Suddenly aggressive female kitten

[despondentatwork]

So...we have 2 5mth old kittens. Male was neutered last week. Female will be this week. However, she disappeared for 24hours & has been aggressive towards the male since she returned. Is this normal? She's hissing & growling at him!! The kids are upset, and I'm worried one of them will get scratched or bitten or our male kitten is.... help!

Any chance she came into heat, was pestered by males and is now lashing out at your boy?

It could be because he'll smell different after being at the vets.

Why was she allowed outside when she hasn't been spayed?

It's likely that what PP said happened.

@Snozzlemaid

It could be because he'll smell different after being at the vets.

Yes, it's likely this. Try to keep them apart for a few days and it should settle down. Be prepared for similar when girl kitten is spayed. A Feliway diffuser might help.

She escaped!
She has been with him since vet's, it's only been since she arrived back this morning. Nothing else here is different. It's like she's come back with a new attitude..Feliway is a god idea.

Check she's not concealing an injury as sudden aggression can indicate pain.

If she's been out then she needs to be neutered ASAP.

Are you sure she's not been mated?

I’m thinking she got mated and got hurt, check her for injuries.

Separate them so she can cool down.

Thx all, kept them apart unless supervised with limited time together. They've settled, but still sleeping apart for now (they had been sleeping snuggled together before this!). She's booked for neutering on Monday. She seems fine- no injuries we can see. Hopefully it was a hormonal blip....