Hi Kimomo, welcome. I think he is in pain so daily pain medication (at least for now is what I would suggest). I have had a rabbit on tramadol – this particular pain med did not work for him but it’s safe for rabbits. I have also had rabbits long term on metacam and buprenex for arthritis.
Did your vet do bloodwork on him? I imagine so at his age – if not it is important especially if you keep him long term on any pain meds. At his age, and I have 3 seniors who are 10 and up, my own personal opinion on this, is that I would keep my rabbits long term on pain meds if it relieved the pain – I know there are risks but many times they can outweigh the benefits.
I would discuss with your vet if he/she has concerns for Kimo being long term on pain meds and what they are. I think as with any rabbit, you may find one particular pain med that works better compared to others – I suppose it’s because of each rabbit’s own personal metabolism. So if the tramadol is helping as your vet the long term risks and see if he/she agrees that it would be beneficial.