I did some research to see if we wanted to toilet train our cat. Like the person above said, there are some concerns and a lot of people don’t recommend it. However, I know it can work for some!
There are some YouTube videos about toilet training cats. For the most part it seems like a really difficult process and totally is a hit or miss depending on the cat. I don’t find it surprising at all that one cat isn’t getting it. Honestly, I’m not sure if you can fix it!
I’ve heard cats can get upset when their litterbox is displaced and there are changes. The cat could be really uncomfortable with the toilet and just struggle to figure it out. I’ve heard that cats will poop other places or poop on the seat and cover it with the litter from the tray.
One thing that may help is a reward system? Not sure how well that will work, but maybe you could try offering treats whenever they are on the toilet.
Another possible idea is to keep the cat in the bathroom for some time to only give it the option of using the toilet.
You could also slow down the process of making the litter tray hole larger. Give the cat some time to realize he is now using the toilet as a litter box without quickly making it too complicated and scary.
Long story short, I totally get how ideal it would be to have a toilet trained cat! No litter, no scooping, and no stink! But with that said, I’m not sure all cats are capable to be trained to do this and it fails for a lot of people. If you are insistent on the cat learning, though, I bet over time they could figure it out.
Sorry I didn’t have better options on how to fix it! Best of luck!