Bone damage at site of noseband

Report of Bone Damage at Noseband Site

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A new study has identified bone damage at the site of the noseband. This research has important ramifications regarding the use of this part of the bridle which is not only common, but compulsory in certain disciplines, like dressage and showing.

The changes were either thickening (exostoses) or thinning (concavity) of the nasal bone and/or the mandible and were   identified by palpation and with x-rays. The research was conducted by a seven-strong team from the National Autonomous University of Mexico and was led by veterinarian Lucia Pérez-Manrique.

They randomly selected 144 horses from a population of 700 cavalry horses housed at the Equine High-Performance Centre (CEAR) of the Mexican army, in Mexico City where they begin their working career and start being trained for dressage, showjumping and eventing. Some horses also participate in army parades.

Among this population of military horses, 37.5% 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 mandible.

While the study does not detail the equipment each horse uses, it notes that non-ceremonial gear for each horse depends on its equestrian activities and individual requirements. Ceremonial gear for this unit generally involves a curb bit and a cavesson noseband. Noseband tightness is not routinely checked with any taper gauge or similar device.

Two senior vet students working separately and blinded to the purpose of the study, were trained to examine the head of all horses for the presence of lesions, pain on palpation, and the presence of white hairs on the nasal bone at the site of the noseband and the lower jaw (mandible) at the sites of the noseband and curb chain.

The examiners were required to score the horse as normal or suspicious concavity, confirmed concavity, suspicious exostoses, or confirmed exostoses. They were also asked to note the colour of the horses and the presence of white hairs and skin damage at the site of the noseband and at the site of the curb chain.

Bone damage at site of noseband
Photograph of profile of horse in which both examiners confirmed: (a) exostosis and (b) concavity in the nasal bones. Photos courtesy of Missael Garcia-Marquez.

Approximately a week later, radiographs were taken and studied by two specialists in diagnostic imaging, who also worked separately and did not know the age, breed, and sex of the horses studied. They were asked to score the degree of bone deposition, bone lesions (lysis), bone homogeneity, fractures and swelling of surrounding soft tissue.

Two examples of bone damage at site of noseband
Radiographs showing the nasal bones of a horse in which both radiologists agreed there was bone thinning that was: (a) typical of affected horses and (b) moderate.

For the nasal bones, the two radiologists reported bone deposition in 6.9% and 8.3% of the horses, and bone thinning in 33.3% and 56.9% respectively.

The senior students who palpated the horses who also worked separately found that 82% and 84% had palpable bone deposition of the nasal bones and 32% and 33.4% had palpable bone thinning, respectively.

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.

These results suggest that radiographic bone thinning is more apparent in the nasal bones than in the mandible and that both palpable and radiographic bone deposition are more likely in the mandible than in the nasal bones.

The researchers remind us that correlation never implies causation, that is, the study is not intended as evidence that nosebands caused the bone remodelling but simply reports on bony changes at the site of the noseband.

Despite the standard disclaimer, it is difficult not to state that this study has important ramifications, particularly because it is adding to concerns raised over the last ten years which are captured by the International Society for Equitation Science in their position statement about the use of restrictive nosebands, and their recommendation that noseband tightness is carefully monitored.

The ISES recommends a minimum space of two fingers is achieved under the noseband strap and measured at the nasal bones. They designed a standardised, taper gauge that can be used by competition stewards to check noseband adjustment.

Researchers had already hinted that bone damage was likely but many dismissed the idea saying that bone changes at this site are rare, and if found, they are probably unrelated to noseband use and more likely caused by a single high impact event (like stepping on the lead rope when wearing a halter).

Finding changes in both, the nasal bones and lower jaw bones, doesn’t fit the ‘he stepped on the lead rope’ story.

When previous research led by Dr Orla Doherty warned that noseband peak pressures were much higher than what is deemed safe for tourniquet use, some argued that because the pressure peaks were intermittent (it peaks and troughs depending on the horse’s movement), one simply cannot make a comparison with the damage that can be caused by tourniquets.

The blind spot has been the effect of regular, single bouts of very high peak pressures on the same area of bone – over time. (And, since some of the horses in this latest study were as young as three, it doesn’t seem to take that much time either.)

Unfortunately, these findings could well mean that horses are inadvertently causing themselves bone-changing damage each and every time they open their mouths and come against the noseband strap (in their attempt to avoid or relieve bit pressures). Basically, as riders, by placing a noseband that restricts mouth opening, we are forcing horses to choose between two evils – pain inside the mouth or pain on the nose and lower jaw.

It pays to remember that in Dr Doherty’s study, the horse was wearing a noseband adjusted to allow a two fingers gap under the strap yet still recorded extremely high peaks. This finding should have resulted in compulsory checks that nosebands, across all disciplines in all countries, achieved a minimum space at the nasal bones, but this idea has only been adopted by a handful of nations.

Now the question has progressed to whether we should be using nosebands at all? Particularly since it is possible to train horses without them.

It’s a genuine question but it divides the equestrian public. While some riders never use nosebands or know they can have deleterious side effects, others are not prepared to consider it since they use it for aesthetic purposes like ‘framing the face’, or for control, particularly keeping the tongue under the bit. Will these recent findings sway their view?

Like all the best research, this latest study raises more questions and the researchers note that further studies on this horse population will be conducted and will keep adding evidence that links the bone damage to nosebands and/or training failures, like revealing the equipment they regularly use and how it is adjusted, as well as their E-BARQ scores.

But maybe we should be asking a different question altogether? Since the rules of the International Equestrian Federation (FEI) rules state that nosebands should not be adjusted in such a way as to cause the horse harm – could we ask the FEI to check horses more carefully and provide veterinary evidence that the equipment is not causing harm?

Thermographic cameras are routinely used at FEI showjumping events to check for sensitisation of the legs (sadly, some riders use irritants on their horses’ legs which increases the pain they feel when they touch the fence poles, to make them ‘more careful’). It is also proving to be a useful tool in helping assess saddle fit and highlight problems.

If nosebands are causing bone remodelling it is very likely they are leaving a heat trace that could be picked up thermographically. This non-invasive technique which is already in use, would flag the need for further investigation.

The well-being of horses in sport and recreation is under the spotlight. Governing bodies state that equines are partners in horse sports and have even introduced awards for the ‘happiest’ equine athlete. If we want to continue to enjoy horse sports, we should at the very least do everything we can to show we are not causing harm.

The open access study titled Prevalence and Distribution of Lesions in the Nasal Bones and Mandibles of a Sample of 144 Riding Horses by Lucia Pérez-Manrique, Karina León-Pérez, Emmanuel Zamora-Sánchez, Sarah Davies, Christopher Ober, Bethany Wilson and Paul McGreevy can be found here.

 

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