Pooping outside the box (I've tried EVERYTHING) :(

Hi everyone. I'm at my wits' end and I hope that this place can provide some more ideas for me to try.

Here's a little background:

I adopted Luna, a 10yo Himalayan, last year. I don't know much about her past life except that she was abused (she's missing almost all of her teeth because they were kicked out of her head) and not very well tended (she arrived with horrible dental problems on top of the broken-off teeth, matted fur, a positive heartworm screen, and the absolute worst case of ringworm I have ever seen). So far the heartworm appears to have either been a false-positive or something she was just exposed to, because her health is fine. The ringworm is long gone, she's been properly vetted, her fur is now glorious, etc. She's a healthy, happy kitty. The only problem she currently has is a recent diagnosis of acanthomatous epilus in the gingiva by her lower incisors; she had an excision and for now, it hasn't recurred. I know it's a matter of time, especially at her age, but I want her to have the best quality of life possible.

Luna was understandably VERY shy when she first arrived. I live alone in a large studio apartment in a quiet building. It took me months of treats, gently pulling her out of hiding to hold her, etc to finally bring her around. She's much more gregarious now--she'll jump up to join me on the couch, purrs up a storm when she's held, rolls over for belly rubs, and keeps up a constant stream of conversation with me. She still feels more secure in "secluded" places to spend the night, but usually likes to find places where she can keep an eye on me, in case any treats fall out of my pocket.

Luna has always peed in her box religiously. In the time I've had her, she had one accident in which she urinated on the couch (a loud noise outside startled her) and when we moved apartments half a year ago, she pooped the first day in the middle of the floor. However, she's intermittently been pooping outside of the litterbox (literally right outside it) for a while, and for the past three weeks, it's been daily.

Luna eats a high-quality high-protein/low-carb wet food (Solid Gold) and gets a few Tbsp of dry (also Solid Gold) as a treat in the morning. I give her Greenies treats, a few a day. Her bowel movements are regular and of appropriate consistency, and very low-odor (yay for good food).

I have tried just about everything. She's obviously been to the vet, who said it wasn't any health-related cause. I added a second box, tried switching litters, spent a week dumping out and putting in brand new litter every day and scrubbing the boxes clean in between (horribly expensive--and it didn't work). I use a nonscented clumping litter, which she likes the best out of the litters I've tried (I can hear her digging in it much more than she did in the others). I clean the boxes twice a day. She'll urinate in both boxes, but will defecate on the floor like clockwork. This is almost always when I'm asleep (a present in the morning) or in the afternoon when I'm not home (a present after work). I have tried scrubbing the tile where she's pooped with enzymatic cleaners and citrus oils; I've tried moving one of the boxes OVER the spot she pooped to see if she'd poop in it instead.

Nope. She just finds another patch of floor.

I heard that as cats get older, their joints can get stiff. One of the boxes has VERY low sides. The other has higher sides, to encourage her to have privacy. I've tried both low and high depths of litter in both boxes. Nothing is working.

I thought maybe it was because she'd peed in the box, but often there'll be a pee clump in one box, the other box will be empty, and poop on the floor. Sometimes both boxes are completely clean and untouched, and there's poop on the floor.

She's pooped in the boxes in the past, at least almost consistently. Now she's not anymore. The ONLY thing that changed is that my partner, who lives overseas, was home for a week about a month ago. Luna was fine (she loves my partner), but since then has pooped in her boxes literally once. I don't know if she just misses my partner (or just having someone home during the day), but I can't help that situation.

Please, please, please help. I'm going through boxes of gloves and cleaning products, and I just want my kitty to poop in the box again. Is there anything else I can try?

1) Fresh Step odorless clumping
2) One is an "extra large" litter box (I believe about 24" x 18" x 7" high), the other is 20" x 14" x 3" high
3) No. I haven't seen that anywhere. I've tried several clay litters, various clumping litters, sterilized sand, newspaper pellets, and the corn stuff (yes, I know, some of those aren't ideal, but I wanted to try everything)
4) In the bathroom. I'm in a studio apartment; they HAVE to be in the bathroom. The floors in the rest of the apartment are old (18th Century) battered pine floors, and I would never, ever get the bits of litter out from between the boards. My landlord told me if I put the boxes anywhere that isn't tiled, I forfeit my $1,500 deposit. The kitchen is 4' x 6', so no space in there for a box. I've tried every location in the bathroom (it's large). It's the lowest-traffic part of the apartment, and well away from any distant road noise.
5) uncovered. I tried putting the cover on the larger box (it came with one), to see if she'd prefer the privacy, and she never peed in it when the cover was in place.

