Background Trigeminal-mediated headshaking (TGMHS) is a neuropathic facial pain disorder of horses characterized by a reduced threshold for trigeminal nerve activation. Subtle alterations in sensory neuron morphology may contribute to neuronal dysfunction and could remain undetected by conventional histopathological evaluation. Objectives To investigate neuronal morphometry in the trigeminal ganglion of horses affected by TGMHS and compare findings with those of neurologically normal horses. Study Design Retrospective case–control Methods Trigeminal ganglion samples from control horses and horses diagnosed with TGMHS were retrospectively evaluated. Histological sections were digitally imaged. Neuronal cross-sectional area was determined by manual delineation of the soma perimeter using Image J, and morphometric data were analysed using GraphPad Prism. Only neurons displaying an intact soma and clearly identifiable nucleus and/or nucleolus were included. Results A total of 500 neuronal profiles from five control horses and 500 neuronal profiles from five horses affected by TGMHS were analysed. In control horses, neuronal soma area ranged from 801 to 32,217 µm2 (median 5,708 µm2; IQR 3,496–9,127 µm2), while median Feret diameter was 102.8 µm (IQR 80.7–127.9 µm). In TGMHS horses, neuronal soma area ranged from 582 to 21,711 µm2 (median 3,619 µm2; IQR 2,611–5,239 µm2), and median Feret diameter was 82.2 µm (IQR 68.6–100.0 µm). Compared with controls, TGMHS horses exhibited a 37% reduction in mean neuronal soma area (P = 0.0109) and a significant reduction in Feret diameter (P = 0.0079). Pooled neuronal populations demonstrated significant leftward shifts in both soma area and Feret diameter distributions (Kolmogorov–Smirnov, P < 0.0001). Main Limitations The retrospective design, limited sample size, use of formalin fixed paraffin embedded samples, and lack of neuronal phenotyping prevented correlation of morphometric changes with specific sensory neuronal subpopulations. Conclusion Morphometric alterations accompany trigeminal dysfunction in the trigeminal ganglion of horses with TGMHS.

BackgroundClothing in human medical environments has been shown to be contaminated with micro-organisms. There is little work in this area in the veterinary environment and none in equine veterinary environments.ObjectivesTo characterise microbial contamination of veterinary clothing throughout a work shift in an equine hospital. The pattern could help determine whether an intervention could reduce contamination.Study DesignCross-sectional, observational pilot study of staff at B&W Equine Hospital in February 2023. The study used convenience sampling of staff clothing.MethodsNinety-two swabs from the clothing of 46 staff were taken at three time points (start of the day [AM], lunch and end of the day [PM]). Samples were cultured with colony-forming units (CFUs) per swab, and the genus of the microbe present was identified. Statistical analysis was performed.ResultsFive genera of microbes were identified on clothing. Veterinarians became significantly more contaminated from AM to PM (p = 0.034). All groups of staff arrived at work already contaminated. All AM samples from staff had Streptococcus spp. present. Rhodococcus spp. were not present on nonclinical staff.Main LimitationsSmall sample size not representative of all equine hospitals. Hospital-based not representative of ambulatory practices. Volunteer bias and the use of a nonprobability sampling method. Genetic sequencing not performed to determine the species of the microbe present.ConclusionThis study found that veterinarians became significantly more contaminated throughout the day. This suggests that a simple intervention such as changing outer layers of clothing at lunchtime could reduce contamination levels. All groups were contaminated on arrival to work, suggesting that in-house laundering to regulate the cleanliness of uniforms could reduce microbial contamination. To reach a full conclusion on the diversity of contamination, further research, including full identification of microbes, is required.

BACKGROUND:Accessory pathways (APs) are muscular bundles directly connecting the atria and ventricles, bypassing the atrioventricular (AV) node-His-Purkinje system. Anterograde conduction along the AP results in ventricular preexcitation. A retrograde conducting AP allows ventriculo-atrial (VA) conduction, creating a reentry circuit that mediates orthodromic atrioventricular reentry tachycardia (OAVRT). This condition is well described in humans and small animals, but has not been reported previously in horses. OBJECTIVES:Describe clinical and electrocardiographic findings of horses with retrograde AP conduction and reporte mapping and radiofrequency ablation results in one horse. ANIMALS:Six horses with retrograde AP conduction. METHODS:Records from six horses with retrograde AP conduction were reviewed. RESULTS:Resting ECGs showed P' waves in the ST segment with fixed coupling intervals to the preceding QRS complexes. In five of six horses, P' waves were conducted back to the ventricles along the AV node, resulting in OAVRT. All horses had episodes where P' waves were blocked at the AV node, which resulted in orthodromic atrioventricular reentry bradycardia (OAVRB). In one horse, the AP conducted bidirectionally resulting in ventricular preexcitation. An electrophysiological study in one horse identified a left-atrial AP insertion by the shortest VA interval. Radiofrequency ablation using an impedance-based mapping system could not eliminate the AP. CONCLUSIONS:Retrograde conducting APs in horses caused OAVRT and OAVRB. APs in horses behaved differently compared to those in humans and dogs. Further research is necessary to elucidate AP behavior, evaluate risk and effect on performance, and assess treatment by ablation.

