Older sibling being aggressive after intro to new kitten

kaybee988

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I am at a loss of what to do. I have two cats, Jack and Elle, who are siblings from the same litter. They've been inseperable, always sleeping together or grooming each other.

Recently I adopted a 3 month old neutered kitten, Archie. I've kept him in a separate room and he seems to be getting along with the Jack when they've sniffed each other through the gate. Elle however has totally changed her personality. Once she got a scent of Archie, she immediately started growling, hissing, and lashing out at Jack. I was afraid they would really hurt each other since Jack didn't understand why she was being so aggressive and would try to get closer which would just antagonize her more. He would just stare at her and whine. They've been separated for about a week now, except for a few times Jack has slipped past me and ran into the bedroom. Not really much progress here. Still growling and hissing.

It makes me so sad to see him cry at the door. I get even sadder when I'm with Elle and she's her old sweet self.

I've brought Archie in the bedroom in his carrier and she just sat under the bed and gave a little hiss.

I expected tension between the new kitten and my older cats but I wasn't prepared for Jack and Elle to start fighting.

How do I fix this?
 

rubysmama

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Hello and welcome to TCS. Sorry though for the situation that's brought you here.

Sounds like the aggression between Jack and Elle is re-directed aggression, where Elle knows something has changed, and blames Jack. TCS has an article with info about it: Re-directed Aggression In Cats – TheCatSite Articles

It also sounds a bit like non-recognition aggression: How To Deal With Non-recognition Aggression In Cats – TheCatSite Articles

In both cases, separating them, as you're doing, and working on re-introducing them is the right thing to do.

One thing you could try is dabbing a drop of vanilla extract on both Elle and Jack, so that they smell the same. That might help Elle realize the new cat scent she smells isn't Jack. Here's a TCS thread with more info: Ode to vanilla extract

And as for the kitten, and doing that introduction, TCS has a couple articles with tips and steps to follow.
How To Introduce A Kitten To An Older Cat – TheCatSite Articles
How To Successfully Introduce Cats: The Ultimate Guide – TheCatSite Articles

Good luck. Hope things settle between the siblings soon. And that they eventually accept the kitten into their feline family.
 
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kaybee988

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Hello and welcome to TCS. Sorry though for the situation that's brought you here.

Sounds like the aggression between Jack and Elle is re-directed aggression, where Elle knows something has changed, and blames Jack. TCS has an article with info about it: Re-directed Aggression In Cats – TheCatSite Articles

It also sounds a bit like non-recognition aggression: How To Deal With Non-recognition Aggression In Cats – TheCatSite Articles

In both cases, separating them, as you're doing, and working on re-introducing them is the right thing to do.

One thing you could try is dabbing a drop of vanilla extract on both Elle and Jack, so that they smell the same. That might help Elle realize the new cat scent she smells isn't Jack. Here's a TCS thread with more info: Ode to vanilla extract

And as for the kitten, and doing that introduction, TCS has a couple articles with tips and steps to follow.
How To Introduce A Kitten To An Older Cat – TheCatSite Articles
How To Successfully Introduce Cats: The Ultimate Guide – TheCatSite Articles

Good luck. Hope things settle between the siblings soon. And that they eventually accept the kitten into their feline family.
Thank you so much for all the links!

What's really strange is Elle obviously knows Jack's scent because it's all over the house and when I have them trade places she has no problem sniffing his bed or laying on one of their favorite blankets. Everything was okay for a minute when they were playing but then Jack went to give her a hello by sniffing her butt and it's like she remembered "Oh yeah I'm supposed to be mad at him."

I tried the vanilla extract and I'm not sure if it worked that well but I'll give it a few more tries.
 

rubysmama

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Sounds more like re-directed aggression then. Maybe try giving them both yummy treats together, so she starts to see Jack as something good, instead of the cause of the new cat scent in her home. And tell her you love her, that everything is ok, she's not being replaced. It may take a bit of time, but things should hopefully get back to normal between them.
 

di and bob

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She is just that nervous and scared with the new boy in the house and is lashing out. I have found that females are much more likely to not want to share what territory they have. Your boy will become buddies with the new little guy and they will play together. She will watch over them all and keep them in their place. These things just take time, you can't rush introductions. It takes really months, not weeks. She will get used to his presence and won't be so nervous, and your boy will be delighted to gain a brother. Make sure she has high-up places to retreat to, give them all yummy things to eat in sight of each other, and keep a stiff piece of cardboard around to stick between any skirmishes that may break out. She will come around eventually, just don't try to force anything. You could leash her, or keep her in a kennel for a while too, just make sure she has a small box to hide in so she doesn't feel trapped. Females are usually NOT team players, especially when they get older. but that is their role and they love it. My little girl still screams and swats the boys daily when they approach her, and she is their mother!
 
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kaybee988

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Thank you for the replies! There has been some definite progress where I don't think I need to separate them any longer out of fear for their safety. There's still hissing and growling but they are able to see one another, eat in the same room and occasionally bump noses.

Does anyone know why they would be ok smelling each other but then she starts hissing and tries to swat at him?
 
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kaybee988

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Also, since they just started getting along again, how much longer should I wait for Archie to have free roam of the house with them?

For the past few days I set up a playpen and he's dying to get out of it and his sanctuary room. I wouldn't want him to get hurt but I also don't want all the progress Elle has made to go away.
 

rubysmama

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I think I'd wait a bit longer before letting Archie have free run of the house with them. That might set everything back again. Do let Archie have run of the house from time to time. Just make sure Elle and Jack are safe in another room before you let him out.

What happens when the other cats see Archie in his playpen?
 

di and bob

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She is still on alert because she knows Archie is there somewhere. Females are just naturally hissy too since they are the limit setters. Jack is still a little too close for her to be comfortable. It WILL all work out in time.......
 
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kaybee988

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I think I'd wait a bit longer before letting Archie have free run of the house with them. That might set everything back again. Do let Archie have run of the house from time to time. Just make sure Elle and Jack are safe in another room before you let him out.

What happens when the other cats see Archie in his playpen?
Jack will get up close now and then and Elle usually keeps her distance but when she gets close she hisses and keeps growling. I noticed when he’s in the room behind the gate it’s the same but now once I close the door she may growl at Jack but they’re back to normal in a few minutes. So out of sight, out of mind which is why I’m concerned with letting him out.
 
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kaybee988

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This is what I woke up to this morning ❤
 
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kaybee988

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Awww... that must have made you smile. :catlove:
You have no idea! :D

Overall, there's more moments of peace than animosity but I hope they can get back to how they were before. I feel like playing/tousling will take a while. I can tell Jack wants to play but every time he surprises her it's met with a hiss.
 
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