Monday, January 08, 2018

Researchers: Tennessee Walking Horse Shoeing and Chains Caused No Pain, Stress or Inflammation in University of Tennessee Study

When efforts to increase Horse Protection Act restrictions on how Tennessee Walking horses are shod failed at the end of 2016, the shows went on, under the pre-existing rules, throughout 2017. Walking horse inspections by USDA and industry groups continued, but there were few new headlines. But the year ended with announcement of new research results on hoof pad stacks and pastern chains, conducted at the University of Tennessee Knoxville's College of Veterinary Medicine. The paper will be in the January 2018 edition of the American Journal of Veterinary Research, published by the American Veterinary Medical Association.  The horse in this photo wears pad stacks and chains on its front feet, as currently allowed under the Horse Protection Act, and is not one of the horses in the study. (Marty Barr photo)

Eight veterinarians and animal science researchers at the University of Tennessee Knoxville have collaborated on a study testing the effects of hoof pad stacks and chains on a group of Tennessee Walking horses. In what would literally be the closing hours of the 2017 calendar year, the American Journal of Veterinary Research (AJVR) posted the new research paper online.

The article describes the first research in more than 30 years aimed directly at factors affecting Walking horse welfare and show practices. While improved technology available today could either verify or challenge previous studies, which used thermography to evaluate potential negative effects of heavy shoes, pads, and chains, the new research used a different method and study design, but asked a similar question.

The new study evaluated the effects of pad stacks and chains on 10 Tennessee Walking horses by comparing them with 10 Tennessee Walking horses shod without pads, using simple St Croix heeled "keg" shoes.

The horses were exercised for 20 minutes each day on a horse walker, without riders, and without attempting speed or the show horse's characteristic running walk. They were tracked for five days.

The horses were subjected to blood tests to measure any changes in stress, pain, and inflammation indicators such as cortisol, substance P, and fibrinogen. The researchers found no significant changes in levels in the stack-and-chain horses when compared to the minimally-shod control horses.

A Tennessee walking horse shod with stacks and bands in Kentucky for a demonstration. The research horses at Knoxville also wore pastern chains. (Fran Jurga photo, Hoof Blog archives)

Rather than attempt to paraphrase the researchers' conclusion, the final sentences of the study's conclusion are an excellent summary of both the value and shortcomings of the findings:

"Although no evidence was found that these training devices, commonly applied to Tennessee Walking Horses, had an impact on horse welfare for the 5-day period of evaluation, the conditions under which the effects of these training devices were tested were not completely similar to those conditions used for Tennessee Walking Horses in training, and the results should not be generalized to the long-term use of these devices in horses performing the running walk. 

"Indeed, the effects of these devices should be examined when horses are exercised with a rider at a speed and duration typical of those demanded while horses are in training. The long-term effects of these devices should also be evaluated. However, despite the aforementioned limitations, the study findings should be considered when making evidence-based decisions regarding the welfare implications of the common practice of applying stacked wedge pads and chains to Tennessee Walking Horses."

The study was supported by the Tennessee Equine Veterinary Research Organization of the College of Veterinary Medicine, University of Tennessee.

The Hoof Blog reached out to UT's Professor James Schumacher, DVM, MS, PhD, DipACVS, corresponding author for the study at the University of Tennessee; he kindly gave some insight into the study, but also said, "I have no plans for other studies in this area."

• • • • •

As background, readers should know four facts.

1. The first is that while pad stacks of various types are worn by show horses of several disciplines and breeds, the more extreme Walking horse "package" has been singled out by critics because the use of the stacks and chains has been generally linked to illegal chemical or mechanical "soring" methods that intentionally use pain and discomfort to enhance front limb action in the show ring.

This study, unlike some of the previous research conducted in the 1970s and 1980s, shows no direct harm to the horse caused by the addition of pad stacks and chains alone. (Previous research was done on horses with scarred and unscarred pasterns and with varying weights of chains so direct comparison is not possible.) However, the UT authors state that a limitation of their study is that it does not test the effects of the equipment when worn for weeks or months at a time, or when worn tacked up with the weight of the rider and the exertion required to perform the elaborate, exaggerated show gaits.

2. The second important fact to know is that both the American Veterinary Medical Association (AVMA) and the American Association of Equine Practitioners (AAEP) have stated their preference for outlawing pad stacks and chains under a revised American Horse Protection Act. Unscrupulous trainers may (among other cruel measures) add excessive weight between or within pad stacks, trim hooves so short that each landing causes pain ("pressure shoeing"), and/or fail to relieve full tension on hoof bands after a performance or training session.

The case might also be made that even if the stacks and chains caused no harm by themselves, they make it difficult to inspect hooves for intentional soring.

3. The third fact is that, as far as is conveyed in the paper, the research at the University of Tennessee was conducted or funded by neither the US Department of Agriculture, which enforces the Horse Protection Act, nor by a Walking horse industry group. So far, no veterinary groups have made statements to either embrace or criticize the research. The show horse industry's Walking Horse Report called the research "highly credible".

“This is a peer-reviewed publication that carries a lot of weight,” said Mike Inman, CEO of the Tennessee Walking Horse National Celebration, referring to AJVR. “The results were favorable as it applies to proper use of the performance package and action device.”

