In modern day horse training, it is common practice to use equipment to help train the horses in head carriage and position. Devices like draw reins or side reins can be extremely useful in correcting the improper position of the head and neck and can also help teach them to lift the back and engage the hind end. Equipment like nosebands, flashes, or figure-eight bridles are used to prevent horses from opening their mouths to evade the bit. These training devices have a number of positive outcomes, but if used improperly, they can lead not only to harmful habits for horses like hyperflexion but also permanent damage. The incorrect use of equipment to modify head position can induce a stress response and damage the upper respiratory tract. 

 

The Relationship Between Head Position and Airway Diameter

 

The head and neck position (HNP) is known to have effects on the upper respiratory tract through flexion of the head and neck and can reduce the upper airway diameter. The respiratory system of the horse draws air through the larynx and trachea down into the alveoli, where oxygen is bound to hemoglobin. This means that when the head is drawn behind the vertical, the diameter of the airway decreases, potentially reducing the amount of oxygen intake.

 

Horses have a unique ability to absorb more oxygen than other species because of their higher body temperature and ability to function with high lactic acid and carbon dioxide levels (Fenger et al., 1). This ability to absorb more oxygen is also part of what makes horses exceptional athletes. In horses, oral breathing only occurs when anatomical abnormalities or disruptive conditions like dorsal displacement of the soft palate are present. During high intensity exercise such as Thoroughbred or Standardbred racing, horses exert 40 times more effort in breathing than at rest (Mellor and Beausoleil, 3). Over flexion of the neck will close off the pharynx and create airflow resistance, reducing the amount of oxygen circulating through the body. 

When the head and neck are completely stretched out, the upper respiratory tract (URT) is left open for airflow. When the head and neck are drawn into a hyper-flexed position, the URT narrows, reducing airflow. In Thoroughbred and Standardbred racing, the head and neck are more stretched out during a full gallop, allowing for greater airflow. In jumping disciplines, the head and neck are typically drawn to a 75-degree angle, which closes the larynx and reduces airflow to about 55% (Cook, 196-204). In dressage, the angle of the head is around 33-degrees, which reduces airflow even more (Mellor and Beausoleil, 6). 

 

Hyperflexion vs. LDR: Understanding the Key Differences

 

Hyperflexion, commonly used in Rollkur training, is the flexion of the horse’s neck achieved through aggressive force and has been declared illegal by the FEI on the grounds of equine welfare. A more detailed description defines Rollkur as the use of overbending or over-flexing of the horse’s head and neck, reducing the angle between a horse’s head and its neck including flexion of the mid-cervical region (Oldruitenborgh-Oosterbaan, et al., 1). 

 

There is a difference between a hyperflexed frame, as seen in Rollkur training, and a long, deep, and round (LDR) frame and this depends heavily on rein tension. The technique of LDR achieves flexion without undue force and is acceptable in competition, but there is a key difference between hyperflexion and LDR. In hyperflexion, the HNP is higher, creating a more extreme angle between the jowl of the horse and the neck. In LDR, the neck is more parallel to the ground, so while the nose of the horse may come behind the vertical line, the angle of the jowl and neck is not as severely affected (Toft et al., 5). 

 

There is one other dressage riding frame that must be taken into consideration when examining the effects of the HNP on airflow, and that is called a competition frame. A competition frame is described as having a higher neck position, with the head on or slightly in front of the vertical line (Tilly et al., 2). In traditional dressage, this frame is the desired position that judges look for and is believed to be the best position to lift the back and engage the hind end. 

 

The Role of Nosebands in Head and Neck Carriage

 

There are many types of equipment used in the pursuit of teaching a horse proper head and neck carriage. Devices like nosebands are used in English disciplines to keep the horse’s mouth closed around the bit. Per USEF regulations, nosebands should be able to fit two fingers between the cavesson and the top of the nasal bone. A study published in 2020 tracked 750 European English competition horses in the disciplines of eventing, dressage, and performance hunter horses. The study found that 44% of horses were ridden with nosebands tightened to allow no space between the device and the nasal bone. 7% of the horses passed the two-finger rule, another 7% only had space for half a finger, 23% could fit one finger between the cavesson and nasal bone, and 19% could fit one and a half fingers (Doherty et al., 11).

 

Flash nosebands are used on horses who show excessive unwanted behaviors with the bit. The flash band is attached to the top center of the cavesson and then wraps around the front of the bit to secure the mouth closed. While the tightness of the noseband itself should remain within the constraints of the two-finger rule, the flash band is tightened as much as possible. 

 

Crank nosebands are another tool used to close the horse’s mouth and are wider than the average noseband. Some designs have a width of up to two and a half inches as opposed to a traditional noseband’s one inch. Crank nosebands also feature a pulley mechanism on the underside of the chin, so the pulley will allow the band to be tightened with little force. These bands are designed to close a horse’s mouth shut without the use of a flash, but it has become common to see them used in conjunction with the flash band in recent years. A poll taken from the study on noseband tightness found that of the 750 horses used, 326 used a flash in conjunction with their noseband (Doherty et al., 9). Another feature of crank nosebands is their extra padding. In some cases, tight nosebands have been known to cause the horse’s hair to rub off, and extreme cases can even cause the nasal bone to swell (Perez-Manrique, et. Al, 2-3). 

 

Effects of Incorrect Noseband Usage on the Equine Airway

 

Overtightening a noseband can cause signs of stress in horses. When a noseband is overtightened, it inhibits the horse’s ability to lick, chew, and swallow during physical activity. When horses exhibit these behaviors, it is a sign that they are processing the instructions of the rider. These behaviors can also be attributed to signs of relaxation. Instead, horses perform these behaviors more after exercise when the bridle is removed (McCluskey, 1). Without the ability to perform these actions during exercise, tension forms in the masseter muscle, making it significantly more challenging for a horse to become relaxed and supple to the rider’s rein aids. 

