What you need to know about skeletal maturity in horses
Horse Anatomy

Do you know why it’s important to understand physical maturity in horses when training them?

A mature horse can be worked very hard, but if the horse is never given the chance to fully develop before being put to work, how much of his full potential will he ever achieve?

When buying, training and starting a young horse – or when looking at problems of a horse you already own – it’s important to consider the physical maturity of the horse.

A horse, regardless of breed or type, is skeletally mature at around 6-8 years old

Horses with long backs and necks can take a bit longer to mature, smaller horses may develop a bit faster.

Parallel with skeletal maturity is the development of the supportive muscles, tendons and ligaments.

Ignoring the developmental rate of a horse when starting him can do great damage and leave your hopes on the ground instead of in the saddle.

Draft horses are bred to pull heavy loads. A mature horse can pull as much as his own body weight.

Strength comes from maturity

A mature horse is a very strong animal. Horses can generally pull around 80% of their own body weight, specialised breeds even more than that.

The Finn-horse can regularly achieve results of pulling up to 110% of its own body weight – in competition horses have achieved as much as pulling over 200% of their own body weight.

But this is only possible with a horse that has been given time to develop his strength and stamina that arises from a fully mature body and training that understands and considers physical maturation.

For riding, the strength of a horse’s back is crucial as this is the part of the horse we sit on.

It is necessary for the horse to have a fully developed spine and to have strong supportive muscles surrounding the spine.

The saying that you should wait until “the knees close” on a horse before beginning to ride refers to waiting until the bones in the knees are mature enough to not take any damage under load.

The skeleton of a horse matures from the legs up and the spine is the last of the bones to mature.

Damage to legs from riding a horse too early is rare, you place more risk on damaging the back

A horse can get a “sway” or “saddle” back from having the vertebrae “slip” away from their normal place, because the immature bone didn’t have sufficient support from strong, developed ligaments and muscles.

This is called lordosis and causes the spine to hang down between the withers and hips in an unnatural arc.

Many horses with a sway back can still live and have a comfortable life, but if the vertebrae slip too much, the spinal cord and the function of internal organs, are at risk and the horse may have to be put down.

Bad habits lead to poor performance

The biggest disservice you will do, to both yourself and your horse if you being to ride him too early, is to teach him bad habits that he may struggle to unlearn.

When your horse expects a load to come onto his back he will, much like us, brace his feet and muscles as well as his diaphragm (hold his breath) to be able to deal with the extra load.

A horse that cannot release his muscles while working will not be able to “round” properly to carry the weight of the rider.

To round a horse uses a complex interplay of bone and muscle assisted by a strong network of ligaments and tendons; the long muscle running down the length of the spine, the muscles between the ribs and the abdominal muscles all play a vital role.

Engaging the core and lifting the chest while elongating the spine are crucial skills for a horse to learn if he is to live a long and healthy life as a ridden horse.

To move efficiently, while being able to carry the weight of both equipment and rider, a horse needs to learn how to flex and release his muscles.

Muscles that are constantly being held in a state of tension are not efficient muscles and will tire more quickly due to a lack of oxygen

The horse that works in tension will never be able to show you what he can really do – he will never achieve that perfect piaffe, he will never soar over those high jumps with ease and he will never learn how to really enjoy working with you.

A horse must learn how to use his core muscles to round his form and effectively use his muscles in the most economical way to be able to carry the extra load of a rider and gear on his back.

Muscle tension accumulates over time and begins to cause the non-alignment of supportive tissues like bone.

In addition, it causes muscle pain, “pinched nerves” that hamper movement control and feeling, and along with decreased blood flow, lowers the efficiency rate at which blood, oxygen and nutrients are carried around the body – in essence, lower performance and slower recovery.

A horse with a sore back might end up being un-rideable if the root of the problem is not sought out and corrected.

Giving your horse enough time to mature and develop physically in the first place will ensure that he will give you the best he can

As a general guideline, you can start your horse with ground handling at around age one, introduction to equipment at two – teach him how to have weight get on and off his back (but not stay there) – start teaching him the ropes of his future job at three and he’ll be ready to gradually start light work at age four.

Rushing ahead of the time, won’t bring results any faster. Letting your horse take his time, both mentally and physically, will give you a strong horse that is eager to work and won’t present any problems later on from being ridden too soon.

For further reading on the skeletal maturation in horses, I recommend you read this now-famous article by Deb Bennett, Ph.D., that started a lot of discussion on the topic.

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