Red light therapy—often called photobiomodulation (PBMT) or low-level laser therapy (LLLT)—uses specific wavelengths of red and near-infrared light (roughly 600–1100 nm) to influence how cells function. In veterinary medicine, it’s used mainly for:

Pain and inflammation (arthritis, back pain, soft-tissue injuries)
Wound and incision healing
Tendon and ligament injuries
Sometimes skin and hair-coat problems

Below is a practical, evidence-based look at how it works and what controlled studies in dogs and horses have actually found.

How Red Light Therapy Works in the Body

At the cellular level, red and near-infrared light stimulates mitochondria, modulates nitric oxide and blood flow, Influences inflammation and pain signaling, and supports tissue repair.

Light is absorbed by mitochondrial enzymes such as cytochrome-c oxidase. This can increase ATP (cell energy) production, which fuels repair processes. PBMT can promote local vasodilation and microcirculation, bringing more oxygen and nutrients to damaged tissue and helping clear metabolic waste.

Studies show down-regulation of pro-inflammatory mediators and changes in nerve conduction may reduce pain and swelling. PBMT can stimulate fibroblasts, collagen synthesis, and angiogenesis (new blood vessels), essential wound, tendon, and ligament healing.

Red light therapy is delivered directly to the skin over the target area for a set time and energy dose, repeated over days or weeks.

Evidence in Dogs

Osteoarthritis and Joint Pain

A 2022 trial in the American Journal of Veterinary Research evaluated PBMT in client-owned dogs with hip osteoarthritis. Dogs received either active PBMT or sham treatment over 3 weeks. PBMT dogs showed reduced pain scores, better function and gait, and improved joint range of motion, with benefits persisting up to 90 days.

Another blinded placebo-controlled trial in dogs used PBMT over 6 weeks. 9 of 11 dogs in the PBMT group were able to reduce their NSAID dose, compared with 0 of 9 in the sham group. Pain scores improved significantly more in the PBMT group.

For canine osteoarthritis, especially hips and elbows, multiple controlled trials show that properly dosed PBMT can reduce pain and improve mobility and may lower reliance on anti-inflammatory drugs.

Wound and Incision Healing

A randomized study in Beagles looked at full-thickness skin wounds treated with LLLT versus controls. Dogs receiving LLLT showed faster wound contraction and re-epithelialization compared with untreated wounds.

A 2019 prospective study of 9 dogs after surgery (orthopedic and soft-tissue procedures) found that incisions treated with LLLT received better cosmetic and clinical healing scores than untreated control incisions.

In a 2021 pilot trial, dogs with experimentally contaminated wounds were treated with LLLT. Compared to controls, laser-treated wounds showed lower bacterial counts Improved wound scores over time suggesting both antimicrobial and pro-healing effects at the parameters used.

Bone, Tendon, and Joint Function

An experimental study in dogs undergoing palatal expansion found that LLLT was associated with increased bone formation (osteogenesis) and better tissue remodeling.

A 2025 study of healthy police dogs found that a single PBMT session increased joint range of motion in treated limbs compared with untreated limbs, suggesting benefits for flexibility and performance.

Skin Disease and Hair Coat

A 2022 critically appraised review identified 19 clinical trials of LLLT for canine skin conditions (including wounds, chronic otitis, and non-inflammatory alopecia). Overall, the authors concluded that LLLT appears beneficial for several dermatologic conditions, but protocols and study quality vary, and more standardized research is needed.

Evidence in Horses

Back Pain and Muscle Soreness

A controlled clinical study in 61 western-performance Quarter Horses compared LLLT alone, Chiropractic care alone, and LLLT + chiropractic. LLLT significantly reduced back pain, muscle tightness, and trunk stiffness. And combining LLLT with chiropractic care led to even greater reductions in muscle hypertonicity and stiffness.

A 2023 preliminary study looked at HILT applied to the longissimus dorsi muscle in sport horses. HILT was reported as safe and associated with improved back pain scores and muscle tone, supporting its role as a supportive treatment for equine back pain.

Tendon and Ligament Injuries

Tendon and suspensory ligament injuries are a major reason horses receive laser/LED therapy. A 2022 study used a controlled model of suspensory branch injury to examine high-power laser therapy. Laser-treated limbs showed improved histological healing and collagen organization, and changes consistent with more advanced healing compared to controls.

A large retrospective series followed ~150 sports horses with tendon or ligament lesions treated with high-power, multifrequency laser therapy plus rehabilitation. At the 12-month follow-up, many horses had returned to competition, suggesting a favorable clinical outcome, though lack of a strict control group limits how strongly we can interpret these results.

A critical review in Veterinary Evidence looked at controlled studies of HILT for equine tendinopathy and desmopathy and concluded laser therapy may support tendon and ligament healing, but existing studies have methodologic limitations and non-standardized protocols, so stronger evidence is still needed.

What Conditions Are Most Supported by Evidence?

The follow conditions are most supported by evidence:

Osteoarthritis pain and mobility (hips and elbows)
Post-operative incision and acute wound healing
Some skin conditions and chronic wounds
Thoracolumbar back pain and muscle soreness
Tendon and suspensory ligament injuries
General performance recovery and stiffness

Benefits are most consistently reported when wavelengths and doses are within accepted PBMT ranges, treatments are repeated over several weeks, and therapy is used alongside appropriate veterinary care and rehab.

Safety, Limitations, and Practical Considerations

When used correctly, PBMT is considered very safe, with adverse effects rare and usually mild (e.g., temporary sensitivity).

Protocols vary widely between studies (different wavelengths, power, and treatment times), making it hard to prescribe a “one-size-fits-all” protocol.

For medical treatment, it’s best to work with a veterinarian who uses PBMT and follows evidence-based dosing. Home-use devices vary widely in power output; some may be too weak to reach deeper tissues like hip joints or equine tendons.

Bottom Line

Red light therapy is a genuinely promising, low-risk tool in veterinary medicine. In dogs, the best evidence supports its use for osteoarthritis pain and for enhancing wound and incision healing. In horses, research supports benefits for back pain and suggests potential advantages in tendon and ligament rehabilitation, though studies are fewer and not as robust.

Used under veterinary guidance and integrated into a full treatment plan, PBMT can help many dogs and horses move more comfortably, heal faster, and return to work or play sooner.