losing hair

Question
"Angel" Our family Guinea pig has lost most of her hair on her lower sides of her body only near the rear and on her rear legs. She is not losing hair any where else.  This happened several months ago.  We changed her diet at that time and her hair appeared to be coming back, but recently her condition looks like it is returning.  Searching the internet, I have read about mites and the use of Advantage (imidacloprid) and Ivermectin, but many sites state that the skin would be crusty and painful.  The skin is not crusty and Angel appears to be in NO distress.  She eats, drinks, runs around, lets you hold her, but is losing her hair.  Her cage is cleaned several times a week and she is well taken care of.  I contacted a vet and was told they would need to do skin scrapings to determine a cause.  Several sites on the internet said this is not necessary and can be very painful for a guinea pig.  If her condition is mites can I treat it myself and where would I purchase medication/cream to care for her?

Answer
Mike,

I don't think it is mites that Angel has. If it was mites you would notice some of the fallowing signs of mites. These species specific microscopic mites cause unbearable itchiness for the animal and can result in thinning and/or patchy loss of hair, scurfing of the skin (may resemble dandruff) and eventually, open sores as a result of extreme scratching and biting which aggravates the hair loss. Scratching an area of skin infested by mites by hand may produce such pain and irritation in your cavy that it looks like it's having a fit. A guinea pig suffering from mites may become less friendly and be reluctant to interact with its owner.

So mites isn't it, she isn't showing signs of that. Not showing signs of scurvy. Which the signs would be these, Lethargy, weakness, unwillingness to move
Hopping instead of walking, enlarged or stiff limb joints
Not eating, loss of weight
Diarrhea
Eye and nose discharge
Rough coat
Tenderness to touch (may cry out in pain if restrained), poor flesh condition
Internal skeletal-muscular hemorrhage

So scurvy is ruled out along with mites, unless she has had pups (babies) recently she isn't loosing hair to that either. So it is either Ovarian cyst, let me give you some signs for that so you can check her for them,
A slight loss and redistribution of weight, like her shoulders become bonier and abdomen, rounder.
Sexually aggressive.
Enlarged nipples.
Hair loss
Or she could have cushings disease. Take her to the vet and have an ultrasound done. The ultrasound will help in diagnosing both conditions.

I hope this helps and that everything is alright with Angel,
                Take care,
                    Jules