Laser Therapy in the Companion Animal
Laser is defined as: “Any device which can be made to produce or amplify electromagnetic radiation in the wavelength range from 180 nn to 1 mm primarily by the process of controlled stimulated emission.”
Laser Classifications - all lasers are classified according to their potential to cause damage to biological tissue.
Class I Lasers – These lasers cannot, under normal operating conditions, cause any biological tissue damage. Examples of this laser would include; compact disc player or a laser printer.
Class II Lasers – These lasers fall into the visible range of light. Due to the red color, the normal human response is to avert one’s eyes therefore do not present an optical hazard. They have the potential for an optical hazard only if viewed directly or for long periods of time. Example of this laser would be a bar code scanner.
Class III Lasers – These lasers or laser systems are of medium power and require control measures to prevent viewing of the direct beam. This class is further subdivided into III a and III b categories.
Class III a Lasers – These lasers would not produce a hazard if viewed only momentarily by the unshielded eye. Even if not deemed a hazard, this class of laser should never be directed toward any ocular tissue.
Class III b Lasers – These lasers do create a biological hazard if viewed directly. This class is not limited to a direct view of the beam itself but also includes a hazard it the beam is viewed off a reflective surface. Examples of these lasers are a laser pointer.
Class IV Lasers – These lasers are divided into two groups; Surgical and Therapeutic. Both of these lasers are capable of causing injury to the eyes regardless of if it is direct exposure to the beam or the beam reflecting from a surface. Surgical lasers cut tissue while therapeutic lasers heal tissue.
The Three Properties of Laser Light
This penetration of light to the cellular level is possible through the three properties of laser light. Laser light is:
Laser light is monochromatic, that is, it is composed of light from only one color wavelength. Because the wavelength of laser light determines its effect on tissue, the monochromatic property of laser light allows energy to be delivered to specific tissues in specific ways.
Laser light is coherent in that it radiates in a very orderly fashion from its source. Each photon moves in step with all the others that are belong emitted at the same time.
Laser light is collimated. The term refers to the tight, strong and concentrated nature of the laser beam.
The Importance of Wavelengths
The biological effect upon the cells is significantly related to the wavelength of the light emitted by the therapy laser. In general, the shorter the wavelength is, the more readily the energy is absorbed in the body. This is the reason why wound care studies utilizing lower wavelengths demonstrate the best clinical outcomes. The longer wavelengths allow deeper penetration of photon energy into the tissue.
The Class IV Therapy Laser provides wavelengths that achieve optimum cellular stimulation to enhance wound healing and penetrate deep within the tissues to encourage healing within tendons, ligaments, muscles, nerves, dermal layers, intra-articular structures and even the periosteal layer of bone.
The word energy means the ability or power to work or make an effort to accomplish some goal. A joule is the International System unit of energy or work. This unit of energy can be measured scientifically and the Companion Class IV Therapy Laser screen provides a digital readout of the number of joules emitted for each individual therapy session.
The power of the laser is the rate at which energy is delivered, not the amount of energy itself. The power settings on the Companion Therapy Laser can be selected from one Watt-10 Watts.
The power of the laser is expressed in Watts (W).
1 Watt=1 Joule/Second
Spot size is the area of the laser beam. It is the area on the tissue that is receiving therapy. The depth of penetration and the ability of the laser to provide enough photons deep enough within the tissues is function of the power of the laser together with the spot size and the wavelength of the photons.
Continuous and Pulse Emission
The Companion Laser is constructed to emit photons continuously for long periods of time. Remember, the goal of all laser therapy is to deliver as effective dosage of photons to the target tissues therefore achieving a positive physiological outcome. The terms pulsing and frequency are used interchangeably to describe the same concept. This concept is the interruption of energy flow on a predetermined basis.
The Companion Laser can be set to deliver continuous wave emission of photons or deliver these photons at numerous frequencies through convenient preset protocols.
Constantly moving the hand piece over the desired treatment area in one direction and then the next provides periods of photo-stimulation to the cells similar to a pulsed format.
Light Interaction with Tissues
When photons are absorbed by the cells, there is a transformation of the light energy into another form of energy. Depending on the wavelength of light, the photons may be strongly absorbed by one type of tissue and be transmitted or scattered by another. Each type of tissue has its specific absorption characteristics depending on its specific components (i.e. skin is composed of cells, hair follicles, pigment, blood vessels, sweet glands, etc). The laser system provides enough power to transmit photons deep within the tissue. This deep penetration of photons allows the stimulation of cells throughout all of the target tissues.
