My mare has also developed some hock arthritis at 14, and I just had this conversation with the vet. She was grade 1 lame in her lameness exam. We x-rayed her hocks, and found mild arthritic changes, then gave her IV Legends, which she'll be getting every two weeks for now, and once a month later. He suggested that I put her on Cosequin ASU, but I prefer the Smartpak branded supplements, so I've started her on SmartFlex Senior. I've also gotten her some back on track hock boots, but haven't gotten to use them much yet. My vet emphasized that arthritis can be unpredictable, but thought she'd be sound to ride for 2-5 years, and encouraged me to continue to ride her since motion helps. I'd consider my horse mild/moderate. She was perfectly rideable before any treatment, but I took her in because she ended up with swelling of the tendon sheath after a really hard ride (3 hours, jumped a big embankment, galloped up some big hills) and I had noticed slight stiffness this spring. I'm planning to make more of an effort to hold her back when we're out on the trail by ourselves so that she doesn't strain herself again, and hopefully with management I'll be able to ride her for a long time to come. I'm a little sad that I'm not going to get to do much jumping with her though. I thought about selling her to a trail rider, but I've decided that hock arthritis at her age is not the end of the world since she is otherwise a really good match for my current lifestyle. I don't have the time and energy to commit to a young horse right now. I try to ride her 3x a week, but sometimes am too busy. I do a H/J lesson once a week, a long trail ride, and 1-2 shorter rides in the pasture. Like I said, she doesn't seem off when I ride, but occasionally seems stiff standing in the pasture. I've had older horses with worse arthritis, and managed them with only MSM and bute, but they were not my primary riding horses, so I just wanted them comfortable in the pasture and ok for the occasional ride. Do you know what joints your horse is most affected in? I think that makes a difference.