Ozone Therapy for Horses

Introduction

Ozone therapy has gained significant traction in equine medicine, particularly in sports horse management and rehabilitation. Its anti-inflammatory, antimicrobial, and regenerative properties make it valuable for the demanding conditions faced by performance horses – from joint stress and tendon injuries to reproductive challenges in breeding stock.

This guide covers the main applications of ozone therapy in horses, the evidence supporting its use, and important considerations for competition horses.

Musculoskeletal Conditions

Horses are athletes, and like human athletes, they suffer from joint problems, tendon injuries, and ligament damage. Ozone therapy can help by reducing inflammation, improving blood flow to injured tissues, and supporting the healing process. It’s commonly used for:

• Osteoarthritis and degenerative joint disease
• Suspensory ligament injuries (desmitis)
• Tendon injuries (SDFT, DDFT)
• Synovitis and capsulitis
• Bone spavin, ringbone, and other joint conditions
• Back pain and sacroiliac issues

Treatment usually involves injecting ozone directly into affected joints or around injured tendons, often combined with other regenerative therapies like PRP (platelet-rich plasma) or stem cells. Most horses tolerate the procedure well, and many owners report improved movement and soundness.

Clinical Detail

Intra-articular and peritendinous ozone injection has become an established component of equine sports medicine protocols. Mechanisms include:

• Modulation of inflammatory mediators (IL-1β, TNF-α, PGE2)
• Stimulation of chondrocyte and tenocyte metabolism
• Enhanced local oxygen delivery and perfusion
• Activation of endogenous antioxidant pathways
• Mild oxidative stimulus promoting controlled tissue remodelling

Ozone is typically used at concentrations of 10-30 μg/ml for joint injections, with protocols of 3-6 treatments at 1-2 week intervals. It integrates well with PRP, stem cells, and shockwave therapy as part of multimodal rehabilitation.

What does the research say?

Vendruscolo et al. (2018) studied the effects of medical ozone on healthy equine joints in a controlled trial, demonstrating safety and favourable synovial fluid changes without adverse effects (PLoS One), 13(5), p.e0197736.)

Orsini (2017) reviewed management of serious wound infections in horses including soft tissue injuries, noting ozone among emerging adjunctive therapies (Journal of Equine Veterinary Science), 55, pp. 18-26.

Reproductive Medicine

Breeding mares can suffer from uterine infections (endometritis) that reduce fertility and make it difficult to get them in foal. Ozone therapy offers an alternative to repeated antibiotic treatments, which is particularly valuable for mares with resistant infections or those being bred via AI where uterine health is critical.

Ozone is used for:

• Endometritis (uterine infection) — acute and chronic cases
• Supporting fertility in problem breeders
• Post-breeding inflammation management
• Mares with fluid accumulation in the uterus

Treatment involves flushing the uterus with ozonated saline or introducing ozone gas/foam. This area has some of the strongest evidence in equine ozone therapy.

Clinical Detail

Intrauterine ozone therapy has been extensively studied in mares with endometritis. Administration routes include:

• Ozonated saline lavage – well-tolerated, established safety profile
• Oxygen-ozone gas insufflation – direct uterine application
• Ozone foam preparations – commercial products with standardised dosing

Mechanisms in the uterine environment include: direct antimicrobial action against common pathogens (Streptococcus, E. coli, Pseudomonas); stimulation of endometrial angiogenesis and regeneration; modulation of local immune response; and reduction of persistent inflammation.

Studies have compared ozone favourably to systemic antibiotics for bacterial endometritis, with the advantage of significantly reduced antimicrobial resistance risk compared to systemic antibiotics.

What does the research say?

Equine reproductive applications have a robust evidence base:

Köhne et al. (2023) compared systemic trimethoprim-sulfadimethoxine with intrauterine ozone for bacterial endometritis, finding comparable efficacy (Frontiers in Veterinary Science, 10, 1102149. https://doi.org/10.3389/fvets.2023.1102149)

Ávila et al. (2022) demonstrated effectiveness of ozone therapy in treating endometritis in mares Journal of Equine Veterinary Science, 112, 103900. https://doi.org/10.1016/j.jevs.2022.103900

Donato et al. (2023) evaluated a commercial ozone foam preparation, confirming safety and positive effects on endometrial environment and fertility J Equine Vet Sci. 2023;121:104222. doi:10.1016/j.jevs.2023.104222.

Camargo Ferreira et al. (2021) showed that uterine insufflation with oxygen-ozone induced beneficial endometrial angiogenesis (Reprod Domest Anim. 2021;56(9):1176-1183. doi:10.1111/rda.13958

Mazzuchini et al. (2022) established the safety of uterine lavage with ozonated saline in mares (Arch Vet Sci. 2022;27(1). doi:10.5380/avs.v1i1.81197

Wound Healing

Horses are prone to distal limb wounds, which are notoriously difficult to heal due to poor blood supply, movement, and contamination. Ozone therapy can help by fighting infection, reducing proud flesh (exuberant granulation tissue), and supporting healthy tissue formation.

