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availability seems to play the biggest role in triggering the behaviour. Affected horses tend to experience more symptoms when outdoors on sunny days. Therefore, headshaking occurs most often during the spring and summer months when sunlight is more prevalent. 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. The symptoms of photic headshakers lessen when indoors and during the nighttime.
531:, in which the trigeminal nerve is cut or blocked, has been used to attempt to treat headshaking. This method is not used anymore, as the rate of success was quite low and the surgery had serious side-effects on the horse. 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.
66:
45:, or ridden, and typically subsides while the horse is at rest. 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. Because of its prevalence during exercise, many riders incorrectly attribute headshaking to a behavioural problem or to poorly fitted
403:
Headshaking is a condition which impacts the life and the welfare of affected horses. Since the behaviour is caused by facial pain, the horse may be in constant discomfort. The intensity of the behaviour can range and therefore, some horses may experience greater pain than others. Various scales have
93:
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. It was distinguished that there is no difference in the involvement of the left or right branch from the trigeminal nerve. The horse's pain is
485:
to the nerves of the face. This method is noninvasive, cheap and is also permitted to be worn in most equestrian competitions. It is one of the most successful treatment methods, although it does not eradicate the problem completely. Approximately 70% of owners who attempted this method reported at
89:
was tested and is in healthy horses established at 10mA, while affected horses show a result of 5mA. Research shows that the infraorbital nerve branch of affected horses is sensitized and has an increased threshold compared with unaffected horses. The branch, therefore, has a lower firing threshold
462:
may be possible to infer similarities in pain between affected humans and horses. It is thought that the horses feel sensations of tingling, itching, burning and electric-like shocks. They attempt to alleviate this pain by throwing and tossing their heads, as well as rubbing the nose, snorting and
306:
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. Approximately 1.4% of horses are affected by headshaking and of those with the condition, 64% are affected seasonally. Light
29:
Minor head tossing is quite common in most horses as a response to insects and airborne irritants, however headshaking is a separate, severe issue. The headshaking needs veterinary attention if it occurs spontaneously with no sign of any external stimuli that may cause the motion. The behaviour is
594:
has also been used as a treatment for horses suffering from photic headshaking. 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. Many researchers argue that the effects of feed
310:
Headshaking appears to occur in horses all over the globe, but variations in the symptoms can be based on region. In the USA, 91% of affected horses were found to experience increased headshaking during the spring and early summer. While in the UK, only 39% of affected horses displayed worsened
56:
known as trigeminal neuralgia. It has been found that many factors, such as environment, sex, and breed, contribute to the prevalence of the behaviour. Many treatments have been proposed to help control the symptoms of the condition, but a solution to cure the behaviour has yet to be found.
347:
Exercise can also influence the intensity of headshaking behaviour. Intense or more frequent exercise provides more stimulation to the brain causing increased firing of the trigeminal nerve. The increased airflow over the muzzle and nostrils while riding or lunging may also play a factor.
90:
and can be triggered by various, even minor stimuli. But some seasonally affected horses seemed to have a normal threshold, when tested out of season. If the clinical symptoms are in fact connected to the threshold of the nerve, it holds the possibility of a reversible condition.
502:
Face masks can be successful in reducing the symptoms of photic headshakers. Usually the mask contains ultraviolet shades to block out any sunlight. This method works to reduce the stimulation affecting the ophthalmic branch, thus reducing the stimulation of the trigeminal nerve.
268:
The veterinarian has to observe the horse during exercise, at rest and under the influence of different environments and possible triggers. It sometimes can be helpful to have video materials of the owner and observe the horse on different days, to distinguish certain triggers.
335:. In some studies, as high as 90% of headshakers were found to be geldings. It is thought that geldings may be more susceptible to headshaking, as they do not have testosterone feedback, therefore during the spring when horses typically mate, the gelding's
322:
Headshaking seems to be an acquired condition that develops during the prime of the horse's life. It affects a wide age range, but the majority of horses develop the behaviour after reaching maturity, usually between 6-10 years old. A larger percentage of
1201:
Roberts, V. L. H.; Patel, N. K.; Tremaine, W. H. (2016). "Neuromodulation using percutaneous electrical nerve stimulation for the management of trigeminal-mediated headshaking: A safe procedure resulting in medium-term remission in five of seven horses".
602:
Percutaneous electrical
Nervous stimulation (PENS) is used as a treatment for human patients with trigeminal facial nerve pain. It was tested on horses recently and could turn out to be a working treatment, more research on this method is necessary.
486:
least somewhat of an improvement in the symptoms of their horse. 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.
30:
most commonly described as a vertical flicking of the head, as if an insect has flown up the animal's nostrils. Many horses also show nasal irritation and engage in rubbing or striking the muzzle off of stationary objects, such as walls and fences.
