This list is not exhaustive but includes the most important published, veterinary papers on headshaking. They are listed in order of publication, most recent first. You should be able to get hold of them from the library of your nearest university that runs zoological or veterinary courses.  You might also be able to buy reprints from the publishers directly. The links to the publishers, a summary or the actual article are given, where possible. 

Mills, DS and Taylor, K (2003) Evaluation of three types of nose net for the treatment ofequine headshaking. The Veterinary Record 152; 41-44.

Thirty-six owners of seasonally headshaking horses took part in a trial to compare the effectiveness of three types of nose net, a traditional cylindrical net (full net) and two forms of larger mesh nets which cover only the nostrils and dorsorostral muzzle (half nets). Baseline data relating to the overall severity of the problem and 18 specific behaviours describing the nature of the problem were recorded on a check sheet by the owners. A within-subjects repeated measures design experiment, with each net used for a week before reassessment, was then used to assess the effect of the nets on the headshaking problem. Approximately 75 per cent of owners reported some overall improvement with each net; around 60 per cent recorded a 50 per cent or greater improvement and 30 per cent a 70 per cent or greater improvement. The nets significantly reduced the overall headshaking score and the following specific behaviours: up-and-down headshaking, nose flipping, acting as if a bee had flown up the nose, shaking at exercise, shaking when excited, shaking in bright sunlight or in windy conditions (P < 0.0001), striking at the face, shaking at night, rubbing the nose when moving, rubbing the nose on objects, sneezing, shaking in the rain and shaking indoors (P < 0.05). There was no evidence of a significant effect on side-to-side headshaking, shaking at rest or rubbing the nose when stationary, but the effect on snorting was uncertain. There were few significant differences between the nets, but the half nets were reported to be significantly better at controlling 'bee up the nose' behaviour. Horses more than 10 years old were reportedly less likely to show a 50 per cent or greater improvement in 'nose flipping' and 'headshaking at exercise.

Cook, W.R. (2003) Bit-induced pain: A cause of fear, flight and facial neuralgia in the horse. Pferdeheilkunde 19, 1-8. (A German equine journal)

An ethological survey was based on 605 written reports from horsemen who had switched from a bitted bridle to a new bitless bridle. The comparison of equine behaviour was between an invasive and painful method of control (a bitted bridle) and a non-invasive and painless method (a bitless bridle). The unprecedented opportunity to switch a horse, overnight from painful to painless control revealed many new and serious manifestations of the syndrome ‘aversion to the bit’. The survey demonstrated that the bit method of control caused 58 adverse behavioural effects. All 58 effects could be classified under four major effects; to instil fear, to trigger flight, to make the horse fight back and to cause facial neuralgia (the headshaking syndrome). These effects could all, in turn, be categorised as responses to oral pain. The sensory pathway for registering pain caused by the bit is the trigeminal nerve but the motor pathways involved many systems, with the nervous, respiratory and musculoskeletal systems predominating. The behavioural responses interfered, in particular, with attitude to exercise, breathing and locomotion. A survey of 65 horse skulls revealed painful, bit-induced exostoses on the mandibular diastema in 49 (75%). It was concluded that a bit is harmful to the health and safety of horse and rider, and an impediment to performance.

Mills, DS, Cook, S, Taylor, K and Jones, B (2002) Analysis of the variations in clinical signs shown by 254 cases of equine headshaking. The Veterinary Record 150 (8); 236-240.

A national survey of headshaking in 254 horses was undertaken to describe the clinical signs of the conditions as observed by horse owners. Principal component analysis was used to determine the underlying structure of 11 signs and the criteria by which the affected horses could be most effectively differentiated; the analysis suggested 5 components with a variance greater than 1 which together explained over 60% of the total variance. Other analyses of the data indicated that headshaking could develop at any age and that twice as many males were affected as females; 64% of the horses shook their heads seasonally and geldings were more likely than mares to be seasonally affected. Seasonal headshaking tended to be significantly worse on sunny days but improved on rainy days, windy days, at night and indoors.

DS Mills, S Cook and B Jones (2002) Reported response to treatment among 245 cases of equine headshaking The Veterinary Record 150; 311-313.

