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Chiropractic, Back Pain & Hoof Imbalances

Rowan Kilmartin BVSc MCSc (Animal Chiropractic) Grad Dip Animal Chiropractic.

Introduction

This paper deals with the resolution of equine back pain by chiropractic intervention and considers the possibilities of hoof imbalances causing back and pelvic pain. Studies by Crevier-Denoix [1] and Chateau[2] have considered the effects of hoof imbalances on the metacarpophalangeal joint and the digital angles. These studies would indicate there remains an extensive amount of work to be done to demonstrate the effects of such imbalances on the biomechanics of the spine and indeed the whole animal. Consequently the effects of imbalances are reported here for the purpose of introducing discussion and providing some means of assisting the animal and reducing discomfort and pain until such studies are undertaken.
The use of chiropractic in animals has been acknowledged in the Western world for some time [3]. By definition chiropractic care is a form of complementary and alternative veterinary medicine (CAVM)[4]. As such to understand the rationale for the use of chiropractic in equine clinical practice requires a brief insight into chiropractic theory.

The basis of chiropractic

Chiropractors recognize innate intelligence which can be defined as the intrinsic ability of a healthy organism to react physiologically to the changing conditions of the external and internal environment. The core principle of chiropractic theory is that the nervous system controls and coordinates function of all tissues of the body. If the nervous system is not functioning normally then the area of the body supplied by that part of the nervous system will be adversely affected.[5-7]. Thus chiropractic is concerned with the investigation of the relationship between structure (primarily of the spine) and function (primarily of the nervous system), of the human body, that leads to restoration and preservation of health.

Spinal joint mobility

The spinal column is rigid to protect the spinal cord but mobile to allow movement. If the mobility of the column is altered the environment of the spinal nerves is changed. Altered mobility is a common reason for nervous system dysfunction. If the mobility is decreased which is the most common situation it is known as being hypomobile. In hypomobile segments the spinal nerve reflexes tend to ‘lock’ intrinsic spinal muscles to protect the spinal cord. This should be a self-resolving situation. If the mobility of the spinal column is increased between vertebrae then it is said to be hypermobile. This occurs usually from trauma where there is joint sprain and associated soft tissue damage. These intervertebral hypermobile segments are very unstable and require special attention.

Chiropractors palpate and adjust a vertebral motor unit or motion segment. This is a three joint unit which consists of two facet or zygapophyseal joints and the IV disc which is also really a joint. In any joint there is an active and passive range of motion. The active range of motion is the normal distance of travel that the joint goes through when opening and closing. The passive range of motion goes beyond the active range of motion entering the joint’s elastic limit and encountering the elastic barrier. Beyond the elastic barrier is a small space called the Parphysiological Space. Following cavitation the parphysiological space extends the passive range of motion.[5] If the joint is carried beyond the parphysiological space to the anatomical limit serious joint damage will result. Chiropractors learn to adjust joints into the paraphysiological space within the anatomical limit.

When a client complains that their horse “has his back out” what they really mean is that he has a vertebral motion segment dysfunction involving a complex interaction of pathological changes in nerve, muscle, ligamentous and vascular and connective tissue. The result is thoraco-lumbar or back pain which can compromise performance and affect the horse’s behavior or both.

A chiropractic listing is the language used to describe the abnormal movement characteristic of one vertebra in relation to adjacent segments. Static listing refers to the spatial orientation of one vertebra in relation to the other similar to what is seen on an x-ray. [5] In veterinary chiropractic, motion listings are used. These are similar to dynamic listings and can describe movement in various planes. Consequently we can describe situations of motion dysfunction or kinesopathology namely hypomobility and hypermobility.

Consequences of altered spinal joint mobility

In normal situations as tissues heal the intrinsic spinal spasm resolves and spinal joint movement returns to normal. Relaxation of the protective reflexes of the intrinsic spinal muscles allows normal spinal movement. When the animal has an area of spinal joint dysfunction and pain, proprioception and global movement are affected. There is an increased chance of new falls or tripping causing even further spinal damage. Of course in quadrupeds there must be compensation in gait patterns when the animal is favoring one part of its body which is in pain. Confinement, poor nutrition, obesity, poor fitness, emotional stress and postural problems are but a few reasons that tend to exacerbate existing spinal joint problems that may be minor but quickly increase in significance.

