Effects of stacked wedge pads and chains
On behalf of the AVMA Animal Welfare Committee, we would like to comment on the recent study by Everett et al, 1 which evaluated the effects of applying stacked wedge pads and chains to the forefeet of Tennessee Walking Horses for 5 days. Committee members are particularly concerned about the potential for misapplication of the study's data and results to the chronic, pervasive, and well-documented problem of soring in Tennessee Walking Horses and seek to provide context for those who may be unfamiliar with this practice.
Everett et al1 state, in reference to stacked wedge pads and chains, that “To our knowledge, no scientific evidence exists to suggest that the legal use of these instruments induces pain or stress in horses.” However, as early as 1982, Purohit2 reported for 2 horses that “Raising the heels 8 degrees caused both horses to stumble and tire easily. They did not regain a sound gait for about 7 days.”
Importantly, in their study, Everett et al1 did not work their horses at a running walk, the distinctive gait typically used for showing Tennessee Walking Horses, with a rider. Instead, horses were exercised without a rider at a flat walk on firm ground for 20 min/d by use of a horse walker apparatus. Because these devices are used on horses working at greater intensity and with an additional load placed on the horse by the weight of a rider, we do not believe that the study conditions adequately replicated the conditions under which these devices are typically used. Additionally, in the study by Everett et al,1 horses in the treatment group wore the stacked wedge pads and chains for an extremely short period—only 5 days. However, the Tennessee Walking Horse show season runs from approximately early March to early November, and horses used for show purposes typically wear so-called performance packages (ie, stacked wedge pads) for the entire season, if not year-round. The authors acknowledged this discrepancy, noting that “Tennessee Walking Horses that wear stacked wedge pads do so for extended periods, often years.” However, they do not, in our opinion, adequately address the severe limitations imposed by their short observation period.
In sum, we believe that Everett et al1 did not see behavioral changes or biochemical indicators of pain, stress, and inflammation because of the low exercise intensity and short time horses in their study wore the stacked wedge pads. Thus, we do not believe that findings from this study can be used to support a conclusion that use of stacked wedge pads and chains for training and showing Tennessee Walking Horses does not cause harm.
Michelle Sprague, dvm, Chair
Harry Werner, vmd
Representative, American Association of Equine, Practitioners, AVMA Animal Welfare Committee
1. Everett JB, Schumacher J, Doherty TJ, et al. Effects of stacked wedge pads and chains applied to the forefeet of Tennessee Walking Horses for a five-day period on behavioral and biochemical indicators of pain, stress, and inflammation. Am J Vet Res 2018;79:21–32.
2. Purohit RC. Thermography in diagnosis of inflammatory processes in horses in response to various chemical and physical factors. Report to the USDA, 1982. Available at: https://web.archive.org/web/20140202175740/http://www.ahdf.org/pdf/Soring/AuburnStudy.pdf. Accessed Jan 19, 2018.
The authors respond:
We are grateful that the AVMA's Animal Welfare Committee has a continuing interest in incorporating principles of evidence-based medicine when assessing animal well-being. Studies such as the one we reported1 are often controversial and can evoke emotional responses in people who, like us, have a sincere interest in improving animal well-being and eliminating practices that cause harm for no benefit. The scope of our study was limited to the acute effects of stacked wedge pads and light chains alone on the welfare of Tennessee Walking Horses. The long-term welfare effects of stacked wedge pads and light chains cannot and should not be extrapolated from the results of our study. Likewise, the use of training devices should not be equated with the harmful, unethical practice of soring. We are adamantly opposed to any procedure, like soring, that induces pain or harm in any animal of any species for the purpose of cosmesis, entertainment, or exhibition.
We stand by our statement that, to our knowledge, no scientific evidence exists to suggest that the legal use of stacked pads or simple chains induces pain or stress in horses. The unpublished report2 referred to by the AVMA's Animal Welfare Committee was extremely limited in scope and did not undergo rigorous peer review prior to publication. In our opinion, therefore, its findings do not constitute the type of scientific evidence needed to evaluate these issues. That portion of the report referred to by the AVMA's Animal Welfare Committee is titled “Preliminary Studies to Evaluate the Effects of Change in the Heel to Toe Ratio” and was limited to subjective observations of 2 horses shod with stacked wedge pads. Further study would require control groups and objective, measurable data that can be statistically analyzed. Findings based on subjective observations without the use of controls, such as those reported by Purhoit,2 are open to bias and should not be used as the basis for regulations.
We acknowledge the limitations of our study, such as lack of a rider, and agree that our study did not answer the long-term effects of stacked wedge pads applied to the forefeet of Tennessee Walking Horses. The results of our study, however, did demonstrate a lack of short-term adverse effects. Longer-term studies are required to determine the effects on well-being of horses in which these devices are used for long periods. We invite others to examine the long-term effects in a controlled, scientific manner, so that regulations concerning the use of these devices can be based on scientific evidence. These long-term studies, by their nature, require immense funding and must be designed to closely replicate typical training conditions and minimize variables inherent to long-term studies.
James B. Everett, dvm
Jim Schumacher, dvm, ms
Brian Whitlock, dvm, phd
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, Tenn
1. Everett JB, Schumacher J, Doherty TJ, et al. Effects of stacked wedge pads and chains applied to the forefeet of Tennessee Walking Horses for a five-day period on behavioral and biochemical indicators of pain, stress, and inflammation. Am J Vet Res 2018;79:21–32.
2. Purohit RC. Thermography in diagnosis of inflammatory processes in horses in response to various chemical and physical factors. Report to the USDA, 1982. Available at: https://web.archive.org/web/20140202175740/http://www.ahdf.org/pdf/Soring/AuburnStudy.pdf. Accessed Jan 19, 2018.