Applications include:

• Traumatic wounds, especially on lower limbs
• Surgical site complications
• Wounds with proud flesh formation
• Infected or necrotic wounds
• Wounds in difficult locations

Treatment typically involves ozonated oils or water applied topically, sometimes with ozone bagging for limb wounds.

Clinical Detail

Equine lower limb wounds present unique challenges: limited soft tissue coverage, high motion, and propensity for exuberant granulation. Ozone addresses multiple aspects:

• Antimicrobial action reduces bioburden without the resistance concerns associated with antibiotics
• Controlled oxidative stress modulates fibroblast activity
• Improved local oxygenation supports epithelialisation
• Anti-inflammatory effects help manage excessive granulation

What does the research say?

Filippo et al. (2020) studied ozonated sunflower seed oil for equine lower limb wounds, finding reduced hypergranulation, lower infection rates, and improved healing compared to pure sunflower oil (Revista Brasileira de Medicina Veterinária, 42(1), e113520. https://doi.org/10.29374/2527- 2179.BJVM1115321)

Repciuc et al. (2025) evaluated ozone bagging therapy in eight horses with chronic distal limb wounds, reporting improved healing, reduced inflammation, and positive clinical outcomes (Veterinary Sciences, 13(1), 16. https://doi.org/10.3390/vetsci13010016)

Other Applications

Respiratory Conditions

Ozone has been investigated for equine asthma (RAO/IAD) and respiratory infections. Systemic administration via rectal insufflation or ozonated saline may help modulate airway inflammation, though this application requires more research.

Hoof Conditions

Ozonated oils and water can be applied to hooves affected by:

• White line disease
• Thrush
• Hoof abscesses (post-drainage)
• Canker

The antimicrobial and tissue-supporting properties of ozone make it useful for these often-stubborn conditions.

Performance Recovery

Some practitioners use systemic ozone therapy to support recovery after intense competition or training. The proposed benefits include enhanced oxygen utilisation, antioxidant support, and immune modulation. While anecdotally popular, controlled evidence for this application is limited.

Semen Preservation

An interesting application: low-dose ozone treatment has been shown to improve equine semen quality during cooling and cryopreservation.

Pereira et al. (2022) found that low ozone dosages had positive effects on the cooling and cryopreservation of equine semen (Journal of Equine Veterinary Science).

Ribeiro et al. (2025) investigated the effect of ozone gas on stallion semen, reporting impacts on sperm quality parameters and potential fertility outcomes J Equine Vet Sci. 2025;145:105319. doi:10.1016/j.jevs.2024.105319

Gastrointestinal Support

Rectal ozone has been investigated for intestinal conditions:

Alves et al. (2004) studied ozone effects in equine jejunum reperfusion injury, relevant to colic surgery recovery (Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 56(4), 433–437. https://doi.org/10.1590/S0102-09352004000400002

Carvalho et al. (2022) evaluated the effects of ozone therapy via autohemotherapy and rectal insufflation on hematological, biochemical, and oxidative stress parameters in vaquejada athlete horses, finding significant changes in red blood cell counts and selected biochemical markers but no difference between the two treatment methods Arq Bras Med Vet Zootec. 2022;74(6):1024-1038. doi:10.1590/1678-4162-12733

Competition & Regulatory Considerations

For horses competing under national or international rules, ozone therapy requires careful consideration:

• FEI (International): Check current Equine Prohibited Substances List and guidelines. Ozone itself is not a prohibited substance, but competition rules may have specific requirements about treatments close to competition.
• National Federations: British Eventing, British Dressage, British Showjumping, and other bodies may have their own guidelines. Always verify current rules.
• Racing: BHA and other racing authorities have strict medication controls. Consult with your vet and the relevant authority.

Best practice: Maintain treatment records, inform your vet of competition schedules, and allow appropriate time between treatment and competition. When in doubt, contact the relevant governing body.

Administration & Safety

Ozone therapy is generally well-tolerated by horses. What to expect:

• Joint/tendon injections: similar to other intra-articular treatments
• Uterine treatments: performed during routine reproductive examinations
• Topical applications: straightforward; your vet may provide ozonated oil for home use
• Systemic treatments: rectal insufflation is simple and stress-free for most horses

Treatment is typically given as a series. Your vet will advise on the number of sessions and timing based on the condition being treated.

For Equine Veterinarians

Key safety considerations:

• Never administer ozone gas IV — risk of gas embolism
• Use appropriate concentrations for route (typically 10-40 μg/ml)
• Ensure adequate ventilation during procedures
• Consider competition status and withdrawal recommendations
• Document treatments thoroughly

Contraindications:

• G6PD deficiency: ozone’s oxidative mechanism poses risk to erythrocytes in deficient animals
• Uncontrolled hyperthyroidism: may increase susceptibility to oxidative stress
• Severe hepatic insufficiency: compromised antioxidant capacity may be overwhelmed
• Pregnancy: exercise caution with systemic ozone administration in pregnant mares

Ozone integrates well into multimodal protocols. Consider combination with PRP, stem cells, shockwave, and rehabilitation programmes for optimal outcomes.