Tight nosebands cause stress in horses, according to Australian researchers, who have flagged welfare issues arising from the use of “relentless pressure”.
The University of Sydney study team say restrictive nosebands are common in equestrian sport, and suggest that FEI dressage guidelines may play a part in their popularity.
Professor Paul McGreevy and his colleagues set out to investigate relationships between noseband tightness and oral behavior, and to check for physiological changes that indicated a stress response.
Twelve horses of varying breeds were used in the study. All had been started under saddle but none had been exposed to either a double bridle or a crank noseband.
For the experiment, the horses were randomly assigned to four treatments involving a double bridle and crank noseband, as is common in dressage at elite levels.
They were monitored in an enclosed test area made of hay bales and canvas. Beforehand, they were placed in a double bridle and bit, with a padded crank noseband that was left unfastened. Baseline levels were gathered over 10 minutes in the test area before one of the four noseband treatments was applied.
The noseband was either left unfastened, fastened with a conventional two fingers of space under the noseband, with one finger of space left under the noseband, or with no area under the noseband.
The horses were again monitored for 10 minutes, after which the bridle was removed and they were monitored for a final 10 minutes.
The study team monitored the heart rare and heart-rate variability of the horses, and used infrared thermography to measure any changes in eye temperature – all of which can provide an indication of stress in the animals.
During the tightest noseband treatment the horses’ heart rates increased, heart-rate variability decreased, and eye temperature climbed when compared to baseline readings. The heart-rate changes suggested the tight-fitting noseband caused enough discomfort to provoke a stress response, they said.
“This stress response may be a result of either the inhibition of normal behaviors, or from pain or discomfort, or a combination of the two,” they wrote.
The researchers said the horses were stationary during data collection, so the cardiac and eye temperature responses recorded could not be from physical activity.
“The behavioral results suggest some effects from bits alone, but the chief findings are the physiological readings that reflect responses to the nosebands at their tightest,” the study team reported in the open-access peer-reviewed journal, PLOS ONE.
McGreevy, Kate Fenner, Samuel Yoon, Peter White and Melissa Starling noted that chewing decreased during the two tightest treatments. Yawning rates were negligible in all treatments. Similarly, licking was eliminated in the tightest treatment.
“Following the removal of the noseband and double bridle during the recovery session, yawning, swallowing, and licking significantly increased compared with baseline, indicating a post-inhibitory rebound response.”
This is where the frequency of the behavior increases after a period of inhibition.
“This suggests a rise in motivation to perform these behaviors and implies that their inhibition may place horses in a state of deprivation.
“Physically preventing horses from engaging in these behaviors to the extent where they display a build-up in motivation to perform them must be considered a violation of the freedom to express normal behavior, which is one of the Five Freedoms that are a cornerstone of animal welfare assessment,” the study team wrote.
“It is evident,” they said, “that a very tight noseband can cause physiological stress responses and inhibit the expression of oral behaviors.”
They continued: “The cardiac responses in this study are consistent with previous studies of equine responses to stressful events, such as exposure to novel objects.”
The study team said nosebands have long been a popular piece of equestrian equipment. The simplest form is the cavesson noseband, traditionally loosely fitted and unrestrictive. Crank nosebands were developed in the 1980s and are frequently used in equestrian sports today. They are similar to a plain cavesson noseband with the addition of a leveraged buckle to allow for tighter fit.
“Their purpose can best be understood through the standards upheld by the FEI, which is the international governing body of equestrian sports.
“The FEI stipulates that horses should demonstrate submissiveness, and penalises ‘resistance, evasion, putting out the tongue, or teeth grinding’.
” ‘Submission’ is a term used in the discipline of dressage to describe a horse’s attentiveness, willingness and confidence to behave with lightness and ease in the way it executes different movements.
“Therefore, submission ‘does not mean subordination, but an obedience revealing its presence by a constant attention and a state of relaxation’. It is therefore beneficial in competition for horses to appear submissive, and nosebands may be used to give this appearance,” the study team said.
They continued: “It is thought that, chiefly by pressing the bit against the tongue, a tight noseband restricts tongue movements, which are among the mechanisms by which horses attempt to dissipate pressure from the bit within the oral cavity.
“The resultant inability to escape bit pressure leads to the sensitisation of the horse’s mouth, increasing the horse’s responsiveness to rein pressure and thereby making the horse appear more responsive.”
They said modern crank nosebands can be tightened to the extent that they can compromise blood supply, and may even cause nerve and bone damage.
“The use of these crank nosebands and the extreme tightening of nosebands is thought to be increasing in equestrian sports, and is likely to have an impact on the welfare of the horse, but this impact has not yet been quantified,” the study team noted.
The researchers acknowledged that the horses in the study were responding not only to the effects of noseband tightening but also to two bits, rather than simply one.
“It is possible that the combination of a tight crank noseband and two bits virtually immobilises the tongue. This may explain why the rate of swallowing halved, chewing was significantly reduced and licking was absent during this treatment.
“Future research should investigate both the use of a single bit and crank noseband together with the effects of applying rein tension,” they said.
In conclusion, they said the horses showed a physiological stress response when wearing a tight noseband in combination with a double bridle.
“Significant shifts were seen in heart rate, heart-rate variability and eye temperature in association with tight noseband use, suggesting that horses experience pain or discomfort when nosebands are tightened such that there is no space available underneath them.
“We predict that the impact on horses would increase still further with the addition of rein tension and a rider.”
They said gear stewards in a competition environment should be required to check that each rider was complying with rules that prevented excessive tightening of the noseband.
“The dressage rules that call for ‘submission’ in horses, demonstrated by a willing acceptance of the bit cannot be properly upheld if the equipment in use prevents the expression of the very behaviors that would indicate oral discomfort and a lack of submission,” they wrote.
Further research should focus on the process of habituation to these devices, the measurement of tension in nosebands and the tension level at which the noseband produces a stress response.
“This may help dissect the sequential roles that inhibition and discomfort play in the emergence of the stress response associated with this practice.
“Either way, on ethical grounds, the use of relentless pressure to eliminate oral behaviors in pursuit of a competitive advantage may be difficult to justify.”
Yoon, White, Starling and McGreevy are with the Faculty of Veterinary Science at the University of Sydney; Fenner is with Kandoo Equine in New South Wales.
Fenner K, Yoon S, White P, Starling M, McGreevy P (2016) The Effect of Noseband Tightening on Horses’ Behavior, Eye Temperature, and Cardiac Responses. PLoS ONE 11(5): e0154179. doi:10.1371/journal.pone.0154179