Shock wave therapy is a noninvasive treatment used in human and veterinary medicine to relieve pain and improve healing in soft tissue injuries. It works by emitting high-energy sound waves to targeted areas, stimulating the body’s natural healing processes to reduce inflammation and increase bone and tissue formation. Horse owners and equine vets use shock wave therapy (also referred to as Extracorporeal Shock Wave Therapy, or ESWT) to treat horses of all breeds and disciplines for conditions including back injuries, lameness due to navicular syndrome, osteoarthritis, and tendon injuries.

A study conducted in 2022 and 2023 by Beau Whitaker, DVM, CERP at Brazos Valley Equine Hospital in Salado, Texas, was one of the first to look at the use of shock wave therapy to treat a respiratory condition in horses. The study used a PulseVet electrohydraulic shock wave device on horses with known respiratory conditions, and the results showed promise for alleviating the symptoms of multiple ailments.

Shock Wave for EIPH

Whitaker’s study was designed to assess the effect of shock wave therapy on horses with Exercise Induced Pulmonary Hemorrhage (EIPH), colloquially known as “bleeding.” This condition may cause nosebleeds, shortness of breath, coughing, and excessive swallowing, and is seen almost exclusively in racehorses and speed event horses.

“Horse's capillary walls inside the lungs are very thin (0.5 microns thick) to allow efficient exchange of oxygen and carbon dioxide,” said Whitaker. “When the horse is running hard, the heart is beating four times per second, pumping blood through the capillaries at very high pressures. At the same time, the horse is taking in four gallons of air per minute. This creates very high negative pressures in the lungs that essentially exert a pulling force on the outside of the capillary. At some point, the pull and push forces exceed the ability of the capillary walls to stretch, and fissures are created that allow blood into the airway.”

The 21 horses used in the study were barrel racing horses that had exhibited nosebleeds, or otherwise had a high likelihood of EIPH. Each horse’s condition at the start of the research was evaluated through several different assessments. This included an endoscopy to screen for pathology in the upper airway; a thoracic ultrasound to evaluate the thickness of the membrane surrounding the lungs known as the pleura, and a bronchoalveolar lavage (BAL). This is when the lungs are rinsed and the resulting fluid is evaluated for red blood cell concentration and white blood cell concentration. The red blood cell concentration is graded 1 to 4, with 1 being the most clear and 4 being the most contaminated (indicating the most severe bleeding). The white blood cell and red blood cells are also evaluated on cytology to characterize the type and quantity.

Shock wave therapy was administered to the horses in the study using a PulseVet electrohydraulic shock wave device. After treatment, the horses were prescribed one week of light exercise before returning to their normal training routine. Each horse in the study competed in a barrel race within two to four weeks of the treatment and were re-evaluated by the research team within two days of the race.

The results brought good news for horse owners. The second round of BAL showed 16 horses improving at least one grade on red blood cell concentration, and of those, 10 improved at least two grades. No horses had an increased grade over the preliminary test.

Shock Wave for Equine Asthma

While Whitaker’s study was designed to evaluate the effects of shock wave on EIPH, the initial evaluation of the horses in the study showed that each had some degree of equine asthma syndrome. One indication of asthma is neutrophilia, the overproduction of a certain type of white blood cell called neutrophils. Sixty-five percent of the horses in the study showed an improvement in their neutrophil count by at least 6%.

“Based on our BAL findings, we saw a really interesting trend,” said Whitaker. “There was a very strong correlation between horses improving on the percentage of neutrophils in the BAL fluid and the horses that improved on bleeding. Elevated neutrophils in BAL fluid is the gold standard for diagnosis of equine asthma syndrome. It appeared that in the horses we treated, when we improved their asthma, we improved their bleeding, for the most part. This makes sense as asthma increases the negative pressures in the lungs by narrowing the airway and creating more resistance for air to flow.”

Asthma is a much more widespread condition than EIPH and can affect horses of all disciplines and levels of performance. While further research is necessary, this study into shock wave therapy showed promise as a safe, non-invasive treatment that could enhance the lives of a wide range of equines.

“Based on the results of the EIPH study, we started to research the effects of lung shock wave therapy on equine asthma syndrome, and the results so far have been fairly remarkable,” said Whitaker. “We have been treating horses that are presenting with a chronic cough with even better results than the EIPH study based on improving or resolving the cough. The study is ongoing, but it looks like a promising treatment for mild to moderate equine asthma.”

Shock wave therapy cannot be used within three days of competing at a USEF-licensed competition with some exceptions. Refer to GR414 in the USEF Rulebook for current rules and information.

Learn More:
Shock Wave Therapy Research
Shock Wave 101