Grumpy siblings- should I order Feliway?

Hello all.

I have two 1.5 year old cats who are brother and sister.   They used to be best buds as kittens and occasionally playfight too rough and the sister would hiss.  However recently in the last few months they have been bickering a bit more than usual and the sister keeps hissing at her brother and sometimes biffing him on the nose!!! Not constant fighting and not mega aggressive but it still makes me sad they aren't best buddies anymore  

I've read about re-directed aggression and stuff but not sure what would have happened and its been going on a while now. Also sometimes they do still snuggle up and groom each other.  Its quite random!

I was considering getting some Feliway but then I almost want to keep that as a last resort to use if they ever get really stressed or upset and don't want to use it in a 'non-emergency' incase they become immune!?!

Any advice on rebuilding their friendship? 

I've had cat siblings sort of become apart when they grew up. They just develop their own personality. But they do sometimes cuddle and groom each other. I would not worry so much.

But to make sure, I recommend you have them checked by the vet. It is possible one of them is not well and the other one can sense it. It could be the reason for the sudden aggression. 

As long as they are "fixed" and not full blown fighting, I say they are OK.  I have 3 cats that are siblings that grew up and live together.  They are 4 yrs old now.  They get along pretty good.  But they do bicker sometimes.  Animals, especially cats, are just like people that way.... Sometimes they don't always get along with siblings but as long as they are still grooming, they are still bonded and still "friends." 

PS- Feliway works for some but not for all.  It's really expensive.  I would suggest a less expensive Comfort Zone with Feliway for a month and see if it helps.  Or you can try the Calming Collar.  But, it's more for anxiety and stressful situations like recent moving, surgery, or maybe a scary storm.  It's not really for normal bickering siblings.... I don't think you'd see much of a change with Feliway because of this.

Thanks so much for the responses.  Hopefully they will just grow out of it.  The sister is a growler as well as a hisser but I think it sounds worse than it is!  Yayi -they recently had check ups at the vet so hopefully all good health-wise.  Dennis is just getting over an UTI.  They have changed soooo much in the 1.5 years we have had them maybe this phase will pass in a few months as well!  Thanks for the advice re Feliway - I think I will give it a miss for now.

Females are usually the more dominant and prone to alpha cat syndrome sex in my experiences.  So she might be trying to tell him she is boss.  Some cats are drama queens, too.  My Piper is for sure!  Whenever she is mad, she screams and squeals like she's being killed but she is just that way.  I find it amusing though it sure can sound awful.