By Mary Ellen Goldberg, LVT, SRA, CCRVN, CVPP, VTS-lab animal medicine (research anesthesia), VTS-physical rehabilitation

Photobiomodulation—a.k.a laser therapy—has become commonplace in veterinary medicine, with knowledge gained over the last eight to 10 years coming from evidence-based data and shared clinical experience. Achieving predictable and reproducible results with laser therapy is dependent on properly managed treatments, proper dosing, effective use of therapy laser hardware and software, and appropriate treatment technique.¹

Low-level laser therapy (LLLT) applies low-level (low-power) lasers to the surface of or in orifices of the body. Whereas high-power lasers are used in laser medicine to cut or destroy tissue, application of low-power lasers is said to relieve pain or stimulate and enhance cell function. Laser therapy is a unique and extremely gentle form of treatment with the ability to stimulate tissue healing, virtually without side effects. It is very different from laser surgery, as it avoids heating the tissue, which can cause cell and tissue damage. As such, photobiomodulation is often called “cold laser” therapy.²

What’s it for?

Laser therapy has been postulated to exert three main effects: reduction of pain, modulation of inflammation, and acceleration of healing.³ The primary categories with the strongest support—largely via experimental studies—include its use in pain, wounds, musculoskeletal conditions, neurologic pathology, and in conjunction with complementary medicine techniques (e.g. regenerative medicine, acupuncture).^{4, 5}

When reading over lists of conditions or reasons for using laser therapy, it almost appears too good to be true. Yet, biological responses are induced by photochemical reactions using this modality.⁶ The claims laser therapy aids in wound healing, tissue repair, and prevention of tissue death have all been substantiated.^7,8,9 Additionally, reducing inflammation, pain, and edema have been shown to be backed by evidence as well.^{10, 11, 12}

When creating a treatment protocol for therapeutic laser, it is important to consider these effects to maximize patient outcome. The actual time the tissue is exposed to light energy also may affect the result.¹⁴

Understanding contraindications requires study of current textbooks and papers. Suggestions from 10 years ago have changed and are no longer simply black and white.¹⁵

The only absolute contraindication for laser therapy is direct or reflected exposure through the pupil onto the retina. Irradiation of or near the eye should not be performed.¹⁶ Patients that fall under special considerations will most often not be candidates for laser therapy; however, if the trained veterinary laser therapist thinks there could be some benefit to the treatment, a consent form should be obtained. If a location for an injected medication also is going to be treated with the therapeutic laser, first treat with laser therapy, and then administer the injection.

It is generally viewed laser therapy should not be used on malignant tissue.¹⁷ It has always been suggested that using laser therapy over a pregnant uterus is contraindicated. Epiphyses and open fontanels have been listed as contraindications because these areas comprise rapidly dividing cells. Because of the vasodilatory effect of laser therapy, it should not be used where there is active bleeding. Reports from veterinary practices using laser therapy during and after invasive procedures—and for treatment of wounds—confirm that hemorrhage is not reactivated once hemostasis has been achieved.¹⁵ Studies suggest excessively high doses should not be applied directly into the testicle.¹⁸ An objective analysis reveals that repetitive, high-dose treatment directly over the glands should be avoided. It also indicates occasional inadvertent exposure of the thyroid glands when treating nearby tissue is not contraindicated.¹⁵

What are false contraindications? These are conditions for which laser therapy is not approved. Areas of hyperpigmentation or tattoos should be watched during treatment and skin temperature monitored. If a temperature other than pleasant, gentle warming is detected, the speed of movement of the handpiece should be increased. Faster movement of the laser beam across the surface of the tissue can help avoid accumulation of unpleasant warmth, even when using veterinary therapy lasers that deliver a higher-power‐density laser beam.¹⁵ Therapy laser wavelengths do not have a detrimental effect on metal or synthetic implants, suture material, or tissue adhesives used in veterinary medicine. Use when implants are present is not contraindicated.¹⁵ Laser therapy is often performed over metallic orthopedic implants. To reduce reflection of the laser off metallic implants within the body, the laser beam should be angled away from them as much as possible.

In the past, there has been a concern about using laser therapy in the presence of microbial infections. Recent studies indicate laser therapy, when applied in vivo, has a variety of immune‐stimulating responses that help overcome microbial infection.¹⁵

In 2014, a review of publications for any report of adverse effects from laser therapy in patients on photosensitizing medication was conducted.¹⁹ This study has helped disprove photosensitization is a reason to not use laser therapy.

Why use goggles?

All class III b and IV lasers should come with their own set of safety glasses for use by the person delivering the laser therapy (i.e. veterinarian, physical therapist, or veterinary technician). Each laser manufacturer makes their goggles specific to their machine, and will include stamping on the corner of the lens indicating what wavelengths are covered. It is important to note no other shaded glasses can block out laser irradiation, including sunglasses or surgical laser glasses.¹⁶

Some laser companies make “doggles” for the patient; however, it can be a challenge to get animals to wear them. In cases where the doggles do not remain properly in place, ensure the patient’s face is turned away from the laser beam. A towel or e‐collar may be useful to keep a patient from turning its head. The person handling the laser and everyone within range of the beam must wear safety goggles. If there are any metallic surfaces nearby (e.g. treatment table), cover them with a towel or blanket to prevent any reflective surface meeting the laser beam. Treating a patient inside a stainless steel cage is strongly discouraged, as the risk for scatter is too great. It is recommended to remove metallic rings, watches, bracelets, and dog collars or harness with tags and metallic claps or adornments.¹⁶

Frequent veterinary reassessment is needed to monitor the effectiveness of laser therapy and to modify treatment as needed. The veterinary technician/nurse can help with the assessment of therapeutic effect by taking an accurate history of home behavior since the last therapy visit and by carefully palpating the affected area to monitor pain level (analgesic effect).

