Age appropriate training: when do horses physically mature

fractures it is not until a certain age that these areas solidify to form hardened bone.
The completion of growth plates varies throughout the entire skeleton for example the coffin bone within the hoof capsule is fused at birth the hock solidifies at 12 months of age and the scapula at four years.
The vertebrae which run along the length of the horses body to form the spine specifically from the tail to the start of the thoracic vertebrae behind the wither right where the weight of a rider and saddle sit dont complete this process until around six years of age.
Unlike the bones in the legs where the growth plates of the limbs run vertical to the ground the spine is horizontal and relatively unsupported relying on structures of connected soft tissue. This leaves the vertebrae extremely vulnerable to the impact of a rider on the back before they are fully fused.
The final plates to close are those of the spinous process of the withers and the base of the neck.
When are horses mentally ready to work?
An often underdiscussed aspect of training is a horses mental readiness psychologically and emotionally.
There is a belief that does the rounds on yards that a horse started late usually referring to an age of six seven or eight experiences behavioural problems as a result of that late starting.
While the horse is skeletally and physically mature mentally he has difficulty with certain aspects of his work likely from a lack of preparation being asked too much in comparison to his level of experience and expectations due to his age.
Should ridden work wait until theyre older?
So should we leave our horses in the field until they are six? No. The consequences of leaving a horse in the field until they are six and then starting a hard
fast training programme can be just as poor as those of starting a horse at two.
The development of the muscles and soft tissues of the equine athletes body is just as important as skeletal development and they must be conditioned correctly. Tissue and bone adapt to changes that take place throughout life not just in a set period.
The key is to work at a level appropriate for each individual horse from a young age. Work progressively over a period of years not months to prepare the horse physically by conditioning and strengthening soft tissues promoting bone density and a responsive and confident mind to produce a wellprepared riding partner.