Has her bladder been flushed? We have always had Danes around and I have Dobes and a cocker now, Quoia had a similar issue (F dobe spayed) found out she had somehow gotten a foxtail lodged upwards that was creating a constant irritation and repeated infection. It is worth a call to the vet to see if he can flush and see before doing the scoping, the flush is nearly painless(uncomfortable I was told but painful) and was relativley inexpensive.

K