Manifestations of laterality or crooked horse syndrome

Dr. Kerry Ridgway

 Dr. Kerry Ridgway had, in the last three years, been working both as a veterinary clinician and as an educator, regarding laterality expressed as the“crooked horse syndrome.” Through client and horseman education, it was his goal to prevent and avoid so very many of the musculoskeletal problems that he encountered day in and day out.   He wanted to get the horse-owning public to understand the manifestations and how to bring the horse into balance and straightness. It is such an enormous key to soundness.

At lectures he presented on June 22nd, 2013, at Reaseheath College, among other topics, he presented the evidence for the 75 to 80 percent of all horses as being right forelimb supporting dominant, while the remaining horses are left forelimb supporting dominant.

Since Xenophon, every riding master, expert trainer, and most deep thinking riders have recognized that all horses start with a difficult side to their bodies – a hollow side and a convex side. Most remain this way for their entire lives. They exist within the context of the “Crooked Horse Syndrome.” These inherent aspects create the biomechanics of movement of the “natural horse.” Such biomechanics serve the horse well in its natural wild/feral state but are antagonistic to those required of the ridden horse. Because of this dichotomy, many techniques are utilized to “straighten” the horse. The essence and purpose of all the techniques are to minimize limb dominance and create/develop the biomechanics necessary for riding horses, i.e. the goal is to make them more ambidextrous.

Failure to achieve ambidexterity, balance and straightness creates problems in performance, a shorter useful life and eventually leads to unsoundness.

It matters not, whether you are a rider (pleasure or performance), a trainer, a veterinarian (conventional or integrative medicine oriented), a groom, a farrier/trimmer or a massage/physiotherapist, nearly every musculoskeletal injury or pathology that we identify and attempt to cure or manage is related to the “Crooked Horse Syndrome.”

The “Crooked Horse Syndrome” is part and parcel of the genetic quality called “Laterality.” Laterality is expressed as a “dominance” of one side of the body (associated with brain laterality). This is expressed, in common language, as being “right” or left handed.” We have carried this handedness terminology over to the horse. Dr. Ridgway did, however, think that the term “right” or “left handed” is totally inappropriate and leads to confusion.  Humans are bipeds and horses are quadrupeds, different biomechanics come into play and the limbs are not used for the same functions.

So Then, How Did Dr. Ridgway Define The Terms?
He Asked:
Are we attempting to determine which limbs and which side of the body are more in control of movement? Have we confirmed which side of the equine brain is dominant (in terms of Laterality)?
What role do muscles play in Laterality?
What muscle actions create more ease of movement in one direction versus the other?
When we use the term “dominance,” are we referring to use of muscles as more supporting, more balancing, or stronger in propulsion?
Are the muscles, in a given limb facilitating – stabilizing or mobilizing?

These are the problems that Dr. Ridgway encountered when extrapolating from the biped to the quadruped and were some of the problems Dr. Ridgway discussed during a lecture at Reaseheath College in the UK.

He believed that dominance of a front limb might require a shift in definition as we moved from the bipedal human to the quadrupedal equine. But, by placing the human in a quadrupedal position, he demonstrated that we could still use the human as an example of a change in what we are calling“limb dominance.”

How did Dr. Ridgway come to be so vocal about Laterality and its relationship to problems of performance, soundness, and conformation? His interest, initially, became piqued when Martina Steinmetz, a German Veterinary acupuncturist presented some acupuncture aspects of laterality at an International Veterinary Acupuncture Congress. Later, he got together with her and had discussions about the asymmetry of the feet in the “high/low” syndrome, a favorite topic of his.

Confusion and disagreement about the role of laterality led him and his wife Christine to research more of what is known about equine laterality and “straightness training.” They extensively studied and discussed various material, read and dissected the Schöneich book, “Correct Movement in Horses” many times over. This led to them traveling to Germany to meet and spend time with both Klaus and Gabriele Schöneich.

Klaus, as a rider and trainer, has been involved in “straightness training” with horses for nearly 30 years and has developed and used his system of training on approximately 6000 horses. Dr. Ridgway and Christine were absolutely captivated with the concepts that he expressed. Those concepts have enormous significance not only to riders but very importantly, to the pathology that Dr. Ridgway and every veterinarian observes day in and day out.

