09/13/2026
Idiopathic trigeminal-mediated headshaking causes severe facial pain in horses. Learn the signs, triggers, diagnostic process, and management options.
https://thehorse.com/1146690/idiopathic-trigeminal-mediated-headshaking/?lid=z9fccfc4mr6j
“What’s on your mind?” FB askes on a “New Post”. Well FB, this is what is on my mind after a mindless reprieve from designing another PPT presentation for equine biomechanics. The mindless clicking and deletion of irrelevant emails in my inbox became answering FB’s question as an email from TheHorse.com Newsletter stating “Vet & Professional: Idiopathic Trigeminal-Mediated Headshaking” article from September 07, 2026 caught my eye as relevant as soon as I saw the words Idiopathic Trigeminal-Mediated Headshaking. I click on the article and read the description of the article: “Idiopathic trigeminal-mediated headshaking causes severe facial pain in horses. Learn the signs, triggers, diagnostic process, and management options.” Please read the article attached below before reading on further as this condition is another “mystery” unsolvable and supposedly “untreatable” condition to equine veterinarians.
“What’s on my mind?” Well FB I am happy to answer your question with facts and science and procrastinating further on another PPT slide being written on equine biomechanics. Because of this article in The Horse Magazine, YOU as a reader can decide WHO is “Gatekeeping” and controlling the advancement of science to help these horses with Idiopathic Trigeminal-Mediated Headshaking. WE, DeClue Equine and other veterinarians, do have many of the ANSWERS AND TREATMENT PROTOCOLS to this complex condition based on over 100+ horses treated with complete resolution of clinical signs! Read on and decide as my patience runs thin from the daily phone calls, emails, and messages from owners and trainers desperate for help for their horses with this condition. Owners and trainers that are frustrated beyond even my level of personal patience at my own profession where some in the power of decisions made are unwilling to listen, learn or ALLOW scientific advancement to occur due to “Gatekeeping” of information that would help our patients.
This spring (March 2026) myself and Dr. Gabrielle Martel presented three “How-To” Papers to AAEP (American Association of Equine Practitioners). The AAEP is the world’s largest professional organization dedicated to equine veterinary medicine with over 9000 veterinarians and veterinary students as member per their website. The three “How-To” papers included:
1. How to Diagnose and Manage Trigeminal-Mediated (Idiopathic) Headshaking in Horses
2. How to Diagnose, Treat, and Manage Sciatica Clinical Signs via Ultrasound-Guided Evaluation and Injection In Equid Species
3. How to Understand Biomechanical Dysfunction Due to Injury as a Cause for Horses Being Sleep-Deprived and Collapsing
All three “How-To” papers were not accepted. To understand the purpose of submitting “How-To” papers to the largest association of equine veterinarians means one needs to understand the requirements. Below is from the AAEP website for the purpose of “How-To” papers. Below is copy and pasted from AAEP:
Purpose of “How-To” Papers
“How-To” papers are designed to describe and explain a technique or procedure used in equine veterinary medicine or industry practice. The method presented should be either novel, not widely understood, or not commonly applied in daily clinical use.
Required Section Headings
1. Paper Title
o Must begin with “How-To” and clearly identify the technique or procedure.
o Should be concise, informative, and written in title case (capitalize key words).
o Avoid sentence-style titles and unnecessary punctuation.
o Example: How-To Perform Ultrasound-Guided Cervical Facet Injections
o Not Ideal: This paper describes how to perform cervical facet injections under ultrasound guidance.
2. Take-Home Message
• A concise summary (1–3 sentences; approximately 50 words) of the key clinical value or practical outcome.
• Should clearly express practical application for the equine practitioner.
• Take-Home Message Example:
There are multiple upper respiratory conditions that impact performance during high-speed exercise. Differentiating between these allows for targeted treatment and improved outcomes.
3. Introduction
• Briefly outline the rationale for the technique and its relevance to equine practice.
• Reference significant prior work or publications, if applicable.
• End with a clear statement of the paper’s objective or purpose.
4. Description of Technique/Procedure
• Provide a step-by-step description of how the technique is performed.
