Hi, so about less than a week ago my girlfriend and I noticed a bald line spot on my guinea pig Biscuits’ back. It doesn’t look like it has any irritation but it is still worrisome. I checked online about bald spots on backs and all I could find was that she could have mites? However, her cage mate and none of our other guides pigs have any spots either. We do bath them with dry shampoo, which I know isn’t recommended. We recently bought a different brand of dry shampoo that we don’t really like but was the only one available so maybe it might be that? She doesn’t itch or anything and she is perfectly fine and healthy. I don’t think it is mites, can you guys please help me to maybe find out what it is? 
