I have two kittens that i got back in feburary (brother and sister). They've been very close and got on very well but i had the male neutered today and suddenly his sister is being very hostile towards him since he's been back from the vets.
Hissing and growling at him.
Is it just a temporary thing as he might smell "funny" or is it something else?
She was meowing all day without him (they've never been apart before)