Headshaking
[2] Minor head tossing is quite common in most horses as a response to insects and airborne irritants, however headshaking is a separate, severe issue.
[5] Many horses also show nasal irritation and engage in rubbing or striking the muzzle off of stationary objects, such as walls and fences.
[6] This makes riding a horse with the syndrome dangerous, as they may begin to violently toss their heads and thus, throw off the rider's balance.
[7] Headshaking may be caused by a variety of medical issues, such as ear ticks or mites, dental diseases, airway abnormalities, skull trauma, sinusitis, etc.
[1] The maxillary branch of the trigeminal nerve plays a major role in facial sensation, thus causing the horse to feel intense pain in the face and muzzle area.
[1] Research has shown that trigeminal-mediated headshaking may be triggered by various external factors, such as temperature, season, time of day, wind, light, and many others.
[3] This side of the syndrome is termed "photic headshaking" and is thought to occur due to the close proximity of the optic and trigeminal nerves.
[1] It affects a wide age range, but the majority of horses develop the behaviour after reaching maturity, usually between 6-10 years old.
Intense or more frequent exercise provides more stimulation to the brain causing increased firing of the trigeminal nerve.
[1] Some studies show that the behaviour is more common in Thoroughbreds and Warmbloods, however this point is refuted by other researchers who argue that headshaking is equally likely to be seen in any breed.
[1] Humans who suffer from neuropathic facial pain describe their symptoms as anything varying from tingling sensations to feelings similar to intense electric shocks.
[10] The net prevents irritants from entering the nostrils, decreases the amount of stimuli affecting the horse's muzzle area and may provide a constant counter-stimulation to the nerves of the face.
[10] It appears to be more effective if used immediately after diagnosis, as older horses who have lived with the condition for longer, were found to be less likely to show any improvement.
[7] Sodium cromoglycate eye drops are used to stabilize mast cell membranes and has been effective in a limited number of seasonally affected horses.
[1] More recently, compression of the caudal infraorbital nerve via platinum coils has been attempted as a last option treatment, although the rate of success is only 50% and the chance of injury post-surgery is quite high.
[7] Magnesium supplemented into the diet of affected horses has shown some successful reduction of headshaking behaviour, especially when combined with boron.
[5] It works to alter the horse's internal clock and shows the best results when administered at the same time every night, so that its effects will kick in during the day.
[1] Percutaneous electrical Nervous stimulation (PENS) is used as a treatment for human patients with trigeminal facial nerve pain.
