EXTRACORPOREAL SHOCK WAVE THERAPY (ESWT)
ESWT is non-invasive, used to stimulate healing to return horses to a level of fully sound, useful activity without recurrence of disease.
This treatment modality is used for a variety of soft tissue (i.e. bowed tendons, suspensory ligament
desmitis, sore backs, etc...), bone (i.e. fractures, sesamoiditis, buck shins, navicular disease or
heel pain) and joint (I.e spavin, osselets, arthritis) injuries. From outside the body (extracorporeal),
the machine generates high-intensity shock or pressure waves, which pulse to a specific site within the
injured tissue. Though its actual mode of action is still in dispute, it stimulates and accelerates the
healing process, essentially combining an immediate analgesic (pain killing) effect with a reduction in
inflammation, neovascularization (new blood vessels) in soft tissue and osteogenesis (new bone formation)
in bone. It is this new blood flow that promotes tissue healing. Electrical energy is used to initiate
the pressure wave. The energy settings and the number of pulses are important. Too low energy or too
few pulses might not create the desired therapeutic effect. Excessive energy or pulses may result
in tendon damage. The pressure waves penetrate fluid and soft tissue, and their effects occur at
sites at the bone/soft tissue interface. Pressure waves might help physically break down or move
a hematoma or fluid from the lesion to allow the fibroblasts to more rapidly fill the defect.
According to some research, ESWT is an effective method of decreasing clinical signs of lameness
associated with osteoarthritis. In a study comparing horses treated with a common non-steroidal
anti-inflammatory drug, ESWT performed better, promoting improvement in clinical lameness and increased
synovial fluid total protein, and increased amount of glycosaminoglycan released into the bloodstream.
ESWT treatment reduced the clinical signs of pain measured by lameness evaluation 42 days after the
final treatment. The results of the study suggested that ESWT is an effective method of reducing
clinical lameness and synovitis, but it does not improve gross or histologic progression of arthritis
significantly; thus, it would be best considered in combination with a chondroprotective agent.
The handheld wand of the unit attaches to an energy source. For the simplest shock wave procedure, the
horse is lightly sedated; the area to be treated is shaved to provide for good contact; a contact gel
is placed on the horse's skin, and the hand unit is applied to the horse to deliver the shock wave pulses.
The treatment takes minutes. The horse does not experience pain. Sedation is recommended so the horse
remains still so the treatment is applied accurately, targeted to the specific treatment location, and
if fractious, the veterinarian is protected.
Among possible concerns of ESWT for horses is potential local analgesia (pain killing) after treatment,
and for bone micro-lesions, micro-fractures. Some studies have found slight skin analgesia for three to
five days, but no bone lesions have been produced. Data indicates that a horse should not be subjected
to strenuous activities where local analgesia pre-disposes the horse to injury for at least four days
after ESWT.
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