The potential consequences of starting a horse under saddle too young.
Today, more and more, the big money futurities for performance horses are for three-year-olds, so in order to be competitive, these horses MUST be started as two-year-olds, and sometimes even when they are long-yearlings (18-24 months old). Because of this, many of these horses end up with bowed tendons, Navicular Syndrome, bone spavins, bone chips, stifle injuries, blown-out hocks, hairline fractures, arthritis, severe back problems, sprained necks and a myriad of other problems and conditions associated with stress and strain to young, developing bodies. Many horses will end up with debilitating problems at only four or five-years-old and already receiving anti-inflammatory medications and/or painkillers on a daily basis in their feed, or in the form of injections. Some older horses, in their teens, will develop problems that can be traced directly back to being started too young and too hard. It will take 10 or so years for the stresses they experienced when younger to appear as problematic
Even at two and a half years old a horse is still just a teenager. He’s not physically mature, nor will he be completely mature, until he’s at least six. In spite of what many in the horse industry believe, all horses regardless of breed mature skeletally at the same rate. Even the most conscientious of horse owner concentrate their concern on a horse’s developing legs, but growth plates are not just in a horse’s knee. There is a growth plate on either end of every bone starting behind the skull, and continuing throughout the remaining skeletal areas. In the case of some bones like the pelvis there are multiple growth plates. Taking the age of final maturity which ranges between 4 – 6 years of age into consideration, as well as the rate of bone fusion in the growth plates, ideally a horse shouldn’t be ridden and worked regularly until the minimal age of four. This does not mean you have to wait until all growth plates are converted to bone, but the longer you wait the safer you will be. There is a definite schedule of fusion and the decision to ride a horse should be based on that rather than external appearance of the horse. Many breeds like the quarter horse are bred in such a manner they appear mature long before they actually are mature. This puts these horses in jeopardy from people who are either ignorant of the closure schedule or more interested with their own schedule than they are in the welfare of the animal.
The Schedule of Growth Plate Conversion to Bone.
The process of growth plates converting to bone goes from the bottom of the animal up.
- The growth plate at the top of the coffin bone, the most distal bone of the limb, is fused at birth. This means it gets no taller after birth but does get larger around, through another mechanism. After that the growth plates fuse as follows:
- Short pastern - top and bottom between birth and 6 months.
- Long pastern - top and bottom between 6 months and one year.
- Cannon bone - top and bottom between 8 months and 1.5 years
- Small bones of the knee - top and bottom of each, between 1.5 and 2.5 years
- Bottom of radius-ulna - between 2 and 2.5 years
- Weight-bearing portion of glenoid notch at top of radius - between 2.5 and 3 years
- Humerus - top and bottom, between 3 and 3.5 years
- Scapula - glenoid or bottom (weight-bearing) portion – between 3.5 and 4 years
- Hindlimb - lower portions same as forelimb
- Hock - this joint is "late" for as low down as it is; growth plates on the tibial and fibular tarsals don't fuse until the animal is four (so the hocks are a known "weak point" - even the 18th-century literature warns against driving young horses in plow or other deep or sticky footing, or jumping them up into a heavy load, for danger of spraining their hocks).
- Tibia - top and bottom, between 3 and 3.5 years
- Femur - bottom, between 3 and 3.5 years; neck, between 2.5 and 3 years; major and 3rd trochanters, between 2.5 and 3 years
- Pelvis - growth plates on the points of hip, peak of croup (tubera sacrale), and points of buttock (tuber ischii), between 3 and 4 years.
- The vertebral column is last. A normal horse has 32 vertebrae between the back of the skull and the root of the dock, and there are several growth plates on each one, the most important of which is the one capping the centrum. These do not fuse until the horse is at least 5 ½ years old. The taller the horse and the longer its neck, the later the last fusions will occur. Fusions in male horses generally take up to an additional 6 months.
The lateness of vertebral "closure" is most significant for two reasons. One: in no limb are there 32 growth plates! Two: the growth plates in the limbs are (more or less) oriented perpendicular to the stress of the load passing through them, while those of the vertebral chain are oriented parallel to weight placed upon the horse's back. Bottom line: you can sprain a horse's back a lot more easily than you can displace those located in the limbs.
