Hissy cat

[Kiwidoll]

My two male cats were neutered yesterday. When we bring them home last night, the females were hissing at them. Momma cat and their two sisters. Today just one of the girls still hisses and shows her teeth at one of the boys. What can I do to get her back to normal. They’re about 6 months old and have gotten along fine until now. We’ve never had cats before until we took in stray with her kittens this spring.

 

[ArtNJ]

This is a common thing that happens because they come back smelling a little different and cats don't recognize their friends by sight alone -- smell is a big thing for them. You can rub one of their favorite blankets/towels on them to rescent them. If they don't have favorites, you can rub a towel on the other cats and scent them with that -- that way they will all smell the same. However, if the vet said you should separate them for some number of days so they don't play, that separation should take care of the issue without any further action on your part.

 

[She's a witch]

Off topic as I have nothing to add to the response above, but please be aware that even if they were neutered, it’s still theoretically possible that they can impregnate your females for another several weeks or so, until they get rid of the hormones; so that’s another reason to keep them separate for some time.

 

[rubysmama]

Hello and welcome to TCS. How are things going today?

As A ArtNJ posted, that often happens when one cat goes to the vet and comes back smelling differently. It's called non-recognition aggression. TCS has this article on the subject with explains all about it. How To Deal With Non-recognition Aggression In Cats – TheCatSite Articles