Thanks everyone. Ivy seems fine this morning. She slept in her usual spot last night, curled up under the covers beside me. No sign of distress. No more trouble with Onyx. I think part of the problem last night may have been Ivy was already already under the desk when Onyx came by. She hangs out there quite often. I know cats hate to be cornered so mabye she felt trapped and escalated things.

I did try to clean her tail, but I can't actually find the wound! She spent a good deal of time cleaning her tail last night. She is the cleanest cat I've ever met! I'll keep a close eye out for any signs of infection.

I talked to my vet this morning--one of my dogs is having surgery today so I had to go to the clinic anyway! He just happened to have a Feliway diffuser in stock. I'll be getting that when I pick Paxil up tonight. I'm not sure it will help, but it won't hurt! If the aggression continues, I will ask about medication.

Thanks for all the suggestions. Everything was peaceful again this morning. I hope it stays that way! Maybe the cats are just tired of the dogs causing all the chaos and decided to cause their share too!