She's still pooping just outside the boxes. If I continue to scour an area she's been pooping in, she'll continue to poop there. If I move a box over that spot, she'll poop in another spot (adjacent to, but not under, where the box had been). I've tried the whole box shuffle--she doesn't have just "one" spot in the bathroom where she'll poop, ie, when I moved both boxes farther away, she continued to poop in front of the box in the new location, not where the boxes had originally been and where she'd pooped on the floor before.

Aside from the one time she defecated in the main living area (literally the morning after we moved here), she has always, always pooped in the bathroom. When she does poop in the box (or used to ), it always seems to be against one of the short sides. (I do clean the sides regularly with enzymatic cleaner, every day. She's never gotten urine against the sides, and the few times I've seen her urinate in the box, she faces the wall and pees with her butt close to the short end.) She doesn't cover her urine or feces; she's not declawed, but she also doesn't use a scratching post (or scratch furniture, rugs, etc). I've tried different surfaces, and she's just not interested. I clip her nails regularly (once every 2-3 weeks for her front, about once a month or less for the rear, as needed), which she's very tolerant of. I have a feeling that her previous owners might have discouraged any sort of scratching/kneading behavior. She won't even "claw" at toys when she plays, just uses the pads of her paws as if she didn't have any claws at all. Maybe the fact that she doesn't feel she can cover her urine or poop has something to do with being scared to poop in there? Then again, having her poop right out in the open seems even less logical...

Yup, I remember that from my days volunteering at the Philly Animal Welfare Society. I don't sterilize with bleach anymore, just a litterbox-specific, biodegradable, unscented enzymatic cleanser. I know she doesn't mind because when I did use to clean with (very diluted) bleach, even after the box was thoroughly dried and new litter in it, she'd sniff it suspiciously every time. Since I switched cleansers, she's stopped doing that.

I live downtown in a big city, so all I have are very small local stores. I'll definitely ask if they can order it for me, though. Sounds like it's worth a shot. Maybe I'll try the longhaired cat specific litter they have, too!

Awesome, thanks. I'll call my vet in the morning and see if she stocks it. Anything is worth a try!

It's definitely not medical, unless somehow the cancer in her lower jaw is affecting her. Since she had the excision two months ago, she's been MUCH happier, more playful, etc--the lesion that she could feel every time she ate or meowed is gone. She's not in pain or distress as far as I can tell, the lesion hasn't returned, her mandible isn't sensitive or painful on palpation, and again, her vet says that all things considered, she's in great health.

It breaks my heart to think that after 9 years with a kitty, someone could just dump her--then again, these same people were probably the ones who kicked her in the face repeatedly. Gods, it makes me so, so angry! And now with the cancer diagnosis, I know she might not have very long, but as my partner said, at least this past year she's been pampered, loved, spoiled, treated with the best food, had all her health issues sorted out... she's no longer anorexic, no longer has digestive or skin issues, and loves to curl up in the bay window to keep an eye on my neighbors. Progress with her has been slow, but steady. Last year, she was hiding under the bed--now, she greets me at the door, yowling at me because I've been gone all day, how DARE I do that. And after all this, I haven't even ONCE heard her hiss or bite or claw--even when I had to clip her down, even with the thrice-weekly baths (topical ringworm Tx to go with the oral Rx), pills, opening her little mouth to check on her gingiva... she's such a great, great cat.

Sorry, I'm rambling! :x Thanks for the advice!

I haven't tried the mat trick, maybe I'll give that a go, too! There isn't enough space to put the box in an even bigger box, and I don't want to risk making her dislike the box even more by getting one with higher sides (since she's older, and doesn't seem to like to jump onto/from anywhere).