Download Further information on the equine condition of bone spavin

Bone Spavin is a common orthopaedic condition in the horse, causing
lameness in the hock. Not to be confused with Bog Spavin, a distention of the
joint capsule in the hock. Bone spavin is the secondary disease to this. It is the
final phase of degenerative joint disease (DJD), in the lower three hock joints. It
usually affects the two lowest joints of the hock (the tarsometatarsal and the
distal intertarsal joints).
Bone Spavin is commonly seen in fast growing young horses or in much older
horses, however if injury has occurred this can contribute to the problem.
Causes of bone spavin include cartilage compression. Over time, the cartilage
between the upper and lower surfaces of the lower tarsal bones can become
compressed and eroded. The joint spaces then become smaller and new bone
growth may occur. Poor shoeing or foot balance is also a factor, uneven
loading causes excessive compression of the cartilage and bone on one side,
and strain in the joint capsule and supporting ligaments on the other side.
When the joint is repeatedly overloaded, exostoses, or ‘bone spurs’, occur.
Strain of the supporting ligaments can cause exostoses around the joint as
well. Poor conformation is a contributing factor. There are several
conformational defects that contribute to bone spavin. Conformations that
cause uneven loading of the hocks, such as “sickle hocks”, and “cow hocks”,
are especially noteworthy. Activities such as dressage and show jumping,
which require a greater hock flexion or where there may be excessive
concussion acting on the hock joints, may contribute to uneven or repeated
loading of the lower hock joints, and thus bone spavin. "Juvenile spavin" is the
occurrence of bone spavin in horses less than 3 years old. It usually occurs
before the animal has done much work.
Initially signs of bone spavin can be slight inflammation or sporadic lameness
that can be confused with stiffness, this is usually seen following exercise. In a
lot of cases the ‘stiffness’ can be assumed to be back pain. Many horses will
show problems walking down hill, have problems with one leg lead in particular
and if the horse is used to jump it may even refuse to jump. If the lameness and
inflammation worsens over time, further investigation will be required by the vet.
Investigation can be carried out in a number of ways. Flexion tests would
usually be the first test the vet would do. Holding the leg is a flexed position for
30- 60 seconds and then watching the horse trot away would indicate if the
lameness increased. X-rays could be done, however it is usually necessary to
do four different images of the hock to be able to see the different angles
needed. Scintigraphy can give a good understanding of the area in the hock
that is most affected by inflammation, indicating the main problem area.
Many vets use a technique called Intra-articular local anaesthesia to treat the
problem. This is done by the introduction of 3-5ml of local anaesthetic into a
joint. This should abolish, or at least significantly lessen, the lameness. This
technique is not absolutely specific, as the distal pouches of the
tarsometatarsal joint are immediately adjacent to the suspensory ligament. This
means that anaesthetic in the tarsometatarsal joint can occasionally desensitize
pain arising from suspensory ligament, giving the false impression that joint
pain has been abolished. In server cases surgery is necessary.
As a physiotherapist the ultimate result you are looking for when bone spavin is
present, is for fusion of the related joints. As the joints present produce very
little movement, this only has a minor effect on movement and once joints are
fused the horse will become sound and pain free.
To assist with the healing process PEMF (Pulsed Electromagnetic Field
Therapy) can be used to encourage joint fusion and pain relief. This can only
be done if the vet has confirmed that there are no further unwanted bone
formations present in the joint. Using a base setting of 50Hz and a pulse of
25Hz (or constant) you can treat the horse for as long as possible, as often as
possible with four hours between sessions. This treatment should be continued
until the fusion of the joint has taken place. It is difficult to put a time frame on
this because each case will be different depending on how advanced the
problem is and how the joint reacts to the treatment. Further scans would need
to be done in order to confirm the fusion and at this point the horse would not
be receiving any pain killers.
Compensatory muscle pain should be treated. This would be done by applying
phototherapy (red light laser) to relax the horse, increase circulation, warm up
muscles and release endorphins. Then a range of massage techniques and
stretches would be used to release any tension. In some cases muscle pain
and spasm will be server because the horse may have masked the pain and
problems for a while, therefore ultrasound could be used on the problem areas
to release tension.