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The Snaffle Bit: A Review

Single Jointed and Double Jointed

A snaffle, either single or double-jointed is often referred to as the lightest type of bit available because of its simple mouthpiece design and larger surface area contacted. It is said that the thicker or smoother a bit is, the less pressure it will exert onto the horses bony and soft tissue structures within the mouth (Vogel, 1995). This statement, however, stands to be argued in more recent times where research has emerged challenging this notion. In examining the anatomy that is distinct to the horse’s mouth conflicting evidence has arisen that challenges the “softness” of these bits. Considering these relatively new discoveries, the snaffle bit should be investigated further and the effects both physically and psychologically will be discussed.


The single jointed snaffle bit consists of a mouthpiece in varied thicknesses with a ring on either side. Snaffles are designed to cue the horse from direct pressure via the reins of the rider. The double-jointed snaffle has an additional center piece which is thought to decrease the tenting effect on the horse’s soft palate as well as decrease the pinching of the tongue while delivering a more precise pressure to the bars of the mouth. When a single or double-jointed snaffle is sitting in neutral within the horse’s mouth cavity (i.e. no tension on the reins) it shouldn’t have any pressure effects on the tongue, soft palate, or sides of the lips (Miller, 2013). When tension increases from a shortening of the reins this will cause the bit to hinge at the center contacting the soft palate and applying pressure to the bars of the mouth. The actual size of the oral cavity in a horse is relatively small compared to its bony outer structure.  The tongue sits between the narrow lower jaw and fills almost all the horse’s oral cavity (Anatomy of the Horse’s Mouth, 2015). When the horse’s mouth is closed with the tongue in resting position there is not normally a space between the palate and the tongue which is why we often hear a suction type sound when we ask the horse to take the bridle (Miller, 2013). This noise is the sound of the tongue unsticking from the upper soft palate. The soft palate can also be very sensitive to pressure and due to the small oral cavity space, the bit literally has nowhere else to go but up. The bars of the mouth are the flat bones behind the front teeth but before the cheek teeth. There is only a thin layer of skin covering this portion of bone making them susceptible to pain and damage with very little pressure (Anatomy of the Horse’s Mouth, 2015). The inner lips of the mouth provide some fleshy protection to the bony bars but, as the bit is drawn backwards, the angles between either side create a hinge in the center which will get smaller regardless of thickness of the bit itself. This decrease in angle will cause the bit to contact the bars in a cutting motion, the tongue in a pinching motion, and the soft palate in a jabbing motion resulting in an overall painful stimuli or negative reinforcement to the horse. 

In a recent study examining the effects of bit position on the soft tissues of the mouth, it was determined using radiographic evidence that snaffle bits were the most mechanically devastating to a horse’s mouth when compared to five other bits including three from the Myler grouping (Manfredi et al, 2005). The researchers applied the same force (25N) via reins to each bit while it rested inside the head of a cadaver horse to demonstrate the positioning and angles from start to finish of such movement (Manfredi et al, 2005). They found that the mouthpiece “rolled caudally on the tongue when tension was applied to the reins” while the Myler bits showed no change in centerpiece angulation due to their non-hinged design (Manfredi et al, 2005). They also found that rein tension moved the snaffle “closer to the cheek teeth as the angulation of the cannons relative to the cheek teeth decreased” (Manfredi et al, 2005) when compared to the other bits. Based on the limited space in the horse’s mouth anatomy discussed above it becomes obvious why and how the tongue can become entrapped or pinched and the bars to be directly contacted when pressure is applied.  The study also found that double jointed snaffles did indeed decrease the nutcracker effect on the soft palate but instead moved the entire mouthpiece downwards towards the inferior bones of the mandible which then also compressed the tongue as it was forced downwards with the pressure of the bit and sometimes pinched between the lower teeth and the bars (Manfredi et al, 2005). 

Pain caused from improper or forceful positioning of the snaffle can lead to major issues within the poll and down the spine of the horse. With the horse trying to escape pain or pressure they may attempt to lock the jaw or utilize the lower neck muscles to change their head position (Higgins & Martin, 2005). Both strategies can cause increased tension in the muscles of the TMJ as well as the paraspinal and neck muscles. Sustained tension to an area can cause altered motor patterns if the horse repeatedly seeks positional changes that are biomechanically unnatural. This repeated change in movement could then potentially inhibit basic movements required such as flexion at the poll or lateral neck bending (Higgins & Martin, 2005) which are often misinterpreted as “behavioural issues”. 

