Assessment of the Equine Spine

Original Editor - Petra Zikmann Top Contributors - Jess Bell and Tarina van der Stockt

Introduction[edit | edit source]

Back pain and dysfunction can lead to poor performance and cause changes in a horse’s spinal kinematics.[1] However, it is often difficult to distinguish whether the spine or limb is the primary cause of lameness in a horse as spinal problems are often related to limb lameness.[2]

A comprehensive assessment is, therefore, essential to determine the cause of lameness in a horse. As with any assessment, it is important to first obtain a subjective history of the equine patient, including background information, training / discipline history, history of presenting condition, past medical history and special questions / red flags. The subjective assessment is discussed in detail here.

The objective assessment will be guided by your findings in the subjective interview. A discussion of the overall objective assessment of horses is found here, including conformation, gait and lameness assessments, range of motion, muscle strength, palpation and the neurological assessment. This page will discuss assessments specific to the equine spine that are not discussed in detail in the general assessment page.

Range of Motion[edit | edit source]

It is difficult to ask a horse to perform specific active movements of either the front or hind limbs, so active movement is best assessed during different gait activities. The horse’s stay mechanism (i.e. the tendinous structures that support the limbs during standing[3]) makes localisation of passive testing to a specific joint difficult. Thus, careful observations of the horse’s responses to manipulations of its joints are very important.[4]

Abnormal responses to range of motion (ROM) tests include:[4]

  • Resistance to being moved
  • Excessive movement at proximal (more common) or distal motion segments
  • Excessive stance adjustments with the other limbs

These movements can be used as stretching exercises to increase the range of motion.[2]

Cervical Spine[edit | edit source]

Cervical Active ROM[edit | edit source]

Horses who have normal cervical mobility will be able to move their heads and necks from side to side and bring their chin to near their girth, hip, or tarsus without difficulty.[5]

Poll Flexion[edit | edit source]

  • Use a treat to encourage the horse to bring its chin to its chest
  • If the horse deviates to one side, repeat the test standing on the other side to see if there is internal consistency of this deviation[4]

Poll Extension[edit | edit source]

  • Use a treat to encourage the horse to move its nose forward and up
  • Any deviations should be carefully assessed for consistency

Poll Rotation[edit | edit source]

  • Place one hand on C1 and use it to stabilise the upper cervical area - this will localise the movement to the poll
  • Use a treat to encourage the horse to bring its nose laterally towards you and up
  • It is important to observe both the horse’s willingness to move and the actual range obtained[4]

Differentiating between C0/C1 and C1/C2[edit | edit source]

The C0/C1 joint is responsible for flexion and extension of the head[8] (i.e. dorsoventral glide of the occiput on C1). A unilateral restriction of C0/C1 means that there is only a dorsoventral glide on the unrestricted side. Thus, the horse’s head will move towards the side of restriction in flexion and away from the side of restriction in extension.[4]

C1/C2 is largely responsible for rotation of the head,[8] which is seen as a lateral deviation of the horse’s nose when viewed from the front. A localised, unilateral restriction of C1/C2 will cause lateral deviation away from the side of restriction regardless of whether the poll is flexed or extended.[4] For example, if you observe a horse’s left eye is higher than the right in poll flexion and extension, there is a likely joint restriction at C1/C2 on the right side.[9]

Global Lateral Flexion[edit | edit source]

  • Use a treat to encourage the horse to bring its nose around to the caudal border of the triceps
  • The examiner observes both the horse’s willingness to bend its head and the quality of the movement (i.e. does it bend in a smooth curve through the cervical spine or does the horse hinge at a specific level?).[4]

Lower Cervical Flexion[edit | edit source]

  • Use a treat to encourage the horse to bring its nose towards the ground, keeping the poll as neutral as possible
  • The examiner will look for any deviations or rotations in the cervical spine
    • Deviations in head position during this test are likely to be caused by unilateral stiffness in brachiocephalicus[9]
  • It is possible to do this movement using a Theraband to apply unilateral resistance as a strengthening exercise[4]

Activation of the Deep Neck Flexors[edit | edit source]

  • Grasp the base of the brachiocephalicus muscle in a lumbrical grip
  • Gently apply pressure with your whole hand
  • The horse should respond by arching and lengthening its neck forwards and downwards
  • This should be performed on both sides
  • You should not perform this test on horses who have significant trigger points in their brachiocephalicus muscle[4]

Cervical Passive ROM[edit | edit source]

Jaw Glides[edit | edit source]

  • Place one hand on the horse’s nose
  • Slide the thumb of your other hand into the corner of the horse’s mouth in order to open the mouth slightly
  • Glide the jaw away from you taking note of range and any resistance that is present
  • Perform on both sides[4]

Manual Flexion and Extension of the Poll[edit | edit source]

  • Check for any lateral deviations
  • Palpate the occipital bone in order to assess symmetry of movement between the occiput and C1
  • Tilt the horse’s head laterally by drawing the cranial border of the head towards you while thrusting against the angle of the mandible
  • Assess if the movement is equal on each side and if there is any resistance in either direction[4]

Cervical Lateral Flexion[edit | edit source]

