Twin cats of 2 years are now starting to fight

2 Years ago I adopted two male american short hairs. They were the only two cats in the litter and have been together sharing living space and eating space their whole lives. In the past few months they have begun to fight each other quite often. I've never seen it reach the point of an all out brawl, but they will scratch, hiss, and spit at each other...mostly instigated by the same cat every time. They used to wrestle all the time when they were younger, but they would end it by grooming each other. They would constantly be together outside the house too. I can't understand why they don't seem to get along anymore...or at least why one of them seems to have a problem with the other cat. Is this something that will pass and is there anything I can do to help the situation?

-Kurt

Are they neutered? Male cats in my experience tend to tolerate each other better, so if they're not full out caterwauling/screaming I wouldn't worry too much. Do you feed them separately? It's generally a good idea to keep two food bowls, as well as multiple litter boxes so they don't claim ownership of something they both need.

Also, how long does it take them to calm down after a fight? If they just seem to go their own way, then it's probably nothing to worry about. If it were a real fight, they would be growling and hissing at each other for hours afterwards often times.

I would think that the encounters will lessen as the pecking order becomes more established, but unless they're being injured (or kept from eating, something horrible like that), I wouldn't worry too much. My girls fight from time to time, and they've been together all their lives - the youngest is about two years old now. Oddly, she's at the top of the pecking order.

When one cat senses some sort of weakness in the other such as illness the stronger cat can start fights. If you have not had them for a check-up recently - NOW might be a good idea