Unresolved spinal joint dysfunction can be asymptomatic particularly in young, fit animals. More often there is an inability to use a body area or limb properly resulting in changes in gait. This can lead to altered body posture, stiffness, and ultimately arthritic changes. Initially small areas of muscle spasm and intrinsic spinal muscle pain can be found. Over some weeks this will lead to muscle weakness and atrophy. Sometimes there is referred pain and behavioral changes . There can be also changes in the health and condition of the skin or coat or altered sudomotor activity as seen in cases of equine anhydrosis. In some animals there is unexplained abnormal function of internal organs. because the spinal joint dysfunction has the potential to affect autonomic nerve supply as well.

Probably one of the major areas of spinal dysfunction occurs in undiagnosed lameness cases. The lameness may be primary due to muscle dysfunction but more often secondary due to unbalanced movement creating weakness, limb overloading, and compensatory lameness

Treating spinal joint dysfunction with chiropractic

There are a number of modalities that the equine practitioner can employ to help resolve these spinal problems. Soft tissue techniques such as massage, Bowen therapy, physiotherapy, Trigger point therapy, or the use of LEPT (medical laser), can be useful. Acupuncture can be a highly effective treatment for spinal conditions. Osteopathy and chiropractic are two of the most effective therapies for spinal dysfunction.

There is a cultural perception that chiropractic is dangerous or unsafe. In the hands of unskilled or unqualified practitioners carrying out non-specific moves there is the danger of potential damage or even death of an animal. Chiropractic does not revolve around getting a joint to crack. Long lever manipulation (leg jerking), unskilled cranking, and the use of force to bend or twist an animal into a position it is resisting is a formula for disaster. Similarly the nervous system does not function under the effect of anesthetic or even a sedative or tranquilizer. Under sedation or a general anaesthetic the joints are taken to the anatomic limit with the potential for soft tissue damage much more likely.

Veterinary chiropractic involves careful examination to identify areas of abnormal motion, muscle tension and soft tissue changes signaling spinal joint dysfunction. Abnormal areas are treated appropriately to restore normal movement. This is called an adjustment. Most spinal joint dysfunction involves restricted movements of the facet joints. The adjustment has the effect of loading and stretching the facet joint capsule and causing a reflex inhibition of local muscle activity. This affectively “resets” the mechanoreceptors in and around the joints of the spinal column. Resolution of dysfunction in the musculoskeletal system and the spine affects central neurological function and enhances the bodies sense of well-being and its ability to self regulate.
Chiropractic techniques are generally short lever and specific. Sometimes referred to as high velocity low amplitude (HVLA). There are also mobilization, soft tissue, non-force, mechanically assisted and other adjunctive procedures. The later includes the use of the activator, sometimes known as activator technique. It also includes trigger point, myofascial release, visceral adjustment and sacro-occiputal techniques[5]

Applying safe effective chiropractic technique and learning to acquire diagnostic palpatory skills involves extensive practice and training In diagnosing problems of facet joints in the vertebral column a chiropractor must be able to differentiate compromised or changed quality of movement and increased or decreased range of movement. The compromised vertebral segments or joints must be assimilated with the presenting signs and history of the patient. The chiropractic technique involves restoring the range in quality of movement of the affected vertebral segment with the use of manual spinal manipulation or adjustment. It is not always a vertebra that has compromised movement. Often there are appendages or extremity joints affected. A chiropractor must recognize contraindications to adjustment and then design and implement an effective rehabilitation plan.

Many people have the idea that a bone in the human spine is “out of place” or “a nerve is being pinched”. These are grossly oversimplified misconceptions of what is really happening in spinal pain. Chiropractic is a health care system which emphasizes the inherent recuperative power of the body to heal itself without the use of drugs or surgery The use of chiropractic in treating animals has been largely attributed to Dr Sharon Willoughby. In the early eighties Sharon Willoughby, a veterinarian, studied to attain a chiropractic degree and worked on applying chiropractic technique to animals. This has led to chiropractic training in the United States and Australia by both veterinarians and chiropractors.
There exists an enormous demand for animal chiropractic care from properly trained and qualified professionals. Veterinary chiropractic care is in its relative infancy and today’s practitioners are somewhat pioneers. In some ways bearing in mind cultural values and beliefs the animal chiropractic profession may take another 25 years to become of age. To become competent requires application and practice of over 1500 equines after two years training.

