We're running out of options here... we've had this cat for the last 15 years. So she's getting up there in age.
It started when my gf put a rug on the tile in front of the front door, around late October. Until then she's never had an accident in the house. After several days of the rug being there, she urinated (a lot) on the the rug. We cleaned it up thoroughly, rug and tile. Used OdoBan for pets on the area as well. She did it again. We switched rugs to a different style. It happened again, the same spot, twice. We removed the rug. Took the cat to the vet and had bloodwork done... no diabetes or anything like that. He put the cat on antibiotics in case of a urinary tract infection, and also a glucosamine/fish oil medication in case she's arthritic and having trouble using the litter box. We kept the rug up during treatment and she only had one incident over several weeks on the tile. She finished the antibiotics last week. We bought an indoor/outdoor rug with a rubber backing... COMPLETELY different and it happened again this morning.
Starting a couple days ago, she started defecating right outside the front of the litter box on the linoleum floor. We've been making sure the box is cleaned at least once a day, we had switched litter brands before this all happened and went back to her original brand that she's used forever.
She's always been a thin cat even though she's always had unlimited access to food and water; but lately it seems like her hindquarters are getting even thinner than normal. But the vet had checked her out and didn't think anything was wrong.
With the defecation on the floor this is getting even worse, and we can't have this happening in the home. The cat litter box had a hood over it (and always has); we took off the hood today in case that might suddenly be a problem. But today before we did that, I noticed her sniffing around where she normally urinates, took her into the laundry room where the litter box is and closed the door. She went right in front of the litter box, squatted down and defecated again.
I don't know what to do. This cat is a part of the family but this is getting worse and worse, and with no apparent health problems I really don't know what to try next.
Please, does anyone know anything else I can try? This cat has NEVER been outside in her entire life and I don't want to have to find her an outdoor home. My son is devastated but understands this can't continue.