My mare is 28 (29 in March) and is still doing great. I wouldn't suggest any hard riding, but they are still great for leisurely trail rides and such. I just got the okay from my vet to start riding again, and I will be only doing short trail rides or ponying my daughter on her pony....
I love the Arabian breed. I have owned 2 now, one from birth. They are smart, and usually very people oriented... They can be hard to keep weight on as they get older. But I love my mare and wouldn't trade her for the world. (I've had her for 16 years btw) Good luck
I'm an Arabian enthusiast, they're my breed of choice and always will be. So I'm probably a bit biased but I've been raised with them from birth. I find them the most sweet natured, personable, loyal and docile horses imagineable. I'm sure most people can say that about their breed of choice but there's just a presence, a spirit and a mischevious quality about Arabians that grabs me. I've worked with tons of other breeds, and I still stand by my choice. I value each breed and each horse for their differences, but Arabians have always had something a little extra that I adore.
A lot of people find them "hot" but I personally think that's just the Arabian who's had his spirit channeled in the wrong direction. They're brimming with energy, but a properly trained Arabian will only deliver when you ask for it. I spent my childhood racing around the pastures on our purebred broodmares bareback with nothing but a halter at 7 years old!
Anyway, I think you'll find even for 25 years old, the old guy has plenty of piss and vinegar left! Arabs are well known for the longevity. My good friend in Texas has a 27 year old Arabian mare who's nowhere near close to wanting to retire!
Hmm, Well I will tell you what I know for what it is worth. We had some arab morgan crosses years ago and they made an exellent cross, very smart and gentle but we never had a fullblood arab. Arabs are a hot blooded breed and are in the foundation of several other breeds such as throughbred. A fullblood arab can be very intellegent but also can be very highstrung and energetic plus some that have been overbred have too much dish in their face and a popeyed look with too small a nose. I guess more to the point what is your experience level? If it turns out to be one of the high energy ones would you be comfortable with that, what sort of riding would you do, I mean 25 is kinda of getting up there for a horse especially for strenous activities, you wont get too many years out of it possibly depending on what you want to do with it.