Tramadol is a man-made pain reliever similar to morphine. As with all medications there can be side effects and unfortunately seizures are one of them. I am not a vet and would not presume to tell you what other drugs to use but I would advise you to check with a holistic vet as to other appropriate medications for pain. You might want to ask about using glucosamine/chondroitin and omega 3 as supplements.
Sorry for the delayed answer due to computer problems.