If Daquin is the same as Seraquin (which I think it is), then it contains Glucosamine, which is probably adversely affecting the kidneys. Most
dogs can take
Glucosamine without problems, but CKD
dogs may have a problem with it. On the other hand, if it is helping with the joint problems, then it's a Catch-22 scenario - you might protect the kidneys more by not giving it, but then your dog may suffer more from the joint pain.