 

Signs of stress in horses can affect their ability to perform athletically. A study performed on 12 horses wearing double bridles with crank nosebands was conducted to examine the stress response exhibited when the noseband is over tightened. The study found that an increased heart rate and eye temperature, as well as a decrease in heart rate variability, were found when the noseband was tightened past the two-finger rule before physical activity started (Fenner, et al., 12-18). These stress responses indicate that the overtightening of nosebands can have a negative physical and psychological effect on horses during exercise. Rises in eye temperature have a correlation with salivatory cortisol concentrations, which can indicate stress or pain in horses (Dai, et al.). 

 

Overtightening the noseband can negatively impact the pharyngeal diameter, as tight nosebands inhibit the horse’s ability to lick and chew on the bit, and it can cause horses to retract their tongues and press them against the soft palate (Scholler, et al., 7). This pressure by the tongue on the larynx decreases the pharyngeal diameter, limiting the intake of oxygen. 

 

Further analysis of horses ridden in over tightened nosebands shows that in conjunction with stress responses, some horses will curl their heads behind the vertical line and hyperflex in an effort to avoid the increased pressure that the bit exhibits on the tongue. The combination of this hyperflexed position and stress responses caused by an overtightened noseband can lead to pharyngeal collapse (Cehak, et al.). 

 

There is also risk of structural damage when over tightening a noseband. The pressure exerted by an overtightened noseband, and the horse resisting it can cause bone deposition, bone thinning, and loss of bone homogeneity (Perez-Manrique, et al., 17). As horses mainly use oxygen through the nose, these changes to the bone structure can cause respiratory issues. The issue of bone thinning in particular could lead to discomfort, pain, and in extreme cases, bone fractures that would cause compromised airflow. 

 

Draw Reins: Purpose, Proper Use, and Potential Risks

 

Draw reins are another tool commonly used in training horses. The purpose of draw reins is to encourage the horse to engage its hind end to lift the back and stretch the neck into the rein contact. When used properly, draw reins are a good choice to teach horses to stretch, however, there is much confusion with use. Draw reins put pressure on the horse’s mouth by connecting to each ring of the bit and attaching to either the center of the girth or the sides of the saddle. The attachment points of draw reins change based on the desired frame a rider is seeking for the horse. If the rider wants the head and neck to be lowered, then the draw reins attach to the girth. If they wish to raise the frame, then the device is attached to the sides of the saddle. 

 

Because of the amount of pressure draw reins put on the horse’s mouth, it can be easy to unintentionally teach the horse to hyperflex as it works to relieve the pressure. Hyperflexion can be caused by both attachment points of draw reins if they are not long enough. As with any training device, draw reins should be used to influence position, not create it. 

 

The Impact of Training Equipment on Equine Welfare and Performance

 

When used correctly, training equipment for horses has many benefits in teaching correct head and neck position. Used incorrectly, devices like nosebands, flashes, and draw reins can cause harmful habits in the horse’s head and neck that lead to issues with the airways of horses. These devices, used improperly, not only cause habits like hyperflexion, but can also induce stress responses like excessive increased heart rate, increased eye temperature, and behavioral changes such as excessive grinding of the bit. 

 

Over flexion of the head and neck, otherwise known as hyperflexion, can close the diameter of the airway and reduce the amount of oxygen a horse intakes. The practice of Rollkur, which draws the horse’s nose deep behind the vertical line, also closes the diameter of the airway, preventing horses from maximizing their breath. As found in the study on Thoroughbred and Standardbred racing, when the horse’s head and neck are fully stretched out, they are able to breathe fully and deeply. In the discipline of jumping, where the head and neck are drawn to a 75-degree angle, airflow is reduced to about 55%. Dressage disciplines show an angle of 33-degrees which further limits the amount of oxygen. 

 

Excessive tightening of nosebands, when the band is tightened past the two-finger rule, also has an effect on horses’ airways. When nosebands are over-tightened it limits the horse’s ability to lick, chew and swallow. The prevention of these behaviors can induce a stress response in horses, resulting in elevated eye temperature, heart rate, and cortisol levels. Overtightening of the noseband can also cause horses to push the tongue further back into the mouth in an attempt to avoid bit pressure. This action can cause pharyngeal diameter reduction, reducing the amount of airflow. Studies have also shown that the overtightening of nosebands can lead to hyperflexion in horses as they attempt to relieve the pressure caused by the devices. This behavior, in combination with harmful tongue movement, can exacerbate airway resistance and risk pharyngeal collapse. There are other physical signs of pain or stress an overtightened noseband causes as well. Structural damage to the nasal bone such as bone thinning and bone fractures can compromise the nasal passageway and affect nasal airflow. 

 

The incorrect use of draw reins can also have an effect on the upper respiratory system of horses. Draw reins are designed to help teach proper head and neck position, but when over tightened horses can instead develop habits like hyperflexion. This hyperflexion can have a negative effect on the URT, causing the diameter of the pharynx to close and reduce airflow. 

 

In conclusion, the misuse of training equipment like nosebands, crank nosebands, flashes, and draw reins can not only undermine their intended purposes, but also affect the health, performance, and well-being of horses. Riders who use these tools must not only be educated in how to properly use these devices but also be aware of the risks incorrect usage can bring. By adhering to safety guidelines like the two-finger rule on nosebands, equestrians can safeguard against negatively affecting the airflow of the URT. Additionally, by understanding stress signs in training, riders can help prevent harmful habits in training like hyperflexion and maintain a healthy respiratory system.