Serious questions around the use of nosebands have been raised by the findings of a new study, in which head x-rays revealed bone lesions on the nasal bones and lower jaws of horses.
The bony changes — thickening or thinning — were identified at the site typically subjected to pressure from restrictive nosebands.
The scientists stressed that their study provides no evidence of a causal link between the lesions seen and any piece of gear, nor its tightness.
However, the causes of the lesions seen at the site of nosebands merit further investigation, they said, because inadvertently damaging the bones of horses as part of equitation is difficult to justify on ethical grounds.
“The identification of these lesions at the site of restrictive nosebands raises concern for the welfare of horses ridden with such devices,” Lucia Pérez-Manrique and her colleagues wrote in the open-access journal Animals.
Pérez-Manrique, with the National Autonomous University of Mexico, was part of a seven-strong research team that set out to learn more about the prevalence and distribution of lesions in the nasal bones and lower jaws of riding horses.
The researchers noted that the use of restrictive nosebands in equestrian sports is of increasing concern to veterinarians and equitation scientists. “The chief concern is that restricting behaviour by tightening the noseband may cause distress and apply pressure to the tissues of the horse’s head.”
It has been suggested that this pressure may cause injury to the soft tissues of the face and possibly the underlying bones.
The study centered on 144 mature cavalry horses, all Warmbloods. They were all housed at the Equine High-Performance Center of the Mexican army, in México City, where they begin their working career and start being trained for dressage, show jumping, and eventing.
Some horses also participate in army parades.
The non-ceremonial gear for each horse depends on its equestrian activities and individual requirements. Noseband tightness is not routinely checked with any taper gauge or similar device.
There were two phases to the study — a physical evaluation and an x-ray procedure.
For the first phase, two senior veterinary students who were unaware of the purpose of the study were trained by the first author to examine the head of all horses for the presence of lesions, pain on palpation, and the presence of white hairs at the sites of the noseband and curb chain.
The examiners were required to assess the horses as either normal, displaying suspicious concavity, confirmed concavity, suspicious exostoses (bone thickening), or confirmed exostoses.
They were also asked to note any presence of white hairs and skin damage at the site of the noseband and at the site of the curb chain.
A week later, the x-rays were taken under a standardized protocol.
The images were then assessed by two specialists in veterinary diagnostic imaging, who were blinded to the age, breed, and sex of the horses studied.
The x-rays were evaluated for any evidence of bone remodelling, soft tissue thickness, and radiographic opacity at the sites of the noseband where it meets the nasal bones and lower jaw.
For the nasal bones, the two radiologists (who worked separately) reported bone deposition in 6.9% and 8.3% of the horses, and bone thinning in 33.3% and 56.9%.
The senior students who palpated the horses (again, working separately) found that 82% and 84% had palpable bone deposition of the nasal bones and 32% and 33.4% had palpable bone thinning.
For the lower jaw, the radiologists reported increased bone deposition in 18.8% and 32.6% of the horses, but no bone thinning.
By palpation, the two students reported 30.67% and 32.7% of the horses had palpable bone deposition in the lower jaw, and 10.4% and 11.1% had bone thinning.
The x-ray results suggest that bone thinning is more apparent in the nasal bones than in the lower jaw, and that both palpable and radiographic bone deposition are more likely in the lower jaw than in the nasal bones.
“This,” they said, “is the first confirmation of bony lesions at the site typically subjected to pressure from restrictive nosebands.”
“These findings are critical to the advance of ethical equitation that advocates a three-step process for equestrian stakeholders who seek to retain the social license to operate.
“It demands that we identify the causes of distress in the horses we ride, that we mitigate these stressors as much as possible, and we justify the retention of those that cannot be mitigated.”
In all, 37.5% of the horses had one or more radiographic changes to the nasal bones according to both radiologists, and 13.8% had one or more radiographic changes to the lower jaw.
“The inadvertent deformation of bones in the horse’s head for competitive advantage is difficult to justify on ethical grounds,” the authors wrote.
Of the 144 horses, 76 were assessed as having unnaturally white hairs in the nasal bone region, whilst 68 horses were judged as naturally white in the region due to markings, or were grey.
The researchers reported that the findings of bone thinning or thickening by the examiners who palpated the head correlated well with the findings of the radiologists.
However, they suggested that visual appraisal and palpation alone should not be relied upon diagnostically. As clinical indicators, they may well lead to imaging, but there is evidence that radiological lesions are more profound.