  • Place one hand on the horse’s nose and your other hand on C3
  • Flex the horse’s neck towards you, while gliding the body of C3 away from you
  • Move down the spine, increasing the amount of lateral flexion at each vertebral level
  • Feel for resistance or segmental hypomobility (compare each vertebra with its cranial or caudal vertebra) - hypomobility would indicate a lack of facet joint gapping on the opposite side[4]

Thoracic Spine[edit | edit source]

Thoracic Active ROM[edit | edit source]

Thoracic Flexion[edit | edit source]

  • Use a treat to encourage the horse to bring its nose to its sternum
  • The horse will activate its pectoral sling to flex its thoracic spine
  • The assessor should observe the quantity of movement just caudal to the wither[4]

Thoracic flexion can also be assessed by running a hoof pick longitudinally along the horse's sternum:[4]

  • Observe the spinous processes for the quantity of thoracic flexion
  • It is important to remember that a horse may kick your hand when performing this test

Extension and Lateral Flexion[edit | edit source]

  • Use a pen or hoof pick and run it gently along the thoracic spine just parallel to the spinous processes
  • Assess the quantity of movement away from the pressure[4]

Global Lateral Flexion[edit | edit source]

  • Use a treat to encourage the horse to bring its nose around to its quarters
  • Please note that this test is not specific to the thoracic spine
  • Repeat the test on each side and assess the symmetry and quality of the movement[4]

Thoracic Passive ROM[edit | edit source]

It is not possible to passively assess the equine thoracic spine due to the deep joint levels, tight connective tissue structures and restrictive facet joint morphology. Some rib springing may be possible, depending on the horse's soft tissue tone.[4]

Lumbar Spine[edit | edit source]

Lumbar Active ROM[edit | edit source]

All active testing of the lumbar spine also involves the sacroiliac joints and hips, so it is important to observe the quality of segmental movement. [4]

Lumbar Flexion[edit | edit source]

  • Stand on a box behind the horse and run your fingers or two hoof picks caudally along the caudal border of biceps femoris
  • The horse should arch its back (i.e. flex) and tilt its pelvis downwards at the tail
  • You should assess the range of motion and alignment of the spinous processes - vertebral rotation is more obvious during this movement
  • It is important to beware of your safety during this test - while most horses will not, they could kick during this test[4]

Lumbar Extension[edit | edit source]

  • Stand on a box behind the horse and draw your fingers or two hoof picks caudally along the lumbar paravertebrals
  • Assess the quantity and symmetry of movement[4]

Lumbar Lateral Flexion[edit | edit source]

  • Stand on a box behind the horse and draw your fingers or two hoof picks caudally from the tuber coxae to the base of the tail
  • Observe quantity and symmetry of movement
  • Assess each side[4]

[10]

Lumbar Passive ROM[edit | edit source]

The passive tests discussed below are unlikely to cause any significant movement at a vertebral level. However, they generate a reflex muscle guarding response at the affected vertebral motion segment.[4]

Unilateral dorsal-ventral mobilisations[edit | edit source]

  • Stand on a tall box or step
  • Apply a gradual downwards force over the transverse process of each lumbar vertebra
  • Perform on both sides[4]

Central dorsal-ventral L5 and L6[edit | edit source]

  • Stand on a tall box or step
  • Apply a gradual downwards force over the spinous processes of L5 and L6
  • Horses who have pain in this area (usually ligamentous in origin) will dip away from the pressure
  • Horses who have no pain will show no response (and no movement should be palpable)[4]

Sacroiliac Joint (SIJ)[edit | edit source]

All movement tests for the SIJ are non-specific as it is not possible to isolate SIJ movement from lumbar movement.[4]

SIJ Active ROM[edit | edit source]

Weight-bearing weight displacement[edit | edit source]

  • Stand on a box behind the horse (or next to the horse if you suspect it may kick)
  • Palpate the tuber sacrale bilaterally, and have an assistant lift one hind leg
  • Feel for any cranial shift of the contralateral tuber sacrale as the SIJ of the weight-bearing leg assumes its close-packed position
  • Repeat with the other leg[4]

Movement during limb protraction[edit | edit source]

  • Stand on a box behind the horse (or next to the horse if you suspect it may kick)
  • Palpate the tuber sacrale bilaterally, have an assistant lift one hind leg and stretch it forward
  • Feel for a slight caudal shift of the contralateral tuber sacrale[4]

SIJ Passive ROM[edit | edit source]

  • Stand on a box or step next to the horse
  • Apply a slow, repetitive downwards force on the tuber coxae
  • Feel for reflex muscle guarding in response to the movement
  • A horse who does not have pain should let you perform a soft oscillation of the ilium
  • Compare to the other side[4]

Please click here to read about the SIJ Stork Test.

