"popped a curb?" Know anything?

[Elizabeth Kohler <ekohler@psych.umass.edu>]

Hello out there,

I am a lurker in need of advice.  I have a young horse, 5 years
old, that I have been preparing for distance riding.  (I am
currently campaigning a 9-year-old at the same time).  I have
been conditioning this horse for 1.5 years slowly building up.
Last season we did some pleasure rides, no competition.  This
season we've done pleasure rides and one hard 25 in VT.  Two
weeks ago we did a 20-mile judged plaesure ride on home turf.  He
did very well, he was very "forward" and we moved fairly fast but
I did not feel it was nearly as stressful as the 25 in VT.  Yet,
he came out of it as very sore in the hind quarters (he did get
1st place although there were only three people going as judged).
He was much more sore than at the end of the 25 miler.  The next
day as I groomed him I noticed a bump below his hock on both hinds
that I had never noticed before.  I am not very experienced so I
began to look at the other horses at the barn, no one else had
this.  I asked my farrier (who happened to be around that day) and
he did not know what it was.  I asked two experienced distance riders
and neither had seen anything like it.  They all ruled out splints,
capped hock, bog spavin.  There was no heat or tenderness and no
real swelling.

Two people since have looked and called it a popped curb (?) (one 
a race track person, one a dressage instructor).  They differ in their
opinions about his future use as a trail horse.  I have not called a vet 
in yet.  He is not lame or off at all.  I plan to call today to
have one come.  What I want to know is whether anyone has had
experience with this.  Can I still condition him in hopes of
doing at least limited distance?  I love this little horse and
would not compete him if it will shorten his effective life.  I
will "retire" him to be my daughters "pony club" type horse.
Any info is appreciated.

Thanks!!

Libbie Kohler (sure wish I'd just gone to vet school!)