Working a Showmanship pattern somewhere in the great Northeast...
The mare I've been showing in Novice and Amateur classes will be 16 next year...but she has never really changed jobs other than starting out doing the lunge line and 2 year old classes with a pro and now being an ammy horse.
I have never shown all that much, but did show a couple of quarter horses into their early 20s successfully, including one at the Washington International Horse Show foxhunter's night back in the late 80s. The other- won year end championships/reserve in the state all breed show assn in both English and western disciplines in the same year on a then- 16 yo qh.
In both cases, they'd had successful full time show careers in their youth and then spent years at what became their 'main' job, foxhunting, with occasional showing throughout their lives.
I'm pretty sure a 24 year old gelding showed in the Jumping at the AQHA world show a few years ago... That's successful--if you ask me.
Argh, but did you see it? Poor thing was there last year - needs a good brushing and a more than a few bags of feed. I wanted to bring him home and stuff him full of carrots, then rub him with a fluffy sheepskin mitt while whispering "no more OKC for you..."