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EQUINE REVIEW
AUTUMN 2010
8
systems, each of which needs to be assessed
independently. Some problems are more
likely to cause an issue in one discipline
but not another.
Initially horses will be given a full clinical
examination and usually blood tests taken to
assess hematology (looking for anaemia and
chronic infection) and biochemistry (liver,
kidney and muscle enzymes). The examination
will include checking the heart and respiratory
systems at rest, palpation of the limbs, neck
and back, and examination of the mouth and
eyes. Horses are then examined in straight
lines, on the lunge and ridden to assess for
low grade lameness issues. Seeing the horse
without a rider is as important as seeing it
with a rider as experienced riders may
inadvertently mask low grade lameness by
their own riding ability.
Horses doing specific disciplines can be
subjected to repetitive strain type injuries. If
these occur on both limbs, which is common,
then lameness may not be overt. Common
problems for example would be low grade
foot or hock pain in jumping horses which
may affect a horse’s desire to take off or land.
In hindlimbs in dressage horses injuries to the
suspensory ligaments are common. On some
occasions it may be necessary to nerve or
joint block a horse then the rider to ride the
horse to help to assess the results. Other
conditions such as muscle problems are
also tested for.
To test the respiratory system horses should
have an endoscopy performed at rest and
samples taken from the airways to be
anaylsed. Unlike humans, who cough readily
with lower respiratory tract (lung) disease,
horses often do not show many outward signs
with low grade disease. These horses
however when pushed to the edge of their
athletic ability may not be able to perform.
Obstructive disorders of the upper respiratory
tract can be evident at rest. Many of you
will be aware of conditions such as left
sided laryngeal hemiplegia (a 'roarer') and
entrapment of the epiglottis amongst others.
Collapse of these structures and physical
blocking reduces the diameter of the airway
leading to lower airflow and increased
work of breathing.
In some cases these changes will only occur
at exercise. Traditionally the only ways of
diagnosing these was to endoscope horses
on a treadmill. There are very few horse
treadmills available in the country and horses
have to be trained to use them. Obviously
riders are not involved in these cases so
they may not necessarily simulate real
working conditions.
During the past few years advances in
technology have enabled the development
of endoscopes that can be used in the ridden
animal. These are very lightweight and safe
to use for horse and rider allowing the ability
to test the horse in its natural environment.
Once the horse is used to having the
endoscope in place, exercise commences
and a video is made of the horse's larynx
and pharynx (structures at the back of the
throat) at exercise. This system has been
used in all sorts of disciplines from reasonably
sized ponies (it is not generally suitable for
small ponies) to large eventers.
The horse's heart functioning normally is
essential to being able to perform at high
levels of exercise. Hearts are initially assessed
by listening with a stethoscope to rate, rhythm
and any abnormal noises indicating valve
disease. An ultrasound examination of the
heart can be performed in poor performance
cases to assess heart size and valve function.
Heart rate and rhythm are assessed by heart
rate monitor and ECG recoding during
exercise. There are some cases where heart
rhythm may change only during exercise.
Poor
Performance
Many of the conditions that are detected on these cases can
be treated or managed to enable your horse to return to
competing at an appropriate level. The important thing is for
the vet, rider and trainer to work together to establish the cause
of the problem and make a treatment plan. If you have any
queries arising from this article please contact your local
XLVets practice to discuss them further.
‘The horse's heart functioning normally is essential to
being able to perform at high levels of exercise. Hearts
are initially assessed by listening with a stethoscope
to rate, rhythm and any abnormal noises indicating
valve disease...’
Wendy Furness
Scarsdale Veterinary Group