Spinal Stability

There is another other aspect of neurophysiology that is useful to remember when we are considering the function of the spine of the horse. Mechanoreceptors signaling touch and pressure are extremely sensitive to changes in their shape, produced by mechanical deformation. These mechanoreceptors are sensory nerves which relay information to the brain concerning movements and the position of the body or proprioception. Proprioception can be either positional or reflex, both of which are mediated by proprioceptors (mechanoreceptors). The intrinsic muscles of the spine are used for spinal stability as well as movement. If we were to dissect the muscles away from the spine it would sag or collapse supported only by ligaments and fascia. In other words the position and mechanical stability of the spine requires constant muscle activity. Hence, in the presence of spinal pain there are some implications considering the functionality of the entire spine from the point of view of stability as well as global movement. Human patients suffering from lower back pain complain of feeling weak and unstable in the spine. Maintaining stability and thus protecting the spinal cord would appear to be a major function of the spinal musculo-skeletal system.

Spinal movement requires a sophisticated and coordinated monitoring system. Ninety percent of all the information relayed to the CNS comes from mechanoreceptors. The contribution from articular joint receptors is separate from muscle receptors. These mechanoreceptors are concentrated in the joints and connective tissue of the spinal column. The highest concentration is in the occipito-atlanto-axial region. The greatest load to the thalamus is from the cerebellum. The greatest load to the cerebellum has been shown to be from unconscious mechanoreception. [8].

Spinal mechanoreceptors can be separated or classified by nature of their function rather than their structure. For instance Type I mechanoreceptors tell where the joint is moving to and where the joint is when it is not moving, Type II tells if the joint is speeding up or slowing down. Type III mechanoreceptors tell when the joint is at extremes of motion whereas Type IV are mainly nociceptors [9]. Mechanoreceptors are found in the intervertebral disc (IVD), ligaments, joint capsule and of course muscles. Polysynaptic circuits modify spinal reflexes so that muscle function co-ordinates for spinal stability. Inhibitory interneurones ensure the appropriate combination of synergistic and antagonistic muscles is activated and inhibited. These inhibitory interneurones receive input from the mechanoreceptors of the IVD, joint capsule, ligaments and muscle spindles.

Equine Posture, spinal pain and hoof imbalance

So what is the purpose of this discussion on unconscious mechanoreception in relation to the horse? The equine’s spinal stability from this mechanoreception is so finely tuned that it can actually sleep standing up with the aid of some other mechanisms in its limbs called stay apparatus. In the event that it’s posture is altered, as in say acute laminitis, then the animal’s intrinsic spinal muscles fatigue and thoraco lumbar and sacropelvic spinal pain increases. It can be argued that the animal has to make conscious effort to support itself to avoid the pain coming from the feet. The animal not able to rest without the use of a NSAID or other appropriate form of pain control. This is why these horses have a look of distress and worsen as time goes on in the absence of appropriate treatment.

In the event then that any alteration in foot balance is made whether it be cranial to caudal or medial to lateral the mechanoreceptors in the intrinsic spinal muscles must adapt to maintain spinal stability. If the imbalance is small the degree of spinal pain is small. As time goes by the muscles begin to fatigue. In chronic cases the horses back and sacro-pelvis can get to the point it seems totally unresponsive to manual stimulation, unable to flex or extend, or even laterally flex. Sometimes these horses are referred to as being ‘neurologically dead’ or having a neurologically dead skin. With appropriate chiropractic treatment, restoring movement through the facet joints they usually respond quite quickly. In any event appropriate podiatry is always required to sustain rehabilitation.