Table of treatments reported by 245 owners and their level of success (adapted from paper)

Treatment	No. horses	Reported Success %
		Complete	Partial	None
Nose net	179	27	34	39
Face net	51	8	41	51
Homeopathy	93	6	31	62
Feed supplement	105	5	31	65
Ear net	82	4	29	67
Trad. Vet. treatment	129	6	22	72
Back specialist	50	0	8	92

Taylor, K, Cook, S and Mills, DS (2001) A case-controlled study investigating health, management and behavioural features of horses commonly described as headshakers. Ippologia 12 (3); 29-37. View this entire paper using Adobe Acrobat reader.  Click here: Taylor imp.pdf

There is much opinion about putative risk factors associated with headshaking, however these factors have not been investigated in a rigorous scientific manner to date. A case-control study involving 83 pairs (headshaker and matched non-headshaker control) of general-purpose riding horses was therefore conducted. The results suggest that headshakers may be at a slightly higher risk of developing non-respiratory allergies, but management factors, in general, were not found to be significant in the occurrence of the disorder. The owners of headshakers were more likely to use non- conventional therapies such as homeopathy and back specialists for treating their horses. This might be a consequence of their frustration with failed attempts to find successful conventional veterinary treatments for the headshaking condition. Comparison of the symptoms of the two groups suggested that many of the behavioural signs associated with headshaking are reported to occur only rarely if at all in horses not described as headshakers by their owners. These results are consistent with the hypothesis that headshaking is a sign of head pain rather than a behavioural or reactive state. In this case attention should be paid to different potential causes of such a potential complaint. A careful exploration of the horses' symptomatology, response to trial treatments and history may be more useful aids to a diagnosis than examination of current management practices and diet.

Madigan, JE and Bell, SA (2001) Owner survey of headshaking in horses. Journal of the American Veterinary Medical Association. 219 (3) 334-337

OBJECTIVE: To determine signalment, history, clinical signs, duration, seasonality, and response to various treatments reported by owners for headshaking in horses. DESIGN: Owner survey. ANIMALS: 109 horses with headshaking. PROCEDURE: Owners of affected horses completed a survey questionnaire. RESULTS: 78 affected horses were geldings, 29 were mares, and 2 were stallions. Mean age of onset was 9 years. Headshaking in 64 horses had a seasonal component, and for most horses, headshaking began in spring and ceased in late summer or fall. The most common clinical signs were shaking the head in a vertical plane, acting like an insect was flying up the nostril, snorting excessively, rubbing the muzzle on objects, having an anxious expression while headshaking, worsening of clinical signs with exposure to sunlight, and improvement of clinical signs at night. Treatment with antihistamines, nonsteroidal anti-inflammatory drugs, corticosteroids, antimicrobials, fly control, chiropractic, and acupuncture had limited success. Sixty-one horses had been treated with cyproheptadine; 43 had moderate to substantial improvement. CONCLUSIONS AND CLINICAL RELEVANCE: Headshaking may have many causes. A large subset of horses have similar clinical signs including shaking the head in a vertical plane, acting as if an insect were flying up the nostrils, and rubbing the muzzle on objects. Seasonality and worsening of clinical signs with exposure to light are also common features of this syndrome. Geldings and Thoroughbreds appear to be overrepresented. Cyproheptadine treatment was beneficial in more than two thirds of treated horses.

Scott, S. (2001) Acupuncture and headshaking in horses. Veterinary Times 6th August 2001, 19-20.

Newton, S. A., Knottenbelt, D.C. and Eldridge, P. R. (2000) Headshaking in horses: possible aetiopathogenesis suggested by the results of diagnostic tests and several treatment regimes used in 20 cases. Equine Veterinary Journal 32 (3), 208-216.  A summary of this is available in pdf form from the website: http://nvdls.unl.edu/let00/Oct00.pdf Scroll down to page 6.

Cook, W.R. (2000) A solution to the problems for man caused by the bit method of control. Pferdeheilkunde 16, 333-351. (A German equine journal)

Cook, W.R. (1999) Pathophysiology of bit control in the horse. Journal of Equine Veterinary Science 19 (3), 196-204.

Mair, T. S. (1999) Assessment of bilateral infra-orbital nerve blockage and bilateral infra-orbital neurectomy in the investigation and treatment of idiopathic headshaking. Equine Veterinary Journal 31 (3), 262-264.

Madigan J.E. and Bell S. A. (1998) Characterisation of headshaking syndrome - 31 cases. Equine Veterinary Journal Supplement 27, 28-29.

