The battle continues

I have 5 cats....3 are 8 yrs old and brothers and sister....the problem is Mike and Scooter...they are brother and sister..Mike is a male and he is the only one that goes outside..but NOT in the winters...so he has been bascily house bound since Nov...Scooter is female....100% indoor cat...Lately Mike has been attacking her...last night they managed to knock over a litter box....and a plant that was on the fridge...I have NO idea why he is going after her like he has been....It goes on for a bit then it seems to stop but lately its been every few weeks...I have some rescue remedy and put it in their water but its not stopping the attacks...And as most of you know the worst sound in the middle of the night...wakes the whole house...and he did it again this morning...so I thought well its nice outside I put him out but he just sits on the steps til I let him in...I thought going out might do his some good....Scooter is walking around on egg shells ..I'm at a loss on what to do to stop this...Any suggestions ?

Are Mike and Scooter two of the 8-year-old siblings, or are they the other two cats? How old are they? Have they been spayed and neutered? Is there any other inappropriate or changing behavior going on?

Do you have a place in the house where you can separate the cats, other than putting one outside?

Sorry, I have more questions than suggestions. I have no idea why cats do what they do.

If Rescue Remedy isn't working you might try Feliway instead. Different cats may react to one better than the other. Another (cheaper) home remedy that I've seen suggested is to put a drop of vanilla on the back of their necks to make them smell alike.

Yes they are siblings...they are both 8 and yes they have been "fixed" at 6 months old...nothing new has been going on...The younger kitten I got was spayed last week but this battle has been going on b4 that...

Are they actually trying to hurt each other, or is it just scuffling?

If the latter, just ignore it and let them work it out between them. Be Switzerland.

Well they make a alot of noise.....I have found blood on the floor after one of their fights.....but never really found a wound....I will head towards them when it happens to kinda break it up...but other than that I don't know what to do to stop it....

Could this be something like "redirected aggression"?
http://www.thecatsite.com/forums/sho...threadid=20837

Maybe another cat is roaming outside and Mike is attacking his sister because he cannot get to the outside cat. We may not see or hear a stay cat outside, but they sure do. That might explain why it happens at night. I hope things settle down soon.

Who knows why they do what they do at times.....Like this am..I had my bedroom door closed...when I opened it there was Mike and Scooter sitting there together waiting for breakfast....