Recently, there have been a couple of posts about the stresses caused by the nose bands worn by Olympic dressage horses. A journal article was cited as proving that these 'crank' nosebands are basically cruel and should be even further regulated than they already are. I'm a biology research nerd (Howard Hughes Biomedical Research Grant among others in Molecular Biology) from way back, so I happily delved into the journal article to see what the science actually said. Imagine my surprise when the data as well as the conclusions are anything but as controversial as indicated...
A small group of horses unused to double bridles were randomly assigned to having a noseband either unfastened (UN), conventionally fastened (CAUN), tightened half again as much as conventional (HCAUN), and tightened all the way (NAUN). Horses unused to double bridles were used, supposedly to eliminate them from being used to 2 bits and/or tight nosebands. Standard control methods were used in that all horses were treated the same except for the tightening of the nosebands. Horses were observed on video, had their heart rates monitored, as well as their eye temperature before, during, and after the experimental phase. Increases and decreases in heart rate, heart rate variability, and eye temperature have been established as stress responses in the animal kingdom. Oral behaviors such as licking, chewing, swallowing, and yawning were also observed and recorded. The results were tabulated in multiple figures and discussed at length in the article. I'm going to cut some of the science lingo and break it down into bite sized pieces below.
The horses were not subjected to any exercise during the experimental phase. They were simply tacked up and placed in a small stall for observation. So their heart rates should have been fairly steady. Across the board, except for NAUN, the horses' heart rates were fairly steady. The NAUN horses' heart rates rose an average/mean of 12 bpm with the nose band tightened, but dropped in the recovery phase. What I found interesting in this graph is that the horses with the lowest heart rates are NOT those with the unfastened (UAUN) or conventionally fastened (CAUN) nosebands, but instead are those with half as much as conventional distance between noseband and nose. Actually, the group with the second highest heart rate is the group that should have remained unconcerned and unstressed - those with the unfastened nosebands. What conclusion can be drawn from this information? Tightening or even just fiddling with the noseband induced at least a slight increase in heart rate for all the horses. Those with the noseband tightened the most did have the highest heart rate increase. However, the opposite is not true - having a looser noseband did not yield the lowest heart rates.
Heart Rate Variability
Again, the horses were not subjected to any exercise during the experimental phase, so their heart rates shouldn't have varied a whole lot. After all, they were just standing in what amounted to a tie stall with monitors on them. For this observation, the unfastened (UAUN) and conventionally fastened (CAUN) horses had remarkably similar results--heart rate variability staying consistent before, during and after the experiment. That is expected. However, the CAUN horses had lower variability rates than the UAUN. The biggest surprise is that the heart rate variability for the HCAUN horses didn't change at all from before to tightening the noseband. All the other groups had a change at that stage--even the UN horses. All the horses had their heart rate variability lower during the recovery phase - even the UAUN horses. Predictably, the NAUN horses had the highest variability. What conclusion can be drawn from this? Tightening or fiddling with the noseband causes heart rate variability regardless of whether the band is truly tightened or not. There is not a direct linear correlation between noseband tightness and heart rate variability.
Without exercise, there should have been no reason for the horse's eye temperature to increase. This experimental variable also showed that the UN and NAUN values had a similar change from the baseline to the treatment value. This again indicates that just fiddling with the noseband is enough to cause a response in the horse. The difference between the experimental value and the recovery values of the HCAUN and NAUN were a bit larger, but still similar. In fact, the only group that didn't completely recover from tightening/fiddling with the noseband was the UN group since their eye temperature stayed at a higher value than it had been initially. What conclusion can be drawn from this? Tightening or fiddling with the noseband causes an eye temperature increase regardless of whether the band is truly tightened or not.
The researchers used video to observe the horses licking, chewing, swallowing, and yawning during all phases of the experiment. While bridled, regardless of noseband tightness, all horses ceased yawning and almost ceased swallowing. The HCAUN group showed horses that exhibited more of the behavior in the recovery phase than in the baseline phase. Licking was most affected in the NAUN group as opposed to the others. Yet, still the other groups showed significant changes in licking behavior too and all recovered to similar rates. Swallowing was also significantly different between the NAUN and HCAUN groups and the UN and CAUN groups. However, the recovery rates of swallowing were similar across all groups. What conclusion can be drawn from this? Tightening or fiddling with the noseband causes a change in oral behavior regardless of whether the band is truly tightened or not.
Methodology Improvements That Matter
These horses were bridle trained to varying degrees and the experiment was done in as controlled and blind a manner as possible. However, there was plenty of room for bias and even simply room for improvement in methodology in this experiment. One of the biggest improvements of methodology would be to eliminate all of the variables except for the noseband tightness. In other words, no bit or at least a bit the horse is accustomed to wearing.
Another improvement of methodology would be to use a set numeric factor for each tightness to, perhaps, identify the point at which the difference is most noticeable. Additionally, using horses unused to double bridles and tightened nosebands is good from a purely scientific viewpoint, but it does not take into account the horse's ability to adapt to work comfortably in what we humans think are difficult conditions. Using horses on the dressage circuit, that are already used to the equipment, would improve the study because these are the horses most affected by the rules or lack thereof. This would also eliminate the fear response horses have to new equipment regardless of its pain-inducing capability.
Additionally, a larger subject size than 12 is needed before broad conclusions can be made in a matter such as this. In science, 120 or even 1200 subjects are not enough to definitely judge a situation--especially on a controversial subject.
Since this is a controversial subject in which even non-horsemen have strong opinions, bias is apparent in the reporting of the oral behaviors. The authors even admit to this fact. Perhaps a less biased, but still oral comfort-telling, measure could be used than viewing raw video. Or even editing the videos so that only the horses' mouths forward of the bit were observable could eliminate this bias error. In fact, even the "fact" used as the basis of this study is biased since no quantifiable measurements of "crank" nosebands in the field have been recorded. Even the authors indicate that show stewards should use numeric gauges to detect when a noseband is 'too tight' instead of the conventional one or 2 fingers' width or 'eyeball' done currently. So it could be that the whole study is flawed based on these unquantified observations that obviously vary between the authors and show stewards.
The Take-to-the-Barn Message
In horses unused to a double bridle and noseband, tightening and/or fiddling with the noseband produced stress-like responses regardless of the tightness of the nose band. There was no direct or linear correlation between noseband tightness and stress response. More studies are necessary to evaluate the true nature of this relationship if such a one exists. Basically, there is no reason to get up in arms over a single study with such small numbers and obvious bias.
I have an advanced degree in Molecular Biology with an emphasis on research and journal articles from a "Public Ivy" University. I have done research in several areas under the Howard Hughes Biomedical Institute as well at my University. My career as a Forensic Biologist, kept my finger on the heart-beat of science and journal articles. I also gained an exceptional understanding of Ethics and Morality through the Forensic community as well as my continued research of my Catholic Faith. I have owned and ridden horses my whole life. Although I do not show currently, I respect those who do. However, I also hold them to a high standard of horsemanship while acknowledging their horses aren't the pets most of our horses are. I try to be as unbiased as possible when performing a journal review. I have also made a lifelong anatomy study of horses for the sake of my artistic pursuits as well as my early intentions to become a veterinarian. Therefore, I am more than passably familiar with the anatomy and biomechanics of the horse.
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