• Include enough detail that a veterinarian familiar with the field could reproduce the procedure. Include: all medications, supplies, and equipment used .
• Use generic names for medications and equipment; trade names may be footnoted if critical to the technique.
5. Outcome
• Describe the outcome of applying the technique.
• Include the number of horses treated, how success was evaluated, and any supporting data or observations.
• Clearly explain how the technique’s value was assessed (e.g., resolution of clinical signs, imaging outcomes, owner feedback).
6. Discussion
• Offer insights on why the technique is effective, based on experience or data.
• Discuss pros, cons, limitations, and appropriate case selection.
• Include follow-up information and summarize the clinical relevance in a final statement that reflects the Take-Home Message.
7. Acknowledgments
Declaration of Ethics
Conflicts of Interest
Funding/Material/Technical Support
AI Use and Disclosure
8. References
Sounds like all three of our “How-To” papers should have been accepted as they are ALL NOVEL. This is the meaning of Novel from Google:
A novel idea is a concept or plan that is completely new, original, and different from anything done or known before. [1, 2]
Key Characteristics
• Originality: It introduces an approach or perspective that is fresh and unprecedented.
• Unfamiliarity: It may feel slightly strange or unusual because it has not been tried before.
AND ALL THREE fit the next criteria after being novel of “not being widely understood”, or “not commonly applied in daily clinical use.” Check, check, and check all three categories for meeting the criteria and “Purpose of “How-To” papers” via the AAEP.
Here is the selection of “How-To” papers this year that will be presented and selected. Read and decide for yourself if they fit the criteria and requirements of “How-To” Papers per the AAEP?
How To Prevent Barn Fires In Equine Veterinary And Client Facilities
How to Collect Samples for Genetic Testing and What to Test For
How Stallion Factors Can Affect Pregnancy Rate, Early Embryonic Loss
How to Use PET to Identify Suspensory Apparatus Injury in the English Sport Horse
How to Perform Advanced Equine Physiotherapy Exercises
How to Retrain Proprioception and Motor Control in Equine Rehabilitation
How to Treat Periocular Sarcoids in Horses with Injectable Mitomycin-C
How to Manage Lameness and Optimize Hoof Balance: The Role of Acrylic Repair in Hoof Compression Rehabilitation
How to Use a Non-Articulating Borescope as a Rudimentary Overground Dynamic Endoscope
How to Identify and Address Barriers to Referral
How-to: Optimize Outcomes of Emergency Case Referrals
How to Optimize Outcomes Through Early Referral: Recognition of Key Clinical Features
How and When to Start Treatment in Emergency Cases in the Field Prior to Referral
How to Address and Identify Barriers to Referral
How to Establish and Maintain Relationships Between Referring and Receiving Veterinarians
How to Prepare Clients for Referral: A Guide for Referring Veterinarians
How to Keep the Success Going After Discharge
How to Navigate When You Suddenly Find Yourself Bought by Corporate
How to Manage Hoof Compression and Restore Hoof Balance Using Acrylic Repair
How to Decide When Advanced Imaging Referral is Appropriate
How to Monitor and Reduce the Spread of EHV-1 at Equestrian Events
How-To Decide When and How to Perform Whole Blood Transfusion in Horses with Acute Hemorrhage
How to Decide Whether a Palmar/Plantar Digital Neurectomy is Indicated in Horses with Chronic Refractory Caudal Heel Pain
How-To Formulate a Treatment Plan After EOTRH Diagnosis: A Practical Clinical Framework
How to Manage the Difficult Equine Dental Patient Using a Five-Domain Clinical Framework
How-To Respond When Every Drop Counts: Practical Strategies for Managing Hemorrhage
That is the entire list that I could find. Twenty-six “How-To” papers. Almost HALF are on nothing clinical, practical, or novel to equine veterinarians practicing in the trenches of veterinary medicine or not. They sure do not fit the PURPOSE and CRITERIA of “How-To” papers required by the AAEP. My favorite is the first one on the list:
How To Prevent Barn Fires in Equine Veterinary And Client Facilities.
