Equine conflict behaviours shown more in snaffle bridles than doubles, research finds

Double bridles’ effect on equine behaviour and noseband tightness were among the topics discussed at a session on biomechanics at the 2025 British Equine Veterinary Association 2025 congress.

Researchers presented abstracts of studies yet to be published in full, on hot topics in the industry.

Russell MacKechnie-Guire covered a study on the effect of double bridles. H&H reported on some of the findings of this work, which found that doubles exert similar or less nasal pressure and rein tension than snaffles in elite horses; this abstract considered behaviour.

“Welfare concerns have been raised over the use of the double bridle, and the double bride in itself is often associated, or suggested to be the cause of, conflict behaviour, such as mouth separation, tongue retraction, tongue bulging or discoloration, lateral displacement,” he said. “But there is no quantitative data to explicitly say it’s the bridle that’s causing it.

“Oral lesions have been associated with bars of the mandibles with a straight bit and in a snaffle in the [folds] of the lips. The double bridle is as topical as noseband tightness, and there are groups and stakeholders calling for a ban of the double bridle on welfare grounds.”

But the study found no differences in most measured conflict behaviours between bridle types, in the high-level horses studied. When differences were observed, conflict behaviours were more frequent in the snaffle than the double.

Conflict behaviours

“Using a ridden horse ethogram, we found two conflict behaviours increased in the snaffle bridle,” Dr MacKechnie-Guire said. “Is this due to the rein aid being less clear when the horses were ridden in the snaffle bridle? Elite riders may have a more refined application of the rein aid, aiding improved communication with the double bridle, and maybe it’s more subtle for the rider to communicate with the horse due to the action of the two bits.

“Rein tension is similar for the double and snaffle bridle, the combined rein tension, but for the double, the force is distributed over two bits. Is it possible that the focal force from the snaffle bridle may have led to those conflict behaviours? We don’t know. Food for thought.”

Dr MacKechnie-Guire stressed that this was high-level horses and riders, and that more work is needed.

“Bridle-horse interaction is complex, and it’s likely other factors cause the presence of the conflict behaviors, not just bridle type.” he said. “And we really need more work to take this forward, and of course, in less skilled riders.”

Dr MacKechnie-Guire’s other abstract presented did consider lower-level combinations, and noseband tightness. The researchers had already found that pressure on top horses’ faces in trot was not significantly increased when nosebands were tightened from two fingers’ space to 1.5. This study had the same findings with novice horses and riders.

“We’ve had a significant step forward with the FEI introducing the noseband measuring tool in May; data used for that was partly from our studies in elite horses, but now we’ve got non-elite horses, so this data supports its use there too,” Dr MacKechnie-Guire said. “And the values at one finger tightness, as it’s always good to keep things in perspective, were less than 15 kPa, a value thought to cause pain and discomfort on the head.”

Controversial topic

One guest, vet and behaviour expert Gemma Pearson, said: “Thank you for continuing your lovely work on this controversial topic. I think it’s probably worth saying; I’m certainly aware of one yard where the girls weren’t allowed to tighten nosebands because they couldn’t get them physically tight enough. So the fact we’re arguing between 1.5 and two fingers feels like we’ve come a long way, and I think we all need to remember that.”

Julia Lanfear, a vet student in her final year, presented work on whether pulling loads can build equine topline more than ridden work. She assessed the back shape of 42 load-pulling and 26 ridden-only military horses, and found that the former work “resulted in increased convexity of the equine back compared to ridden exercise only”.

“It’s possible that load pulling could lead to hypertrophy of epaxial muscle [topline] in horses, because the musculature functions to stabilise the equine back by counteracting the forces produced by the hindlimb and forelimb muscles,” she said. “Load pulling could increase this requirement for stabilisation by increasing the propulsive force that the limbs need to generate to move the load. Load pulling could result in increased activation of the epaxial muscles and their hypertrophy.”

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