sibling cats fighting - new problem

hi, i'm new to the forum. my wife and i have two wonderful neutered male cats - django and snoop doggy dogg. they are 4-year old brothers from the same litter. they are both indoor-outdoor cats, coming and going as they please during the daytime thru a window in our small trailer home; at night, we keep them inside. and they have lived the last four years with us in pretty much loving harmony - cleaning each other, hunting together, playing together and the usual playful fighting (nothing serious). now, all of a sudden, they are extremely aggressive with each other. they stare at each other warily and suspiciously inside the home - sometimes one will get close and lean forward to sniff the other's face before hissing/growling and backing away quickly. normally, if one even tries to walk past the other, they will hiss, growl and ultimately brawl. they come home with big cuts, scrapes and scratches on their heads and necks, and we're pretty sure they're beating each other up (as opposed to other cats in the neighborhood) b/c we have once or twice found chunks of their fur lodged in their claws. the only time they tolerate each other is at night when they sleep in our bed, but there always has to be one of our sleeping bodies between them.

this is a new problem, it started about 6 months ago. then it got considerably worse after my wife and i left in mid-november for a 6-week trip to africa. we had a catsitter/homesitter staying in the home the entire time. she said the cats were pretty aggressive with each other. she also said that Snoop was very affectionate with her, while Django spent a lot of his time outside and wasn't very affectionate with her (which is unusual b/c django is usually the creampuff of the family). now that we're back, both cats are still very affectionate with us - they just can't seem to stand each other.

any suggestions anyone?

thanks!

I would suggest that one of them is injured. When cats are outside, they are prone to all sorts of dangers, fights with other cats, pressure injuries, losing battles with automobiles. If one cat has become injured or ill- his scent will change, at first subtle then drastically. Because of the smell difference the other one will not recognize him. Letting your cats outside you really take the risk of bites becoming abcesses, or worse. I am not lecturing you here, for my cats go outside as well. The only difference is my cats are ferals and I treat their wounds aggressively or get them to the vet if it is severe and I can't deal with it effectively. Cats can be ill for a long time before us humans catch on. If I were you, I would take your cats to the vet and have them checked out. And deny them acess to the outside. We are now in the process of building a cat enclosure for my crew. Last year was costly for us, both in vet bills and loss of quality felines. It is now clear to us that we cannot protect these guys adequately as we have in the past, by allowing them in the woods and on our property and beyond.

I agree with hissy. Sudden aggression is often a sign that one of the cats is ill or injured. Perhaps take both cats off to the vet for a check-up, in particular, looking for abcesses or bite wounds. If both are given the all-clear, I would try keeping both cats inside for a few days and investing in a Comfort Zone plug-in. you can read about it here. This will help calm the cats. You can also use the vanilla extract trick. Dab some vanilla extract on both cats under the chin, between the shoulders and at the base of the tail. This helps the cats smell the same and masks any bad or strange scents in their fur that you may not be aware of.

thanks all. our vet came by a couple of days ago (she's a mobile vet who comes to your home - fantastic service, she's great) b/c the boys needed their feline leuk and distemper shots, and we told her about what was going on. she looked over their scabs and cuts and none were infected. and aside from a minor blister on django's foot, there were no signs of major injury. she recommended the Feliway spray, which we've been trying to spray on various corners in the house. no huge results yet. is the comfort zone auto-mister a must-have?

we'll definitely try that vanilla trick - sounds like it's worked for others real well.

hi hissy & kumbulu:

back again with an update. i tried the Feliway spray and the vanilla under the chins and tails - and those seemed to work a little bit, but not entirely. the boys are better this month, but still not great. they can sleep in the same bed with us and be in the room together, but they still get pretty aggressive whenever one tries to pass the other, either through the window in/out of the house, or in the hallway around the food dishes.

they seem to be fighting a lot also in the neighborhood with other cats, which they've actually always done. but i'm wondering if there is some re-directed aggression going on here. lastly, when they do fight in the house, what's the best way to break it up? we've been told to never use the water spraying trick or any other "aggressive" tactics to stop bad behavior with cats. fyi, we live in a very small space - converted RV on a plot of land - so putting each cat in a separate room is not an option.

thanks!

tom