Originally Posted by smrobs
You will get a ton of opinions in a thread like this and most of them will be different. Some will say that horses skeletons stop growing around 3-4, others say that they grow until they are 8-9, even others will say that it depends on breed and that some horses mature slower than others.
I can't say with any real certainty but I go by the rule of thumb that most horses (especially stock horses) will not change in height past their 6 year old year, though they will continue to build muscle and bulk up sometimes until they are around 10.
Only reason why I chose those numbers is because I have a mustang gelding that shot up another 2 inches after I started riding him the fall of his 5 year old year and I have a QH that kept building muscle and getting bigger every year until he was about 11.
So I would say that it is entirely possible that your guy could grow more, but it isn't a certainty. Have you tried the string test on him? My grandpa swore by it.
don't want to sound ignorant but what string test? How is it done? I really appreciate your help!