EQUINE MATTERS
12
SPRING 2015 ISSUE
L IMB DEFORMI T I ES
Summary...
ALD's are commonly seen in
foals, particularly those that
are premature or dysmature
and must be assessed at the
earliest opportunity to decide
on the best course of
treatment. At their mildest
they will be self-correcting
and will not affect the future
athletic potential of the
animal. At their most severe
they can result in permanent
disability and lameness.
The single most important decision when dealing with an ALD is to determine which of the previous categories it is
that you are dealing with, bearing in mind it is common to see more than one category in the same foal or even joint.
This is particularly the case in premature or dysmature foals (dysmature refers to foals which are not born early but
show the signs of a premature foal). Radiographs (X-Rays) should be taken to assess the degree of ossification of
the bones. This will help differentiate the first two categories. A radiograph taken from directly in front of the limb will
show where the actual deviation is occurring, e.g. from within the joint or from the growth plate. If it is the former it is
likely to be due to collapse of the joint, if the latter it is likely to be a growth plate problem.
Assessment of ALD’s
Treatment options depend on the cause
of the problem and its severity. In cases
where there is mild flaccidity of the joint
structures, good ossification of the bones
and a deviation which can be temporarily
manipulated back into line, box rest will
often suffice. As the foal gains in strength
the deviation will disappear. Cases caused
by incomplete ossification may require
support of the limb with the use of casts
or braces. If these are not recognised at
birth the joints may collapse and suffer
irreparable damage. Growth plate
problems are treated in a number of
different ways depending on which joints
are affected, their severity and at what age
they are first noticed. Outward deviations
of the knees (carpal valgus) are one of the
commonest presentations we see, and in
the majority of cases are self-correcting over
the first couple of weeks of life. In contrast
a turned-in fetlock (fetlock varus) is rarely
self-correcting and needs immediate
attention because the growth plate
responsible only produces new bone, and
hence growth, in the first 3 months of life.
If these are not treated quickly, treatment
options become less effective. In contrast
the distal radius growth plate which is
involved with deviations of the knees will
produce new bone for the first 6 months
of life, giving a much longer treatment
window, if necessary.
Treatment of angular limb deformity
Figure 2:
Ossification problem: The red lines
indicate where the centre of the limb should
run while the blue lines indicate where it
actually is. The arrows indicate the growth
plate; it is evident that the deviation is coming
from the growth plate.
Figure 3:
In comparison with figure 2, this
image shows the intersection, and hence the
cause, to be in the middle of the knee and is
due to collapse of the poorly ossified carpal
bones.
Acknowledgements
Many thanks to Professor Tim Greet FRCVS of
Rossdales Equine Hospital for the photographs.
Figure 1:
The carpal (knee) bones are poorly
ossified and hence liable to compression
damage.