Within the chain of vertebrae, the last to fully close" are those at the base of the animal's neck (that's why the long-necked individual may go past 6 years to achieve full maturity - it's the base of his neck that is still growing). So you have to be careful - very careful - not to yank the neck around on your young horse, or get him in any situation where he strains his neck
Relationship of Skeletal to Sexual Maturity
People often think because a male horse can physically reproduce at age 2 he is considered fully mature. By that definition every 14 year old boy is mature. The ability to achieve an erection, penetrate a mare, and ejaculate semen containing live sperm cells occurs before skeletal maturity, both in humans and horses.
The Significance of Too Much Too Soon.
What will happen if you put a young horse to riding much too early Two important things - and probably not what you're thinking of. What is very unlikely to happen is that you'll damage the growth plates in his legs. At the worst, there may be some crushing of the cartilages, but the number of cases of deformed limbs due to early use is tiny. Legs can be damaged much quicker and more seriously by over feeding a young horse.
Structural damage to the horse's back from early riding is somewhat easier to produce than structural damage to his legs. There are some bloodlines that are known to inherit weak deep inter vertebral ligament sheathing; these animals are especially prone to the early, sudden onset of "saddle back'" However, individuals belonging to these bloodlines are by no means the only ones who may have their back "slip" and that's because, as mentioned above, the stress of weight bearing on the back passes parallel to its growth plates as well as parallel to the inter vertebral joints. However, the frequency of slipped backs in horses under 6 years old is also very low.
When trying to explain the justification and common sense of waiting until at least 3 years of age to introduce a horse to light work under saddle and incrementally increasing that workload over the next year to a competitive/ performance level by age four, I am almost always inevitably confronted with an impatient disapproving owners condescending response in notifying me that race horses have been started early for centuries and are already often competing at age two.
Why then is it such a big deal to start my trail/pleasure horse before three?
The answer to that is simply; because most of us would like our trail/pleasure horses to live and prosper longer than race horses do.
In the U.S., around 5,000 horses leave racing every year, the same numbers who enter it. A recent study showed that for every 22 races, at least one horse suffers an injury severe enough to prevent him or her from finishing a race.
Race horses frequently suffer injuries because they are forced to train and race before their skeletal system has finished growing.
To compete in the races with the largest purses — which are for 2 and 3 year olds — horses must be trained and raced at too young an age, before their bones’ growth plates have matured. This causes many lower-limb ailments and injuries, including fractures, pulled ligaments, and strained tendons. Such injuries are common in horse racing.
The unnatural stresses inherent in competing so aggressively and at such a young age also cause or make worse other serious problems, such as stomach ulcers, heart murmurs, and bleeding in the lungs, not observed in horses worked at reasonable levels. These health and injury problems once again necessitate the use of drugs to maintain the horse’s racing value (but not wellbeing).
One study reported in the Equine Veterinary Journal noted a doubling of one type of heart murmur and a tripling of another in 2-year-olds after 9 months of training. Horses' heartbeats can increase tenfold during a race, from a relaxed 25 beats per minute to an excessive 250 beats, leading to exhaustion, collapse, and sometimes, to a fatal heart attack.
Riding horses are started at 3-4 years old, while race horses are often started as young as 1-1/2 years. Riding horses are brought along slowly and with as little stress to their still-maturing joints as possible, while race horses are forced to run beyond their limits, pounding their still-developing joints into the ground. The average riding horse commonly lives to 18-20 years, while the average race horse lives only 5-7 years of their 25 year lifespan. When the riding horse is just entering his prime, the race horse is ending his career, and possibly his life.
Given all the information available today, on the possible adverse affects, starting a horse too young can encompass, I can’t imagine a scenario where it’s worth the risk. Putting it all into perspective; what is there to really be lost in giving up starting a young horse for a year to year and a half. At the end of the day you might miss a futurity or two and delay your horse’s performance/competitive debut for a year or so, but wouldn’t it be worth it to extend his working career and life an extra 10 to 15?
Much of the information compiled to give an informative assessment regarding age appropriate training for young horses are combined excerpts taken directly from the following sources:
- The Equine Studies Institute Knowledge Base by, Dr. Deb Bennett.
- International Fund for Horse Site ~ Welfare Reforms Needed In Horse Racing Article
- TodaysHorse.Com ~ Why People Start Horses Too Hard, Too Young by, Laura Phelps-Bell