Hi All
I have a young “Kentucky Spotted Mountain Horse”, who came to live with our herd last June. When he arrived, he was on the thin side (est. BCS ~4), and I measured him at just barely 14hh. (I have an appropriate tool; don’t know what it is called; a long “ruler” with an adjustable cross-bar/level.)
I was scratching his ears for him yesterday, and it hit me that little “Rosy” had grown somewhat. I got the tool out and measured again. No doubt about it; my boy had gained three inches in 6 months, on top of having obviously improved his BCS to 5.5-6.
Would this sort of rapid growth be considered normal at his age, and is it likely that his improved diet had anything to do with it? If this keeps up, we’ll be shopping for another saddle for him come Springtime 
(Currently in an older Stüben Dressage saddle.)
Just curious; this boy is my first “baby”. TIA Steve and “El Rosado”
Yup, sounds normal. Both genes and nutrition play into this. And in many breeds, they are not fully mature until 7 or 8 yo.
I’ve had one decide to grow at 6 years old. They also gain height as they gain muscle and improve their hooves (the bony column literally rises up in the hoof capsule as they gain sole depth). Not a lot but enough to be noticeable!
I never know how to differentiate between “normal” and “common”. Maybe like this - for blood work, there are normal ranges for everything, which are really just based on averages. BUT, it’s relatively common for a given horse to have his own personal “normal” as slightly above or below that average.
So in this case, I’m not sure I’d say it’s all that normal for a horse to grow 3" in 6 months as a 4yo, but also, it isn’t all that uncommon.
Some breeds grow more slowly, the bigger they are, the longer it takes to get to their mature height. Ponies are more or less done by 3/4, but big WBs, and drafts, easily take 6-7-8 years.
A lot of TBs coming OT as even 3-4-5yos often seem to have big growth spurts like this, when their energy intake isn’t being consumed by racing. It seems less common if they grow up outside of the racing world.
And like fivestrideline said - some of the later growth is wither sprouting, but also the musculature physically lifting up the shoulder sling.
and yes, it is very likely his improved diet had a lot to do with that, similar to the OTTB situation above, where he was suddenly getting the fuel for growth.
Totally normal, especially for horses who were underfed. Make sure you are supplementing vitamin E.
One of mine grew about 2 inches at 6 years.
My 18 year old mare sticks at 15.3, then if you make her do a belly lift she is 16 even. The withers can lift independent of the shoulders. So better muscles and self carriage will add height too.
Well, thanks for that, folks. I wasn’t really worried, but at least now I know where all of the chow was going :-D. Rosy is lookin’ good, and our farrier was out today for trims; said his feet are looking better as well. (He came with shoes on all four, which I promptly had pulled. Seems like some people just have this thing about horse shoes . . .)
This young fellow is as bright and shiny as a new penny; extremely inquisitive, and a terminal trouble maker. (Goes with “smart” in my experience.) He is already a reasonably unflappable trail horse, and will only get better as the miles accumulate. And he loves his pet human.
Just as a data point (and because all of the “experts” told me differently), he “gaits” just fine in the English saddle, and a Dr. Cooks bitless bridle. Took all of 10 minutes for him to figure out what the bitless was about. He was trained in a Western saddle, and a Pelham bit, with what appeared to me to be an uncomfortably snug curb chain. Personally, if I can’t get an Equine to work for me by asking politely, I’ll go find something else to do.
Not terribly common, but I’m not surprised, especially as someone who raises WBs.
But I mainly came here to say he is gorgeous. I like to believe he is raising his back hoof as if he were extending his pinky and doing it to be fancy.
Thank You on Rosy’s behalf.
I’m pretty sure he was swatting a fly :-D.
He’s gorgeous!
It’s called a measuring stick.
My gaited filly is 2.5 years old and measures about 14.1. She doesn’t look done to me. Her rump/shoulders look too small. Her breeder thought she would stay small. She is level on the topline, but is not fat by any means. I’m hoping some good nutrition will help. Maybe she’ll make 15 hands, but if not, it’s not a big deal. She just looks immature.
My paint grew about 6 inches between 2-3 years. It was miserable trying to find a saddle that would fit. Although she was all legs so it wasn’t entirely surprising that she would get taller.
Thanks!
A “Measuring Stick”! Who’d of thought it
Ditto this. It isn’t hard to vary a horse’s measurement by an inch to 1.5", depending entirely on how they are standing. Not square, sprawled out, head up like a giraffe, or head down, belly lifts, measuring stick placed a few inches forward/back/out to the side…can all give different heights. I have an aluminum stick with a bubble level, and I measure my horses a lot (barn full of growing foals/youngsters). It is surprising how much you can manipulate their height if they aren’t standing consistently for measurements. In my experience, all of the “he grew an inch!” after age 5+ is just finished wither height, from topline and shoulder development. The legs certainly aren’t getting any longer after 24mos. 
Agree with @EventerAJ that most “growth” in height after age 3 is muscle, not skeletal. Horses can measure very differently depending on hoof care, fitness, and positioning.
Case in point: My old gelding measured 14.3 when I bought him as an undermuscled barely 5 year old. For most of his performance career, he measured 15.1. Following his retirement, he was back to measuring 14.3.
