how much vanilla for fighting cats?

I was recommended to put vanilla extract on the chin, shoulder blades and base of the tail of both my cats to help reduce/stop fighting... but how much do I use on each? I just started this morning, and used a Q-Tip for each. Is that enough? Also, is it likely to stain their fur?

They've known each other since we brought the male home at 8 weeks old. They're now 3 and 1, and the fighting has gotten more serious. No blood, but there's biting, hissing, kicking, and the female (oldest...3 yrs. old) has started puffing out her tail. Both are fixed, and have all their claws.

I just put a bit on my finger for each location, but I'm sure a Qtip is fine.

Thanks Sicycat... how long does it take before you're supposed to see a difference? It's been a day, and they're still going at it (me? impatient? No way! )

Have you taken them to a vet? Sometimes, sudden aggression play is a stimuli from pain. One of them could be ill, and now he smells funny which is why the other one is attacking him.

this is probably going to be more info than you need, but here goes anyway.

Kermitte (female..3...spayed...has all her claws) has had a reoccurring UTI, but we've got her on a prescription diet, and things seem to be going well now. We feed her on top of the fridge. We give her a spoonful of wet food and a scoop of dry kibble, that we soak in water (my mother thinks the UTI might have her evacuating more water than she's drinking, so we're increasing her water intake that way)

Elmo (male...1...neutered...has all his claws) has a clean bill of health, and is eating the same food as Kermitte (except he gets grocery store brand wet food). We feed him on the ground.

Both cats will initiate the wrestling matches. Within the last few days, I don't recall hearing any hissing or sounds of pain/anger when they fight, but with my work schedule, I'm often out of the house most of the day. I've noticed that 'Mo (Elmo) will stare Kermitte down, and I know that's an intimidation thing. I know you're supposed to have "safe" places for your cats to retreat to when they're being pestered, but both cats have access to the same places, so if Kermitte tries to get away from Elmo, where she goes, he can go too. That's probably one of the reasons she gets peeved at him. Elmo will also chase Kermitte as soon as she comes down from the fridge... Elmo is a real bully. He'll even pester the dog (who's easily 5 times his size) until she plays with him. He pouces on the dog's tail, chews her tags, licks her legs, and will rub up against her then flop over on his side. He LOVES having the base of his tail rubbed.

That's all I can think of for now... does the info help?