BACKGROUND:Trigeminal-mediated headshaking (TMHS) in horses shares clinical features with human trigeminal neuralgia (HTN). Increased levels of the neuropeptide calcitonin gene-related peptide (CGRP) have been found in the blood and cerebrospinal fluid (CSF) of HTN patients. Inhibition of CGRP in humans has shown promise for pain relief. Data on CGRP in horses affected by TMHS are currently lacking but if quantifiable and validated, could assist in developing new diagnostic and more rational therapeutic approaches. OBJECTIVES:This study aimed to quantify and correlate CGRP concentrations in the serum and CSF of horses with TMHS; compare CSF CGRP levels across horses with various neurological, painful, inflammatory and chronic conditions; analyse serum CGRP concentrations before and after exercise-induced headshaking in affected horses versus healthy controls. STUDY DESIGN:Case-control study using bio-banked samples and prospective before-after study. METHODS:CGRP concentrations were measured in CSF and serum using a commercial ELISA kit across healthy controls (CONTROL, n = 5), TMHS-affected horses (n = 30), horses with cervical vertebral stenotic myelopathy (CVSM, n = 10) and horses with non-neurologic painful, inflammatory or chronic conditions (MIXED, n = 8). RESULTS:Median (interquartile range [IQR]) serum CGRP concentration in TMHS horses was 14.9 pg/mL (11.3-19.0 pg/mL), while mean ± SD CGRP CSF concentration was 64.9 ± 6.3 pg/mL. No correlation was found between serum and CSF CGRP (Spearman's rho = -0.04, p = 0.88). CSF CGRP levels were significantly higher in CVSM (73.8 pg/mL; p = 0.011) and lower in MIXED (52.0 pg/mL; p = 0.001) compared to TMHS. Serum CGRP concentrations showed no significant difference between TMHS and CONTROL groups. MAIN LIMITATIONS:Small sample size, lack of CSF samples from healthy controls. CONCLUSIONS:Higher CSF CGRP levels in neurologic conditions may suggest shared underlying mechanisms such as nerve irritation or neuroinflammation. Further research is needed to elucidate CGRP's role in TMHS pathophysiology.

Trigeminal-mediated headshaking (TMHS) in horses shares clinical features with human trigeminal neuralgia (HTN). Increased levels of the neuropeptide calcitonin gene-related peptide (CGRP) have been found in the blood and cerebrospinal fluid (CSF) of HTN patients. Inhibition of CGRP in humans has shown promise for pain relief. Data on CGRP in horses affected by TMHS are currently lacking but if quantifiable and validated, could assist in developing new diagnostic and more rational therapeutic approaches. This study aimed to quantify and correlate CGRP concentrations in the serum and CSF of horses with TMHS; compare CSF CGRP levels across horses with various neurological, painful, inflammatory and chronic conditions; analyse serum CGRP concentrations before and after exercise-induced headshaking in affected horses versus healthy controls. Case–control study using bio-banked samples and prospective before-after study. CGRP concentrations were measured in CSF and serum using a commercial ELISA kit across healthy controls (CONTROL, n  = 5), TMHS-affected horses ( n  = 30), horses with cervical vertebral stenotic myelopathy (CVSM, n  = 10) and horses with non-neurologic painful, inflammatory or chronic conditions (MIXED, n  = 8). Median (interquartile range [IQR]) serum CGRP concentration in TMHS horses was 14.9 pg/mL (11.3–19.0 pg/mL), while mean ± SD CGRP CSF concentration was 64.9 ± 6.3 pg/mL. No correlation was found between serum and CSF CGRP (Spearman's rho = −0.04, p  = 0.88). CSF CGRP levels were significantly higher in CVSM (73.8 pg/mL; p  = 0.011) and lower in MIXED (52.0 pg/mL; p  = 0.001) compared to TMHS. Serum CGRP concentrations showed no significant difference between TMHS and CONTROL groups. Small sample size, lack of CSF samples from healthy controls. Higher CSF CGRP levels in neurologic conditions may suggest shared underlying mechanisms such as nerve irritation or neuroinflammation. Further research is needed to elucidate CGRP's role in TMHS pathophysiology.

