I have a 4 year old 70 lb. female Border Collie/English Pointer mix. She has been limping on her left rear leg for about thirteen months now. Started out where she would just favor it or hold it up off the floor when she got up from lying down, but after 10-15 min would walk on it normally. It got progressively worse to the point where she was always limping on it. Brought her to the vet a year ago. He manipulated the leg, knee, hip, foot, checked between the pads, trimmed the nails. Couldn't find anything. Took x-rays of the hip, leg, knee, ankle, foot. Nothing. Absolutely no indication on the x-rays of any pathology causing a problem. Put her on Rimadyl. No help. Brought her back to vet several times. Took more x-rays. Still nothing. No clue. Put her on Gabapentin. No help. Brought her to a Veterinary Chiropractor. He manipulated her, made some adjustments, and increased her dosage of Gabapentin. It continues to get worse. Now, she is kind of rolling that leg inward when she walks and almost swings her hips. We used to walk a mile every day. We stopped the daily walks in favor of every-other-day (if she seems to be doing ok) or, mostly, once a week. Without the walks, though, she's gaining a lot of weight (10 lbs in the last year). Vet now wants to refer us to a Neurologist and get an MRI. EXPENSIVE!! We're willing to do it if it will help, but . . . I'm having a hard time justifying the expenditure when he can't even give me a clue about the problem. Any ideas? Please?