Poor sweet fellow. Have you tried colloidal silver drops on the tumor? It won't work miracles, but often has excellent healing effects that might help dry it up a bit more. It looks so painful, poor guy. My heart goes out to him, and to you. I hope, too, that you can control this and have much more time with him. I suppose you could also try tramadol, if the metacam isn't eventually strong enough. Sending healing thoughts to both of you.