Liz Buchanan BVSc MRCVS
Hello! Cystitis presents like this and can frequently follow stressful episodes (and this is no slight on you or your vet; however well it is handled, going to the vets and having an operation is a stressful episode for a kitten). These signs are therefore definitely worth paying attention to. For a short time after a Spey, small cats can be lacking in body fluid and therefore less likely to urinate out (dehydration). Kidney problems are a much less common possibility. It is worth speaking to your vet as they may well offer to check a urine sample to rule cystitis out and check the kidneys' concentrating ability / rule out diabetes etc. Best of luck, and we look forward to hearing how you get on if you feel like letting us know.