New research has found that radiofrequency therapy was associated with increases in the size of an important spinal stabilising muscle in horses with chronic back pain, raising interesting questions about its potential role in equine rehabilitation.
The study, published in the journal Animals, investigated the effects of an eight-week programme of 448 kHz radiofrequency (RF) therapy on the multifidus muscle and movement of the thoracolumbar spine.
The multifidus is an important postural muscle which helps stabilise the spine. Atrophy and asymmetry of this muscle have previously been associated with back pain and spinal pathology in horses.
Researchers wanted to establish whether RF therapy could increase the cross-sectional area of the multifidus muscle and influence how the backs of horses with chronic pain moved.
Eight horses with chronic back pain studied
The study involved eight adult Thoroughbred horseball horses, aged between nine and 15 years.
All had experienced back pain for at least four months and had previously been diagnosed through imaging with overriding dorsal spinous processes. Veterinary examination also confirmed pain in the longissimus dorsi muscle in the thoracolumbar region.
Each horse received four radiofrequency treatments at two-week intervals over an eight-week period.
The treatment used a 448 kHz RF device, with therapy applied to both sides of the back between T9 and L6. Each session lasted a total of 40 minutes.
Researchers used ultrasound to measure the cross-sectional area of the multifidus muscle at seven locations along the thoracic and lumbar spine. Wearable inertial sensors were also used to assess changes in spinal range of motion while the horses trotted in-hand.
Measurements were taken before treatment, immediately following the first treatment, 24 hours later and again at eight weeks, 15 days after the fourth and final treatment.
What did the researchers find?
At the end of the eight-week period, the cross-sectional area of the multifidus muscle had increased significantly at all of the sites measured.
The largest increases compared with baseline were recorded at T18, where muscle cross-sectional area increased by 2.52 cm², followed by L5 with an increase of 1.90 cm² and T16 with an increase of 1.77 cm².
Importantly, the increases developed progressively over the treatment period rather than appearing immediately following treatment. The researchers said this suggests muscular adaptation rather than short-term swelling associated with the treatment.
Changes in spinal movement were more complex.
There were some increases in movement shortly after treatment, while after eight weeks there was reduced movement in parts of the thoracolumbar spine. The researchers suggest this pattern could potentially reflect improved spinal stabilisation associated with the increase in multifidus muscle size.
No adverse effects were reported and all eight horses completed the study.
What could this mean for horses with back pain?
The researchers suggest that radiofrequency therapy could potentially have a role as an additional treatment within a wider rehabilitation programme for horses with chronic back pain.
The findings are particularly interesting because the multifidus plays an important role in stabilising the spine, and loss of muscle mass has been associated with back pain and spinal problems.
However, the researchers stress that this was a small preliminary study.
Only eight horses were included and there was no separate untreated control group. All were Thoroughbred horseball horses with chronic back pain and overriding dorsal spinous processes, so the findings cannot yet be assumed to apply to the wider horse population.
Crucially, while the study demonstrated changes in muscle size and spinal movement, it did not establish whether these changes resulted in meaningful improvements in pain, athletic performance or long-term function.
The authors conclude that larger controlled studies are now needed to confirm the findings and establish whether the physical changes observed translate into genuine clinical benefits for horses.
The study, “Eight Weeks of 448 kHz Radiofrequency Therapy Increases Multifidus Muscle Cross-Sectional Area and Modulates Thoracolumbar Range of Motion in Horses with Chronic Back Pain”, was published in Animals on 6 August 2026.
Read the research
For the full study, which is open access, click here.
For supplementary data and statistical information, click here.
