[Pebbles82]

Does she seem well and active? Fur loss can be caused by a number of things. Various diseases, mites, inadequate nutrition in the diet, rubbing against something or even pee as cypher says. I agree a visit to an exotic vet and ask for a skin scraping bro rule out mites. If it is mites though she is likely to be scratching until she creates sore areas. Daily linseeds work wonders for getting their fur to grow back and in good condition. I’ve found it is very good for that. A bag of brown linseeds isn’t expensive and lasts for ages. I give a pinch each day - separate from the main food mix - eg on a shelf or separate dish. They seem to like them and lick them up. Takes a few weeks but usually makes a big difference. If it does then there is probably not an underlying cause (or it could have been nutrition) but I’d still have a vet check and ask for a scraping for mites. Don’t buy mite treatment as it may not be necessary and is quite toxic to hamsters. Vets have other treatments available. Linseeds are full of essential oils and vitamins so may improve just Bon a dietary basis but I’ve seen fur grow back thick and glossy.