at the barn i ride at, the horse i ride (his name is tommy) went lame once with an abscess. he had a tiny pebble that lodged in his hoof wall and it worked his way through to the surface. but before it popped out, it became infected and the farrier had to take it out. he was lame for about 3 weeks, but he got better fairly fast after that!
It's too bad that Dexter got an abscess. I hope he gets well soon and you and he can compete together.
I'm so sorry! Those abscesses are real buggers! With just a little TLC (I'm sure he's already getting it) he'll be fine in no time. All the horses I've known to get abscesses recover fully. Good luck!