Pulsed electromagnetic field (PEMF) therapy is a treatment modality for horses in which pulses of electromagnetic fields are directed at specific parts of the body. Research suggests that PEMF can improve bone healing rates, regenerate and protect cartilage cells, and reduce pain and inflammation. [1]

Equine veterinarians commonly use PEMF to treat musculoskeletal injuries such as bone fractures, arthritis, and soft tissue damage in horses. [2] Some practitioners may use PEMF as part of an ongoing wellness routine to heal microfractures or microtears and reduce inflammation. [2]

More research is necessary to determine the efficacy of PEMF in treating common lameness conditions in horses. Although equine research is lacking, the potential benefits and minimal side effects of PEMF make it a desirable treatment option for owners and veterinarians to support healing and recovery.

PEMF Therapy in Horses

The use of pulsed electromagnetic field (PEMF) therapy originated when researchers discovered stress applied to a bone during weight bearing induced an electrical current within the bone cells. [3]

Researchers found these electrical currents enable bone tissues to sense mechanical forces, stimulating tissue remodeling (bone regeneration and structural changes) to better compensate for load bearing. [3]

PEMF therapy leverages this concept by producing an electrical current within the tissue, with the hypothesis that the stimulation will trigger tissue remodeling without having to apply additional mechanical stress to the bone. [3]

How PEMF Works

PEMF technology uses magnetic fields to create electrical currents within tissues. This makes it different from traditional electrical current therapies (e.g. shockwave therapy) in which an electrical current is produced directly by the machine. [3] This allows PEMF treatment to affect deeper tissues that other therapies cannot access using standard treatment methods. [3]

PEMF machines use coils of copper wire to produce an electromagnetic current. [1] By running electricity through the wires, the travelling electrons produce a magnetic field. [1]

The shape of the coil within the machine dictates the shape of the electromagnetic field. [1] Many PEMF machines have coils designed to produce a strong local effect so the practitioner can direct treatment to a specific area. [1]

Many PEMF machines also incorporate traditional electrical current treatment functionality as part of the device. [3] This allows practitioners to combine the effects of electrical current treatment, such as shockwave, with the effects of PEMF therapy.

Effects on Tissue

Research on the impact of PEMF therapy on equine tissues is limited, but there are several studies from human medical literature. These studies report variable efficacy, with one review showing that only 51% of PEMF studies identified cellular changes. [3]

According to studies showing positive effects of PEMF therapy, possible tissue changes include: [1]

  • Increased bone production (osteogenesis)
  • Increased regeneration of cartilage cells
  • Improved cartilage cell survival in joint tissues
  • Anti-inflammatory effects in treated tissues
  • Proliferation of stem cells

Bone Production

Many studies in PEMF-treated cells report cell proliferation or growth. [3] In particular, PEMF therapy increases proliferation of osteoblasts, the main cells responsible for producing new bone tissue. [3]

These findings are the basis for using PEMF therapy to treat bone fractures, as practitioners hypothesize increasing osteoblast proliferation promotes healing in the bone. [3]

Regeneration and Protection of Cartilage

Research suggests cartilage tissues may also respond to electrical stimulation, similar to bone. [1]

Research on the effects of PEMF on joint tissues shows that PEMF increases proliferation and survival of chondrocytes, the cells within joint cartilage. [1]

When cartilage is compressed during weight bearing, the fluid component of the cartilage is pushed out, and electrolytes (electrically charged minerals) within the fluid may produce an electrical current. [1] These electrical currents may produce a proliferation effect in cartilage, allowing it to compensate for increased load bearing. [1]

Studies also show that PEMF can increase the production of proteoglycan, a major component of cartilage. [1] Proteoglycan holds fluid within cartilage tissues, allowing the cartilage to act as a protective cushion during weight bearing. This cushioning effect pads the bones of the joint so they are not in direct contact, preventing pain associated with bone-on-bone rubbing and grinding when the joint is in use.

These findings suggest that PEMF may have applications in treating arthritis, a disease where the joint cartilage degenerates and causes pain. [1]

Anti-inflammatory Changes

Studies in rats show that PEMF may have an anti-inflammatory effect. [1] PEMF treatment can decrease the activity of neutrophils, a major inflammatory cell in the immune system. [1] Decreasing the activity of these cells can have a protective effect on structural cells within the joint capsule. [1]

Additionally, other studies show PEMF treatment can decrease levels of prostaglandin in a treated area. [1] Prostaglandin is a major inflammatory protein that plays a role in the pain sensation associated with inflammation. By decreasing prostaglandin levels in an area, PEMF may reduce pain perception and improve comfort. [1]

Stem Cell Proliferation

There is considerable research into the effect of PEMF on stem cells. Studies show PEMF can stimulate stem cells to transform into osteoblasts and chondrocytes. [3] As stem cell therapy is an increasingly popular treatment for lameness in horses, these findings suggest that PEMF therapy may have a synergistic effect with stem cell treatment.