Dr. Ridgway and his wife watched many horses improve in balance, and consequentially, in soundness, within the short span of the two weeks they spent with Klaus and Gabriele. They had the opportunity to do physical examinations on these horses every couple of days and saw reductions in the muscle pain and hypertension of given muscles.

This experience changed the entire focus of Dr. Ridgway’s veterinary medical practice. For a number of years, he had observed that every horse he examined from a musculo-skeletal perspective, had identical patterns of muscle hypertension and pain upon palpation. This was true regardless of discipline or use of the horse, 75 to 80 percent of the time the pattern was consistent between every horse.  The other 20 to 25 percent exhibited exactly the same pattern, but in mirror image. (There might be relationships of muscle size (hypertrophy and tone)according to use, but the “pain” and “tension” issues were, essentially, within the same sets of muscles in all cases. This obviously related to how the horse used the same muscles to a different degree on one side of the body versus the other side.

Klaus Schöneich describes 75 to 80 percent of the horses as being right forelimb dominant. These horses are described by Klaus and a number of other highly respected trainers, veterinarians, and others studying biomechanics, as being “right forelimb dominant.” Most commonly, the left side is the hollow side, – the right side being convex. In this instance where the right fore limb is dominant then the following are easily observed and experienced:

Typically most horses, when being started, have an easier time picking up a left lead than the right lead.
When starting a young horse it will respond better to the left rein and be resistant to right rein.
When lunging the horse to the left most horses “pop out” the right shoulder and exhibit the effects of centrifugal force – thus they keep widening the circle.
The same young horse who is being started is reluctant to lunge to the right and will often stop and turn towards the trainer.

Regarding muscles … Dr. Ridgway often, facetiously, referred to them as “not the brightest bulb on the tree.” By that, he meant that muscle physiology is based on a polarizing stimulation for contraction followed by depolarization and release. The release part does not occur in the case of overuse, “over facing” muscle(s) by certain overly strenuous movement(s), or by extensive repetitive use of specific muscles – i.e. cumulative micro-trauma. (As a metaphor, think of carpal tunnel syndrome in the human.) These muscles in our “crooked horse” remain in a chronically contracted state and set up markedly reactive points, i.e. acupuncture points (latent and active), as well as trigger points. Prolonged contraction sets up a state of chronic pathology.

Dr. Ridgway found that the majority of horses, 75-80%, who have not been trained for ambidexterity,  have pain and hypertension in the neck muscles on the right side, but not on the left side. Presumably, the severity of this pain will dictate whether gait abnormality or other compensations result ultimately in lameness.  The shoulders will be affected on the right side.

Interestingly these are the same sets of muscles that get more painful or damaged from overuse in a “right-handed” human/biped.  Muscles only get to this state if they are the more used (and abused) set. They have progressed from “tone” to a state of “hypertonicity.”

If we are recognizing heavier muscle use present on the right shoulder and forelimb we can logically describe this as a “muscle dominance” or right forelimb muscle dominance.” Dominance, support, balance and propulsion also are important in a proper evaluation of how we define laterality. So, when Dr. Ridgway assessed the right hindquarters in a “right forelimb dominant” horse, he would find certain muscles which were used as a base of support and balance – both in stance phase and during movement, which would be very tense and reactive to palpation. Examination and evaluation of the left hind quarters revealed quite different muscle tension patterns.

The horse evolved as a grazing animal, designed to place more of its weight on the forehand to facilitate grazing.  The way laterality is expressed and then remains unaddressed when the horse is under saddle will dictate the way the body responds over time with skeletal and muscular imbalances.   Typically, the RF foot is more upright and takes more forceful concussion – as evidenced by a higher incidence of suspensory and check ligament injuries on the RF. This also correlates with the shortened stride of a weighted shoulder. The left front often has a long toe with a low and under-run heel. These horses are often lower in the left heel. This limb is more subject to navicular, impar ligament, distal sesmoidean ligaments, deep digital flexor insertion on P-3, and upper forelimb tendon injuries than the more upright right forelimb. There is more …. sacro-illiac problems are more evident on the right, the  facet joints of the thoracic and lumbar vertebrae exhibit more pathology on the right side of the horse of the right forelimb dominant horse.

The implications of the manifestations of laterality are huge for all horses at all levels of competition, in all aspects of their role as ridden leisure horses.  Dr. Ridgway understood how to assess, monitor and help create balanced, straight horses, in order to reduce the implications of all that asymmetry and “the crooked horse syndrome” created.