“In resting horses, the air entering the upper airway must turn approximately 90º to flow from the nasal passage into the trachea. That change in direction of airflow contributes to the work of breathing. During exercise, the effort needed to change airflow direction is reduced by straightening of the upper airway.

Straightening not only allows air a more direct route to and from the lung, it also tends to stretch and stiffen upper airway tissues, making them more rigid and more resistant to collapse.”

Dressage damage

This study demonstrated for the first time  that head and neck position affects upper airway mechanics in exercising horses.

Rollkur: The above has been reprinted with permission of Horses For LIFE Publications.

Although lots of people understand the pain inflicted on horses from the bit and hyperflexion, the majority just stand there watching without even noticing the clearly visible, uncomfortable, stressful, negative stimulus and pain inflicted on the horses. Humans are the cause of this pain.

What really caught my attention, more than anything else, was the look on the faces of the people watching around the arena. It was clear that they felt nothing about what was happening to the horses there. They look as if they were switched-off mentally, devoid of the feelings that any sensible person in such a situation would feel. It is probably how the FEI wants people to be so as not to cause damage to the business of sport and ignoring the damage being caused to the horses. Hyperflexion like that puts the horse in a state of fear, from where he cannot escape, which spreads from his mind to his whole body.

I would like to add a quote from a Nevzorov Haute Ecole member and good friend of mine, Sascha Day, who has posted in our forum the following scientific research.

To take this to a scientific understanding of the damage going on we should know that the tongue is connected profoundly to the hyoid apparatus; very important as it suspends larynx from base of the skull and is involved in vital processes such as swallowing and breathing. Any damage to the hyoid apparatus is real suffering for the horse. There have been studies conducted which shows suggestion of DJD (Degenerative Joint Disease) and bony proliferation to hyoid apparatus; also called bony growths or “spurs”. The use of rollkur damages nerves of the face, tongue and causes degeneration of the hyoid apparatus as well as surrounding soft tissues.

Connected to the tongue and very important to the horse’s ability to move the tongue is the hypoglossal nerve. Any damage to this will cause paralysis of the tongue and also the surrounding areas of the lips and face. Look again at the horse’s swinging, floppy lips and rigid face and also the excessive drooling seen in this example and in so many others. The irony is that the so called “experts” in the field of sports dressage actually encourage and promote drooling as a good thing for the horse, when clearly the science proves that this is a serious sign of damage to the hyoid apparatus and surrounding vital nerve functions resulting in the horse’s inability to swallow properly.

You NEVER see any of Alexander Nevzorov’s horses drooling.

It can clearly be seen how the humans in this scenario are having their fun and making their money but does it have to be at the expense of the horse? Or is this kind of power and the money just make them blind and sick?

Maurizio Patti
Senior Nevzorov Haute Ecole Instructor

In a an interview with Dr. Derksen, he highly thinks that the key is not that there is any tension in the horses neck causing a collapse. Rather that actually might be the problem that without tension the trachea is more prone to collapse. Being a soft tissue structure that it relies upon other muscle and tissue to help support it when increased exertion requires additional airflow.

“Straightening not only allows air a more direct route to and from the lung, it also tends to stretch and stiffen upper airway tissues, making them more rigid and more resistant to collapse.”

He thinks it is important to note that this was not a static collapse but a dynamic collapse. Meaning that there was no problem breathing out, just breathing in. If this was problem because of existing tension, for example putting pressure on the trachea, then we would expect this to be a static collapse with problems both on inhalation and exhalation.

” The fact that you would have more of a problem during inhaling would make sense as this phase would be more prone to cause instability or collapse of the airway. “

Dressage Damage A

He must admit that it took him a while to wrap his head around this. How it was the actual force of the lungs trying to inhale that was causing the problems He kept wanting to imagine something pushing on the trachea that was causing the problems.

” So as the throat of the horse is constricted you get complicated variations in pressure that tend to cause the surrounding tissue (which is quite flexible after all) to move around and take up less efficient shapes.”

