Take It Easy on Your Horse’s Mouth!

I keep coming across reports of how many riders injure their horse’s mouths, especially during competitions. I do not see many articles about how to reduce the number of horses with injured mouths. Nor do I see any explanation of why those who want top performances from their horses in competition are the very people who should strive the hardest to minimize their interference with their horse’s head and neck.

The old-time cavalry manuals emphasized the free movement of the horse’s head and neck as essential because as they function as the horse’s ‘fifth leg’. But that metaphor doesn’t mean much to people who grow up depending on cars for transportation instead of horses. The metaphor that catches people’s attention now is asking them to think of the horse’s head and neck more as a gearshift than a set of brakes.

Shifting gears affects how a vehicle moves. Changing positions of the horse’s head and neck affects how they move. There is even a neurological equivalent to neutral, or the clutch disengaging the gears. It is called pandiculation or the Stretch-Yawn-Syndrome.

Horses are strictly nostril breathers, so they don’t exactly yawn the way humans do. But, opening their jaws and swallowing while freely moving their tongue can trigger a neuro-reflex chain that resets both the startle reaction in their central nervous system and the tension in their myofascial field, especially in their forehand. Horsemen have a multitude of terms to describe the feeling when a horse does this reset, but ‘suppleness’ is the word used in the old cavalry manuals.

Dr. James Rooney DVM lists specific neural reflex chains that affect the extension and flexion of the horse’s legs in his book ‘The Lame Horse’.

• Their front legs extend and their hind legs flex as the horse’s nose come in towards their chest,
• Their front legs extend and their hind legs flex as the horse’s neck swings upwards, or dorsiflexes

It is important to note that the reflexes triggered by changes in the position of the horse’s head and neck can work together or separately

• Their front legs flex and their hind-legs extend as the horse’s nose extends,
• Their front legs flex and their hind-legs extend when the horse’s neck swings downward, or ventroflexes

Despite the recent fixation on ‘frame’, on keeping a horse’s head in one place, movement of the head and neck is actually essential to a horse’s performance. Horses that show a greater range of movement of their head and neck also show greater speed on the flat and more scope over jumps. The way a horse clears a jump is an example of the neural-reflex chains working together

When taking off over a jump, a horse will raise their head and bring in their nose. Raising their neck extends their hind legs, bringing in their nose flexes their forelegs.

The bascule is seen while the horse is suspended in the air as they clear a high jump. Extending their nose flexes their front legs while lowering their neck flexes their rear legs.

When making a clean landing from a jump, a horse will extend their nose, flexing their hind legs and extending their forelegs.

Understanding how a horse coordinates their movements has pragmatic applications. Many riders cause refusal at a jump because their heavy hands and poor seats resist the elevation of the horse neck making it difficult for their horse to extend their hind legs with sufficient force to clear the jump. Riders also cause their horse to knock down rails by yanking their noses in as they land, triggering the premature extension of their horse’s hind-legs. Making sure that your seat and hands are following your horse’s patterns of neural reflex chains will improve your chances of a fast, clear round of jumps

Just to complicate the picture, the order of leg movement in each gait is set in the cerebrum. In horses, the cerebrum communicates with the cervical and lumbar enlargements on the spinal cord of the horse. The cervical enlargement coordinates the movements of the forelegs. The lumbar enlargement coordinates the hind legs.

Changes in the sequence of leg movements usually begin with one hind leg moving forward.

• If the horse chooses to walk in four beats with no fly-period or suspension, the neuro-logical sequence of leg movements is a lateral four beat pattern. If the horse starts with the left hind, then the left fore, right hind, then right fore inevitably follow.

When transitioning to a two-beat gait with fly-periods when no hooves are on the ground, the horse may be hard wired to:

• Trot, moving diagonal pairs of legs together- left hind and right fore, fly-period, right hind and left fore, fly-period
• Pace, moving lateral pairs of legs together- left hind and left fore, fly-period, right hind and right fore, fly-period

The gallop is a three beat diagonal gait with a fly-period.

• Left hind, right hind and left fore, right fore, fly-period

Dr. James Rooney describes the canter as a four-beat gait. A horse hard-wired to coordinate lateral pairs or pace will usually offer the same leg sequence as a walk with an added fly-period as the sequence at the walk speeds up. A horse hard-wired to coordinate diagonal pairs or to trot may offer ‘broken’ diagonals as the sequence of leg movements at the gallop slows down.

• The Pacer’s canter sequence is left hind, left fore, right hind, right fore, fly-period
• The Trotter’s canter sequence is left hind, right hind, left fore, right fore, fly-period

“Gaited’ horses offer many different variations on the basic pattern of four-beats and broken pairs. Those who train ‘gaited’ horses may not be aware of this list of neural reflex chains, but they apply them pragmatically, using the positions of the horse’s head and neck to influence the timing and quality of their leg movements.

There are also very specific neural reflex chains that affect leg movements triggered by changes in the position of the head and neck. One area neural reflex chains control is balance. When a horse’s head tips to one side or their neck bends, that change triggers a neural reflex chain.

• If the head tilts to the left, the reflex chain straightens the head by turning the nose and neck to the right, which in turn extends the right legs.
• If the neck bends to the left, the reflex chain straightens the horse by extending the right legs

These neural reflex chains explain why horses tend to lean when circling. Pulling their head to one side even just with the weight of a lunge line will increase the tendency to lean. Horse can learn to circle without stressing their legs, but the changes in how they move around the circle have come from behind, as they integrate the rotation of their lumbo-sacral joint into their stride.

There is no direct English translation of the German dressage term ‘schwung’ thqt best describes this integration. The closest I have come across is the rather cumbersome and misleading English phrase ‘the horse giving their back’. The scientific research available indicates that the feeling of ‘schwung’ reflects the free smooth coordination of the rotation of the vertebrae of the horse’s back with the sequence of leg movements triggered by neural reflex chains.

Not nearly enough research has been done on how the three brains of the horse’s central nervous system work together. That is partly because coordinating locomotion in the horse is so complex that the cervical and lumbar enlargements should each be considered small semi-independent brains. What little is known about their cooperation supports the assertions of classical horsemanship that teaches impulsion and transitions must come from behind.

Pragmatic experience has long demonstrated that when riding ‘on contact’, movement coming from behind changes the rein tension in the rider’s hands. Science now informs us that those subtle changes reflect the neural reflex chains that have been triggered. If a rider has light educated hands and their horse has learned that changes in the degree and direction of tension on the reins are meaningful, they can discuss how the horse moves within a specific gait as well as through transitions between gaits.