Brothers fighting-Help!!

My two cats (who are brothers and until yesterday have been inseperable) are at each others throats now. I tried unsuccessfully to introduce a new cat. After that cat got scared and went back out my two cats are attacking one another. I have them in seperate rooms right now. They are both neutered cats however the cat I tried to bring in was female. One or both my cats sprayed extensively.

Right now re-introducing the female is very secondary until I can get my others back to normal. Any advice? I'm sick to my stomach over how badly this went.

It is likely that the new scent of the cat freaked them out and they do not recognize each other for the moment. I have had two foster brothers who occasionally pick up the scent of one of my non-foster cats (the fosters are in their own room) and they will puff out at each other and circle each other, totally freaked out. This can last for a while until their fear and adrenaline subsides.

On the new girl cat, if you reintroduce her, you should work her into the play therapy I recommend below. Also you will need to take time to introduce her scent everywhere. The spraying is territory marking and shows that these boys are indeed freaked out by the new scent.

If the fighting continues:

Can you tell that they are fighting in earnest, i.e. leaving claws in each other's faces? How old are they? Is one getting beat up more than the other? How often do they fight? And do they puff out their fur and screech at each other or just fight roughly?

The spraying is territory marking and unless this occurred before you introduced the new cat, it should be ok.

Other than that, if it were me I would introduce frequent and structured play sessions (the same times and amount of times each day) with a feather toy on a string, the scruntchy throw balls for fetching, the laser light, and call each one by name when you want them to go after it. Encourage them by name to "Get the toy!!". They will respond.

If they are teenagers or younger they won't pay any attention to their name being called, but they will recognize that you are engaging them in group play with the toy and it should divert them from each other and let them focus aggression on the toy. At the end of the play sessions reward them with a treat and give pettings to each one.

Is the female spayed? If she is not, she probably is in heat. Has she been checked by your vet? A sick cat can cause a lot of stress to the resident cats.
As for the fighting and spraying, even neutered males will behave as aggressively as any other cat when it comes to territory or females.
Keep the lady away from the boys until things settle down between them. It will be safer to introduce her then.

I hope it does not last but the fighting is not in play. The screams are blood-curling. Our neighbors probably hate us right now. This morning I let the one who has been confined to the guest bedroom out. They saw each other at first and were OK and the aggressor starting sniffing the other. After a couple minutes the hissing and attacks started again. They are currently in seperate rooms.

The female was not spayed yet. That was my next move. The vet made it seem it would be OK to start introducing them as long as I got here spayed soon. She behaved better at the Vet than my other cats do.

The spraying had never happened before yesterday.

I do not have plans to reintroduce the female until I can get her spayed and at that I may just try to foster her until I can get here adopted. She is a real sweet cat and I can't bear to let her spend the winter outside in Chicago. She is still residing on our porch.

You have to make them smell like each other, either by brushing in a little baking powder, putting a drop of pure vanilla on each of their shoulders and right near their tails, or rubbing a towel on one then the same towel on the other and back again. But give them a day or so, it usually works.

Larke,
I will try that tonight. I don't plan on having them out together if we are not home so I will try and let them smell each other under close supervision (and with a spray bottle handy!).
The funny thing is the brother cat who has traditionally been the Alpha-Male dominant cat is the victim. It's our quiet sweet scaredy cat that is scaring the daylights out of us. Thanks everybody!

Whew, meeses, I feel for you. I had one of those fights between a pair who had previously had a perceived mother-son relationship. They carried on for a WEEK, during which time one was locked in the basement, for their safety. I think they were about 8 and 6 yrs old at the time.

They did settle down, but somehow the trust between them was broken and they never completely got along after that. They played "slowly, slowly, I am creeping," every time one wanted to get past the other, for the rest of their lives! I wish I had better news about the outcome, let alone some constructive help to offer.

If you have not got a bottle of Feliway phermone spray, you might want to grab one from a pet store and try it. It can have a terrific calming effect -- and in fact it did help my two.