cats are fighting

Question
I have three cats one is 16yrs old , another is 8yrs old and the other is 3yrs old they have lived together since the other 2 were kittens on a normal basis they cuddle together, lick each other and stick together. Yesterday when I got home they look like attack cats keeping their distnace form each other hissing with their backs up. This morning this behavior continue I tried bringing them all together but they are continuing to fight with one another the oldest cat is getting alone with the other 2 only if they are by themselves once all 3 of them are in the room the have their backs up ready to fight. I just don't know what happened

Answer
The most likely cause of this sudden fighting is redirected aggression - this occurs when one of your cats sees an intruder cat outside (or smells or senses him) and can't get at the intruder. She goes into fight mode and her body is flooded with adrenaline, and in that state she'll fight almost any other animal that she sees as a threat, or even gets too close. Redirected aggression can be helped by

1. keeping cats indoors to avoid contact with strange cats

2. excluding roaming cats from your yard with fences (and cat-proof fence toppers such as chicken wire extensions)

3. Using Feliway plug-in diffusers and/or spray. Feliway mimics facial pheromones cats use to mark their territory by running their cheeks on things, and it is a big help with territorial aggression. You can find Feliway at most pet stores or online. I find the spray most effective but best of all is to use the diffuser for a constant level (it also seems to take 2 weeks or so to work) and the spray re-applied every 3 days. Spray it on doorways and furniture at cat-rubbing level.

4. Nutritionally, you can help reduce aggression by supplementing your cat's food with tryptophan, an amino acid that is a serotonin precursor and helps mellow out mammals. You can buy it at some health food stores and online at places like vitaminshoppe.com. Get capsules, you can pull the capsules apart and sprinkle the powder on canned food and mix in - it has pretty much no taste so your cat should eat it fine.  I recommend giving 100 mg a day per cat.

5. Start adding a few drops of Bach's Rescue Remedy (available online and in health food stores), a herbal calming essence, to their food each day.

Here is an article on redirected aggression in cats:

http://www.sniksnak.com/cathealth/aggression3.html

Good luck!