From the article Grace posted the link to:

The treatment lasts 3 to 5 hours (sometimes longer) during which the patient must calmly sit on a table attached to equipment. Treatments typically are performed three times a week either indefinitely (as in chronic renal failure) or until the kidney has healed (as in acute renal failure).
But I wonder what the cost is...and who (besides us here) would fund the process for a senior cat - he is SO special to us, though, he has fought so hard...

MIND YOU - it is the most obvious thing to blame the kidneys...BUT as someone mentioned here (can't find the post at the moment), let's not rule out other causes.

Human case in point: My uncle was diabetic, and started getting pains in his legs. Of course, that was due to the diabetes and they were testing for circulation, etc. They ASSUMED...Turned out a large tumour from his colon was pressing on nerves in the back...and that cancer killed him.

So, it's not ALWAYS the obvious.

HUGS and PT Prayers to you, Jen, and BraveHeart.