August 31, 2018

Laser Therapy Today

Photobiomodulation can improve healing—and quality of life—for veterinary patients with a host of health conditions.
By David S. Bradley, DVM, FASLMS
Interdigital cyst before (left) and 1 week after (right) laser therapy.

Documentation of light therapy dates back 3000 years, but it wasn’t until about 100 years ago that Albert Einstein theorized the possibility of a LASER (light amplification by the stimulated emission of radiation)—yet his theories did not come to fruition until 1960, when the first working laser light was produced. Since then, lasers, laser light, and light-emitting diodes have become integral to everyday life, from communication and entertainment uses to industrial and military applications.

The medical front is rife with life-changing advances attributed to lasers, including treatment of disfiguring dermatologic conditions, ophthalmologic diseases, dental and oral maladies, prostate disease, neurologic and orthopedic conditions, and intrathoracic and abdominal conditions.

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It is estimated that about 40% of veterinary practices offer laser therapy, officially termed photobiomodulation (PBM), as part of their armamentarium. This is due in large part to a greater understanding of laser therapy and a maturing of the technology, making it safer, easier to use, and more effective on for a wider variety of clinical conditions.
 

How Laser Therapy Works

Laser therapy uses a wavelength-specific form of PBM to restore normal biological function and repair injured or stressed cells. Cellular chromophores within the bloodstream and tissue mitochondria absorb the laser energy, stimulating or enhancing a series of primary biochemical processes, along with a broad cascade of secondary and tertiary effects.

The primary response is a direct photochemical reaction similar to photosynthesis or vitamin D production in the skin. This occurs when photons in the infrared range emitted by the laser reach the cell mitochondria and membranes. The photonic energy is converted to chemical kinetic energy within the cell, resulting in improved efficiency of the respiratory chain within the cell mitochondria due to changes in membrane permeability, nitric oxide formation, increased oxidative metabolism to produce more adenosine triphosphate (ATP), and improved signaling between mitochondria, nuclei, and cytosol.1 Other direct effects include the production of reactive oxygen species such as superoxide dismutase and a beneficial shift in the redox state.

Secondary and tertiary reactions amplify the primary photochemical reactions, resulting in improved cell metabolism and regulation of signaling pathways responsible for tissue repair. Blood vessels and lymphatics respond favorably, enhancing tissue perfusion and providing oxygen and nutrients needed for recovery.2,3 Studies document enhanced cell migration, RNA and DNA synthesis, cell mitosis, protein secretion, and cell proliferation.4 This enhances healing and production of collagen and epithelial cells.

PBM also stimulates a more normal distribution of type I and type III collagen during the healing process.5,6 Damaged muscle and nerve cells heal faster and/or function better. The immune system, including white blood cells, functions efficiently to fight infection and clean up debris.

Not only does laser therapy enhance positive cellular processes, but it inhibits negative processes such as pain, exuberant inflammation, and aberrant immune responses. In vivo, it also stops further growth when healing is complete. This acceleration of normal healing and tissue regeneration without producing overgrowth or neoplastic transformation is a critical and unique feature of laser therapy.7-11

 

Laser therapy can be used to treat cervical intervertebral disk disease.

Therapeutic Uses in Veterinary Medicine

Laser therapy offers 3 main benefits: analgesia, reduced inflammation, and faster and better recovery. It allows veterinarians to improve and resolve conditions that traditionally have been less responsive to other therapies. Soft tissue, musculoskeletal, neurologic, dermatologic, and even some intra-abdominal and intrathoracic conditions can be improved or managed more efficiently and with fewer drugs by adding laser therapy to the treatment regimen.

According to the investigators in a University of Florida study on laser therapy in spinal cord–injured dogs, “the results were so profound that we’re doing this procedure now on all dogs that come to us with this condition.”12 Other areas of interest include peripheral nerve injury, traumatic brain injury, stroke, and even depression.

Laser therapy is used in a wide range of dermatologic conditions, from acute injuries, trauma, and postoperative applications to management of chronic allergic and autoimmune/idiopathic syndromes including otitis, perianal fistulas, lick granulomas, and hot spots.

Many pathologic lung conditions respond favorably to laser therapy.13-15 It has helped slow the progression and/or decrease the intensity of drug therapy in conditions such as interstitial pulmonary fibrosis (Westie lung disease), feline asthma, and even tuberculosis.

Patients with chronic kidney disease have shown clinical improvement related to appetite, well-being, and nausea. The addition of laser therapy has also demonstrated improvement in chronic bladder issues including persistent infections and feline idiopathic cystitis, and it has been used as an adjunct to improve inflammatory bowel syndromes and other enteropathies.16 There are even anecdotal reports of decreased morbidity and mortality in parvovirus enteritis with the addition of laser therapy.

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