Using cats claw isn't going to help him at all. I've never heard of such a treatment and I'd be wary of using this. You should definitely consult a nephrologist
if his kidney
function is worsening. He may end up needing dialysis
, but he can at least treat his swelling in the meantime with some medications such as diuretics.
I hope I have answered your questions. Please feel free to contact me if you have any further questions or if you feel I haven't addressed your question adequately.