Laser Safety and Precautions
The number one safety concern with the use of any laser is the protection of the eyes of the patient, therapist, and anyone assisting in the procedure.
The eye of the animal or human absorbs infrared wavelengths just as it absorbs visible light. The light passer through the cornea with very little loss of power and the shape of the eye is designed to focus the light onto the retina. If this event happens, you will feel no sensation at all, particularly if the incidences are small and cumulative.
In addition to the possibility of direct exposure to the beam, laser light can also reflect and/or refracted in the same way as visible light, resulting in an indirect exposure to the eye. The most common reflective are: Jewelry (rings, watches, bracelets), exam table surfaces and hardware on collars and leashes. To avoid reflective exposure place all patients on a matt prior to treatment.
Eye Safety Measures
Always wear the goggles that are supplied with the laser unit (green lens). They are made specifically to filter out the wavelengths emitted by the laser system. DO NOT think ordinary sunglasses will suffice. Any person assisting with the procedure must wear protective eyewear.
If the laser therapy is to be applied around the head of the animal, care must be taken to protect the animal’s eyes from exposure. This can be accomplished in several ways, a piece of thick black felt can be held in place by hand directly over the patient’s eyes, depending on the size of the patient place the canine safety goggles (check manufacturer for goggles) on the patient. Always consider using an extra set of hands to hold the animals head still.
Do not merely use your hand to shield the animal’s eye as the laser beam can penetrate through portions of your hand.
Never look directly into the hand piece or into the direct path of the laser beam.
Always hold the hand piece in a perpendicular position to the area being treated.
After the therapy session is completed, immediately put the laser in standby mode.
Keep equipment clean and dry, do not expose to moisture.
Power supplies vary depending on the facility you are working in. If the laser fails to turn on, make sure there is power to that particular outlet. Only if it is absolutely necessary, should an extension cord be used.
There are several general safety guidelines concerning the dermis of the companion animal:
- When applying therapy to long haired patients, apply laser in opposite direction of the hair while using a comb or brush to lift the hair out of the way. In rare occasions you may have to consider shaving some of the fur.
- Some animals object to having their hair rubbed in the opposite direction or maybe an inflammatory condition makes this an uncomfortable procedure. In these cases, it may be beneficial to wet the hair with water before applying laser therapy.
- Hold the hand piece perpendicular to the dermis and ½ to 1 inch off the skin.
- Sensitive skin may elicit a “tingling” or ‘warming” sensation to the skin. Comforting restraint may have to be applied to the animal until the initial fear response from this stimulation has subsided.
- Be cautious when applying laser therapy to any patients on photosensitive medication. If any signs of hyperemia occur, evaluate fully before therapy is applied.
- When applying a large number of joules to a small area, watch the dermis closely for any signs of irritation or reaction. Evaluate each case on an individual basis before proceeding.
- Caution should be taken when applying laser therapy to patients with black fur and pigmented skin. The melon will attract the laser and cause more heat.
Clinical Application and Treatment Options
The goal of therapy with the Class IV laser should be:
- A relief of symptoms, i.e. pain and inflammation
- Restoration of the range of motion or function
- A reduction or elimination of their medication level
- A higher quality of life for the patient
Establishing a goal or desired outcome for photonic therapies will be instrumental in deciding in what protocol to follow and the frequency of therapy sessions to achieve that goal.
- Have a designated room to perform laser therapy
- Prior to turning the unit on, inspect the hand piece. If the glass is dirty or has hair in it, use compressed air and cotton tipped applicators with alcohol to clean the glass. Do not turn the unit on until the glass is dry.
- Plug in power cord
- Place the patient on a matt.
- Turn key to the “on” position
- Select preset setting
- Choose a setting
- Set the power, as instructed by the veterinarian, also see the accompanying manufacturers manual
- Press stand by
- Pick up hand piece
- Position over the site to be treated and hold the button down on the hand piece, emission will begin
- Keep the hand piece in a perpendicular position to the area being treated
- Keep the hand piece ½ to 1 inch off of the skin at all times
- Keeps the laser moving at all times, move slowly from right to left and then up and down to cover the whole surface. Do not use in a circular motion, this may cause you not to cover the whole area.
- Laser one inch beyond the area if interest in all directions
- The laser will make a sound while it is working
- Touch the area being treated occasionally to make sure it is not getting too warm. If so back away from the site and consult the veterinarian. Your setting may have to be lowered. Also make sure the hair is not burning, yes it is a possibility if it gets too hot.
- When finished, exit all the way to the main menu, turn off with key, unplug, gently wrap the cord, and cover the unit.