British Breeder May 2023

Health Article - Limb Deformaties
Foal with hind slack tendons
The angular limb deformities are where
the limb deviates inwards (varus) or
outwards (valgus) through a joint when
viewed from the front. Many foals are
born with quite marked hind limb
deviations, often one hind limb has a
varus deviation through the hock and
the other limb has a valgus deviation
through the same joint making the foal
look like it's limbs have been blown by
the wind, you will have heard the term
“wind swept”. The vast majority of these
congenital angular limb deviations will
correct within a couple of weeks if the
foal is only allowed limited exercise.
Carpul varus
It is common practice to ask your farrier
to apply glue on hoof extensions to
correct angular limb deviations that
involve the fetlock joint. A varus or
inward deviation requires a lateral or
outside extension. Conversely a valgus
or outward deviation requires a medial
or inside extension. These are applied
within the first few days of the foals life
to the hoof and the foal is kept on a
relatively firm bed so that the mechanical
affect of the altered load on the growth
plates straightens the limb. Exercise must
be restricted until the limb is straight.
Foal toe extension
There is another limb deviation that is
very difficult to correct, this is where the
bone column is straight, however the
limb is rotated usually outwards from the
upper limb in the fore limb, giving the
foal a very toe out conformation and
action. Many such foals will correct with
time as they grow and develop.
Once the foal has developed to the point
that everyone is happy with the limb
conformation it should then have
exercise in a safe paddock with a good
level surface. It is as important for foals
to exercise, as it is for them to be rested
if their limbs are not straight. Exercise
stimulates the development of bone
density and also the necessary tendon
and ligament fibres required for these
soft tissues to stand up to the rigors of
equestrian sport later in life.
It is however important to keep a close
eye on your foals limbs as it is
developing, particularly when the
ground start to get hard in the middle
of the summer. Often foals will get foot
sore and as a consequence they pull
themselves up on to the tips of their toes,
off-loading the weight from the sore
soles of the hoof. The muscles contract,
the tip of the toe gets warm away and
an upright hoof conformation known
as a boxy foot develops - an acquired
flexural deformity. You may also have
heard the term “ballerina syndrome”, this
can ruin a foals future value and affect
it’s likelihood of staying sound in sport.
If you spot your foal becoming upright it
is important to get it in on a soft bed and
administer pain relief as directed by your
vet, the farrier may need to be involved
to perform corrective trims.
The hard ground and rapid growth rates
can also cause the growth plates at
the ends of the long bones to become
inflamed (physitis), particularly the distal
radial growth plate above the knee
and the growth plates either side of the
fetlocks. Physitis can cause disruption in
the lengthening of the bone and often
the growth becomes uneven across the
growth plate resulting in one side of the
limb growing faster than the other
bending the limb - an acquired angular
limb deviation develops. Again if this is
noted to be happening rest on a deep
bed and the administration of
anti-inflammatories and appropriate
intervention from the farrier may salvage
the situation.
There are some surgical procedures that
can be performed to correct foals limb
deviations, however we try very hard to
manage foals in such a way as to avoid
performing these procedures. Foals
that develop severe flexural deformities
involving a boxy foot may undergo an
operation to cut the check ligament of
the deep digital flexor tendon - I have
not had to have one of these done for
many years.
Occasionally we may need to help an
angular limb deviation correct, most
commonly the fetlock and carpal joints,
but occasionally the hock. There are
two types of procedures that can be
performed, the most simple is known as
a periosteal strip, this involves a small
skin incision over the growth plate on the
inside of the deviation (so for a fetlock
varus - the incision is on the inside of the
distal canon bone, the a carpal valgus
the incision is on the outside of the distal
radius), the periosteum on the bone
surface is lifted off the growth plate, this
speeds up the growth of the long bone
on the side of the incision relative to the
side of the bone not operated on and the
bone straightens as it grows.
The second procedure is more invasive
and is reserved for very severe angular
limb deviation. This involves stopping the
growth on the outside of the deviation
(so for a hock valgus - on the inside of
the hock, for a carpal varus the surgery
would be performed on the outside of
the radius). The growth can be stopped
by bridging across the growth plate,
usually by placing a screw through it.
This stops the growth on that side of the
bone, the opposite side continues to
grow and when the limb is straight the
screw is removed.
Xray of foal tarsal screw
In summary it is important to carefully
manage the amount of exercise
new-born foals are allowed to have,
also to carefully monitor how the foals
limbs are developing as they grow.
Standing them up on a firm level surface
and walking them up to observe their
limb flight is something worth doing
every 3 or 4 weeks during the foals first
few months of life. If in doubt consult an
experienced vet and your farrier.
Tel: 01903 883050
Email: info@sussexequinehospital.co.uk
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