So, when did equine veterinarians become qualified electricians? I believe that I may be the ONLY equine veterinarian in the world QUALIFIED as a high voltage ELECTRICIAN as a JOURNEYMAN LINEMAN. I am not qualified as a low voltage, industrial/commercial nor home/indoor electrician ONLY HIGH voltage! Absolutely NONE of us as equine veterinarians are QUALIFIED nor EDUCATED to do an electrician’s job! Yes, we must have fire extinguishers in veterinary facilities but requirements of what is “code”, especially electrical code in a “CLIENTS” facility is completely NOT OUR JOB! My simple solution is common sense: CALL an ELECTRICIAN to do an ELECTRICIAN’S JOB! Do we need a “How-To” paper to make this decision as a profession? OBVIOUSLY, WE DO!
Common sense is absolutely and completely NOVEL to some in this profession as answers and solutions to problems like Idiopathic Trigeminal-Mediated Headshaking, Sciatica, Sleep-Deprived Collapsing, and Shiver-Stringhalt clinical signs are conditions in sport horses some in my profession has decided to write off as IMMATERIAL. Your horse with one of these conditions is immaterial thus irrelevant. What is NOT immaterial or irrelevant is ALL the lameness issues my profession still cannot resolve nor understand that the owners and trainers are stuck dealing with by bigger spurs/bits or physical restraints, “cowboys” and/or abusive “techniques” used until the horse becomes too dangerous and behavioral that no one can get close to, or deal with it. Those horses, dangerous and behavioral or the immaterial-irrelevant, become the “survivorship bias” of some in my profession unwilling to learn from their own logical errors.
I must state that we: Dr. Sharon May Davis, myself and Dr. Kate Workman also submitted our peer-reviewed published paper February 2026 titled: Identifying by Radiograph Grade 4 Aplasia of the Caudal Lamina Ventralis in the Equine Sixth Cervical Vertebra and Three Coinciding Morphological Variations. This paper was also not accepted for unknown reasons, meaning they did not tell us why. No reason just not accepted.
I must state that Dr. Sue Dysons paper: An Investigation of the Role of Ridden Exercise, Including Application of the Ridden Horse Pain Ethogram, in Pre-Purchase Examinations of Sport Horses, was also not accepted. This paper was published in July 2026. When there are literally hundreds, if not thousands, of Pre-Purchase Examinations (PPE) world-wide done every week by equine veterinarians, you would think that this would be relevant to the profession? However, the equine profession, and its associations representing the profession, would have to first RECOGNIZE that horses are “painful” long before they become “behavioral” as the Ridden Horse Ethogram proves by science and repeatability that it is accurate.
“Painful” before “Behavioral” is a simple linear fact of progression that owners/trainers describe these clinical signs daily to some equine veterinarians that consider their findings as “novel” while flexing and blocking the same limb/limbs repeatedly finding nothing. This paper, along with many other ethogram papers from Dr. Dyson, would help our profession recognize pain in our patients earlier if only she were able to represent this information by being accepted to present at AAEP.
My favorite case last week was a $500,000 horse that “passed” a PPE with clean radiographs and “sound” on AAEP lameness scale. HOWEVER, clearly noted on the PPE, the veterinarian was UNABLE to pick up and flex BOTH hind limbs. Noted in PPE was the fact that the horse was “behavioral” attempting to pick up either hind limb. This is NOT a dig at the veterinarian doing the PPE of the horse. Nothing was said, and it is assumed by me, that he/she was able to pick up and flex the front limbs. This is simply an example of the many lameness issues and conditions that equine veterinarians (and farriers), practicing in the trenches of sports medicine and lameness, are dealing with DAILY with NO ANSWERS TO WHY. What if there were answers to these problems? What if there IS a physical reason WHY horses cannot pick up their hind limbs but can easily pick up their front limbs for the veterinarian or farrier.
The answers to this horse’s problem, whether purchased for $500 or $500,000 does not matter, can be resolved and treated as I did last week. The knowledge of why and treatment is based strictly on biomechanics of how a horse works. This science-based knowledge on practical results-based evidence was not accepted by AAEP in our “How-To” Biomechanics paper mentioned earlier on Sleep Deprived and Collapsing Horses as the “Gatekeeping” of the science is irrelevant to those in power to decide relevance in/of daily practice in the trenches they have never done.
