Our 18 1/2 year old cat, Trixie, has been in kidney failure for the
past 7 months. I administer lactated ringers twice a day. She is
eating, drinking, grooming, but will not has not used the litter box in
over a week. I had her urine expressed last week at the vet's. He said
it could be arthritis in her spine, causing her to hold her urine. He
said she is not blocked and her urine will eventually leak out (which
is does, on whatever she is lying on). He gave her a prednisone shot
last week also. He said an old injury may be acting up (see below)

When she was a year old, she broke her tail and the nerve that
transmits to her brain that the bladder is full, was damaged. After my
vet  consulted my alma mater's vet school (Auburn) she put her on two
human drugs, which corrected the problem within about three months.(She
suffered through three times weekly visits to have her bladder
expressed.) Since then, she holds her urine for a longer period than a
normal cat, but eventually empties her bladder in the litter box.

Has anyone out there had experience with this? Hopefully, her quality
of life will remain good until the end. We hand-raised her from the age
of one week and she is the only "child" we have ever had.