I have a 31 year old who still comes cantering to the barn .... to be fed his smushy feed because he has no teeth. But his quality of life is good and he still is the perfect gentleman for giving our company (little kids) rides. I have a 29 year old mare who's still able to hitch to my cart for drives, and she gives my 25 year old daughter occasional rides when she's home for visits. We don't push them hard or fast or do long rides but they perk up and really seem to enjoy it when they have their 'jobs' to do!
They get extra careful feedings, extra shelter in the bad weather, annual (or more often) dental care, regular farrier care and the occasional joint supplement for arthritis. And extra horse cookies and love.
My horse is 17 and I can barely tell any difference from 14 when I started riding him. He just needs to warm up a bit more before galloping up the hills. He is nicer, too.
Aging really depends on the horse, conformation , care and type of riding. Some horses don't slow down at all until the pass 20. My experience is that horses don't age as gradually as we do. They tend to stay fit for a long, flat time and then their old age is shorter/sharper decline, happening relatively later in life than humans.
I bought my now 21yr old mare when she was 12. I thought that 12 was old. She taught me how wrong I was! She's been the best horse ever. The older the better I say. Their brains are nice and mature! She still doesn't act her age! I've seen a few changes in her but that's to be expected with age. Other than that she's still got a solid back and still runs like an arab! Posted via Mobile Device
I used to have a 30 year old mare (RIP baby) that right up until the day she died would be able to nudge you so hard you fell over. One day we left the trot poles in the field that we use to train Tazz and she was trotting over them having a ball. It really does depend on the horse. Yes 30 was old but that was more than some lame young'uns can do, you can't classify them that easily.
My gelding is almost 19 and has a bit of sway back just from age but that's about it. He has a bit of arthritis but it is closely looked after. Most of the time he acts like a spunky 5 year old. He runs around the arena full force screaming his lungs out at every other horse and he gets the whole barn talking. He also is still ridden and shown.
I bought my now 23 year old mare when she was 11. I have on and off worried as she ages thinking about the day that she isn't here. However, at 23 she is still my full time trail horse, barrel horse and training buddy to the younger horses. She has no troubles with a long trail ride and a good long mile or two of galloping home. She does get stiff IF she isn't ridden as she's one to stand around, but she's left outside 24/7 with the younger crowd to KEEP her moving and everything is great. Everyone comments on how she looks no different than when I brought her home. And lucky for me, her sire is now 31 and still looking just as gorgeous as he did at 12. She will tell me when its time to slow down and we will take things back a notch, until then keeping her going keeps her young so that is what we shall do!