24/06/2026
🐴THE "OPEN MOUTH" MYTH - FLASH, GRACKLE & DROP
When a horse opens its mouth while being ridden, it is not simply misbehaving or trying to avoid work. Instead, the horse is showing that it feels uncomfortable.
Different mouthpieces apply pressure to areas such as the tongue, bars, or hard palate. David J. Mellor explains that using a bit can cause mouth pain in horses because of compression, cuts, inflammation, reduced blood flow, and tissue stretching. Closing the horse’s mouth with a strap does not solve the real issue; it only hides signs of discomfort. (Mellor, 2020) If your horse keeps trying to open its mouth, the mouthpiece may not be right. It is best to work with a qualified bit and bridle fitter to find a comfortable setup or consider bitless options. You can find trusted professionals through the Association of Professional Bit and Bridle Fitters (APBBF).
The tongue connects directly to the hyoid bone through the lingual process of the Basihyoid, along with related muscle groups. Forced restriction affects more than just the mouth. It can also cause restriction of the horse’s limbs, making it harder for the horse to move its legs freely and shortening its stride.
ANATOMICAL DAMAGE
Even if people say their flash, grackle or drop noseband is not very tight, where the strap sits is still a problem.
According to a 2019 study published in Equine Veterinary Education, the mental foramen is an important site for nerve blocks in horses. Pressure on this area can affect the nerves that supply sensation to the jaw, lips, and chin, potentially leading to numbness or discomfort. It also pinches sensitive cheek tissue against the molars. (What is a restrictive noseband, and how does it harm horses?
A 2024 study found that tightening nosebands on horses can significantly increase pressure on the face, potentially causing discomfort and long-term harm. Scholler et al. (2024) reported that sub-noseband pressure increased by up to 338 per cent when the noseband was tightened. The study also found that too much tightness can harm the horse’s upper airways. This means that areas like the nasal bone and jaw, which are not meant to handle constant high pressure, can be damaged, and the horse’s breathing can be affected if nosebands are too tight.
MOVING FORWARDS
Thankfully, things are changing in the horse world. With more equine behaviour consultants, professional bit fitters, and bridle fitters available, we no longer have to rely on guesswork or restrictive equipment.
If we observe the horse’s facial expressions and behaviour, the message is clear. We should stop using quick fixes and instead address the root cause of the discomfort.
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REFERENCES
Rosenstein, D. (2022). Oral Dimensions Related to Bit Size in Adult Horses and Ponies. Frontiers in Veterinary Science 9. https://doi.org/10.3389/fvets.2022.879048
McGreevy, M. A., McLean, J. D., McManus, C. M. & McGreevy, J. M. (2019). Mouth Pain in Horses: Physiological Foundations, Behavioural Indices, Welfare Implications, and a Suggested Solution. Animals 9(6). https://doi.org/10.3390/ani9060171
Mellor, D. J. (2020). Mouth Pain in Horses: Physiological Foundations, Behavioural Indices, Welfare Implications, and a Suggested Solution. Animals 10(4). https://doi.org/10.3390/ani10040572
(2015). Equine Welfare during Exercise: An Evaluation of Breathing, Breathlessness and Bridles. Animals 7(6). https://doi.org/10.3390/ani7060041
Staff, K. E. (2016). The Horse’s Mouth: Understanding the Soft Palate. Kentucky Equine Research. https://ker.com/equinews/horses-mouth-understanding-soft-palate
Cook, R. (2018). Mouth Pain in Horses: Physiological Foundations, Behavioural Indices, Welfare Implications, and a Suggested Solution. Animals 8(4). https://doi.org/10.3390/ani10040572
(2025). What is a restrictive noseband and how does it harm horses?. RSPCA Knowledgebase. https://kb.rspca.org.au/knowledge-base/what-is-a-restrictive-noseband-and-how-does-it-harm-horses/
Scholler, D., Wittenberg, J., Zablotski, Y. & May, A. (2024). Do tight nosebands have an effect on the upper airways of horses?. Vet Med Sci 10(4). https://doi.org/10.1002/vms3.1478
(2024). Do tight nosebands have an effect on the upper airways of horses?. PMC11182419. https://doi.org/10.1136/vr.104.3.65