Reducing chronic back pain and inflammation in horses using a commercial herbal liniment- a Research Overview

Lower back pain is a very common acute and chronic problem in horses. It also presents challenges both to diagnose and treat effectively, especially out in the field where both equipment and practical treatment options can be limited. In a field test involving 18 horses in a university riding program, herbal liniment Sore No-More Performance Ultra by Arenus Animal Health was found to significantly reduce measurable signs of pain and inflammation by 23 days of use while producing no irritating side effects. Sore No-More Performance Ultra shows promise as a practical topical option to address lower back pain without the concerns of harsh chemicals found in other liniments.

Lower back pain is a common problem in horses, especially in riding programs where horses may be under saddle and ridden multiple times a day by different riders of varying experience levels. Horses may experience both chronic and acute forms of lower back pain. Although different underlying causes can exist for lower back pain, specific diagnosis is not always practical out in the field. Treatment options can also be limited and have variable efficacy. Non-steroidal anti-inflammatory (NSAID) use has long-term toxicity concerns often requiring other approaches for chronic pain and performance training for competition. Muscle relaxants like methocarbamol can “dull” a horse’s responses and can affect performance and rider safety. Other modalities of addressing back pain, including shockwave, acupuncture and chiropractic adjustment can have variable degrees of efficacy. One very practical approach to addressing lower back pain chronically while avoiding the risk of long term injectable and oral medication use could be a topical product. A topical liniment is very portable and easy to apply in the field. However, topical liniments have not been traditionally used due to concerns about burning and irritation at the application site, along with a perception of low efficacy. In this study, the goal was to utilize the herbal liniment Sore No-More Performance Ultra by Arenus Animal Health, which contains no harsh chemicals, and see its possible benefits for a population of riding horses experiencing lower back pain.

This study included the use of 18 horses from the Truman State University riding program. This included 5 mares and 13 geldings with an average age of 11.7 years, ranging from 5 years to 20 years of age. Horses were selected for the study based on a veterinarian’s exam confirming the presence of mild to moderate lower back pain. Additional diagnostics to determine the specific pathology causing lower back pain was not pursued, in an effort to both provide uniformity for the study, as well as to help simulate the limitations that many field veterinarians have in diagnosing and treating these conditions. After initial identification for the study, horses were rested for a full 30 days from any work. On Day 0 of the study, these same horses were then re-palpated by the same veterinarian to confirm the continued presence of chronic lower back pain.

Pressure algometry is a method that uses measured, focused pressure to determine the lowest stimulus that will arouse a sensation of pain. It is considered a method of excellent reliability for humanely measuring pain response. On Day 0 of the study, pressure algometry was first applied to determine pain response, using a Wagner FDX 20 pressure algometer. All horses showed a pain response at 5.9kg/cm2, which was used as a baseline for the study. Initial readings were obtained by the supervising veterinarian who trained an evaluator for the remainder of the study. On Day 2, the trained evaluator’s readings were not found to be significantly different from those on Day 0 with the supervising veterinarian, indicating good consistency of readings.

Thermography is a non-invasive test method using an infrared camera to detect heat patterns. This has traditionally been considered a reliable way of detecting inflammation in areas of the body that have increased heat and blood flow. In this study, thermal imaging measurements were collected using a Flir E-30 thermal imaging camera, which was operated throughout the study by a level 1 certified thermographer.

For all horses in the trial, the area of study and for application of the liniment was determined by dividing the spine into four sections, starting at the highest point of the withers, and ending at the sacroiliac joint. The third of the four sections, which was called section 3, correlated with the lumbar spine and was the area of focus for the study. Section 3 was further divided into nine total data point sections incorporating both the left and right sides of the lumbar spine. After initial pain assessment using algometry on Day 0 and Day 2, pain was assessed weekly during the study on Day 9, 16, 23, 30, 37, and 44 of the trial. As all horses in the study had initially been sensitive to 5.9kg/cm2, a negative response was assessed as no response to 5.9kg/cm2 of pressure from the algometer. Pain response was assessed as tightening of the muscles, dropping of the back, pinning the ears, and/or raising and turning the head. A 0-10 pain score was then developed. The score had an inverse relationship with perceived pain with a horse reacting to a lower level of pressure having a higher score on the scale. Each score above 0 indicated a 0.45kg/cm2 decrease in applied pressure from the algometer. For example, a horse with a score of 1 responded to 5.44kg/cm2 of pressure and a horse with a score of 10 responded to 1.36kg/cm2 of pressure. Thermal imaging temperature measurements were performed weekly in the same area of the lumbar spine but were collected on a day separate from the pressure algometry readings. The 18 horses in the study were divided randomly into treatment and control groups. The treatment groups received topical application of Sore No More Performance Ultra, a natural herbal liniment containing arnica, comfrey, rosemary, ginger, and witch hazel. Sore No More was applied over a 0.02cc/cm2 area. The control consisted of water and xanthium gum (an inactive ingredient in Sore No More Performance Ultra). In general, all horses in the trial maintained a very light schedule of riding during the week, taking off on weekends. For application of the treatment and control liniments, all horses were engaged in a short period of controlled exercise which consisted of 10 minutes on a lunge line. This was in addition to regular riding engagements at the university. On the days when thermal imaging was performed, temperature measurements were taken just prior to this controlled exercise. The treatment or control liniment was then applied immediately following this controlled exercise and thermal images were then taken at 15, 30, 45, 60, and 90 minutes following application of the liniment.