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Uses in Equine Medicine

Most veterinarians use PEMF treatment to encourage healing in bone fractures or soft tissue injuries. [2] PEMF treatment may also reduce muscle pain and muscle spasm. [2]

Treatment protocols often depend on the specific machine used, and vary significantly. [2] Typical treatment protocols range from 30 minutes per day up to 8 hours per day. [1][2] PEMF can be used daily, with reports of daily use for up to 8 weeks in dogs. [2]

Each machine produces a slightly different electromagnetic field, which may have a different effect depending on the treatment area, frequency of treatment, and duration of treatment session. [3] Therefore, standardizing PEMF treatment protocols is difficult in both human and equine medicine. [2][3]

Parameters of the electromagnetic fields that vary between machines include: [3]

  • Intensity of the magnetic field
  • Duration of the pulses
  • Frequency of the pulses
  • Shape of the electromagnetic pulse

Some machines allow practitioners to adjust these settings to produce a desired effect. [1][2] There are currently few studies describing ideal PEMF treatment protocols for different conditions, so most practitioners use previous experience and anecdotal evidence to design a treatment protocol for each case. [2]

Scientific Evidence

Although most practitioners use PEMF to promote bone healing, there are several studies investigating uses of PEMF in treating other conditions. Further studies are necessary to determine the efficacy of PEMF for treating various conditions in horses and to design corresponding  treatment protocols.

Bone Healing

Most studies in equine literature focus on the use of PEMF in lameness cases, particularly injuries to bone. This parallels human medicine, where doctors use PEMF in orthopedic medicine to stimulate bone regeneration. [3]

Studies in human medicine show that PEMF can reduce healing time of bone fractures and may reduce associated pain. [3] In particular, PEMF may improve treatment rates of non-healing fractures. [3]

In horses, one study examined whether PEMF improved healing of bone grafts placed on the cannon bones of young ponies. [4] There was no significant difference found on X-ray between bones that received PEMF treatment versus the control group. [4] However, microscopic examination of the PEMF-treated grafts showed slightly improved graft incorporation into the cannon bone, suggesting a benefit. [4]

In canine research, PEMF treatment increased new bone formation in six dogs healing from bone surgery compared to controls. [5] These dogs were also faster to return to weight bearing on the affected limb, and the tissue had higher mechanical strength after recovery compared to the controls. [5]

Joint Disease

Some medical practitioners use PEMF as part of treatment protocols for patients with arthritis. [3] One review paper evaluating 11 human clinical studies showed pain associated with arthritis decreased after PEMF treatment, with additional improvements in physical function and joint stiffness. [3]

Another review of human medical literature revealed that half of the studies assessing PEMF therapy’s effectiveness on arthritis showed positive results. [6] The researchers concluded that PEMF is a safe and effective method to relieve pain and improve function in the short term for arthritis patients. [6]

There are no studies on the effect of PEMF on arthritis in horses, however there is a study in dogs. In this study, 40 dogs with arthritis received either PEMF treatment or no treatment. [7] The dogs treated with PEMF showed reduced lameness, reduced pain on palpation of the joint, and increased range of motion. [7]

Another study in dogs examined whether PEMF could improve healing rates of cartilage injuries treated with a cartilage graft. [8] The study showed PEMF-treated joints were more likely to have a normal microscopic appearance than untreated joints three months after graft surgery. [8]

Wound Healing

Some studies from human medical literature show increased wound healing rates when PEMF is part of the treatment protocol. [3] One study showed patients with chronic foot ulcers had an 18% reduction in wound size compared to 10% reduction in untreated patients. [3]

More research is necessary to confirm the benefits of PEMF on wound healing.

Back Pain

One study involving 20 polo ponies measured the effects of PEMF therapy on the mechanical nociceptive threshold (MNT), which indicates when a pain response is occurring. The researchers also examined the horses’ spinal flexibility. [9]

The ponies were separated into treatment and control groups. [9] The treated horses received 40 minutes of PEMF treatment for 10 days during the first phase of the study. [9] The study was then repeated with the treatment and control groups reversed. [9]

The study showed that there was no change in MNT or spinal flexibility for treated versus untreated horses. [9] This finding may not be representative of PEMF’s potential as a treatment for back pain, as only healthy horses participated in the study. [9]

Tendon Injuries

A study examining the effect of PEMF treatment on superficial digital flexor tendon inflammation showed that PEMF treatment did not improve lameness or the healing rate of damaged tendons. [10] From this study, the researchers concluded that PEMF does not have a significant impact on tendon injuries. [10]

Neurologic Disease

A specific type PEMF therapy called transcranial magnetic stimulation, is used in treatment protocols for nervous system disease in human patients. [3] Studies show that PEMF treatment can reduce inflammation and promote blood flow in the brain to benefit Alzheimer’s patients. [3]

In dogs and cats, studies show that PEMF can improve treatment outcomes after spinal cord injury. [11] Spinal cord injury often results in paralysis of the hind limbs with no pain or touch sensation.