Tail[edit | edit source]

Many important muscular and connective tissue structures have attachments at the base of the tail.[4] It is not possible to elicit any controlled active tail movement from the horse. However, careful observation of tail movement during gait can provide significant information:[4][9]

  • Asymmetry or rigidity in the tail carriage is usually a guarding response or due to intrinsic muscle spasm or atrophy resulting from SIJ dysfunction
  • Tail deviations may also indicate facet joint restrictions (i.e. alignment issues)
  • NB: Some breeds have a genetic tendency to non-pathological, asymmetrical tail-carriage (e.g. Arabian horses)

Tail Passive ROM[edit | edit source]

  • Using a lumbrical grip, lift the base of the tail upwards
  • Then lift at angles towards the left and right and compare tone and end feel[4]

Distraction[edit | edit source]

  • Place one hand on the dorsum of the tail base where it articulates with the sacrum
  • With the other hand, apply a traction force to the base of the tail
  • Joint gapping should be palpable between the sacrum and the first coccygeal vertebra[4]

Appendicular Skeleton[edit | edit source]

Because it is often difficult to distinguish whether the spine or limb is the primary cause of lameness in a horse,[2] the limbs must also be assessed.

Hind Limb Range of Motion[edit | edit source]

Separation of joint movement is particularly difficult in the hind limb. It is, therefore, important to observe movement responses both proximally and distally. The following movements should be assessed:[4]

  • Hip flexion and extension (keep the stifle and hock in +/- neutral
  • Hip internal and external rotation (using the hock as a lever)
  • Hip abduction (challenges balance of contralateral hind limb)
  • Stifle extension (can only be achieved by protracting the entire limb, so some hip flexion will occur)
  • Hock flexion and extension
  • Fetlock flexion, extension and rotation

Forelimb Range of Motion[edit | edit source]

  • The scapula glides cranially, caudally and dorsally
  • Shoulder flexion and extension are assessed with the elbow flexed
  • Shoulder external and internal rotation - this is not a true rotation, but rather a compound movement of scapula glide and shoulder abduction / adduction
  • Shoulder abduction is assessed with the elbow and carpus flexed
  • Elbow flexion and extension are assessed with the shoulder and carpus flexed
  • When assessing carpal flexion, include medial and lateral deviation
  • Carpal extension can only be assessed during protraction of the entire limb, so it is important to look for compensatory responses
  • Fetlock flexion, extension and rotation[4]

Palpation[edit | edit source]

For a detailed discussion of palpation, please click here. It is important to note that a horse's first response to palpation may not be the most accurate[9] and in addition to palpating the spine and limbs, you must also assess the horse’s tail.

The tail is an easily overlooked structure, but it needs to be considered as part of a spinal assessment as it is an extension of the spine.[4] Many spinal muscles have attachments to the coccygeal vertebrae of the tail and, because of this, the tail muscles are directly influenced by the back and spinal muscles (and vice versa).[11] The sacrocaudalis dorsalis medialis, which is part of the multifidus complex is believed to be an important muscle in SIJ function.[4][12] It is often atrophied in horses who have SIJ dysfunction. Thus, it is important to check the tail base for symmetry and intervertebral mobility.[4]

References[edit | edit source]

  1. Hardeman AM, Byström A, Roepstorff L, Swagemakers JH, van Weeren PR, Serra Bragança FM. Range of motion and between-measurement variation of spinal kinematics in sound horses at trot on the straight line and on the lunge. PLoS One. 2020;15(2):e0222822.
  2. 2.0 2.1 2.2 Haussler KK. Review of the examination and treatment of back and pelvic disorders. AAEP Focus Meeting - Lameness and Imaging. 2007.
  3. Gussekloo SW, Lankester J, Kersten W, Back W. Effect of differences in tendon properties on the functionality of the passive stay apparatus in horses. Am J Vet Res. 2011 Apr;72(4):474-83.
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28 4.29 4.30 4.31 4.32 4.33 4.34 4.35 4.36 Van der Walt A. Assessment and Management of the Equine Spine Presentation. Physioplus, 2021.
  5. Story MR, Haussler KK, Nout-Lomas YS, Aboellail TA, Kawcak CE, Barrett MF et al. Equine cervical pain and dysfunction: pathology, diagnosis and treatment. Animals (Basel). 2021;11(2):422.
  6. LMU CVM. 9 Equine Head & neck flexion and extension. Available from: https://www.youtube.com/watch?v=xxmGnfgy9rQ [last accessed 28/4/2021]
  7. LMU CVM. 8 Equine Head & neck flexion side to side. Available from: https://www.youtube.com/watch?v=HN30vJ6_FWQ [last accessed 28/4/2021]
  8. 8.0 8.1 Rombach N. The structural basis of equine neck pain [dissertation]. East Lansing: Michigan State University. 2013.
  9. 9.0 9.1 9.2 9.3 Zikmann P. Assessment and Management of the Equine Spine Course. Physioplus, 2021.
  10. Ameya Prentice-Grice. Equine physiotherapy. Available from: https://www.youtube.com/watch?v=WtDwZg3Xoyk [last accessed 28/4/2021]
  11. Higgins G. Pilates for horses - part 4: the tail [Internet]. Horses Inside Out. 2020 [cited 28 April 2021]. Available from: https://www.horsesinsideout.com/post/pilates-for-horses-part-4-the-tail
  12. Van Weeren PR. McGowan C. Haussler KK. Science overview: development of a structural and functional understanding of the equine back. Equine Veterinary Journal. 2010;42(suppl 38):393-400.