THE BEVA HELD ITS 55TH
CONGRESS in Birmingham’s ICC
from 7th to 10th September with a
substantial attendance from many
countries.
The session on “Lame or
Neurological” was moderated by Kevin
Corley of
Anglesey
Lodge
Equine
Hospital,
Kildare,
and began
with Martin
Furr of the Center for Veterinary
Health Sciences at Oklahoma State
University describing how he goes
about differentiating lameness and
neurological disease.
Lameness and neurological disease
can exist together and they are hard
to sort out. Nowadays, there is
more awareness of the neurological
component.
Take the time to get a detailed
history and signalment; a horse
presented to Martin as a complicated
lameness turned out to have a simple
injection abscess. The clinician’s hands
and eyes, backed up by brain and
experience are the most important
instruments for diagnosis.
Observing response
Observe the horse at rest and in
motion. How responsive is it? Is it
standing base wide? Does it know
where its limbs are in space? Observe
the rate, range and direction of
movement, where the foot is placed
and whether it is placed fast or slowly.
To confuse the issue, a horse with
bilateral hind limb lameness or muscle
soreness may look ataxic. Orthopaedic
lameness is confirmed by response
to nerve blocks. It is essential to
record all findings at the time of
examination.
Once the horse is moving, a
neurological gait deficit is irregular
from step to step because the
horse has poor control of the limb
movement. This pattern is even more
marked on turns and transitions: the
horse may “fall apart” on the trot to
walk change.
The irregularity does not increase or
decrease throughout the examination,
whereas the musculo-skeletal lameness
may warm out or show up on moving
up or down an incline or on a
different surface.
Time can clarify a confusing
situation; a mild neurological difficulty
can progress into a full-blown neurological disease whereas musculo-skeletal lameness may reduce on rest
and anti-inflammatories which would
not influence a neurological condition.
Is the horse safe to ride?
Martin continued with “How to decide if the
neurological
horse is safe
to ride”.
Riding is
risky. Riding
accidents
topped a
survey in New Zealand, ahead of sports such as
snowboarding and swimming.
There are several aspects to consider
in advising the owner. First, there is
the safety of the rider, the horse and
everyone who is in contact with the
animal.
The level of use needs to be
determined; the horse may be t to
ride on the at in a sand school but
not across country over fixed obstacles.
What does the owner want? What is
fair to the horse from the welfare point
of view?
Then there is the matter of
suitability for insurance and, finally,
legal implications which vary between
countries and between states. The
clinician needs to evaluate the severity
of the de cit and how it is likely to
progress.
Is it static or likely to increase slowly
or is it episodic and unpredictable?
How is the horse in itself? How does
the owner rate on skill, knowledge and
experience?
It is the veterinary surgeon’s
responsibility to assess the risk and
provide clear, unambiguous, written
instructions to everyone involved
with the horse. If you consider the
horse unfit to ride, say so. Always get
advice from appropriate professionals
regarding legality.
Horses with low grade spinal ataxia
may still be t to ride. Horses with
seizures should not be ridden until they
have been off medication, without
seizuring, for at least 30 and preferably
60 days. If they have a history of long
intervals between seizures then they
should have a break of at least three
times the seizure interval.
Neck lesions
Sue Dyson of the Animal Health Trust
discussed neck lesions as a cause of
lameness or poor performance.
Neck lesions are a rare cause of
lameness but if the limbs do not
provide an answer to the clinical problem or neck signs such as stiffness,
abnormal positioning, local pain or
patchy sweating, then the neck needs
to have a thorough clinical examination
backed up by accurate interpretation of
radiographs.
Pain in the brachiocephalicus muscle
can cause forelimb lameness. A poor
rider or badly fitting tack can also
initiate muscle pain causing forelimb
lameness. A badly-fitting collar may
make a driving horse show lameness
only when it is pulling.
Locking up
“Neck locking” is a syndrome of
severe episodic neck pain which can
last for hours or days. The horse may
hold its neck in a low position or show
severe forelimb lameness, holding
the leg semi- exed at rest. It can be
relieved by careful manipulation of the
caudal neck region.
Definite cause has not been
established but the caudal cervical
articular process joints (APJs) are
enlarged so that the intervertebral
foramen is narrowed, causing nerve
root compression, hence pain.
Benefits of medication are unproved
because of the sporadic occurrence of
the pain. Nerve root compression also
occurs if there is osteoarthritis of the
APJs where the considerable amount
of new bone growth impinges on the
intervertebral foramen. This can cause
patchy sweating, lameness and either
local or referred pain.
There can be alteration of the nerve
supply to the muscle so that there is
muscle atrophy which reduces limb
control and so alters gait. The patchy
dermatomal sweating follows upset to the local autonomic nerve fibres.
It may be accompanied by local
hypoaesthesia. In severe cases the
vertebrae can fuse so that the neck
stiffens permanently.
Lymphocytic infiltration of nerve roots and a positive PCR for Borrelia burgdofreri in cerebrospinal fluid has occurred in a horse presenting with central neurological signs and neck stiffness but generally B. burgdorferi seems to be commonly incidental to, rather than causal of, neck problems.
Sometimes the first rib may be congenitally abnormal or it may be injured with consequent damage to the eighth cervical nerve. This can be the cause of muscle atrophy and forelimb lameness.
Neck problems are generally rather intransigent; in a study* of 59 horses, 32% returned to full function, 31% improved more than 50% but follow-up showed poor long-term resolution with 55% losing improvement by one to six months’ post-treatment.
- Birmingham, A., Reed, S., Mattoon,
J. and Saville, W. (2010) Qualitative
assessment of corticosteroid cervical
facet injection in symptomatic horses.
Equine Vet Educ 22: 77-82.
