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Bartels,
Kenneth E. "Laser Use Grows
in Veterinary Medicine." Biophotonics
International, July/August 1997.
SUMMARY
Although human applications get much more
attention and financial consideration, veterinary medicine is
another market for biomedical lasers. The cost as well as the
debatable returns for this type technology investment have limited
the veterinary applications primarily to the academic community,
research institutions and specialty practices. As efficacy is
proven and equipment costs decrease, however, laser surgical
and diagnostic devices will become mainstream in clinical veterinary
practice.
The introduction of laser technology in veterinary medicine has
been heavily influenced by economic considerations, and by the
fact that governmental regulation of innovative technologies
is considerably less restrictive when the patients are animals
rather than people.Occasionally, the reduction in restrictions
has been advantageous in implementing new techniques. For some
applications such as "soft" laser therapy for biostimulation
(supposedly to improve healing by applying low-power red laser
light), protocols and devices that are restricted for human use
in the U.S. have been heavily marketed to veterinarians, often
on the basis of subjective assessments and anecdotal reports.
In any event, the use of lasers in veterinary medicine for photothermal,
photomechanical and photochemical applications is expanding rapidly,
both in research and clinical practice.Because applications for laser surgery
in human medicine are expanding, the desire of physicians and
hospitals to purchase state-or-the-art equipment has also increased.
As hospitals acquire equipment with advanced designs and options,
their used equipment becomes available for veterinarians to purchase.
However, even used equipment can be expensive in the long run,
since maintenance costs can exceed the initial capital investment.
As with the acquisition of any new technology,
it is extremely important that laser applications in veterinary
medicine reflect responsible medical and scientific use. Strategies
and gimmicks that advertise new and unique equipment can also
attract individuals interested in offering treatments that have
little or no proven benefit.
REALIZING THE POTENTIAL
An objective approach to surgical laser
procedures in veterinary medicine is essential if the potential
of this technology is to be realized. "Zap and vaporize"
techniques coupled with a "burn and learn" philosophy
can do harm to both patient and surgeon and can easily outweigh
any benefits. An effort must be made to evaluate the laser's
potential benefit to patients, rather than portraying it as a
marvel of the 21st century.Although the use of biomedical lasers has
generated entirely new treatment concepts, a veterinarian's clinical
expertise and knowledge of pathophysiology myst be the primary
factors for determining whether a laser or scalpel blade is the
better choice for a particular procedure.Many of the first reports of biomedical
laser use in veterinary medicine involved endoscopy; fiber optics
delivered Nd:YAG laser energy to treat laryngeal and upper respiratory
conditions in horses, such as entrapment of the epiglottis and
laryngeal cysts. Since then, both CO2 and Nd:YAG lasers hae been
used in general surgery in small animals where precise dissection
and control of hemorrhaging are important. These procedures have
included liver biopsy and resection of liver lobes, biopsy of
the spleen, partial and complete removal of the kidney, and excision
and resection of intra-abdominal, intrathoracic, cutaneous and
mammary tumors.Recent reports have reviewed clinical uses
of laser energy for ablation and coagulation of brain tumors
and superficial growths or tumors (Figure 1), treatment of eosinophilic
(foamlike) scar growths and ablation of lick granulomas (the
buildup of scar tissue from excessive licking) in dogs.Because advantages such as shorter recovery
time, less perceived discomfort and availability of potential
treatment regimes for conditions not amenable to conventional
procedures, biomedical lasers are being used in the realm of
exotic animal or zoo practice where hospitalization time must
be minimal (Figure 2). Clinical use of the holmium (Ho:YAG) laser
for ablation of intervertebral discs in dogs has also recently
been instituted and shows tremendous potential (Figure 3). The use of medical lasers for veterinary
ophthalmologic applications was established in the early 1980s,
although it is not as common as in human practice because of
the cost and differences between human and animal conditions.
The Q-switched or continous-wave ophthalmic Nd:YAG, argon-ion
and diode lasers have been used as photocoagulators in retinopathies,
for treatment of lens-induced papillary opacification and for
transcleral cyclodestruction of the ciliary body to treat glaucoma,
which is very common in dogs. As experience and interest increases
and lasers become more available to veterinary ophthalmologists,
clinical applications will increase.
Photodynamic therapy has been used clinically
in veterinary medicine by several investigators since 1985. A
number of initiatives have been reported using the technique
to treat dogs and cates with spontaneously occurring tumors,
primarily of the skin and mouth. This exciting method of destroying
tumors employs interaction of light with a photosensitizer in
the presence of oxygen. It will undoubtedly play a much larger
role in clinical veterinary medicine as protocols are established
and photosensitizing drugs are approved by the U.S. Food and
Drug Administration (FDA) for use in animals. Phythalocyanines,
theophorbides, 5-aminolevulinic acid and hematoporphyrin derivatives
such as Photofrin have shown the most promise.
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