Hi! I'm CalCatDoc and I can help with your questions about Tucker.
Since your vet has already checked him out, we can probably look at this as a purely behavioral issue.
It sounds like something upset him when you were gone. Cats normally bond to their environment, and while we are not a major part of that environment, we are a part.
He may very well benefit from long-term use of an anti-anxiety medication like buspirone. I have used it in cats for various problems and it's very helpful.
You should probably also get some Feliway or Comfort Zone pheromone diffusers to plug in to help him feel more at home.
Oops, have a real life emergency hat just walked in - and I see that you are offline. I will switch to Q&A mode but we can still have this discussion. Please bookmark this page for easy return, also. I will be back in about 20 minutes to help with additional questions.
My vet suggested all the things you suggested with the exception of buspirone. I tried Feliway, but it didn't help. Also, if something disturbed him while we were on vacation a whole year ago, wouldn't those fears have subsided by now? I think it must be something else.
Regarding the time since the behavior first started - either things have just been snowballing, which can happen, or there is something in his environment that is still setting him off.
I do think you should try the buspirone. I start them on 5 mg twice a day, and if it seems to be working after a couple of weeks, I keep it up for a couple of months. Then it can be decreased to 5 mg once a day. My current mascot is on it for her redirected aggression problem and it really helps - she has been on it for 18 months with no side effects. I have some patients who have been on it for 2-3 years.
Has the pet sitter been able to offer any insight as to what might have precipitated this? It sounds like a single event that frightened him badly might be behind it. Fireworks or thunder or other loud noise just as he was crossing the middle of a room??
I wasn't so much dissatisfied with your suggestions as with the way this web site works. It took nearly three hours to complete our conversation, which was way too much time. I realize now that you are a working vet and had to interrupt our conversation to take care of patients. There must be a better way to serve on line questioners in a timely manner.
I agree the format is imperfect, but it works for most people. On our end we try to chat and often the customers never respond and just disappear into the ether after we spend 20 minutes typing out War & Peace, lol. I wouldn't give up on it altogether - most people are satisfied in spite of the limitations. And there are some vets on here who do this pretty much full time. If you find one, you can bookmark their profile and ask questions of them specifically.
If you are happy with my response you can upgrade it. In the alternative, we can continue troubleshooting Tucker's problem. I will be in and out today and throughout the week (unless I die of heat stroke, lol).