When there is an alteration of hoof balance in the forelimbs is there is initially alteration in the tone (and often symmetry ) of the shoulder girdle muscles, namely the prescapularis, the trapezius and the rhomboids initially. These muscles become tense and hard. This is followed by a lack of movement (hypomobility) of the upper thoracic vertebrae (withers), particularly T2 and T3. This upper thoracic immobility then impacts the entire movement of the ribcage and the motion (pump-handle motion) is restricted. The thoracic inlet becomes restricted in chronic cases and lymphatic drainage and venous return are reduced. This leads to more serious organ pathology and susceptibility to disease. There is an alteration in posture and gait.[10]

Equine Back Pain

Haussler [11] deals extensively with the problem of equine back pain including chiropractic evaluation and management [12]. There has been consideration of numerous causes of equine back pain in the literature with attention given to specific causes and medical management[13]. There has also been consideration given to various types of treatment such as acupuncture [14] and physical therapy [15, 16]. Denoix presents an excellent synopsis of equine spinal function and treatment [17] The question of hoof disease and pathology as a cause of lameness is a large part of equine veterinary medicine.[18] Consequently attention has been devoted to diagnosis, treatment and prevention. Much attention has also been given to how the horse has been shod, or should be shod, with many veterinarians and farriers advocating corrective shoeing in order to resolve hoof disorders. On the other hand Stassser [19] has questioned the underlying functional theory of types of corrective shoeing and the usefulness of shoeing.

Back pain arising from hoof imbalances

Hundreds of thousands of riders all over the world that are aware that the performance and often the behavior of the horse is affected by back or hind quarter pain. In some cases a full veterinary examination may not produce a reason for such a deviation in performance or behavior. By pressing down on the back of the horse, or even by brushing the horse they find that the animal moves away from the challenge even to the extent of laying the ears back and turning to bite. In some cases this pain can be attributed to the tack or a badly fitting saddle [20]. In clinical situations back pain and associated changes in performance, behavior or even debilitation can at times be attributed to hoof imbalances. To determine the source of the pain requires a thorough chiropractic examination. A chiropractic examination will identify sites of spinal dysfunction and pain as well as musculoskeletal problems in the appendages. It is the aim of chiropractic not only to find and treat these problems but to identify a primary or underlying dysfunction. This is called the primary cause. Areas of secondary dysfunction arise due to compensation. Compensation refers to the horse loading other parts of its body to favor the areas which are sore and causing pain during normal locomotion. Compensation is a characteristic of quadruped biomechanics. All types of lameness will result in a degree of compensation.

More recently it has been highlighted that hoof imbalances will cause compensation [10]. The use of chiropractic in equine is an effective tool for managing these problems. If the primary cause is hoof imbalance then chiropractic will only manage the condition until the hoof imbalance is corrected. When trimming is carried out to resolve degenerative and pathological conditions of the hoof in many instances a return to health, function and performance is aided by the use of chiropractic. Chiropractic has been found to be effective in relieving musculoskeletal pain between trims. Each time the hoof shape is altered the horse goes through a phase of altering its body position to accommodated the forces through its upper limbs and its trunk. There are some simple effective techniques for helping to control back pain that have arisen from the study of equine chiropractic in recent years. One easily learned technique is suprascapular harmonic movement (SHM). This technique seems to work only in the horse (and perhaps other cloven footed animals?) due to the structure of having the spine slung or suspended between two sets of pillars with a large balances weight (the head) on one end. Another technique is the use of the activator in relieving muscle tension. The activator is used on the origin and insertion tendons of affected muscle groups. The fast local lengthening of the tendon stimulates the Golgi organs which allows the muscle to stretch and effects relaxation. Activator methods are well known in human chiropractic but unheard of in equine circles. This is quite distinct from hitting any part of the horse with a hammer or mallet.

Some types of hoof imbalances

Low Heel Hi Heel Syndrome

This commonly observed condition where the heel of one front foot is higher than the other has been previously reported by Ridgway[10]. Ridgway has noted that this is more common on the front feet and results in muscle imbalances and changes in posture. The horse tends to lean towards the shoulder of the lower heel limb. The animal can be easily pushed off balance in that direction. The majority of these horses have restrictions or hypomobility in the lower cervical and upper thoracic vertebral joints. In some instances the lack of lateral flexion in the neck is severe and it is necessary to use several chiropractic techniques to free these areas. These include thoracic inlet opening, forelimb stretching and activator technique on the tendons of the forelimb and adjustments of the lower cervical vertebrae. The cause of this problem is not clear however the consequences can be disastrous if the problem is not rectified.