One study on dogs with intervertebral disc disease causing spinal cord damage showed increased touch sensation and improved proprioception (awareness of limb placement) after treatment with PEMF. [12] A similar study showed dogs required less pain medication and had improved healing rates post-surgery with PEMF treatment. [13]

Similar results were found in cats with spinal cord damage. Cats receiving PEMF treatment recovered hindlimb function sooner than study subjects who did not receive treatment. [14]

Side Effects

There are few reports of side effects from PEMF therapy. [2] This treatment is considered safe for most horses.

PEMF treatment should not be directly applied locally to areas with known or obvious: [2]

  • Metal bone implants
  • Tumors
  • Open wounds
  • Sites of infection or inflammation, particularly of joints

Additionally, pregnant mares should not receive PEMF treatment. [2]

Summary

Pulsed electromagnetic field (PEMF) therapy is a promising treatment modality for horses with compelling evidence from human medical literature. It may be beneficial to support rehab and recovery for a number of muscular and skeletal injuries in horses.

  • PEMF involves treating an area with pulses of electromagnetic fields to stimulate tissue healing and proliferation
  • PEMF may improve bone healing rates, reduce inflammation, and control pain
  • More scientific research is necessary to determine optimum treatment protocols and efficacy in horses
  • PEMF has few reported side effects and is considered safe for most horses

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References

  1. Ganesan. K. et al., Low Frequency Pulsed Electromagnetic Field — A Viable Alternative Therapy for Arthritis. INDIAN J EXP BIOL. 2009.
  2. Schlachter. C. and Lewis. C., Electrophysical Therapies for the Equine Athlete. Veterinary Clinics of North America: Equine Practice. 2016. doi: 10.1016/j.cveq.2015.12.011.
  3. Flatscher. J. et al., Pulsed Electromagnetic Fields (PEMF)—Physiological Response and Its Potential in Trauma Treatment. IJMS. 2023. doi: 10.3390/ijms241411239.
  4. Kold. S. E. et al., Preliminary Study of Quantitative Aspects and the Effect of Pulsed Electromagnetic Field Treatment on the Incorporation of Equine Cancellous Bone Grafts. Equine Veterinary Journal. 1987. doi: 10.1111/j.2042-3306.1987.tb02603.x.
  5. Inoue. N. et al., Effect of Pulsed Electromagnetic Fields (PEMF) on Late-Phase Osteotomy Gap Healing in a Canine Tibial Model. Journal of Orthopaedic Research. 2002. doi: 10.1016/S0736-0266(02)00031-1.
  6. Markovic. L. et al., Effects of Pulsed Electromagnetic Field Therapy on Outcomes Associated with Osteoarthritis. Wien Klin Wochenschr. 2022. doi: 10.1007/s00508-022-02020-3.
  7. Pinna. S. et al., The Effects of Pulsed Electromagnetic Field in the Treatment of Osteoarthritis in Dogs: Clinical Study. Pak Vet J. 2013.
  8. Stefani. R. M. et al., Pulsed Electromagnetic Fields Promote Repair of Focal Articular Cartilage Defects with Engineered Osteochondral Constructs. Biotechnology and Bioengineering. 2020. doi: 10.1002/bit.27287.
  9. Biermann. N. M. et al., The Effect of Pulsed Electromagnetic Fields on Back Pain in Polo Ponies Evaluated by Pressure Algometry and Flexion Testing—A Randomized, Double-Blind, Placebo-Controlled Trial. Journal of Equine Veterinary Science. 2014. doi: 10.1016/j.jevs.2013.10.177.
  10. Javadi. S. R. et al., Effects of Pulsed Electromagnetic Field as a Supplement to Topical Dimethyl Sulfoxide and Controlled Exercise in Treatment of Equine SDF Tendonitis. Iranian Journal of Veterinary Medicine. 2021. doi: 10.22059/ijvm.2020.296949.1005061.
  11. Hyytiäinen. H. K. et al., A Systematic Review of Complementary and Alternative Veterinary Medicine in Sport and Companion Animals: Electrotherapy. Animals. 2023. doi: 10.3390/ani13010064.
  12. Zidan. N. et al., The Effect of Electromagnetic Fields on Post-Operative Pain and Locomotor Recovery in Dogs with Acute, Severe Thoracolumbar Intervertebral Disc Extrusion: A Randomized Placebo-Controlled, Prospective Clinical Trial. Journal of Neurotrauma. 2018. doi: 10.1089/neu.2017.5485.
  13. Alvarez. L. X. et al., Effect of Targeted Pulsed Electromagnetic Field Therapy on Canine Postoperative Hemilaminectomy: A Double-Blind, Randomized, Placebo-Controlled Clinical Trial. Journal of the American Animal Hospital Association. 2019. doi: 10.5326/JAAHA-MS-6798.
  14. Crowe. M. J. et al., Exposure to Pulsed Magnetic Fields Enhances Motor Recovery in Cats. Spine. 2003.