Headshaking is a maturity onset condition with the most commonly reported clinical signs being 'flipping' of the nose, nose rubbing, snorting or sneezing, and acting like a bee is flying up the nostril. A questionnaire was completed by owners of 31 horses with headshaking syndrome. The history, time of onset, clinical presentation and treatment of this condition were reported. Headshaking appeared to be light-stimulated in approximately 60% of the horses. The condition is seasonal and recurring in the majority of horses. Treatment with cyproheptadine produced improvement of symptoms in 76% of cases. The clinical signs are suggested to be compatible with neuropathic pain producing itching, tingling or electric like sensations in the face and muzzle area of affected horses.

Mansfield, J.R. (1998) Treatment of Equine Allergic diseases with allergy neutralisation: a field study. Journal of Nutritional and Environmental Medicine 8 (4), 329-334.

The allergy desensitization technique, known as "intradermal neutralization", was originally described by Dr H. Carlton-Lee. The procedure was later extended and modified by Professor J. B. Miller of Mobile, Alabama and currently is used extensively for treating allergic disease in humans, especially in the USA, but also in Canada, the UK and Australia. The technique has been shown in many clinical papers to be effective in humans as a means of desensitizing both food and biological inhalant allergens. It is also effective in chemical sensitivity. Although there have been sporadic reports of successful use in horses and other animals, this is the first to show a marked effect in equine asthma, otherwise known as chronic obstructive pulmonary disease or heaves. The results in equine urticaria are even better and there appears to be benefit in some cases of headshaking (equine rhinitis). The number of horses treated for sweet itch was too small to draw any conclusion. The positive effects shown in this study lend further support to those studies in humans, as a placebo effect in horses must be highly unlikely.

Madigan, J.E. and Bell, S.A. (1997) Evaluation and treatment of headshaking syndrome. Proceedings of the American Association of Equine Practitioners 43, 340-342.

Moore, L.A., Johnson, P.J., Messer, N.T., Kline, K.L., Crump, L.M. and Knibb, J.R. (1997) Management of headshaking in 3 horses by treatment for protozoal myeloencephalitis. The Veterinary Record 141, 264-267.

Unlike the incidence of equine protozoal myeloencephalitis (EPM), which appears to be increasing, headshaking is an uncommon problem for horses in Missouri and the adjacent states. Equine protozoal myeloencephalitis was incriminated in three horses examined for the treatment of headshaking on the basis of a neurological examination, an analysis of cerebrospinal fluid and their response to treatment. The headshaking and stereotypical behaviour associated with EPM was successfully treated with potentiated sulphonamides and pyrimethamine.

Wilkins, P.A (1997) Useof an infraorbital nerve block in the diagnosis of headshaking. Proceedings of the American Association of Equine Practitioners 43, 156-157.

Wilkins, PA (1997) Cyproheptadine: Medical treatment for photic headshakers. Equine: The compendium for continuing education for the practising veterinarian. 19 (1); 98-111.  Abstract available from http://nvdls.unl.edu/jul97txt.htm 

Madigan, J.E., Kortz, G., Murphy, C., Rodger, L. (1995) Photic Headshaking in the horse: 7 cases. Equine Veterinary Journal 27 (4), 306-311.

Seven horses with headshaking are described. No physical abnormalities were detected in any of the cases. Six of these horses had onset of clinical signs in the spring. The role of light was assessed by application of a blindfold or dark grey lens to the eyes, covering the eyes with a face mask and observing the horse in total darkness outdoors. Cessation of headshaking was observed with blindfolding (5/5 horses), night darkness outdoors (4/4 horses) and use of grey lenses (2/3 horses). Outdoor behaviour suggested efforts to avoid light in 4/4 cases. The photic sneeze in man is suggested as a putative mechanism for equine headshaking. Five of 7 horses had improvement with cyproheptadine treatment (0.3 mg/kg bwt b.i.d.). Headshaking developed within 2 calendar weeks of the same date for 3 consecutive years in one horse. Neuropharmacological alterations associated with photoperiod mechanisms leading to optic trigeminal summation are suggested as possible reasons for spring onset of headshaking.

Mair, T.S. (1994) Headshaking associated with Trombicula autumnalis larval infestation in two horses. Equine Veterinary Journal. 26 (3), 244-245. (Short communication)

Mair, T. S. and Lane J.G. (1993) Headshaking in Horses (Chap 6) In: Equine Practice 2. Ed: E. Boden. Balliere Tindall. pp 109-119. Same as: Mair, T,S, and Lane J,G, (1990) Headshaking in Horses. In Practice. 12, 183-186.

Wilkins, P.A., Ducharme, N.G. and Lesse, F.R. (1993) Headshakers: a diagnostic dilemma. In: Proceedings of the American Association of Equine Practitioners. 39, pp 263-264.