Medial Lateral Imbalance Syndrome

In these horses greater load is taken on the medial side of the hoof. The lateral aspect flares out. There is a tendency for the hoof to rotate slightly as it strikes and takes the weight. This rotation is resisted and stabilized by the muscles of the shoulder girdle in the forelimbs. In the hind limbs it is stabilized through the region of the transverse joints of L6 and S1.Rectifying the forelimb imbalance muscle and vertebral problems is similar to rectifying the Low Heel Hi Heel Syndrome problems. In the hind limb the most effective technique seems to involve using a full limb adduction stretch. This would tend to indicate that the accumulated effects of rotation are being absorbed by the adductor muscles of the hind limb.

The cause of these imbalances are unclear however there are a few points worth mentioning. In the front feet it has been suggested that a right handed farrier may unconsciously strike the lateral aspect of the off fore harder than the medial aspect simply by their body position. On the near side they may strike the medial aspect of the hoof harder resulting in the start of a lateral-medial imbalance[21] Interestingly Bidstrup[22] sees the problem accompanying Girth Pain Syndrome where the pain is mainly on the side of the hi-heel. There is a good possibility that some cases may be present from birth. Foal birthing trauma may result in forelimb imbalances that have never been rectified or recognized. The foal tends to put more weight on one leg than the other, the favored leg having less weight on the foot, less hoof expansion which eventually results in a more upright heel.

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References

Crevier-Denoix N, R.C., Dardillat C, Pourcelot P, Jerbi H, Sanaa M, and Denoix J-M, Effects of heel and toe elevation upon the digital angles in the standing horse. Equine Veterinary Journal, 2001. Supplement(33): p. 74-78.
Chateau H, D.C., Jerbi H, Crevier-Denoix N, Pourcelot P, Audigie F,Pasqui-Boutard V, and Denoix J-M., Normal three-dimensional behaviour of the metacarpophalangeal joint and the effect of uneven foot bearing. Equine Veterinary Journal, 2001. Suppl.(33): p. 84-88.
Willoughby S, Chiropractic Care, in Complementary and Alternative Veterinary Medicine, W.S. Schoen A , Editor. 1998, Mosby: St Louis
Kilmartin R, Veterinary Surgeons' Perception of Complementary and Alternative Medicine, in MCSc (Animal Chiropractic) 2001 RMIT. 2001: Melbourne. p. 86.
Bergman T, Chiropractic Technique. 1993, New York: Churchill Livingstone.
Gatterman M, Chiropractic Management of Spine Related Disorders. 1990, Maryland: Williams and Wilkins.
Halderman S, Principles and Practice of Chiropractic. Second edition ed, ed. H. S. 1992: Appleton and Lange.
McCoy M, Editorial. JVSR, 2001.
McLaine R, Functional classification of mechanoreceptors. Spine, 1994. 49(5): p. 1118-1126.
Ridgway K, G.M., Low Heel / High Heel Syndrome Unrecognized Problems. 2002.
Haussler K, The Veterinary Clinics of North America Equine Practice. Volume 15, Number 1 ed. Back Problems, ed. S.T. A. Vol. 15. 1999, Philadelphia: W.B. Saunders. 286.
HausslerK, Chiropractic Evaluation and Management, in Veterinary Clinics of North America, H. K, Editor. 1999, WB Saunders: Philadelphia.
Marks D, Medical Management of Back Pain, in Veterinary Clinics of North America, H. K, Editor. 1999, WB Saunders: Philadelphia.
Ridgway K, Acupuncture as a Treatment Modality for Back Problems, in Veterinary Clinics of North America, H. K, Editor. 1999, WB Saunders: Philadelphia.
Bromiley M, Physical Therapy for the Equine Back, in Veterinary Clinics of North America, H. K, Editor. 1999, WB Saunders: Philadelphia.
Bromiley M, Equine Injury, Therapy and Rehabilitation. Second ed. 1987, Oxford: Blackwell Science.
Denoix J, P.J., Physical Therapy and Massage for the Horse. 1996, London: Manson Publishing Ltd. 192.
Adams O, Lameness in Horses. 1976, Philadelphia: Lea & Febiger.
Strasser H, Shoeing: A Necessary Evil?, ed. S. Kels. 2000, Qualicum Beach: Sabine Kels. 148.
Harman J, Tack and Saddle Fit, in Veterinary Clinics of North America, H. K, Editor. 1999, WB Saunders: Philadelphia.
MacIntosh, A., Medial lateral imbalances. 2003: Longreach
Bidstrup I, Girth pain syndrome. 2003: Melbourne.