Dressage Damage B

He mentioned that the study by Petsche was on healthy horses with no known breathing problems. All the horses had problems inhaling when put into a flexed position. I think it is important to note that they picked healthy horses.

“These horses had no history of airway obstruction and no abnormalities detected by physical examination and airway endoscopy.”

He emphasized that for a horse at rest that is breathing 20 times a minute with a tidal volume of 5 liters has a minute ventilation of 5 liters. As this horse begins to exercise, respiratory rate and tidal volume increase to achieve a minute ventilation of approximately 1,500 liters/minute. The upper airway must accommodate this large increase in airflow by undergoing changes in caliber, rigidity, and shape. So when exactly does this become a problem?

“In the resting horse, pressure changes are relatively modest and therefore changes in resistance are also small. On exhalation, there is positive pressure in the upper airway moving air out to atmosphere. This positive pressure tends to dilate the upper airway, thereby decreasing resistance. Conversely, on inhalation, there is a negative pressure in the upper airway, relative to atmosphere. This is needed to move air in from the atmosphere via the upper airways into the lungs. This negative pressure tends to decrease airway caliber, thereby increasing resistance. During exercise, these pressure swings are greatly exaggerated because of the much higher airflows.”

Dr. Derksen has been interested for some time in doing a study on dressage horses and rollkur.His research noted a 50% decrease in airflow in when the horse was on the vertical.

The question then became what would happen if you went behind the vertical?

The answer: EVEN a small increase would make a big difference. So, for example, if you double the bend you would MORE THAN double the resistance.

Dr. Derksen finds the difficult part about this kind of research is that unless you bring a lot of peopl

e’s attention to it, there is no drive to extend the research parameters any further. To test, if there are parameters in which this will not occur.

Maybe this article can be part of that, I don’t know.

This is where we need additional research. And for people to ask for and fund this research.

It has been postulated by Cook in 1981 that upper airway impedance is reduced when the head and neck are extended and that upper airway impedance is increased when the neck is flexed and the head is in a tucked position.

Veterinarians have known of this phenomenon for many years,decades even, it wasn’t until the study was down by Petsche and Derksen in 1995, that this was taken into an actual scientific study. While some riders and trainers may not need further documentation, we know that those that follow rollkur do! Insisting that they do no damage to their horses… this study shows that this is just not true. Since we know that it is the amount of bend in the trachea that causes the resistance to the inflow of air causing the dynamic collapse, and we know that increasing the bend even a little will greatly exaberate the problem, this being simple mechanics, we know that these horse’s are suffering. But some are not listening and we need the documentation that further study can provide.

There is also some suggestion that airway obstruction exhausts diaphragmatic vasoldilator reserve. I would suggest that this is also another area that requires further research. This might also provide us with an additional diagnostic tool to see if this was affecting our own horses.

I have a feeling that if everyone truly rode according to the old classical mantra’s of head ahead of the vertical and only approaching the vertical on piaffe and not setting the head; and developing the back end carriage, topline stretch and then allowed the head hang like a chandelier. The masters often knew what they were doing. Many have known of this problem, as it becomes more obvious if another problem already existing problem is present.

The good part of that answer in my mind is that if even a small increase would make a huge decrease in the ability to breathe for the horse, that a small decrease would make a huge increase in the ability to breathe. Thus, coming even a little ahead of the vertical should improve the horse’s ability to breathe.

Let’s go back to our classical heritage and help our horses.

Special Thanks to Dr. Derksen to take the time out of his busy schedule to answer our questions directly. The above has been reprinted with permission of Horses For LIFE Publications.

The horse’s brain stays cool during exercise. While on the other hand, the horse’s head movement greatly affects breathing and drooling in horses.

Dressage Damage A

Guttural pouches are air-filled extensions of the auditory tubes that appear to “puff pad” some of parts of the viscera of the head from harsh contact with bony structures of skull and hyoid apparatus.