Algometry readings were recorded by horse, then divided into either the left or right side of the body, and further divided into the designated test points, with 9 test points per side. Individual readings were converted to pain scores, which were then pooled to establish an average pain score per side of body per test date.

Treated horses were found to have decreases in pain score from the beginning to the end of the trial, which was statistically significant (p>0.001). This correlated with a 2.87 decrease in pain score. Comparatively, control horses had an only 0.72 decrease in pain score (p>/=1.8).

Thermography temperature measurements were recorded by horse then divided into either the left or right side of the body and recorded as an average temperature of the sampling area. The average temperatures of the plotted sample areas were calculated using the standard Flir Tools thermographic camera software. Surface temperature readings for the left side and right side of horses in both groups had very consistent differences from highest to lowest readings. Control group horses showed a range of 1.45 degrees C and 1.49 degrees C between the highest and lowest readings for the left and right sides, respectively. Treatment group horses showed a 1.3 degrees C and 1.35 degrees C difference for the left and right sides, respectively. There was found to be a significant impact on temperature readings made by both the day of the trial, as well as the time following exercise and treatment application (both with p>0.0001). A significant decrease in surface temperature for both the treatment and control groups for both sides started at solution application and continued to 15 minutes post-application. However, liniment treated horses had a lower average temperature near the end of the first 30 days of the trial. Significant correlations were found around the time of Day 23-30 in both pain and thermography. While both groups saw some reduction in pain scores, the control group began to see increases in pain score again by Day 23. This contributed to a significantly lower pain response in the treatment group by Day 30. While the treatment group did also eventually develop higher pain scores, the time it took for this to occur was longer in the treatment group compared to the control group. Correlations during this period were seen with thermal temperature readings as well. Horses treated with Sore No More Performance Ultra liniment had a lower average temperature between Day 22 and Day 29 of the trial. This was seen a little earlier on the left side of the spine at Day 22, but both sides had lower temperatures by Day 29. The lower thermal temperature readings at Day 29 correlated closely with the reduced pain scores found at Day 30 in treatment group horses.

This study was designed to evaluate the effectiveness of the herbal liniment gel Sore No-More Performance Ultra as a practical therapy that can be used in the field to help reduce mild chronic back pain and inflammation in horses that must be continued in work. The study was designed with practicality in mind, utilizing horses from a university equestrian program that were required to continue in light work throughout the trial. Horses in the treatment group that received topical application of Sore No-More Performance Ultra showed a significant decrease in pain scores up to Day 30, while the control group demonstrated a decrease only up to Day 23. This led to a significant difference in pain scores between the treatment and control groups at Day 30. While pain scores did increase over time, this took longer to occur in the treatment group. A significant difference in surface temperature as measured by thermography was also found at Day 29 in the treatment group, which appeared to correlate with the lower pain scores. This correlation at weeks 3 and 4 of the trial would seem to imply that reducing inflammation may be effective in overall reduction of pain over time. These findings also demonstrate the utility of thermography as a tool to help evaluate back pain in horses. Although this study had a practical, “real-world” design using horses in an equestrian program to help demonstrate the ease-of-use benefits of a topical liniment, there were some limitations to the study design. Although only light work was maintained during the week and all weekends were taken off, the types of exercise and amount of time horses were engaged in varied. The number of riders and their experience levels also varied. Further trials could include a more standardized exercise program. To simplify an ease-of-use approach where advanced diagnostics are not as readily available in the field, specific underlying back pathology was not evaluated in the study, only a consistent level of lower back pain. Further trials could involve more diagnostics to help standardize evaluation for specific back pathologies. Sore No More Performance Ultra is an herbal liniment that does not contain harsh chemicals, allowing for a practical, safe, and easy to use method in the field that is also comfortable for the horse. Its ingredients include arnica, comfrey, rosemary, and ginger, processed in a unique and proprietary extraction process. Arnica is known to have analgesic properties, with comfrey, ginger, and rosemary known to exhibit anti-inflammatory properties. Overall, this trial demonstrated that Sore No-More Performance Ultra by Arenus does show promise as a practical and easy-to-apply topical therapy that can help horses experiencing chronic back pain and inflammation that must continue under regular work. The product could also be a great asset to the mobile veterinary practitioner who has limited ability to evaluate underlying pathologies for lower back pain and/or where more traditional treatment approaches are either less effective or demonstrate risk for long-term use.