What type of horse is your little mare? How old? How big (height and approx. weight)? Any idea what type of "work" she did before coming into the rescue? When were the last x-rays of her hock done? Was any blood work done to confirm an infection? Where did you move her from?How long ago? What type of trailer was she hauled in ? How long did the trip take and how often were stops made to let the horses out to stretch their legs? Did she get dead lame on that leg right away after the trip or did it take a few days? What type of ground was she on before (green pasture, hard dry ground, rocky, sandy , level, sloped, uneven etc.) and what type is she on now? Does she wear shoes? Does she have any front limb problems (laminitis, ring bone, side bone, bowed tendons, etc.)? How many horses is she usually in with and where is she on the pecking order with the other horses? Is she on (or has she been one) any joint supplements or other supplements / meds besides the Bute and the steroid injection?
I know this is a lot of questions, but each will affect horses legs. There might be more questions after these get answered.These will all affect the types of things to look for and options that might work for your little mare.
Hind leg lamenesses are usually the easier lameness for horses to get along with, as most of the weight is supported by the front limbs. I have heard of horses getting along with fused hocks, although not familiar with the techniques used to get there. I would look into other options to treat the hock before thinking fusion, however. I know of several horses that were diagnosed with infections in various joints not responding to the usual antibiotic regimen who were helped with acupuncture. If thinking acupuncture you might want to look for a vet that specializes in acupuncture rather than one that uses it along with their allopathic practice. Not saying they aren't as good, just the specialist is just that, a specialist.
Looking forward to hearing back so we can hopefully help you make some educated choices for your little girl.
No matter where you go, there you are.