Friendly cat pair - suddenly hissing at each other.

[RMarieClaire]

We have two cats, a brother and sister from the same litter, who have always lived together and are now 2yo.

The girl was recently injured and has sprained her tail, as of today she's locked in for a week after a trip to the vets this am.

For some reason, this evening the male cat has started hissing at her. I assumed when I heard it that it was her hissing at him, as they sometimes play fight^^ and if she's in pain she might be warning him off, but it's definitely him hissing at her. I can't explain it! They've always got on well, often play together and sleep curled up together. Any ideas what could be going on? I'm worried about her as she's already trapped indoors and in pain - I don't want him picking on her too.

To your male cat, his sister smells different like an outsider as she went to the vets. Before they used to smell the same and familiar to each other but seeing as your female cat went to the vet, she has the vet smell and he doesn't like that.

Maybe she smells of vet and he doesn't like it. See how they are tomorrow.

Yes definitely the vet smells, this is very common in multi cat households. Will probably be fine again within a day or so.

My lot always did this after one of them had been to the vets. As the others said its the smell, he will get over it.

Thanks all. That makes so much sense as we were there for ages and she's never been without him before. Hopefully if I give her a good brush today it'll be ok.