Not really. The best and most proven method is their teeth. Some horses can look and move older than others at an earlier stage if their lives. Bit like us humans.
No, I have been shown how to tell a horses age by its teeth, and when I was shown the head groom told me where to feel in the mouth and the bloody horse bit me! lol
needless to say I have not done it since! lol
I reckon I can tell an old horse pretty well.
Teeth and body, movement etc. It all adds up.
I told a friend the Prix St George Dressage horse she bought for £15,000 looked in his twenties(just a passing observation - well she asked me 'cos she knew I would probably be closer than most speculations) - he was supposed to be 17!
Later on subseqent second and third sales (we kept in contact with the horse as he was so well known) it was later accepted that he was closer in age to 25 or 27.
Fortunately he is now retired and finally getting the rest he deserves for being such a superstar.
Sorry