Not just for companion animals

Therapeutic laser clearly has a role in the treatment and management of multiple conditions in companion animals, but also exotics and zoo animals.¹⁴ There is strong evidence to suggest light energy at the appropriate wavelength and power density can provide modulation of tissues at the cellular level to enhance healing. There are multiple important clinical benefits that should be considered, prompting the practitioner to introduce therapeutic laser into specific patient treatment protocols. As more and more formal studies into the uses of therapeutic laser in animal models are completed, and more and more cases are presented, there is no doubt the use of therapeutic lasers will continue to expand.

Mary Ellen Goldberg, LVT, SRA, CCRVN, CVPP, VTS-lab animal medicine (research anesthesia), VTS-physical rehabilitation, is a graduate of Harcum College and the University of Pennsylvania. In 2017, she was chosen National Association of Veterinary Technicians in America’s (NAVTA’s) Veterinary Technician of the Year. Goldberg has written several books and contributed to numerous chapters regarding anesthesia, pain management, and rehabilitation. She speaks at national meetings on these topics and gives private continuing education to organizational groups. Since 1976, Goldberg has worked in various aspects of veterinary medicine from small-animal and equine to mixed practice, coccidiosis research for a pharmaceutical company, zoo-animal medicine, and laboratory-animal medicine. She can be contacted by email at mewhitester@gmail.com.

References

¹ Godbold JC. The Art of Laser Therapy, Veterinary Meeting and Expo Proceedings, February 3-7, 2018, Orlando, FL, 10-12

² Turchin C. Chapter 1: Veterinary Laser Therapy, Veterinary Laser Therapy 1^st Edition, copyright © 2012 Curtis Turchin, 1-122

³ Chung H, Dai T, Sharma SK, et al. The nuts and bolts of low-level laser (light) therapy, Ann Biomed Eng, 2012, 40:516–533

⁴ Anders JJ, Kobiela Ketz A, Wu X. Chapter 5: Basic Principles of Photobiomodulation and Its Effects at the Cellular, Tissue, and System Levels, Laser Therapy in Veterinary Medicine: Photobiomodulation, First Edition. Edited by Ronald J. Riegel and John C. Godbold, Jr., John Wiley & Sons, Ames, IA, 2017, 36-51

⁵ Hochman L. Photobiomodulation Therapy in Veterinary Medicine: A Review, Topics in Companion Animal Medicine, 2018, 33: 83-88

⁶ Companion Animal Health. Introduction to Laser Therapy for Acute Conditions, https://litecureassets.s3.amazonaws.com/resources/1543587802.pdf, accessed 2/2/2019.

⁷Avci, P. et al. Low‐level laser (light) therapy (LLLT) in skin: stimulating, healing, restoring. Semin Cutan Med Surg. 2013, 32(1):41–52

⁸ Farivar, S. et al. Biological effects of low-level laser therapy. J Lasers Med Sci. 2014, 5(2):58–62.

⁹ Peplow, P.V. et al. Laser photobiomodulation of wound healing: a review of experimental studies in mouse and rat animal models. Photomed Laser Surg. 2010, 28(3):291–325.

¹⁰ Bjordal, J. et al. A systematic review of low level laser therapy with location specific doses for pain from chronic joint disorders. Aust J Physiother. 2003, 49(2):107–116

¹¹ AAHA. 2015 AAHA/AAFP Pain Management Guidelines for Dogs and Cats. Available from: https://www.aaha.org/professional/resources/pain_management.aspx (accessed 02-02-2019).

¹² Mathews K, Kronen P, Lascelles D, et. al. GUIDELINES FOR RECOGNITION, ASSESSMENT AND TREATMENT OF PAIN. Journal of Small Animal Practice, 2014, 55, E10-E68, https://www.wsava.org/WSAVA/media/PDF_old/jsap_0.pdf, accessed 02-02-2019

¹³ Companion Animal Health. Laser Therapy for Chronic Conditions, https://litecure-assets.s3.amazonaws.com/resources/1543587807.pdf, accessed 02-02-2019

¹⁴ Downing R. Laser therapy in veterinary medicine, Innovative Veterinary Care Journal, https://ivcjournal.com/laser-therapy-veterinary-medicine/ accessed 02-02-2019

¹⁵ Godbold JC and Riegel RJ. Chapter 7: Contraindications, Special Considerations, and Precautions, Laser Therapy in Veterinary Medicine: Photobiomodulation, First Edition. Edited by Ronald J. Riegel and John C. Godbold, Jr., John Wiley & Sons, Inc., Ames, IA, 2017 67-73

¹⁶ Shaw KK and Brown L. Chapter 15: Modalities Part 2: Laser Therapy, Physical Rehabilitation for Veterinary Technicians and Nurses, First Edition, edited by Mary Ellen Goldberg and Julia E. Tomlinson, John Wiley & Sons, Inc., Ames, IA, 2018 231-240

¹⁷ Millis DL and Saunders DG. Chapter 21: Laser Therapy in Canine Rehabilitation, Canine Rehabilitation and Physical Therapy 2^nd Edition, Elsevier, Philadelphia, PA, 2014, 359-380

¹⁸ Salman, Y.R. et al. Effect of 830‐nm diode laser irradiation on human sperm motility. Lasers Med Sci. 2014, 29(1):97–104.

¹⁹ Kerstein, R.L. et al. Laser therapy and photosensitive medication: a review of the evidence. Lasers Med Sci. 2014, 29(4):1449–1452.