463:
sneezing. This behaviour can cause the horse to become dangerous to ride, or even handle on a daily basis. The condition can also become an economic burden on the owner, as depending on the method, the treatment may be costly to keep up with.
480:
Nose nets may cover the horse's entire muzzle (nostrils and lips) or only the nostrils. The net prevents irritants from entering the nostrils, decreases the amount of stimuli affecting the horse's muzzle area and may provide a constant
471:
Various treatment methods have been proposed to lessen the effects of headshaking, however, the behaviour has yet to completely cured. The success of a technique may vary depending on the horse's particular characteristics.
518:
membranes and has been effective in a limited number of seasonally affected horses. It is thought that eye drops may only work as a treatment for horses who experience headshaking as a result of environmental allergies.
590:. It is thought that magnesium may have calming effects on the over-sensitive nature of the trigeminal nerve. However, magnesium supplementation can be dangerous, as high doses need to be used to create an effect.
292:
Even though there can be a variety of different causes, 98% of the affected horses in need of veterinary care turned out to have no connection to external causes, leading to a connection to the trigeminal-nerve.
81:, dental diseases, airway abnormalities, skull trauma, sinusitis, etc. However, the most common and well-researched cause is trigeminal neuralgia, a neurological condition that affects the animal's
314:
Other individuals have been found to be triggered by the wind conditions, rain conditions, and the presence of loud sounds, although the reasoning behind these influences are currently unknown.
26:, where the horse continuously shakes its head vertically and/or horizontally. In the 1980s it was considered a bad behaviour, but instead it turned out to be a painful medical condition.
539:
A wide variety of pharmaceuticals have been used in trials attempting to reduce headshaking in horses. Many may have averse side-effects and may also be banned from use in show horses.
364:
Headshaking has been observed in a wide variety of horses and is thought to be able to occur in any breed. Some studies show that the behaviour is more common in
94:
expressed in its obsessive headshaking and evasive behaviour. The condition is known as "trigeminal-mediated headshaking" or "facial pain syndrome".
339:
will be incredibly heightened. The gonadotropins alter the sensitivity of the trigeminal nerve, making it unstable and more susceptible to stimuli.
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supplemented into the diet of affected horses has shown some successful reduction of headshaking behaviour, especially when combined with
551:
which has been effective in significantly reducing headshaking symptoms in many horses. It can be used alone or in conjunction with
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After the inspection, the horse has to be examined for other causes of the headshaking not related to the trigeminal- nerve.
953:
867:
795:
765:
372:, however this point is refuted by other researchers who argue that headshaking is equally likely to be seen in any breed.
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symptoms during only the spring and summer months, with more horses being affected during the spring, summer and fall.
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describe their symptoms as anything varying from tingling sensations to feelings similar to intense electric shocks.
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1146:"Effects of magnesium with or without boron on headshaking behavior in horses with trigeminal‐mediated headshaking"
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Pickles, Kirstie; Madigan, John; Aleman, Monica (July 2014). "Idiopathic headshaking: Is it still idiopathic?".
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or general all-purpose riding horses. Other disciplines that restrict the movement of the horse, such as
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used to treat nerve pain in humans. Other past and presently used forms of medication include:
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Sheldon, Shara A.; Aleman, Monica; Costa, Lais R.R.; Weich, Kalie; Howey, Quinn (May 2019).
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663:"Trigeminal-mediated headshaking in horses: prevalence, impact, and management strategies"
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387:, also tend to have more cases of headshaking. Intense, high activity disciplines like
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Although other causes have been noted, the most common cause of headshaking is the
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Mild headshaking behaviour, insufficient enough to not interfere with riding
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Roberts, Veronica (May 2018). "Managing headshaking in horses: An update".
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Headshaking behaviour severe enough to make riding dangerous or impossible
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When it comes to discipline, headshaking horses are typically found to be
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The behaviour is most commonly displayed while the horse is being led,
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been created and used to rank the intensity of headshaking behaviour.
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Additional diagnostics should be considered as well. These include:
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948:(Fourth ed.). Missouri, USA: Elsevier Inc. pp. 580–708.
862:(Second ed.). Edinburgh, UK: Elsevier Ltd. pp. 503–526.
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Headshaking may be caused by a variety of medical issues, such as
790:(Second ed.). Edinburgh, UK: Elsevier Ltd. pp. 77–109.
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324:
210:
944:
Aleman, Monica; Nout-Lomas, Yvette S.; Reed, Stephen M. (2018).
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713:"Headshaking in horses: Horse & Hound veterinary library"
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and do not actually help with the symptoms of the condition.
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23:
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Madigan, John (October 2000). "Therapy for headshaking".
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Crabbe, Barb (January 2018). "The facts of headshaking".
