our 11 1/2 yr old Golden has been diagnosed with cancer. Two lagre masses in right rear leg and several more smaller ones along his back. Among other drugs his vet has prescribed gabapentin 75mg. 3x/day. He has recently lost control of his left rear leg, his right leg is now supporting him instead of the other way around. They did not find any tumors in his left leg. Any thoughts that the meds could be causing this affect?