older cat stopped using litter box

Question
I have a 14 year old cat that started to loose weight when we adopted a six month old kitten thinking it was about the new arrival. We took her to the vet when she "told us something was wrong" (peeing on my son's bed) After going to the vet we found out she had a thyroid condition.  Things were going good until I was cleaning up urine on our living room carpet (her urine looked liked crystals) then over the weekend I noticed hers eyes and new she was blind.  I got her in that Monday morning and they told me she had very high blood pressure, infection in urinary track or bladder and that she probably had E-coli. Got her on meds and her retinas reattached & feeling much better & gained some weight.  Then she started to use the living room carpet for her toilet. I tried putting the kitty litter box in the middle of the room where she goes, it worked a couple of days then found poop right next to the box. Her box that she use to use faithfully is in the basement & for our new kitty hers is upstairs.  My husband is ready to put her down because I WON'T do it!  Help please if you can.

Answer
Hi Chris,

We can get her back on the right track. You just need to do a few things. I would get her a new litter box. Make sure it has low sides. Your cat may have a touch of arthritis and it may be hard for her to climb into the box. And a good clue to that is her reluctance to climb stairs. I have a cat like that and I use a doggie litter box. It has very low sides and is big. Next get this stuff. http://www.preciouscat.com/  Pet Smart carries this. Use  this in the litter box. It works. Get a good enzymatic cat urine cleaner. Clean the area she has been using with it. This will remove any temptation to reuse the area again.

Get her back to the vet for a recheck on the UTI and the E-coli infection. When a cat is in pain from elimination they sometimes associate the area where they go with the pain. This may be happening. Get something called Feliway Comfort Zone. Your cat definitely sounds a little stressed out. This could be causing some problems with her. Feliway mimics a cat's happy pheromones. This might help. Talk to your vet for maybe a mild tranquilizer to keep her calm until she and the new cat relax with each other.

You may want to change her diet. Here's a good link about cat nutrition. http://catinfo.org/index.htm  With her age and problems this could help. Try these things. I believe that you will have success and she will be using her litter box again. Good luck.

Ciao, Karen