Trixsyn also works well in lieu of Cosequin. Better in fact, according to my vet. You can save money (and mL of liquid to give to cat) by getting the large dog size which is more concentrated.
As you have discovered, this is a really frustrating problem. Having had (and still have) multiple cats, I have a bit of pee experience.
From my experience, peeing in the wrong place is a statement about living conditions. I had 7 cats (a momma I rescued that was prego and had 6 kitties!) - at around 2 years old, one decided to start peeing outside the box. Determined she was being bullied by a littler mate and re-homed the pee’er who has reliably used the litter box since being re-homed. Eventually, my bully cat caused the same thing to happen with another 3 of my cats. The bully found himself in his own room, re-homed the other pee’ers, all of which are now happily using their boxes (I have some contact with owners of the re-homed kitties in case re-homing didn’t solve the problem). I tried to re-home the bully but people seem to want fixed girls, not fixed boys…
So fast forward years and I have momma, bully and girl-1 from the litter. But I’d also been adopted by two kittens living in my culvert. Girl-1 decided she liked the sink better than the box for some reason (this was pre-new kitties). Everyone said UTI. Bloodwork, urine samples revealed no problems. It didn’t matter how clean the box was, what litter was in it… pee in the sink. Annoying but easy to wash away.
So any more I do all the vet workups but pretty much know if there’s pee’ing, there’s probably some reason that I probably won’t likely figure out. Girl-1 has decided that the sink is fine sometimes, but the boot tray the litter box sits in is far superior. Why this change of location happened… don’t know.
Have you always had your other cat? Do they get along? You could try giving your pee-er her own space and private box (a room with a window works) and see if she begins using the box.
Sorry for the length, hope you have vet issue that’s easy to fix. I would be worried about daily vomiting, that isn’t normal to me.
Although I agree that it’s usually a medical issue, if the peeing outside the box coincides with a potentially stressful life event like a move, new pet, etc., it’s definitely worth thinking about environmental factors.
I volunteer with a rescue and we get sooooo many complaints that after introducing a new dog to the household the cat has started going outside of the box because he/she is “mad.”
It almost always turns out that the cat has to walk through the room where the dog is to get to the litter box, the dog can get to the cat while he/she is using the litter box, or the cat otherwise feels like the dog is between him/her and the litter box. The cat then isn’t comfortable enough to use the litter box and ends up going somewhere more private.
Even though I’m hyper-aware of this, I just had this issue on a small scale last week. I noticed that my female cat was using the litter box less, which is odd because we have two boxes that I keep super clean and she’s always been on a consistent schedule - I can practically set my watch by when she uses the litter box! After a moment of panic that something may be medically wrong with her I realized that the weather had been crappy so I had been taking the foster dog into the backyard to do her business more often instead of taking her multiple for long walks every day. My cat had apparently been waiting to use the litter box until the dog was totally out of the apartment, so she had less opportunities to go.
She cat hadn’t shown any particular signs of stress about the dog’s presence and the dog is crated a good part of the day so it never occurred to me that she could be feeling too on edge to use the litter box while the dog was around.
Once I made sure she had plenty of privacy she got right back on her schedule.
