My question is I have a 16 almost 17 year old cat, whom I love dearly, however she no longer uses a litter box on a regular basis, and seems to prefer to use either my furniture or carpet. I've had her to the vet probably a dozen times for this problem, I wasn't sure if it was behavioral or if it was medical, and either way was a little miffed, but concerned. The vet continues to tell me that she has either a kidney infection, or bladder infection, and gives me amoxicilin and sends me on my merry way, however it seems like it NEVER does anything. The vet said they can do more extensive blood work to test her renal function but I honestly don't know what to do. Casper is 16 and has arthritis in her front legs, and doesn't jump well anymore. I'm trying desperately to figure out what to do next.