Page 27 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

2 CHAPTER 1

VetBooks.ir 1.1 Approach to the lame horse

Lameness is common in all types of horse and is was first noted; has the lameness improved or wors-
defined as an alteration in the animal’s normal ened with rest; which limb do the owners think is
stance and/or mode of progression caused by affected or what are they noticing when the horse is
pain or neural or mechanical dysfunction. The ridden; were any traumatic episodes associated (kick
approach to the lame horse should ideally be injury or striking a fence on jumping) with onset of
carried out in a logical sequence in order to lameness; any other associations (e.g. recent change
(1) define which limb or limbs are involved and in shoeing for nail-bind, turn out to lush pasture for
(2) find the exact site of pain. Only then can other a high-risk laminitic pony); and any obvious regions
techniques such as radiography or more advanced of heat or swellings noted by the owner. The owner
imaging (e.g. bone scintigraphy or MRI) be used should be asked if the lameness improves or deterio-
to determine a specific pathological process rates with exercise. It is prudent to ascertain if any
and make a diagnosis. Once a provisional or treatment or shoeing has been tried by the owner
accurate diagnosis is made, a management plan before examination that might change or mask the
can be formulated and a prognosis given to current presentation (e.g. the administration of pain
the owner. In practice, many factors may alter killers to a possible synovial sepsis from a small
this sequence slightly (e.g. the environment penetrating injury).
where the examination is taking place, financial
considerations, impending competition). CLINICAL EXAMINATION

HISTORY At rest
The horse should be visually inspected, ideally
Obtaining an accurate history is essential and this standing square on a level surface, from both sides,
requires careful questioning, as some of the infor- front and behind for overall conformation, signs
mation supplied can be quite subjective. It should of asymmetry of the muscles and bones, swell-
begin with the signalment of the case. Age, sex, ing, sites of trauma, foot conformation and stance
breed and use of the horse can suggest certain (Figs. 1.1–1.3). The conformation of a horse affects
particular conditions. For example, developmental the way it moves at all gaits and there are certain
orthopaedic conditions are seen in young horses, types of conformation in certain breeds and dis-
tibial stress fractures are seen in young racing ciplines of horse that may predispose to lameness
Thoroughbreds in training, and problems of the (e.g. straight hindlimb conformation may predis-
navicular region are usually seen in adult horses pose a horse to upward fixation of the patella or
used for general riding and sport horse activities. proximal suspensory ligament desmitis) (Fig. 1.4).
The length of ownership or training, as well as the Foot conformation is important in the incidence
type and amount of work the horse has been given, of foot lameness. Evaluation of pastern and foot
is useful basic information. angle (dorsopalmar/plantar hoof balance), medio-
Previous lameness problems should be noted. lateral foot balance and foot symmetry/shape is
A history of previous arthroscopic surgery for an important because it determines the load distri-
apical chip sesamoid fracture 1 year ago may be sig- bution of the structures in the foot and elsewhere
nificant in a horse that is still lame in the operated within the limb (Figs. 1.5–1.8). For example, a
limb due to, for example, associated chronic suspen- broken-back foot pastern axis and low heel confor-
sory branch desmitis. mation are commonly associated with palmar foot
To discuss the present lameness problem, ques- pain and conditions of the distal interphalangeal
tions should include when (duration of lameness) and (DIP) joint (Fig. 1.9). Comparing sizes of opposite
where (at pasture or in competition) the lameness feet is important; a smaller foot compared with the