It's interesting to me that now that horses are used primarily for pleasure or entertainment instead of as a means of survival or transportation that we are less patient with putting them to work. Perhaps that is a reflection of our throw-a-way society. Or maybe it is the fault of the the veterinary community that has perfected the band-aids necessary to keep a horse working when it maybe shouldn't be. Or maybe it's the fault of the high end competitive venues that have turned towards making money off of equine children rather than equine adults and the rest of us just follow suit.
I'm talking about the incredibly controversial issue of skeletal maturation and optimum age of starting a young horse. There are many misconceptions and widely spread misunderstandings in this area of the horse world. The modern horse world seems to be more and more impressed with the advanced abilities of a young horse as showcased in a futurity. We prize that young horse who achieves enormous amounts of money earnings early in his career and then retires to the breeding shed as a 3 or 4 year old.
You can see this change in almost every aspect of the horse industry, but maybe nowhere so dramatically as in the American Racing industry. Where race horses used to have to be at least 4 before they began competing in long heats of 4 mile feats of endurance, the concept of the quick sprint futurities was introduced to allow betters a "glimpse" of the talent coming up. Racing of 2 and 3 year olds in shorter more "humane" races became the norm and were immensely popular for the ability to stage a shorter race in a track that could seat more people, allow for more prospective betters and overall increase the excitement of the race. Soon the only horses racing at maturity were cheap claimers or geldings that didn't have a career in the breeding shed to look forward to. What has occurred in the racing industry is a significant drop in the number of starts a horse will have in his life paired with an increase in the number of breakdowns.
The same has occurred in the western reined cowhorse industry. What used to be a competition for a mature bridle horse (generally 6 or older) was then turned into a futurity for hackamore horses. As the snaffle bit increased in popularity for it's ability to accomplish more advanced training more quickly the snaffle bit futurity was born. This is a high dollar competition for young Quarter horses that are 3 years of age. In order to compete in this highly demanding and physical sport those horses are often started under saddle at 18 months.One of the sad parts about this is that right there on the first page of the NRCHA rule book is the purpose of the association: "The purpose of the NRCHA is to improve the quality of the western reined stock horse: to perpetuate the early Spanish traditions of highly trained and well reined working cow horses;" It has traveled quite a way from the goals at it's inception.
Sadly the tradition of the early Spanish horseman were to not put any metal in their horse's mouth until age 5 or 6 and to bring them along slowly to protect not only their physical well-being, but mental well being. Spanish tradition would start a horse at 3 or 4 with very light riding with a hackamore until he was ready to move into the two-rein at 5 or 6 and only after he was carefully prepared would be be straight up in the bridle and riding one handed. For many horses this wasn't until they were 7 or older. Today, a 7 year old reined cow horse is likely ready to retire from the show ring. Not always, but often. It's like seeing Billy Etbauer still riding in the NFR. Not impossible at his age, but very rare.
But it's not just high dollar performance horses that are being started as 2 year olds. Conventional wisdom seems to push folks to start their backyard pleasure horses sometime during their 2 year old year. The conscientious owner knows to wait until "the knees are closed". This piece of equine wisdom is referring to the growth plates at the distal radius. While you can't actually tell by palpating the horse if that growth plate has fused or not, many folks feel that you can and use this colloquial rule of thumb for starting youngsters under saddle.
What we know about rate of skeletal maturity is that the growth plates in the equine body slowly fuse between 1.5 years and 5.5 years. Across the board. There is no truth to the myth that some breeds of horse mature faster than others. All horses reach skeletal maturity at about 5 1/2 to 6 years of age. This really shouldn't surprise us as we know that the horse continues to erupt molars until they are 6. Why shouldn't the timing for completion of growth be at about the same time.
What may not be common knowledge is that it's not the legs that are the slowest maturing part of the body. The growth plates of the knees mature ( or close) at about 2 years for the small bones and 3 years for the distal radius and ulna. The very last growth plates to fuse are in the equine vertebrae. All 32 of them. The last of those are the ones in the base of the neck.
The reason this is relevant to our young horses that we plan to ride well into their advanced years is that the process of riding our young horses can contribute to not only excessive wear and tear on their young joints (the hocks also don't fuse until 3.5 years) but strain to their backs and necks as well.
