strange new fear/aggression

Hi all, new member here. I am happy to have found the site. My wife and I have two cats - Bobby is about six years old, a smart, friendly mellow white male. Bertie is a small black 3 year old male - very friendly but more cautious. They have gotten along fine for the past 3 years since we got Bertie. But recently something changed with Bertie and I am trying to figure it out.

My wife was brushing Bobby one day and accidently stepped on his tail or foot. He screamed as cats will do, but Bertie happened to be standing nearby and got completely whacked out. He hissed at Bobby and chased him around the living room, fur flying and tails puffed out, down into the basement, going for blood. My wife and I followed and separated them. Bertie had to be isolated for a day or two while he calmed down. Whenever he'd get near Bobby, he would meow loudly, hiss and try to chase him/attack him. Bobby didn't know what happened and kept his distance from then on.

Eventually they were reintegrated and all seemed fine. But today I noticed that Bobby meowed in the other room to get my attention and Bertie puffed up a bit and got big pupils and acted strangely. It's as if Bobby's loud meowing threatens him now.

Any thoughts on what is going on? I'd hate to have another flare up. Thanks!

Welcome to TheCatSite.

Any unexpected change in a kitty's behavior should be of concern.
Below is a link to an old thread on our site about cat aggression.
http://www.thecatsite.com/forums/sho...threadid=20837

Check out the paragraph titled....
Aggression Due To Fear, Pain, or Illness.

You might consider having your vet check out Bertie to rule out illness.
Other member will have suggestions for you too.

Please keep us updated about how Bertie is doing.

How long has it been since the first incident happened? And how long had the cats been living in the same household when it happened?

They have lived together for three years, since Bertie was a kitten. All was friendly before this, with the usual playing, mock fighting, cleaning, sleeping together, etc. After the one incident - boom - it all changed. Things are pretty normal now but I fear future issues...

It's been about a week and a half since the first incident...

It's still really soon. I doubt you'll have a long term effect from it. You know how after you've had a car accident you're nervous about driving for a while. It's the same with your kitty. Something scared him and it's still fresh in his mind. Kitties are resilient! He'll forget all about it soon.