Page 917 - Adams and Stashak's Lameness in Horses, 7th Edition

Principles of Therapy for Lameness 883

publications within the veterinary literature investigat- within the electron transport chain, and cellular calcium
5
ing the ideal medication, concentration, and method of channels. Cellular alterations may trigger mitosis and
VetBooks.ir Nomenclature from early work in both human and vet- effects on circulation and analgesia. Classification of
cellular proliferation, which may have biomodulatory
application for their use in a variety of disease processes.
lasers is defined by wattage output. Most used in clinical
erinary medicine, however, made specific route of medi-
cation delivery difficult to ascertain. Those first to practice fall into the class IIIb criteria, which are those
perform “regional limb perfusions” did so through that emit power of 5–500 mW. When used in a thera-
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direct antibiotic delivery within the medullary cavity in peutic setting, these lasers are commonly referred to as
an effort to allow retrograde flow into the venous sys- low‐level laser therapy (LLLT) or cold lasers because
tem to perfuse the limb (see below). In many instances, their use does not generate noticeable heat to the patient.
these were often referred to as intravenous therapy. Class IV lasers are of greater wattage and have started to
However, today, most regional limb perfusions (RLPs) find their place on the human and veterinary market for
traditionally use a peripheral vein – and at times an treating injuries deeper within the body due to their
artery – for application of intravascular therapy, while higher output. 27
intramedullary application is seldom utilized. A previous study examining its use of LLLT in the
Our understanding of IVRLPs has grown dramati- treatment of wounds in the horse showed no benefit.
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cally over the last several years. Current recommenda- The only benefit that has been shown in the horse is
tions for antibiotic administration vary from tourniquet through the application of LLLT in the treatment of
times of 10–30 minutes and perfusate volume of periodontal defects. Furthermore, when LLLT was used
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10–60 mL and typically include an aminoglyco- for treatment of surgically created wounds in dogs, no
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side – and more specifically amikacin – as the class improvement in subjective healing nor wound size was
of antibiotic administered due to their concentration‐ observed compared with control groups. 20
dependent and post‐antibiotic effects. 10,21,22,24,30,35,40 Magnetic and electromagnetic therapy remains a
Many other classes of antibiotics have been explored 12,26,36 controversial subject. A large amount of anecdotal infor-
but are likely poor candidates due to insufficient time mation is available, especially by equipment manufac-
above minimum inhibitory concentration (MIC) to turers. Ironically, this information is highly available to
cause beneficial effects. RLPs have also been used in lay horseman, despite a lack of technical information,
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horses to provide distal limb contrast for MRI, for mes- understanding, and directions for use. In general, an
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enchymal stem cell therapy, 39,42 and for anti‐inflammatory electromagnetic field is created by passing an electric
and antifungal treatment with DMSO and amphotericin B current through a coil of insulated wire. When piezoe-
to combat pythiosis. 13,14 When multiple antibiotics have lectrical properties of bone where discovered, evidence
been used in combination or antibiotics with a local anes- became available, which supported the use of electro-
thetic, a reduction in antibacterial efficacy has not been magnetic fields on bone healing. Limited studies are
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measured. 10,12 available in horses. Some benefit in fracture healing was
observed after 2 hours of daily therapy. Conversely,
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pulsed electromagnetic field therapy delayed tendon
THERAPEUTIC ULTRASOUND, LASERS, healing in experimentally created defects in the superfi-
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AND ELECTROMAGNETICS cial digital flexor tendon (SDFT) in horses. In a rabbit
study, however, beneficial effects were demonstrated in
The use of therapeutic ultrasound, lasers, and electro- tendon healing. Since the last edition of this book,
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magnetics is common in the horse industry. Horse own- more recent work in human medicine has shown an
ers that have done extensive investigation on the Internet added benefit when electromagnetic therapy was used in
where anecdotal reports abound will frequently request combination with shockwave therapy in rotator cuff
equine clinicians input on this therapy. Therapeutic tendinopathy. However, no further elucidation on
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ultrasounds emit unfocused sound waves that may have mechanism of action has been published, nor any fur-
the potential to penetrate underlying tissues. The exact ther evidence‐based studies performed in equine medi-
mechanism of action is unknown, but purportedly, ther- cine. As with therapeutic ultrasound and therapeutic
mal energy is produced as the sound energy contacts the laser therapy, magnetic therapy applications will most
tissues. In vitro studies have reported alterations in likely continue to be touted by the lay horseman until
blood flow, angiogenesis, collagen and protein synthesis, clinical trials are available to prove or disprove efficacy.
and osteogenesis. Clinical trials have shown conflicting
results in treating tendon injuries. Therapeutic ultra-
sound did not improve muscle regeneration in injured COUNTERIRRITATION
tissue nor alleviate chronic heel pain in people. 5,15 One
trial in horses reported improved healing characteristics Topical blistering and pin firing have long been part
4 and 6 weeks following tendon injury. Until more of veterinary medicine, but fortunately, they are rarely
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clinical trials become available, use of this treatment will practiced today due to the lack of clinical data as well
remain empirical. as their inhumane ramifications. They are mentioned in
Therapeutic laser therapy is based on light that is this section only to acknowledge their common usage in
emitted from the instrument, which is a focused beam of the past. Topical blisters historically were made of iodine
photon energy. The power output of lasers used in phys- or mercuric iodide and were mainly used on splints,
ical therapy is in the milliwatt range (low). Mechanisms sore shins, or curbs. More severe blistering agents were
of action of therapeutic lasers are thought to include made from cantharides or croton oil. The technique
alterations in mitochondrial enzymes, cytochromes involved application to the skin and light exercise.