The process of teaching a horse to be ridden at a very young age teaches the horse to protect itself from back pain. To do this the horse braces his back and drops his shoulders and hollows out so that he can help take the weight of his vertebral column. It's a minor thing at first and one that every young horse being started under saddle goes through to a certain degree until their back muscles get better at carrying that weight. But if you persist in riding a young horse who's vertebral column is not able to bear that weight even with muscular conditioning, you create a habit caused by pain that becomes deeply ingrained and prevents the horse from properly learning to round up and use his body.
The next step in training a young horse after getting on their back (especially in many of today's "natural horsemanship" methods) is the one rein stop. This is accomplished by repetitively pulling the horse's head over to your foot and limbering up the neck until it is quite soft and "rubbery". Isn't this putting added stresses on the last vertebrae to fuse in the horse's entire body? Pain here causes stiffness in the bridle that causes the horse to flex by turning his head at the atlas rather than flexing his entire vertebral column. With vertical flexion he then learns to brace his withers and instead of flexing along his entire column will flex at the third vertebra to protect the rest of the cervical vertebrae. All of this might look like a broke young horse to the uninitiated, but in truth it is a horse with reflexes built on pain. Those horses can never move in a true collected frame.
So while the now common and widespread practice of putting a 2 year old to work in a rigorous training program undoubtedly leads to increased incidences of breakdowns in race horses and the widespread practice of injecting young horse's joints to try to stave off juvenile osteoarthritis, the other long lasting effects of braces and pain through their back and neck are less often addressed.
Does this mean that we shouldn't start our horses until they are fully skeletally mature? That, for me, is a harder question to answer.
Paired with the data of skeletal maturity is the data that exists on mental maturity. Horses can and do learn to learn. One of the great things that have been bred into the Quarter Horse performance horses is their ability to calmly and easily learn what is expected of them. They are almost "born broke". This is because they have been selected for train-ability which is really the capacity to learn. (Whether that makes them the smartest breed of horse or just the most trainable is a discussion for another time!) For most folks that work with young horses and start colts the ones that have had an introduction to good handling and training as yearlings are much easier to start as 2 or 3 year olds. That ability to retain a lesson and understand what is being taught is a learned behavior. The younger they learn that, the easier they seem to be to train and quicker to trust.
Therefore, I believe the answer lies in moderation, as with most things. I think you have to take into consideration your youngster and your training program. I am 100% not in favor of futurities that demand a horse be put into rigorous training as a 2 year old. I am also not in favor of any practice that deems it common and prudent to inject a young horse's joints in order to maintain joint health or cover-up a lameness and keep them working. But, that's just me. I have many colleagues happily preforming these procedures and building their retirement accounts much faster than I am.
I don't think you necessarily need to completely stay off your horse until they are 4. I think you can teach a horse some valuable lessons, expose them to important stimuli and situations and in general build their confidence and ability to learn as a young horse. I personally put 10 short (all but one of them were under 20 minutes) rides on my 2 year old this summer. He had already had about a month of various groundwork exercises to establish some basic commands and improve his comfort with me and the tack. Riding sessions would generally consist of going both directions at a walk and a trot with some simple directing with the hackamore. We established whoa and the beginnings of a back. I pushed him into a lope just to get him to feel it and then allowed him to trot again. That was it. I did take him on one short trail ride just to expose him to an area other than our arena and home trail. In my mind, that was about all he could handle.
This year as a 3 year old I will put some more rides on him throughout the summer. He will be lightly ridden and exposed to basic commands and stimuli in a rotation with the other horses. He'll probably be ridden about twice a month lightly through his 3 year old year. He certainly won't be loping circle after circle, going on 4 hour trail rides or schooling on spins and sliding stops. He's almost 15 hands and probably 900#. Had he been smaller (or I bigger) I would have waited until he was 4 to start the process.
I don't feel that lack of skeletal maturity means no work or riding at all, but I think it means conscientious riding and training to preserve not only your horse's mind but his physical ability to be a good sound partner throughout his entire life. I want to be riding my horses well into their third decade and possibly longer. There is nothing sadder to me than a 6 year old that is too lame to be ridden in the show pen anymore because it was ridden too hard as a youngster. That's like seeing a teenage girl that trained too hard as a gymnast and now has collapsed bones in her wrists and deformed radius. Too much work too soon. We need to be smarter than this for our horses. Increasing the usable upper age limits of our horses through smart training will go miles to decreasing the numbers of unwanted or crippled horses out there.