it could be a number of things
1. old age, they do seem to thin their fur
2, skin desiese i.e. either mites, flees, mange, ringworm or dermatitus if i were you go to the vets tomorrow, have a word and if he says its to do with the skin and they dont give yuo anything for it, go to the petshop and look for spot on for hamsters, i done it with my syrian milly and her fur is slowly starting to grow back, it needs to be on every 4 weeks.
the other thing could be she could be alergic to something, i dont know much about dwarfs sorry
