>>Thanks for everyone's concern. My vet said overgrooming is usually triggered by stress. I'm not sure what would have caused this, he is an indoor cat with one much smaller female cat for a companion-they get along well, and there hasn't been much of a break in his routine. He is taking a three week prescription of progesterone to calm him down (he isn't hyper, just a little too nervous sometimes.) I haven't noticed much of a change in his behavior, but he has stopped picking at the hair on his tail and back, so hopefully all is well. I can't wait for it to grow back, he looks a little silly at the moment.
Luckily cats aren't vain and he probably isn't bothered by his silly look at the moment. 
Hopefully he'll be sprouting new fur again soon, though it might be hard to notice for a while as this is shedding season.
I am not familiar with using progesterone as a stress-reducer. I am NOT questioning your vet's decision to use this medication, just saying this is new to me. I'd be very interested in hearing how it works out in the long run, including after he stops taking the meds. I'm curious, hence the name.
Often with these types of behaviors, they become habit even though some other cause triggered them. If the medication keeps him from overgrooming for 3 weeks, the theory is that he'll get out of the habit and will be able to quit the meds permanently. In other words, the meds don't "cure" the behavior on their own per se, but give him a vacation from the disruptive behavior and consequently, an opportunity to replace it with more adaptive behaviors. Please let us know how he's doing at the end of the 3 weeks, and then again a few weeks after that.
Glad you took him to the vet! GLOWs to your kitty.
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PHCurious
Cat Chat Host
