Dogs hind legs

We adopted our dog one year ago (she is estimated to be about three years old). One week after adopting her she had trouble putting weight on her back legs and was unable to walk. Over the course of the last year we have seen several different vets and have been unable to get a diagnosis. We have been taking her to a neurologist for the last 8 months.

The only thing that seems to work temporarily is prednisone.

When we got her she had just been treated for Lyme, Rocky Mountain Spotted Fever and Ehrlichia. She has been on prednisone and an assortment of antibiotics (full spectrum according to vet). She did this for months and whenever we taper prednisone she relapses. Blood test shows “nothing abnormal.” We tried an immunosuppressive dose of prednisone and she has relapsed when going from 20mg a day down to 10mg and now again when going from 5mg to 2.5 mg.

She has been x-rayed several times and there doesn’t seem to be anything wrong according the veterinarians.

I know this is a long shot but running out of hope.