Here is our “How-To” paper submission to AAEP that was not accepted and the reasons why the paper was not accepted by the AAEP. Please read and decide for yourself. This means to think for yourself on the facts and science of logic comparing the “How-To” papers accepted this year and do they fit the criteria and requirements of AAEP even with simply their Titles listed?
Note, Treatment Protocols are removed from our paper because this is ONLY information for equine veterinarians as it is above non-veterinarians pay grade. As is the case of why veterinarians are NOT electricians with the accepted paper of “How To Prevent Barn Fires in Equine Veterinary and Client Facilities” at a veterinary conference is not within our pay grade. It is an electrician’s job, no matter how much we want to rationalize our position, to fix these problems. We, equine veterinarians, also need to stay in our lane of our profession.
How to Diagnose and Manage Trigeminal-Mediated (Idiopathic) Headshaking in Horses
Audrey DeClue, DVM; Gabrielle Martel, DVM
Take-Home Message
Trigeminal-mediated (idiopathic) headshaking in horses can be managed with ultrasound-guided cervical injections, extracorporeal shockwave therapy, and structured rehabilitation. Addressing upper cervical input and global biomechanical dysfunction may improve clinical outcomes.
Introduction
Trigeminal-mediated headshaking (TMHS) is characterized by reduced activation thresholds within trigeminal sensory pathways in the absence of detectable structural nerve lesions.1,2 TMHS is considered a diagnosis of exclusion, established after ruling out identifiable causes of headshaking such as dental, sinus, ophthalmic, otic, upper airway, traumatic, or structural neurologic disease. Although commonly described as idiopathic, this designation reflects an incomplete understanding of a complex disorder of trigeminal sensory regulation. The marked variability in seasonality, severity, and response to treatment further supports the multifactorial nature of the condition.
While clinical attention frequently focuses on peripheral trigeminal branches as the primary source of sensory input, upper cervical afferents may also modulate trigeminal excitability.
The spinal trigeminal nucleus (pars caudalis) extends caudally into the dorsal horn of the upper cervical spinal cord (C1–C3), forming the trigeminocervical complex. Convergence of trigeminal and upper cervical afferents within this region has been demonstrated in humans and in multiple mammalian species, including rodents and non-human primates. 3-5 Although this convergence has not been directly demonstrated in the horse, the conserved organization of trigeminal sensory nuclei and upper cervical dorsal horn anatomy across domestic mammals 6,7 makes similar trigeminocervical interactions anatomically plausible in the equine species.
The upper cervical region contains numerous capsular, muscular, and ligamentous sensory receptors capable of generating substantial afferent input, and is a region commonly subjected to mechanical stress and dysfunction. Furthermore, the nuchal ligament and extrinsic musculature connect the cervical and thoracic regions and contribute to forelimb suspension through their integration within the thoracic sling. Consequently, dysfunction of the cervicothoracic junction or thoracic region—whether resulting from acute or chronic injury, inappropriate training load, or ill-fitting equipment—may influence upper cervical biomechanics and augment afferent signaling from the upper cervical segments.
This How-To outlines a multimodal protocol designed to reduce upper cervical afferent input and restore cervical and cervicothoracic biomechanics as part of the management of horses affected by TMHS.
Materials and Methods
Case Selection
Patients included in this protocol presented with one or more clinical signs identified by the owner or trainer, observed on stall camera review, noted during training or competition, or detected during physical examination and lameness evaluation.
Clinical signs of headshaking ranged from subtle manifestations (repetitive head ticking, tossing, nose twitching, frequent nose rubbing on limbs or surfaces, or repeated nasal blowing) to severe vertical headshaking, which could be violent.
Prior to inclusion in this protocol, dental, sinus, ophthalmic, otic, upper airway, traumatic, and structural neurologic causes were ruled out, and cases were considered consistent with a diagnosis of TMHS.
Treatment
Injection Protocol
Extracorporeal Shockwave Therapy (ESWT)
Additional Biomechanical Evaluation and Management
If pain was identified on examination of the withers, dorsal scapular region, or thoracic region, these areas were also treated. The back, pelvis, and both forelimbs and hind limbs were evaluated, and identified sources of pain or dysfunction were addressed to optimize overall biomechanical function and reduce compensatory overload of the forehand.
