9 month old Ragdoll with diarrhoea

My ragdoll kitten has recently got diarrhoea. We rang the vets and they advised us to change his food to hills/royal canin and keep him off wet food until it improves. It’s been over a week and my kitten still has really runny poos. He is pooing outside of the litter tray and it’s becoming a problem now. We constantly clean the two litter trays we have and we’ve even changed the litter to tray and help it. Any suggestions on what to do next? He’s eating and drinking water perfectly fine but no matter what we do we feel like nothing is working..

Hello.  If you have changed the diet and have only been feeding an approved cat-food for several days (and your cats' diarrhoea is still really runny), then it is time to ask whether you need to see the vet.   Often they will check that your kitten is coping internally with the excessive fluid loss and / or trial-treat the most common things (such as worms) and / or start to investigate that or other possibilities.

I think maybe you can considerer taking your kitty to another vet

As to that, most kitten diarrhoea improves with minimal intervention and a bland diet.  If your vet started big tests every time they saw a kitten with diarrhoea, it could be very expensive for the owners and mildly stressful for the cat and in most cases, would be unnecessary because worming and bland food resolves the problem.   However, if the problem continues then a revisit is always a good idea, to double check hydration after a few days diarrhoea and perhaps to consider whether it is worthwhile doing more tests at this point.   A good question as one leaves a vet office is always, 'at what point do you think I should come back?'   - because with chronic (ongoing) conditions such as this might turn out to be, it can be tricky to decide.   Furthermore, if clients go to a new vet at this point, the new vet might well want to start again with worming, bland food etc unless you take the history from the first consultation with you.