While Metacam may be effective, the only approved use it has in cats is as a single dose injection after surgery, not for oral administration. If the manufacturer could prove that oral use is safe in cats, they would likely to do so. Since they can't, I'm not going to give the substance to my cats--it's nephrotoxic (see the bottom of their page: http://www.metacam.us/index.lasso?page=pain&GUI=gui_1
) and cats are at risk for kidney problems already just because they're cats. It's just not worth it to me. I did give it to my cat several years ago without being warned about the risks. Had I known what I know now, I would never have given it to her. I think each owner should be allowed to make an informed choice on what they give their cats. For more discussion of Metacam risks, which includes questions to ask the vet, go here.
All NSAIDs are contraindicated in cats, and I refuse to give that class of drug to mine. There are other pain medications available with fewer or different risks, such as Buprenorphine