Cook, WR (1992) Headshaking in horses: An Afterword. Equine: The Compendium of Continuing Education for the Practising Veterinarian 14, 1369-1371.

Mair, T.S., Howarth, S. and Lane, J.G. (1992) Evaluation of some prophylactic therapies for the idiopathic headshaker syndrome. Equine Veterinary Journal Supplement 11, 10-12.

Eighteen horses affected by the idiopathic headshaker syndrome were studied in an owner assessed trial to test the efficacy of some prophylactic therapies. Riding the affected animal with a veil over the nostrils gave varying degrees of temporary relief in three of 10 horses. Local (intra-nasal) corticosteroid therapy was reported to be slightly effective in three of nine horses, but treatment with sodium cromoglycate, systemic corticosteroid, flunixin meglumine and an antihistamine were generally ineffective. Bilateral infraorbital neurectomy provided sustained relief in three of seven horses, but in one of these cases, a reaction at the neurectomy site necessitated another surgical procedure after six months. A fourth horse was reported to be slightly improved after neurectomy. A period of nasal irritation resulting in self-inflicted trauma was a common complication of this surgery.

Blythe LL, Waltrous, BJ, Pearson, EG and Walker LL (1990) Otitis media/interna in the horse- a cause of headshaking and skull fractures. Proceedings of the American Association of Equine Practitioners. 36, 517-527.

26 cases of equine otitis media, otitis interna, or both, have been studied at the Veterinary Medical Teaching Hospital at Oregon State University. Two clinical syndromes were evident with this disease process. The first syndrome seen reflected the primary otitis media, with the majority of animals having displayed clinical signs of abnormal behaviour including head tossing, head shaking and ear rubbing. It is proposed that chronic progression of this condition to involve the bony structures of the temporal and proximal stylohyoid bones results in a degenerative arthritis and eventual fusion of the temporohyoid joint. The second syndrome seen was one characterised by acute onset of neurologic disease with vestibulocochlear nerve and often facial nerve dysfunction. Definitive diagnosis was dependent on either a positive tympanocentesis or, in the majority of cases, bony proliferation of the temporal bone and the proximal part of the stylohyoid bone as determined by radiography. Prognosis with treatment was very good with 22 horses returning to normal function.

McGorum, B. C. and Dixon, P.M. (1990) Vasomotor rhinitis with headshaking in a pony. Equine Veterinary Journal. 22 (3), 220-222. (Short communication)

Lane, J.G. and Mair, T.S. (1987) Observations on headshaking in the horse. Equine Veterinary Journal. 19 (4), 331-336.

The clinical records of 100 cases of headshaking in horses were reviewed. Possible causes of the abnormal behaviour were identified in 11 animals; these included ear mite infestation, otitis interna, cranial nerve dysfunction, cervical injury, ocular disease, guttural pouch mycosis, dental periapical osteitis and suspected vasomotor rhinitis. However, in only two of these could it be shown that correction of the abnormality led to elimination of the headshaking. The additional clinical signs exhibited by the other idiopathic cases of headshaking included evidence of nasal irritation, sneezing and snorting, nasal discharge, coughing and excessive lacrimation. Many of these horses also showed a marked seasonal pattern with respect to the onset of the disease and the recurrence of signs in subsequent years. The clinical presentation of idiopathic headshakers and the seasonal incidence of the signs closely resemble allergic rhinitis in man.

Kold, S. E. and Ostblom, L.C. (1982) Headshaking caused by a maxillary osteoma in a horse. Equine Veterinary Journal. 14 (2),167-169. (Short communication)

Gerring E. L. and Thomsett L.R. (1980) Mites in a headshaker horse. The Veterinary Record 106, 490. (Letter)

Pascoe, R.R. (1980) Mites in a headshaker horse. The Veterinary Record 107, 234. (Letter)

Cook, W.R. (1980a) Headshaking in horses, Part 3: Diagnostic tests. Equine Practice 2 (1), 31-40.

Cook, W.R. (1980b) Headshaking in horses, Part 4: Special diagnostic procedures Equine Practice 2 (2), 7-15.

Cook, W.R. (1979b) Headshaking in horses, Part 2: History and management tests. Equine Practice 1 (6), 36-39.

Cook, W.R. (1979a) Headshaking in horses, Part 1. Equine Practice 1 (5), 9-17.

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 © Katy Taylor, De Montfort University, Leicester, UK