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appear to be affected by the condition when compared to
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1077:
Journal of the
American Veterinary Medical Association
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1071:
Madigan, John E.; Bell, Stephanie A. (Aug 1, 2001).
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98:Potential non-neurological causes of headshaking
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760:. London, UK: Elsevier Inc. pp. 311–345.
395:, show a decreased amount of affected horses.
408:Roberts headshaking behaviour grading system
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448:Headshaking behaviour occurs even at rest
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1088:
857:
788:Equine Medicine, Surgery and Reproduction
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667:Veterinary Medicine: Research and Reports
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858:Carr, Elizabeth A.; Maher, Omar (2014).
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1150:Journal of Veterinary Internal Medicine
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1073:"Owner survey of headshaking in horses"
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661:Roberts, Veronica (Jan 9, 2019).
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514:eye drops are used to stabilize
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87:somatosensory- evoked potential
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37:A horse displaying headshaking
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22:is a behaviour displayed by
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498:A horse wearing a face mask
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1090:10.2460/javma.2001.219.334
1050:10.1016/j.tvjl.2014.03.031
786:Lane, J. Geoffrey (2012).
758:Equine Behavioral Medicine
756:Beaver, Bonnie V. (2019).
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1204:Equine Veterinary Journal
977:Newmarket Equine Hospital
424:No headshaking behaviour
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60:
946:Equine Internal Medicine
297:Influences on prevalence
973:"Headshaking in horses"
456:neuropathic facial pain
454:Humans who suffer from
183:Temporomandibular joint
1038:The Veterinary Journal
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460:Translational research
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302:Environmental triggers
103:Oral cavity disorders
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595:supplements are mere
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129:Vision abnormalities
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54:neurological disorder
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680:10.2147/VMRR.S163805
549:serotonin antagonist
352:Breed and discipline
219:Laryngeal disorders
194:Stereotypy behaviour
150:Avoidance behaviour
142:Fractures or trauma
69:Equine facial nerves
512:Sodium cromoglycate
483:counter-stimulation
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200:Pharyngeal lesions
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1162:10.1111/jvim.15499
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155:Buccal ulceration
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1216:10.1111/evj.12394
955:978-0-323-44329-6
906:10.1136/inp.k1493
869:978-0-7020-4771-8
820:Horse & Rider
797:978-0-7020-2801-4
767:978-0-12-812106-1
717:Horse & Hound
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233:Ill-fitting tack
204:Nasolacrimal duct
126:Dental disorders
112:Airway disorders
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1156:(3): 1464–1472.
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115:Skull disorders
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16:Horse behaviour
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1252:Horse behavior
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1210:(2): 201–204.
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1083:(3): 334–337.
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900:(4): 157–161.
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611:
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573:phenobarbitone
557:anticonvulsant
541:Cyproheptadine
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1044:(1): 21–30.
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981:. Retrieved
979:. 2018-04-19
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721:. Retrieved
719:. 2019-11-13
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1125:(10): 630.
894:In Practice
579:Supplements
393:showjumping
318:Age and sex
20:Headshaking
1188:2247641608
983:2019-12-02
922:2210117315
832:1980700610
723:2019-12-02
607:References
561:Gabapentin
535:Medication
529:neurectomy
490:Face masks
370:Warmbloods
264:Diagnostic
225:disorders
206:disorders
189:Neuropathy
185:disorders
161:, masses,
1224:2042-3306
592:Melatonin
584:Magnesium
516:mast cell
507:Eye drops
476:Nose nets
467:Treatment
333:stallions
288:Endoscopy
246:Sinusitis
215:granuloma
211:abscesses
168:Ear mites
163:cataracts
75:ear ticks
1246:Category
1232:25475743
1184:ProQuest
1180:30990929
1099:11497047
1058:24821361
918:ProQuest
914:79847134
828:ProQuest
699:30666296
385:eventing
381:dressage
343:Exercise
325:geldings
229:Myositis
209:Masses,
179:disease
138:Rhinitis
1171:6524471
690:6330979
673:: 1–8.
523:Surgery
1230:
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571:, and
543:is an
413:Scale
399:Impact
389:racing
282:X-Rays
133:Otitis
121:Other
61:Causes
43:lunged
24:horses
910:S2CID
588:boron
555:, an
329:mares
172:ticks
159:Cysts
79:mites
1228:PMID
1220:ISSN
1176:PMID
1095:PMID
1054:PMID
950:ISBN
864:ISBN
792:ISBN
762:ISBN
695:PMID
547:and
391:and
368:and
331:and
47:tack
1212:doi
1166:PMC
1158:doi
1127:doi
1085:doi
1081:219
1046:doi
1042:201
902:doi
685:PMC
675:doi
383:or
279:MRI
170:or
77:or
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