Light and Laser Therapies for Horses

Updated March 29, 2024 | By: Andris J. Kaneps, DVM, PhD, DACVS, DACVSR

Laser Therapy for Horses

Lasers (also called photobiomodulation) have proven their place among the most valuable therapeutic tools in human and veterinary medicine. The word “laser” is an acronym for Light Amplification by Stimulated Emission of Radiation.

Laser light is highly focused and is emitted in a specific wavelength and frequency for the best penetration and optimal biologic effect on the target tissues.

The laser stimulates the cells causing an increase in ATP (adenosine triphosphate) levels - the main energy source for all cellular functions. This stimulation enhances tissue repair and cellular regeneration, which translates to better circulation, healing, and pain relief.

Types of Lasers Used on Horses

Lasers are categorized into classes depending on the potential to damage the human eye, not according to their effect on other tissues.

• Class 1 lasers cannot damage the eye
• Class 2 lasers may cause eye damage only with prolonged, direct eye exposure occurs
• Class 3 lasers emit energy between 1 and 500 milliwatts (mW) and can cause eye damage under special circumstances
• Class 4 lasers have higher energy emit at 500 mW and greater and can cause significant eye and tissue damage if not used properly.

The most commonly used types of therapeutic lasers on horses are Class 1 and 3 (known as cold or low-level lasers) and Class 4 (high-power or regenerative lasers).

Cold laser therapy has been proven effective in accelerating wound healing and is a regular treatment method for tendon and ligament injuries. A regenerative laser is more powerful and delivers light at a higher wavelength but can be harmful if used incorrectly. That’s why only veterinarians can administer Class 4 lasers and require safety measures to protect the eyes and skin from burns.

Understanding Laser Wavelength and Frequency

Laser wavelength and frequency of light pulses affect the tissue response. For example, a wavelength of 900 nanometers (nm) will penetrate the skin most effectively to treat tissues such as a tendon injury. While a wavelength of 470 nm has minimal skin penetration and is most effective for treating superficial wounds.

A laser frequency of 2000 mHz is effective for pain relief but will result in slower tissue healing than a 250 mHz frequency. These factors determine how your veterinarian will establish a laser treatment protocol for your horse’s specific injury.

Cold Laser Benefits for Horses:

• Reduces inflammation
• Stimulates circulatory and lymphatic systems
• Enhances wound healing
• Reduces swelling and tissue repair time
• Helps removes cellular waste

How Cold Lasers are Used on Horses:

• Frequency and the number of treatments depend upon the injury and the specific laser
• No matter what class of laser, always wear safety glasses and never look directly into the laser
• The horse’s coat length and skin pigmentation will affect the penetration of the laser

Examples of Laser Therapy in the Barn:

• Adjunct treatment for a tendon or ligament injury such as tears, tendinitis, or desmitis
• Aiding in wound repair as lasers stimulate the growth factors, collagen production and reduce superficial infection

Red and Infrared Light Therapy for Horses

Light therapy (also known as phototherapy) is the therapeutic use of visible and invisible light. Light is part of the electromagnetic spectrum that is measured by wavelength.

The entire spectrum includes potentially harmful wavelengths that include X-rays and gamma rays, visible wavelengths (includes what our eye can see), and radio wavelengths (can be passed around the globe).

This type of light therapy only penetrates the skin about 1/8th of an inch (5mm), yet heat generated by the light spreads deeper. Red light is visible and most effective for treating tissues on the surface of the skin. While infrared light is invisible and has a slightly longer wavelength. This allows for a slightly deeper skin penetration than red light. Light-emitting diodes (LED) are used to generate these types of wavelengths.

Shining Light on Healing

Red light and near-infrared light may kickstart the body’s biological processes. The wavelengths are absorbed into the mitochondria - the powerhouse within each cell. This boost in energy production helps the body to work more efficiently. In turn, the body has better circulation and improved transport of oxygen and nutrients, which then reduces pain and inflammation.

From Outer Space to the Barn

NASA utilized red LED lights to grow plants on the space shuttle. Then they turned the lights on the astronauts themselves to study their effects on cells inside the human body. They found the red light helped their wounds heal faster, and further research has shown positive effects of infrared light on cellular function, too.

There are numerous studies on light therapies in humans and animals, however, there is not a clear consensus in the equine veterinary community on their effectiveness, standards for application, or dosage. For example, a Swedish study found there to be no positive wound healing effects on horses, while human studies have shown the opposite.

As researchers continue to study the best protocols for horses, there is a multitude of anecdotal or subjective benefits and a wide range of potential uses for light therapy. Low-level light therapy can be administered by horse owners with convenient battery-powered devices and pads. These products can be placed over the back, hindquarters, or shoulders.

Benefits of Red and Infrared Light Therapy for Horses May Include:

• Possible lessening of pain and inflammation
• May stimulate the production of ATP (fuels cellular function)
• Red light may boost the production of collagen

How Light Therapies are Used on Horses:

• Treatment depends on the specific device’s recommendations and is not designed to be used in place of veterinary care
• Depending on the device, its directions may recommend wearing protective eyeglasses

Examples of Light Therapies in the Barn:

• Targeting the light at acupuncture trigger points
• A horse standing under a solarium for warmth and treatment
• Administering the light across the horse’s topline or targeted in areas like the hocks before or after exercise to help ease sore or stiff muscles

Difference Between Light and Laser Therapies for Horses

There is almost a complete library full of names when it comes to laser and light therapies. Their names are often used interchangeably (whether correct or incorrect), including:

• Low-level laser light therapy
• Low-power laser therapy
• Non-thermal LED light
• Infrared laser
• Laser phototherapy
• Soft laser therapy
• Therapeutic laser

Both laser and LED beams stimulate the cells within the body.

Laser emits a beam of coherent light, meaning the light is comprised of waves of the same frequency and tightly focused. This unique coherent light radiates in a narrow, direct path (referred to as collimated) to penetrate deeper tissues. Red and infrared light emitted through LEDs are non-coherent and better used to treat more superficial tissues.

Red light therapy utilizes wavelengths that are visible to the human eye, but the eye cannot see light from cold lasers. Many companies create devices that emit both laser and non-coherent light hybrids to facilitate aiming of the laser.