I have had two cats on Metacam post-surgery. It worked very well. Over the very long term it can damage the liver. Depending on Zingo's age and the dose he gets, it might be very good for him. Ask your vet about the long-term effects and whether they are a concern in Zingo's case.
I hope you can try it for a while and it will give feisty Zingo a good run up the stairs!
"I have six locks on my door all in a row. When I go out, I lock every other one. I figure no matter how long somebody stands there picking the locks, they are always locking three." -- Elayne Boosler