Page 106 - Adams and Stashak's Lameness in Horses, 7th Edition

72 Chapter 2

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Figure 2.6. Rear view of the pelvis of a horse with a history of
an acute onset of right hind lameness. There is asymmetry to the
Figure 2.4. Example of atrophy of the inner and outer thigh sacroiliac region visible and pain on firm palpation of the right
muscles of the left hindlimb that occurred secondary to an upper tuber sacrale.
hindlimb lameness.
normal conformation because the guidelines depend on
the classification, type, breed, and intended use of the
horse. 29,30 Despite these difficulties, it is well recognized
that certain conformation traits may predispose to lame­
ness and these should be observed during the initial visual
exam of any lame horse. For instance, poor forelimb con­
formation was found to be a predisposing factor for
young Standardbred racehorses that developed lameness
in the middle carpal joint. The trick becomes determin­
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ing which abnormal conformational traits are contribut­
ing to lameness in any given horse because many
conformational traits are not always related to perfor­
mance and unsoundness. 21,30 One study that evaluated
conformational traits of Thoroughbred yearlings found
only weak associations between performance and confor­
mation that could not be accounted for by the very strong
relationship between pedigree and conformation. More
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such studies that attempt to evaluate the association
between limb conformation and specific lameness condi­
tions are needed to truly determine the effect of confor­
mation on lameness in performance horses.
Ideally, conformation assessment of a lame horse
should relate to function, but objective studies relating
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specific conformational traits to performance or lame­
ness problems can be difficult to perform. 10,21,23 To com­
Figure 2.5. Example of atrophy of the gluteal muscles (left plicate things more, while many lameness problems
hindlimb) that often accompanies pelvic fractures in horses. occur in the lower limbs, the causative factors may be
located in the upper limbs or body; therefore, overall
CONFORMATION conformation must be considered together with limb
conformation. Objective techniques to assess conforma­
Simultaneously while performing a visual examination tion as it relates to movement and lameness in horses are
on any horse presented for lameness, the conformation of needed to truly quantify its contribution to lameness.
the horse, especially the limbs, should be assessed. It is Furthermore, conformation is often a subjective assess­
important to have a basic understanding of conformation ment, and improved techniques to quantify conforma­
and how abnormalities in conformation may contribute tion as it relates to lameness are needed.
to alterations in limb movement and lameness. Confor­
mation refers to the physical appearance and outline of a Types and Breeds
horse as dictated primarily by bone and muscle struc­
tures. 22,29 It is often a subjective assessment based on Horses are broadly classified as draft horses, light
what a particular breed may consider to be “ideal.” horses, or ponies. Classifications are further divided by
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However, it can be difficult to specifically define ideal or type according to overall body style and conformation