4. Last year's proposed ban of pad stacks and chains on Walking horses relied on research conducted in the 1970s, in which researchers used thermography to detect signs of inflammation. No subsequent studies on Walking horses in show shoes have been published in peer-reviewed journals.

One study in France, "Effects of 6 degrees elevation of the heels on 3D kinematics of the distal portion of the forelimb in the walking horse" by Chateau, Degueurce and Denoix, refers to horses at the walk, not the Walking horse breed, but that study, published in the peer-reviewed Equine Veterinary Journal in 2004, did evaluate four horses shod with wedge pads of the type typically used by farriers to correct a broken-back hoof-pastern axis or compensate for underrun heels and/or negative palmar angle of coffin bone. Those wedges are usually two or three degrees.

The French research concentrated on the effect of wedge pads on distal limb joints and stride phase timing at the walk and was not concerned with higher and heavier pad stacks and double nail pads used on gaited breeds and show Arabians.

In its August 2008 white paper report, "Veterinary Recommendations for Ending the Soring of Tennessee Walking Horses", the American Association of Equine Practitioners called for more research on methods both to detect soring and also to "determine the effect of shoeing alone and shoeing plus chains of variable weights in the development of pastern irritation and scarring on both young and mature TWHs".

Ten years later, some research has arrived.

• • • • •

What a difference a year makes: On New Year's Eve 2016, the decades-old controversy over enforcement of the American Horse Protection Act seemed like it was in its final hours. As the Obama administration prepared to button up the USDA's unfinished business, an executive order was set to be signed that would make an end run around Congress, which had failed to get to a vote on bi-partisan legislation to end soring of Tennessee Walking horses under the proposed Prevent All Soring Tactics (PAST) Act.

How would the executive branch of government end chemical and mechanical soring abuse? By simply banning pad stacks and chains outright. Without the combined mechanics of wedged distal limb joint angles and the weight of the stacks, the running walk gait would be impossible for a show horse to perform.

Tennessee Walking Horse
For many years, a stacked Tennessee Walking horse performed during halftime at the University of Tennessee Knoxville's football games. The crowd cheered the stack-shod horse, often that year's champion, as it went up and down the sidelines at the running walk. In recent years, a flat-shod Walking horse replaced the stacked "Big Lick" performer at UT games. (Photo embedded from from a 2007 game by Josh Wolff.)

As much as people wanted to see an end to soring, this proposal sent a shudder through the horse industry, since the other breeds that rely on pads or heavy shoes could see the likelihood of a prolonged battle in federal courts ahead. Even though other breeds follow strict rules and have no overt chemical or mechanical soring issues, the Walking horse industry would likely argue in court that the government cannot prohibit one breed from using shoes that are legal for other breeds of horses.

For some intentional or unintentional reason, the executive order was not filed in the Federal Register before the Obama administration closed its doors. When the Trump transition team took over the USDA, they did not continue with the proposed executive order.

• • • • •

For the most part, 2017 was a quiet year on the soring legislation and enforcement front. As 2018 dawns, the publication of the research from the University of Tennessee has the potential to re-open Pandora's Box, or at least to rewrite some footnotes for future efforts to ban or protect pad stacks and chains.

The Hoof Blog reached out to Marty Irby, Senior Advisor at The Humane Society of the United States (HSUS) and Humane Society Legislative Fund:

“We will be reviewing the research in the upcoming weeks, but believe this could be another attempt by the pro-soring coalition in Tennessee to maintain the status quo that has marred the Tennessee Walking Horse for more than half a century," Irby said on December 31.

“We hope the University of Tennessee doesn’t attempt to bring the pain-based 'big lick' gait back to the UT homecoming exhibition in 2018 -- that would be a tragedy for the breed, state, and school.”

The article will appear in the January 2018 edition of AJVR. It is available now on the AVMA website, but requires a journal subscription or university library access. The article can also be purchased for individual viewing.

Citation for the research article:

Everett JB, Schumacher J, Doherty TJ, Black RA, Amelse LL, Krawzel P, Coetzee JF, Whitlock BK. Effects of stacked wedge pads and chains applied to the forefeetof Tennessee Walking Horses for a five-day period on behavioral and biochemicalindicators of pain, stress, and inflammation. Am J Vet Res. 2018 Jan;79(1):21-32. doi: 10.2460/ajvr.79.1.21.

To learn more:

Use of Action Devices and Performance Packages for Tennessee Walking Horses
American Veterinary Medical Association policy statement

Horse Soring and the PAST Act (2015)
American Veterinary Medical Association booklet, free to download

Utilizing Thermography to Assess Compliance with the Horse Protection Act
Tracy Turner (2007 approx., not stated)
USDA/APHIS PowerPoint presentation PDF conversion for reference, free to download

Thermography in the diagnosis of inflammatory processes in the horse.
Purohit RC, McCoy MD.
Am J Vet Res. 1980 Aug;41(8):1167-74.
(not found online)

Soring in Tennessee walking horses: detection by thermography.
Nelson, H. A., & Osheim, D. L. (1975).
US Department of Agriculture, Animal and Plant Health Inspection Service, Veterinary Services Laboratory.
(not found online)

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