All equipment used for handling, training, or riding was evaluated. Ill-fitting tack or equipment exacerbating clinical signs was modified or removed.
Environmental triggers were assessed during the initial examination and subsequent re-evaluations and mitigated when possible.
Rehabilitation
Following injections and during the shockwave protocol, horses were maintained in a light rehabilitation program designed to minimize excessive tension or mechanical stress on the upper cervical region. The goal was to reduce ongoing afferent stimulation and allow downregulation of neural excitability.
Outcome
Across several hundred cases managed longitudinally, follow-up assessment—based on owner/trainer reports and repeat clinical examination—demonstrated reduction in frequency and intensity of headshaking behaviors in the majority of horses.
Time to response varied. Horses with mild or recent onset signs improved more rapidly, whereas chronic cases—particularly those with longstanding cervical and thoracic dysfunction—required extended treatment duration and ongoing management.
A transient increase in clinical signs was commonly observed during early cervical intervention. In our experience, approximately 80% of cases demonstrated short-term exacerbation prior to subsequent improvement within days.
Discussion
Electrophysiologic studies have demonstrated reduced activation thresholds in trigeminal sensory pathways in horses with TMHS.¹,² These findings indicate altered sensory processing rather than structural nerve pathology. In this context, cervical afferent input may contribute to trigeminal excitability through the trigeminocervical system.
Treatment aims to reduce afferent input from the cervical region through targeted injections and extracorporeal shockwave therapy. However, sustained clinical improvement beyond the pharmacologic duration of these interventions requires restoration of global cervical and cervicothoracic biomechanics. Because the cervical spine, thoracic region, and thoracic sling function as an interconnected unit, persistent biomechanical dysfunction may perpetuate excessive sensory input. Experimental evidence has demonstrated that cervical posture alters mechanical relationships and pressure at the level of the nuchal ligament, particularly around C1–C2, supporting the concept that altered cervical biomechanics may influence local sensory signaling.⁸
A transient increase in clinical signs was frequently observed during early cervical intervention. This temporary worsening was interpreted as short-term central facilitation within a sensitized trigeminocervical system rather than treatment failure. Such responses are consistent with established models of central sensitization and wind-up phenomena.⁵ In most cases, this exacerbation was self-limiting when management was continued appropriately.
Longstanding cases required longer treatment duration, which may reflect more established sensitization and secondary biomechanical adaptation. Earlier identification of subtle clinical signs may therefore allow intervention at a stage when central sensitization is less advanced.
Owner education is essential, as management is often prolonged and response may be variable. Clear communication regarding expected timelines, transient worsening, and the absence of a definitive cure in idiopathic cases is critical to maintaining compliance and realistic expectations.
In summary, trigeminal-mediated (idiopathic) headshaking should not be approached solely as a peripheral trigeminal disorder. In appropriately diagnosed cases, modulation of cervical input combined with restoration of global biomechanical function may improve long-term management outcomes.
Acknowledgments
Declaration of Ethics
The authors have adhered to the AVMA Principles of Veterinary Medical Ethics.
Conflicts of Interest
The authors have no conflicts of interest.
Funding
The authors have no funding to disclose.
References
1. Aleman M, Rhodes DM, Williams DC, Guedes AG, Madigan JE. Sensory evoked potentials of the trigeminal nerve in horses with idiopathic headshaking. J Vet Intern Med. 2013;27(6):1571–1580.
2. Aleman M. A review of equine headshaking syndrome. J Equine Vet Sci. 2018;66:1–8.
3. Kerr FWL. Structural relation of the trigeminal spinal tract to upper cervical roots in the cat. Exp Neurol. 1961;4:134–148.
4. Bartsch T, Goadsby PJ. The trigeminocervical complex and migraine: current concepts and synthesis. Curr Pain Headache Rep. 2003;7(5):371–376.
5. Sessle BJ. Acute and chronic craniofacial pain: brainstem mechanisms of nociceptive transmission and neuroplasticity. Crit Rev Oral Biol Med. 2000;11(1):57–91.
