Equine Electrotherapy – Horse

Electrotherapy, which directs small electrical currents through the skin for medical treatment, is widely used in human sports medicine and rehabilitation to treat injuries and improve performance. Various methods have made their way into equine sports medicine and rehabilitation. Electrotherapy treatments are built around energy sources that range from sound to vibrations.

electrical stimulation

Electrical stimulation is commonly used for pain relief. The changing pulse durations and intensity mimic nerve patterns, causing the muscles to contract. Transcutaneous electrical nerve stimulation (TENS) operates at 250 hertz (Hz), with the nerves closest to the surface of the skin being activated first. Treatment occurs over 20-30 minutes, continuously or intermittently throughout the day. Use in humans has been well researched, but evidence for use in horses is limited.

Neuromuscular electrical stimulation (NMES), commercially available as functional electrical stimulation (FES) units, is used to stretch large muscles. Similar to TENS, it has longer pulse durations, variable amplitude, and frequency >50 Hz. Frequency is increased over three to five weeks, by one to five sessions per week. One study reported that FES improved contractility and reduced muscle spasms in the hippocampus muscles, those on the back just below where the saddle sits (Schils et al. 2014).

Because these methods involve placing electrodes on the skin, irritation can occur at the contact points if left on for too long. Minimal complications have been reported with proper use.

magnetic waves

Pulsed electromagnetic field (PEMF) therapy uses low-frequency magnetic waves to generate electric currents in tissues. These units are found as blankets and coils with coils and batteries built in, with the coil size determining the size and strength of the magnetic field. Treatment protocols vary by manufacturer, and side effects are rare. Research has not shown any significant soft tissue benefits for horses or humans. However, evidence suggests that its best application may be in bone healing, such as in cases of slow-healing fractures (Schlacter and Lewis, 2016).

Sound and pressure waves

Therapeutic ultrasound uses vibrational frequencies of 1-3 megahertz (MHz) to generate waves of sound energy (inaudible to humans) that can reach deep tissues – effectively a micro-tissue massage. It is used to relieve pain, reduce muscle spasms, and increase blood flow. Treatments occur daily for seven to 10 days, can be pulsating or continuous, and may include the application of heat. Research has shown that horses’ tendons are effectively warmed with therapeutic ultrasound, but muscle heating has not been reported.

Extracorporeal shock wave therapy uses pressure waves that increase as they move through tissues. This results in microdamage caused by the formation and collapse of tiny air bubbles, creating new blood vessels and increasing blood flow. The protocols consist of three to six treatments at two to three week intervals to allow for proper healing of the microtrauma. Unlike therapeutic ultrasound, which can reach deeper tissues, shock waves only penetrate 50-110 mm. Studies have reported improved recovery and reduced lameness in cases of paraesthesia of the fore and hind limbs (Caminoto et al., 2005; McClure et al., 2004). Another study showed reduced lameness in horses with induced osteoarthritis, but no beneficial effects were identified in synovial fluid, tissue, or cartilage of the affected joint. Since pain relief is reported for several days, masking a horse’s pain level, organizations such as the Fédération Équestre Internationale (FEI) have regulations on when to withdraw before competition. Under California Racing Board (CHRB) regulations, horses in California cannot race or work until 10 days after shockwave therapy.

Good skin contact is required, as neither shock waves nor ultrasounds act through air. Patients should be clean and desiccated, if possible. Gel is used to increase contact.

laser

Laser therapy can reduce pain and inflammation. It has similar benefits to acupuncture and is often used on similar trigger points. Low power lasers were used <500 ميغاواط) وعالية الطاقة (الخرج> 500 MW) in horses. Daily, weekly, or monthly treatments are given for five to 30 minutes, depending on the location and type of infection. Tissue temperature can rise if treatment is not applied properly. Studies show that lasers are beneficial for tendon healing (Pluim et al. 2018). Research is ongoing into the effects of laser therapy on wound healing.

vibration

Vibrating plates generate energy in an up-and-down or side-to-side direction, with the amplitude and speed determining the amount of vibration. The vibrations are believed to improve blood circulation through involuntary muscle contractions. Vibration plates may also enhance joint stability by stimulating and strengthening the muscles associated with it. Sessions usually last 10 to 15 minutes. To date, no unwanted effects have been reported. One study showed no changes in bone markers for horses that underwent vibration therapy (Carstanjen et al., 2013). However, bone density has been reported to be preserved in stalled horses (Hulak et al., 2015), and muscle has increased in horses that underwent vibration therapy for 60 days (Halsberghe et al., 2016). Whole body vibration therapy may also be beneficial in increasing the rate of hoof growth (Halsberghe 2018).

Electrotherapy is an evolving field. Although many applications are non-surgical, individual horses may not tolerate some of the methods. Many of the modalities are unstructured, and although research is ongoing, there are few peer-reviewed studies available. It is important that you work with your veterinarian to determine the best course of treatment for your specific condition.

This article was originally written by Amy Young and published on Horse report from the Center for Equine Health at the University of California, Davis College of Veterinary Medicine in summer 2022.

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Caminoto, EH, Alves, et al. Ultrastructural and immunohistochemical evaluation of the effects of extracorporeal shock wave therapy in the hind limbs of horses with experimentally induced suspensory ligament inflammation. May 2005. American Journal of Veterinary Research, 66(5), 892-896.

McClure, SR, VanSickle, D., Evans, R., Reinertson, EL, & Moran, L.. Effects of extracorporeal shock wave therapy on the histological and ultrasound appearance of collagenase-induced suspensory ligament inflammation. April 2004. Ultrasound in Medicine and Biology, 30(4), 461-467.

Blum M, Martins A, et al. Short- and long-term follow-up of 150 sport horses diagnosed with tendinopathy or lipodystrophy by ultrasound examination and treated with high-energy laser. August 2018. Veterinary Science Research, 119, 232-238.

Karstanjen B, Belali M, et al. Short term whole body vibration exercise in healthy adult horses. 2013. Polish Journal of Veterinary Science 16(2), 403-405

holac e, The effect of whole body vibration on bone density in a stuttering horse. 2015. Middle Tennessee State University ProQuest Publishing

BT Halsberghe, P. Gordon-Ross, et al. Whole body vibration affects the cross-sectional area and symmetry of m. multifidus of the thoracolumbar spine in the horse. Oct. 2016. Equine Veterinary Education, 29: 493-499.

BT Hallsberg. The effect of whole body vibration for two months on the horse’s hoof growth rate: an experimental study. August 2018. Research in Veterinary Sciences, 119, 37-42

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