My senior cat is 20.5 years old and has cancer. She's getting depo shots every 2 weeks to slow the cancer growth and on a prescription diet to help her gain weight. She's become unsteady on her feet and has arthritis.
In addition, she's never been willing to get in the litterbox to do her business: she's always perched on the edge.
Lately, she's started defecating just beside the box (she's still using the box to urinate, thankfully). I think it's because she's no longer able to balance on the edge of the box for defecation.
Are there any litterbox styles she's more likely to use? I'm willing to clean up after the defecation (although it gets nasty when she's due for the next shot, because she's likely to have a bout of diarrhea then), but I'd really prefer not to have to clean up if her balance/strength deteriorates to where she's urinating beside the box as well.
My husband and I want to keep her comfortable and happy for as long as we can, so we're looking for options that will allow her to use a litterbox comfortably.
UPDATE (per Monica Cellio's request): When she's perched on the edge of the box, she has front paws between the back paws, tail up. When she's defecating, she usually takes a while and has to strain a bit even when she has diarrhea) where when she's urinating it's a quick, no-strain thing.
She usually has to rebalance herself a few times when she's defecating and her front and back paws are further apart.