Class 4 laser therapy is a highly regarded innovative therapeutic technology, featuring advantages including pain-free, non-invasive, non-surgical, drug-free treatment with virtually no side effects. Thanks to its gentle and safe therapeutic profile, this technology is gaining widespread attention and recognition across the global veterinary industry. It received FDA certification and approval as early as 2003. As a pioneer in China’s Class 4 laser therapy device sector, Vaymed is committed to applying cutting-edge modern technologies such as Class 4 laser therapy to pet healthcare, safeguarding animal well-being and helping every furry companion enjoy a healthy and happy life.

Nevertheless, some veterinary practitioners remain unfamiliar with this technology.

What is Class 4 Laser Therapy?

Also known as High-Intensity Laser Therapy (HILT), Class 4 laser therapy irradiates lesioned tissues with specific-wavelength red and near-infrared light. It stimulates metabolism at the cellular level and triggers a series of photochemical reactions to deliver analgesia, relieve inflammation and promote tissue repair and healing. Compared with Class 3 lasers, Class 4 lasers provide superior tissue penetration. Take Vaymed laser therapy devices as an example: the maximum effective penetration depth reaches 15 centimeters. Treatment sessions are shorter and more efficient allowing therapeutic energy to be rapidly delivered to deep-seated tissues such as nerves, muscles, ligaments and tendons to accelerate recovery.

This photochemical effect triggers multiple cellular responses, mainly including:

Stimulation of adenosine triphosphate (ATP) production

Activation of the cellular respiratory chain

Elevated DNA and RNA synthesis

Promotion of collagen synthesis

Increased concentrations of β- endorphins and serotonin

Abundant clinical cases confirm that Class 4 laser therapy covers approximately 80 % of clinical indications and is applicable to a wide range of muscular, tendinous, articular and other disorders. Its key therapeutic effects are detailed below.

1. Pain relief without pharmaceutical intervention

Analgesia is one of the core strengths of Class 4 laser therapy. Many practitioners note that Class 4 laser therapy serves as an excellent alternative when pain‑killing medications are undesirable for pets. Pain relief does not rely on thermal effects or improved circulation; instead,it results from the combined action of multiple mechanisms:

①  Inhibition of pro-inflammatory pain-mediating substances and reduction of tissue swelling;

②  Reduction of nociceptor sensitivity and pain-signal transmission to the brain;

③  Stimulation of the endogenous secretion of natural analgesics such as β-endorphins, thereby increasing pain tolerance and alleviating discomfort;

④  Repair of damaged tissues to address the underlying causes of pain.

2. Effective inflammation Management

Class 4 laser therapy addresses a broad spectrum of inflammatory conditions including stomatitis, arthritis and tendinitis. Rather than directly eliminating inflammation, it modulates cellular status and immune responses to restore excessively heightened inflammation to physiological baseline levels.

Laser photons are absorbed by intracellular mitochondria and activate intrinsic signalling pathways: production of pro-inflammatory mediators such as TNF-α and IL-1β is reduced, while anti‑inflammatory repair factors including IL‑10 and TGF-β are up-regulated. Macrophages are driven towards a reparative phenotype, preventing tissue injury caused by excessive neutrophil accumulation. Local blood and lymphatic circulation improves to diminish oedema, and antioxidant capacity is enhanced to lessen oxidative tissue damage, thereby calming excessive inflammation and facilitating tissue recovery.

3. Rehabilitation for acute and chronic injuries

Clinically, injuries within two weeks of onset are defined as acute, while those lasting longer than two weeks are classified as chronic.

Acute injuries: Through photobiomodulation, laser therapy shortens the inflammatory phase, activates reparative cells, boosts angiogenesis and granulation-tissue formation, accelerates wound healing and lowers scar-formation risk.

Chronic injuries: Macrophages are induced to adopt a reparative phenotype; persistent inflammation is resolved; dormant repair‑competent cells are activated; local blood perfusion improves; and long‑standing lesions gradually heal.

4. Dermatological applications: wound and scar repair

Class 4 laser therapy can be applied to wounds and scar tissue. Photons absorbed by mitochondria activate cellular signalling cascades, regulating inflammation and macrophage function to support healing of acute and chronic wounds. It modulates fibroblast activity and collagen metabolism, softens scars, ameliorates scar contracture and relieves local inflammation and pain.

5. Adjuvant management of neurogenic oedema

Class 4 laser therapy provides an adjuvant intervention for neurogenic oedema: it reduces microvascular permeability, inhibits neurogenic inflammatory mediators, enhances microcirculation and lymphatic drainage and decreases fluid extravasation. It helps resolve acute oedema and reduces flare‑up frequency in chronic oedema. Laser therapy is purely symptomatic adjuvant care and must be combined with treatment for the underlying primary disease.

Class 4 laser therapy has extensive clinical applications. Nonetheless, operators and bystanders must wear laser‑safety goggles during procedures. Furthermore, laser therapy is contraindicated under the following circumstances:

Do not direct the laser beam into the eye.

Do not irradiate the tumor site

Do not irradiate actively bleeding tissue

Do not directly irradiate the pregnant uterus