Hyoid bones are ancient and honorable vertebrate structures derived from a gill arch in jawless primitive fish. Such fish still living without jaws are hagfish and lampreys. When jaws were invented, the hyo-mandibular gill arches were converted into essential support structures for the neck and skull. Hyoid structures are magnificent and various in vertebrates. In frogs, the hyoid is configured into a large springlike apparatus, powerfully invested with muscles that allow it to “fire” their ballistic tongues to capture prey. Some amazing tongues (including those with special neurologic and hydrostatic operational features) are found in amphibians, but are beyond the scope of this Atlas. The concept here is that in the water, or on land, this is a critical part of the skeleton for most vertebrates!”

Dressage Damage B

In humans, the hyoid is a horse-shoe shaped structure between the bones of the lower jaw. You can feel hyoid connections to your sternum by placing a finger at the notch in the base of your neck, opening your jaw and wiggling your tongue. The six thin muscles that “cable” your “front line” (bottom line for horses) can be felt as you shift your tongue from side to side. If you clamp your jaw, this restricts chest and clavicle movement. Your clavicles are connected to your arms and shoulder blades.

A clamped jaw stiffens a rider’s responses to motions of the horse and interferes with an independent seat. From this point of view, it should be clear that moving a horse’s head has important consequences for its comfort and for its capacity to perform.

The hyoid bone does not articulate with any other bone. Instead, it is suspended by ligaments from the styloid processes of the temporal bone at the base of the brain, in the soft tissue of the neck between the mandible and the larynx. It has a bit of range of motion, but not much. Other examples of ligamentous rather than articulated joints are your teeth (and your horse’s teeth) and the sternoclavicular joint at the base of your neck (horses have no clavicle). The function of the hyoid bone is to provide attachment points for the muscles and ligaments of the tongue, pharynx and neck. And that is the problem for horses! Note the hyoid, which is jointed to the skull by ligaments, keeps approximately the same relation to the base of the skull, not the neck and lower jaw.

According to Derksen and Robinson,  notice that the hyoid at its lower extremity (the two backward-facing hooks) is where the thyroid sits and that needs to stay in pretty close relation to the cartilage of the airway, so it is generally the airway that shifts shape. You can get some sense of how head motions affect the hyoid by turning your head way up or way down and feeling what this does to your tongue… putting your chin down as far as it can go (human rollkur) pulls your tongue up, just as it does for the horse.

Dressage Damage C

Other important structures entering the back of the skull are the facial, glossopharyngeal, vagus, accessory and hypoglossal nerves; continuation of the sympathetic neural trunk beyond the cranial cervical ganglion.

The tongue is attached by its muscle at its base to the forward  prong of the hyoid. In turn, the hyoid is directly linked to the sternum by six muscles of the sternohyoid group.Because of these closely placed soft and hard structures, training methods involving strong repositioning of the horse’s head should be undertaken with care (as in exaggerated flexions), because they affect the carriage of the tongue. In the quest for mobility of forehand anatomy, it is easy to cause interference with vital functions such as breathing and swallowing or to put pressure on nerves. A large salivary gland, the parotid, lies at the back edge of the jaw and is compressed during right to left and downward motions of the head. Some horses have conformation that allows relatively small space for this gland to be seated.

Dressage Damage D

Other important structures entering the back of the skull are the facial, glossopharyngeal, vagus, accessory and hypoglossal nerves; continuation of the sympathetic neural trunk beyond the cranial cervical ganglion.

[Editors Note: Even those horses with relatively good conformation for the placement of the parotid glands may be adveresly effected by extreme positioning of the head, which can then create pressure on the parotid gland.]

Dressage Damage E

On occasion, adverse reactions to movements of the head may be traced to cramped space for this gland or its irritated condition. One symptom of riding with a strong rein that shortens the neck is excessive salivation from pressure on the parotid gland: some foaming around the bit is normal during exercise.

Rollkur: An Overview – The above has been reprinted with permission of Horses For LIFE Publications.