6. de Lahunta A, Glass E, Kent M. Veterinary neuroanatomy and clinical neurology. 4th ed. St. Louis: Elsevier; 2015.
7. Evans HE, de Lahunta A. Miller’s anatomy of the dog. 4th ed. St. Louis: Elsevier; 2013.
8. Dippel M, Zsoldos RR, Licka TF. An equine cadaver study investigating the relationship between cervical flexion, nuchal ligament elongation and pressure at the first and second cervical vertebra. Vet J. 2019;252:
Here is the reasons for non-acceptance by the AAEP:
Reviewer Feedback:
Thank you for your submission to the 2026 AAEP Annual Convention in Las Vegas. This year's submission pool was exceptionally competitive, and we sincerely appreciate the time, expertise, and effort invested in preparing your manuscript. While your paper was not ultimately selected for inclusion in this year's program, we value your contribution and encourage you to review the feedback below, which we hope will provide helpful guidance for future development of this work.
◦ Reviewers found the topic to be interesting and appreciated the effort to address the diagnosis and management of trigeminal-mediated headshaking syndrome. The introductory discussion was viewed as helpful in establishing the relevant anatomy and rationale for targeting the cranial cervical region.
◦ Several reviewers noted that, despite the title, the manuscript places greater emphasis on treatment than on diagnostic approaches.�Additional discussion regarding case definition and diagnostic criteria beyond exclusion of other causes of headshaking would strengthen the paper.
◦ Reviewers also indicated that further detail regarding the treatment protocol, adjunctive therapies, rehabilitation program, case numbers, duration of disease, and methods used to assess outcomes would improve the clarity and reproducibility of the work. Greater objective characterization of treatment responses would help support the conclusions.
◦ Questions were also raised regarding the rationale for the extent and location of corticosteroid administration and how this approach compares with more conventional anti-inflammatory strategies.�Additional discussion supporting the proposed mechanism and therapeutic protocol would strengthen the scientific basis for the recommendations.
Overall, reviewers considered the approach intriguing and encouraged continued investigation with more detailed methodology and objective outcome measures to further establish the clinical utility of this treatment strategies.
One of the “reasons” we were not accepted was: “Several reviewers noted that, despite the title, the manuscript places greater emphasis on treatment than on diagnostic approaches.”
Yes, we focused on the TREATMENT! Something that I believe owners, trainers AND veterinarians who care want to know. They also want to be educated on understanding the complexity of this painful horrific condition. To prevent or get treatment for the clinical signs when they first recognize they are present! Prevention and recognition. Wow, what a simple concept.
This condition in humans, who can talk to their doctors, commit su***de over. Idiopathic Trigeminal-Mediated Neuritis in humans is called “The Su***de Disease” due to the constant intractable severe pain that the person cannot get away or find relief from.
You would think, thus common sense, that the equine veterinary profession would want this information to be presented? I know that equine veterinarians want to be educated on this novel idea that includes treatment protocols based on over 100+ successful cases? I know that my profession DOES CARE and wants to know! Those of us in the trenches of daily equine practice WANT to learn and WANT to know. Those who do not, are “Gatekeeping” science and advancement of veterinary sports medicine and veterinary medicine.
AAEP states: “How-To” papers require that “The method presented should be either novel, not widely understood, or not commonly applied in daily clinical use.” What is your decision? State it below in comments and please share this if you disagree with our non-acceptance to the AAEP. It will not change the outcome decision; however, I am one of 9000+ veterinarians that do need you to state your position on our advancement of education for YOUR HORSES!
As a solution to this problem of “Gatekeeping”, The Horse First Magazine will be coming soon as an online source for all equine professionals and owners that will provide practical evidence-based solutions and science, as the results will come from our patients, who have ALL the answers.
Be the Voice
Be the Advocate
Always Put The Horse First
Now I need to stop an hour of procrastination to do this and get back to designing PPT slides on equine biomechanics. Thank you for your time!
As Gandhi says: "Be the change you wish to see in the world"
AJD
Idiopathic trigeminal-mediated headshaking causes severe facial pain in horses. Learn the signs, triggers, diagnostic process, and management options.
