New Kitten has Middle Cat "Tree'd"?

We have three cats, a 13 year old male, 2 year old female (a dilute tortie), and a 7 month old male. The older cat has recently been feeling much healthier/happier, due to change of diet and having started to get along much better with the middle cat, who we got as a kitten when she was about 4 months old. Before that he was always an only cat.

We adopted the kitten about two and a half months ago, and took our time introducing them. While there was initial fear and loathing from both the older cats, the oldest cat and the kitten have become playful buddies. The playing and chasing between the boys has reached an active but friendly equilibrium. The kitten still provokes the older cat by climbing on him, chewing his tail, etc., but the older cat gives about as good as he gets. They eventually settle into a friendly truce, and almost are cuddling up with each other. The exercise and companionship for the older cat has him looking and acting happier and healthier than he has in years.

The trouble comes in the reaction of the middle female cat to the kitten, who still refuses to have anything to do with the kitten. Unfortunately almost the entire time the kitten is out and about, the female refuses to leave the top of her cat-condo tower, looking suspiciously over the edge at or for the kitten. When the kitten climbs up to the top to her she hisses, growls, swipes, and occasionally spits at him.

We put out food with the dishes a considerable distance from each other. She will come down and eat, but always keeps an eye on him. Invariably the kitten finishes first, and if we don't pull him away, he'll chase her from her plate. They'll go running through the house for a while, with the girl hissing and screaming, until she gets chased back up her tower.

Since we still need to lock the kitten up in his room at night so we can sleep, and there are other times the girl has the run of the house. We can tell she's starting to lose weight and doesn't use the litter box as much because she won't risk an encounter with the kitten.

We have tried trading scents between the cats without much improvement coming from it. We'll be bringing in the girl for her regular checkup in another day or two, and will be taking what advice the vet gives (the cats are in otherwise good health, have all shots, etc). In short, any advice is welcome, and we're hoping for a day down the road when the female will brave the house with the kitten out and about, and that she'll eventually get along with him, at least to some degree.

By Cliff73