I'm so sorry to hear this. I know how frustrating this can be. It could also be a behavioral problem since you said that she's trying to be the alpha cat now. When a cat does the quiver tail without spraying, this happens because they're overcome with emotion towards their owner or even just another person that they've become very fond of. My Ziggy used to do this daily towards me and I thought she was trying to spray but she never did. I did a search about it on the internet and I found that it was because she's in love with me. My RB Storm used to sometimes do this too. Even a male cat that I was cat sitting for did this a few times to me.

I'll now share my own very recent spraying story which I haven't told PT yet. As most of you know Alani just had PU surgery because he was blocked and he had severely damaged the tip of his penis. Ziggy has always growled and hissed at both Alani & Blaze since they were kittens and it never seemed to phase them at all. Ziggy usually likes to stay in my bedroom most of the time but she does come out to the kitchen area during feeding time. On Tues. morning she growled at Alani like she usually does. Alani responed by doing the quiver tail and he did spray a little bit. I was shocked. I cleaned it up with some enzyme cleaner. It didn't have an odor either probably because he's been neutered for several years. He then proceeded to spray on a scratching post and I was able to stop him from doing very much. This all happened in my dining room and I already have a feliway diffuser going in this room.

I e-mailed my vet and she said that his PU surgery shouldn't be causing this and that he may still be in some pain and if it continues that I should bring him in for a urine analysis. Now I've been keeping Ziggy away from him and so far so good. Before this happened though, I also noticed that Alani will sometimes bully both Sky and Colby almost like he's trying to become the new alpha cat. My RB Storm was the alpha cat. To me Alani doesn't seem to be in pain so I think that his is a behavioral thing. I just hope that it doesn't continue to happen. Yesterday I bought more feliway plugins as well as some new adapters since the others are very old.

Good luck and I hope that Lily doesn't continue spraying. I feel your frustration.

I looked up quiver tail again and this is what it says about it: When a cat is very excited and happy to greet its owner he will hold his tail straight in the air and it will quiver or twitch. This is the cat's way of saying he is so pleased to see you that he is overcome with emotion.