FRANK J. MILNE STATE-OF-THE-ART LECTURE


or to one side—and breakover may reflect the site of pain or help to explain why lameness may have developed. Viewing the horse from behind may re- veal that a hind foot is placed axially and the horse appears to collapse laterally over the fetlock, with an unusual wobble of the hock. This may be normal for the horse but may be a predisposing cause for lameness. Abaxial sliding of a hind foot during landing may reflect ataxia. Axial deviation of a hindlimb during protraction may be a way of reduc- ing proximal limb flexion associated with lameness. Careful observation of the horse from the front at


the walk may reveal slight bulging of a shoulder: “shoulder-slip,” usually a manifestation of brachial plexus injury. Watching the hocks carefully from behind may reveal intermittent, slight movement of the superficial digital flexor tendon (SDFT) reflect- ing subluxation secondary to a partial tear of the retinaculum. Unequal height of the hocks may re- flect partial disruption of gastrocnemius or coxofem- oral joint subluxation. No grading system can take into account a bilat-


erally symmetrical lameness. A lameness grade ascribed to the lamer limb or lamest limb in the presence of an asymmetrical bilateral lameness or concurrent forelimb and hindlimb lameness can be potentially highly misleading. With a bilaterally symmetrical forelimb lameness, the horse may show only a subtle shortening of stride. Abolition of pain in one limb by local analgesia may reveal either a low-grade lameness in the contralateral limb or a moderate to severe lameness, but this can be highly unpredictable on the basis of the initial clinical assessment. Many but not all forelimb lamenesses are accen-


tuated on a circle. I prefer to see a horse lunged on a circle rather than led, because it is easier to assess any adaptations of the horse’s balance, posture, and rhythm. Although historically it has been assumed that most horses with foot pain have lameness ac- centuated with the lame(r) limb on the inside of a circle, approximately one-fifth of 718 horses were lamest with the lame(r) limb on the outside of a circle.a Forelimb lameness associated with proxi- mal suspensory desmitis is usually worse with the lame(r) limb on the outside of a circle on a soft surface. Bilateral forelimb lameness sometimes manifests as a shortness of stride, hurried rhythm, loss of balance, and a tendency to look out of a circle. Foot-related pain and some other sources of pain causing lameness may be worse on a firm or hard surface compared with a soft surface. However, se- lection of an appropriate hard surface is crucial be- cause the horse must move confidently; a slippery surface may result in marked shortening of stride and apparent loss of balance in a clinically normal horse, especially those that move extravagantly. I use a gravel surface on an incline immediately adjacent to purpose-built modified tarmac; the gravel provides excellent grip, and the downward slope often accentuates lameness. A horse that


94 2013  Vol. 59  AAEP PROCEEDINGS


Fig. 1. A medium level 7 year old Warmblood dressage horse being lunged to the left. The left hindlimb is crossing in under the body during protraction, toward the contralateral forelimb, crossing in front of the right hindlimb. The horse is leaning in, looking to the outside, reflecting a bilateral hindlimb lameness (leftright) associated with proximal suspensory desmopa- thy. No gait abnormalities were detected when the horse was trotted in hand.


trots sensibly can be assessed moving from the gravel to the harder tarmac surface and back onto the gravel. A horse may move with a rather re- stricted stride, and, if asked to move forward more freely, may break to canter rather than increase the stride length. This is usually a manifestation of hindlimb lameness but can also reflect forelimb lameness.


Evaluation of the horse moving in circles on the


lunge can also be helpful for assessment of hindlimb lameness, with some lamenesses becoming more ev- ident with the lame hindlimb on the inside of a circle and some with the lame hindlimb on the outside of a circle, and may change depending on the circum- stances under which the horse is assessed. In my experience, this is not necessarily related to the source of pain causing lameness. However, with mild lameness that is not modified by being on a circle, detection of hindlimb lameness may be more difficult than in straight lines. The pelvis tilts in- ward on the lunge, therefore comparison of move- ment of the tubera coxae is more difficult than in straight lines. Lameness may modify the horse’s body posture, with a tendency to lean in so that the body is no longer perpendicular to the ground (Fig. 1). This makes evaluation of pelvic symmetry even more difficult, but alterations in rhythm may make it easier to detect the lame limb. The lame hindlimb may cross in under the horse’s body when on the inside of a circle and may have an accentu- ated toe drag. When on the outside of a circle, a


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