Horses have a very sensitive neural system around their skin hair follicles so that they can quickly respond to flies and other insects, toss their head, and swish them away. This is a normal process. However, in Headshaking Syndrome, this action is excessive and exaggerated, occurring without necessarily dealing with flies. About 1.4% of horses globally have been reported as having the syndrome, but in some locations (for instance in the UK) it has been recorded to be as high as 4.6%.1
Headshaking syndrome is also known as ‘facial pain syndrome’ or ‘trigeminal-mediated headshaking’. It’s not actually bad behaviour, as was previously thought, but the horse’s expression of pain or irritation via obsessive headshaking and evasive behaviour. It is of course very important to help your horse alleviate this kind of suffering if encountered. The stress of the syndrome can lead to other devastating health consequences, and it can also be potentially dangerous for a rider dealing with these kinds of involuntary shaking and jerking movements.
Some cases may be attributable to the presence of ticks or mites, dental problems, sinusitis or injuries. However, the most common reason for Headshaking Syndrome is pain or irritation of the trigeminal nerve (responsible for sensation in the neck and face, and motor functions such as biting and chewing).
Horses that are photo-sensitive can have this nerve reflex triggered by sunlight, in the same way that we might get triggered to sneeze in response to sunlight. The symptoms occur more often during seasonal changes and inclement weather. Intense exercise can also increase prevalence. The increased airflow over the muzzle and nostrils while riding or lunging may also play a factor.
Magnesium’s importance for the nervous system to calm headshaking syndrome
These environmental stress triggers causing involuntary muscle movements, pain and irritation have led scientists to believe Headshaking Syndrome could be a result of magnesium deficiency.
According to a recent 2019 study measuring the effect of magnesium and boron supplementation to alleviate headshaking stress symptoms;
“Trigeminal-mediated headshaking, formerly known as idiopathic headshaking, is caused by a low threshold of firing of the trigeminal nerve. Affected horses demonstrate abnormal behaviour with headshaking such as sudden jerking of the head with a downward then upward motion, rubbing the nose on their thoracic limbs or objects, lip movements, and excessive snorting, noted mostly during exercise… The horse’s behaviour suggests neuropathic pain that is manifested as an itching, burning, tingling, or electric-like sensation. In most cases, clinical manifestation is seasonal with worsening of signs during spring and summer months, and geldings are overrepresented.” 2
The study concluded, “Magnesium in combination with boron had the greatest decrease in headshaking. Oral supplementation with magnesium or magnesium in combination with boron should be considered in horses affected with headshaking.”
Boron is a natural partner supporting the work of magnesium in the body, and the study found that the presence of extra boron increased magnesium presence in the blood serum, thereby increasing oxygen supply and the beneficial balancing effect to the nervous system. However, the study showed that magnesium without the boron also worked well.
A study review called Magnesium Disorders in Horses states, “Magnesium (Mg) is an essential macro-element that is required for cellular energy-dependent reactions involving adenosine triphosphate and for the regulation of calcium channel function. Subclinical hypomagnesemia is common in critically ill humans and animals and increases the severity of the systemic inflammatory response syndrome; worsens the systemic response to endotoxins; and can lead to ileus, cardiac arrhythmias, refractory hypokalemia, and hypocalcemia.” 3
Note that naturally dehydrated food grade magnesium chloride salt flakes, as supplied by Elektra Magnesium, contain natural trace elements of boron, as well as other beneficial trace minerals such as iron, potassium, strontium, silica and more, which are naturally present in the salt water. The Magnesium4horses magnesium chloride products use the same magnesium.
The majority is 98% magnesium chloride hexahydrate – which is magnesium chloride joined to six water molecules in a crystalised form. The flakes are completely soluble in water, do not require further digestion, and are very palatable for horses. For more information about how to use in feeds see here.
Sandy Sanderson © 2022
References:
(1) Ross, S. E.; Murray, J. K.; Roberts, V. L. H. Prevalence of Headshaking within the Equine Population in the UK. Equine Vet J 2018, 50 (1), 73–78. https://doi.org/10.1111/evj.12708.
(2) Sheldon, S. A.; Aleman, M.; Costa, L. R. R.; Weich, K.; Howey, Q.; Madigan, J. E. Effects of Magnesium with or without Boron on Headshaking Behavior in Horses with Trigeminal-Mediated Headshaking. Journal of Veterinary Internal Medicine 2019, 33 (3), 1464–1472. https://doi.org/10.1111/jvim.15499.
(3) Stewart, A. Magnesium Disorders in Horses. The Veterinary clinics of North America. Equine practice 2011, 27, 149–163. https://doi.org/10.1016/j.cveq.2010.12.009.