From a psychological standpoint any type of pain can affect the horse’s perception of reward versus punishment in that they predominantly function as prey animals and respond to the principles of pressure and release. Since horses thrive on the release of dopamine as a positive reinforcement from escape of a perceived pressure the snaffle bit could be viewed as a positive training aid given the pressure is released from the mouth when the horse does what is asked leading to a dopamine surge (Peter & Black, 2012). This, however, is not always guaranteed in the hands of a beginner rider, and ill-fitting snaffle that pinches or pokes in a resting position, or an unschooled horse. With all these variables necessary to be in perfect harmony to produce the desired effect it is highly likely that the snaffle bit could cause pain to the horse even with its “simple” design. 


Long term effects of a lack of release can lead to an increase in stress levels to the horse resulting in many negative consequences to the horse’s mental and emotional health. Much like humans, horses are affected by stress and the hormones that are produced whether during one stressful event or over a prolonged period. Stress can result from physical circumstances such as injury or the environment while psychological stressors stem from situations that make the horse fear for their own safety (Malinowski, 2004). When stress arises, the horse produces stress hormones such as epinephrine and norepinephrine which are known to increase heart rate, blood pressure, and respiration (Malinowski, 2004). In the short term these hormones are helpful to activate the fight or flight mechanism but over periods of prolonged stress a secondary stress response is activated leading to the release of cortisol (Malinowski, 2004). Over the long-term excess cortisol leads to physiological changes in cardiovascular function, energy producing mechanisms, digestion, immunity, reproduction, and has been It has also been linked to many psychological conditions such as aggressive behaviour and depression which presents as unwilling behaviour (Malinowski, 2004).  Since the horse’s brain is not wired for behaviours such as planning or plotting against their owners (Peters & Black, 2012) the horse may experience many negative emotional and mental effects when they do not receive the dopamine release they seek or even worse suffer at the hands of an owner who perceives this behaviour as “unwilling” and proceeds to punish the horse. With regards to the snaffle bit, the pain caused by the mechanical structure of this particular bit could lead to long term stress and the release of all the subsequent hormones which, as demonstrated above, can largely affect the horse’s physical and psychological state. 

The snaffle bit does indeed have an uncomplicated design but it remains to be questioned whether the simplicity of it actually distributes pressure more evenly and less harshly as it has been proposed in the past. Based on recent evidence it can easily be argued that the design alone is what makes this bit in fact quite harsh and painful which is only amplified in the hands of a beginner or less skilled rider. Additionally, the bit must fit the horse’s mouth anatomy but since all horses are shaped differently based on breed, stature, and age; proper size is not always ensured with the standard snaffle measurements that exist. Lastly when comparing single versus double jointed snaffles it is important to consider the intended use and again each individual horse’s mouth anatomy. While the double- jointed snaffle does appear to apply less pressure to the soft palate it comes with the consequence of increased and sharper pressure to the bars requiring a highly skilled rider to ensure proper cueing with the least amount of pressure. With all the research that now exists regarding bit pressure and mouth anatomy, many horse owners are seen to be transitioning to bit-less bridles, however, these too come with their own sets of pros and cons which must also be considered when determining the physical and psychological effects on the horse. It is important to understand that any piece of equipment or training aid will present with its own set of variables thus it is the responsibility of the rider or trainer to do the research and investigation into what will work the best with the least amount of negative variability for each particular horse. 


Malinowski, Karyn 2004. Stress Management for Equine Athletes retrieved from(

Manfredi, J, Clayton, HM, Rosenstein, Mary Anne McPhail, 2005. Radiographic study of bit position within the horse’s oral cavity. Equine and Comparative Exercise Physiology 2(3); 195–20. College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824-1314, USA * Submitted 25 March 2005: Accepted 14 July 2005

Miller, Sue (2013). The single jointed-snaffle bit and the effect of rein angles, auxiliary reins and nosebands. Retrieved from

Peters, S., & Black, M. (2012). Evidence-Based Horsemanship. Shelbyville: Wasteland Press. 

Vogel, C (2011). Complete horse care manual. London: DK.


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