed to often. i think you may be right on a fungal infection, so, providing a few things I want you to try a treatment.

providing she...

she seems pretty happy,
is still eating fairly well (despite weight loss)
appears active
doesnt suddenly skip about, like something shocked her
the other guine pig does not show symptoms.

get a hold of some baytril and tea tree oil, use as recommended on the side, baytril is an antibiotic safe for pigs, if it is fungal, then a long steady treatment of this should cure it. tea tree oil soothes and acts as a hybrid of moisturiser and hydro cautizone (mispelt sorry)which is used to treat eczma. the tea tree oil will help the skin heal itself.

try this for now, if it appears to improve her condition then let me know