Background: Equine trigeminal-mediated (TGM) headshaking (HS) is a neuropathic facial pain syndrome characterised by varying intensity and frequencies of head movements and signs of nasal irritation. An accurate method for quantification and/or characterisation of HS severity is lacking. Objectives: To develop and validate an objective measure of TGMHS. Study design: Prospective case control study. Methods: Horses presenting for investigation of HS were recruited alongside those presenting for forelimb lameness (LAME) and pre-purchase examination as well as healthy controls (CONTROL). Head movement data were collected for 5 min whilst trotting on the lunge using a tri-axial accelerometer, with a range of +/- 16 g and sampling rate of 800 Hz, attached to the bridle headpiece. Recordings were exported for processing. Peak detection was performed using minimum and maximum thresholds of -1 g and +1 g (corrected for gravity) and a minimum peak width of 10 samples. Results: Fifty-six horses were included in the study; 18 TGMHS, 10 non-TGMHS, 12 LAME and 16 CONTROL. Characteristics and frequency of vertical (Z axis) head movements of TGMHS horses differed significantly from other horses. TGMHS horses had peaks with greater mean and maximum positive g-force (P < 0.005) and lower mean and minimum negative g-force (P < 0.001), greater frequency of peaks/min (P < 0.001) and over 12 times greater percentage of peaks >+2 g compared with other horses (P < 0.001). Receiver operator curve characteristics of percentage of peaks >+2 g (CI 0.72-0.95), percentage of peaks <-2 g (CI 0.66-0.92) and percentage of peaks <-2 g and >+2 g (CI 0.72-0.96) showed excellent discrimination of TGMHS horses from LAME, CONTROL and non-TGMHS horses. Main limitations: Referral population of horses, small sample size and control horses were not evaluated for orthopaedic disease. Conclusions: Accelerometer data from trotting exercise on the lunge provides an objective measure of HS and can differentiate between TGMHS, non-TGMHS, normal head movements and those associated with forelimb lameness. Accelerometer use may aid HS diagnosis and monitoring of management strategies.

Cannabinoid receptors are expressed in human and animal trigeminal sensory neurons; however, the expression in the equine trigeminal ganglion is unknown. Ten trigeminal ganglia from five horses were collected post-mortem from an abattoir. The expression of cannabinoid receptors type 1 (CB1R) and type 2 (CB2R), and the cannabinoid-related receptors like transient receptor potential vanilloid type 1 (TRPV1), peroxisome proliferator-activated receptor gamma (PPARɣ), and G protein-related receptor 55 (GPR55) in the trigeminal ganglia (TG) of the horse were studied, using immunofluorescence on cryosections and formalin-fixed paraffin-embedded (FFPE) sections. Neurons and glial cells were identified using fluorescent Nissl staining NeuroTrace® and an antibody directed against the glial marker glial fibrillary acidic protein (GFAP), respectively. Macrophages were identified by means of an antibody directed against the macrophages/microglia marker ionized calcium-binding adapter molecule 1 (IBA1). The protein expression of CB1R, CB2R, TRPV1, and PPARɣ was found in the majority of TG neurons in both cryosections and FFPE sections. The expression of GPR55 immunoreactivity was mainly detectable in FFPE sections, with expression in the majority of sensory neurons. Some receptors were also observed in glial cells (CB2R, TRPV1, PPARγ, and GPR55) and inflammatory cells (PPARγ and GPR55). These results support further investigation of such receptors in disorders of equine trigeminal neuronal excitability.

Background: In horses with trigeminal-mediated headshaking (TMHS), clinical signs are likely to be expression of neuropathic facial pain. Currently, subjective assessment of disease severity is used as measure of compromise of animal's welfare.Objectives: To develop and validate a precise scoring system for TMHS: History, Rest and Exercise Score (HRE-S). The HRE-S consists of three subscores: history score (H-S), resting score (R-S) and exercise score (E-S).Study design: Retrospective observational study.Methods: Seven masked observers with different experience used HRE-S to score 40 video recordings taken during rest and lungeing including five duplicates. Video recordings were taken from nine horses with TMHS and three controls. Inter- and intraobserver reliability and practicability of HRE-S were assessed. For every video recording severity of clinical signs was graded by every observer using an intuitive global-type-scale and interobserver reliability was calculated. Convergent validity was evaluated comparing HRE-S to groups created by an existing score (grade 0-3). Discriminant validity was analysed comparing HRE-S to groups created by intuitive global-type-scale.Results: Reliability for HRE-S was excellent, irrespective of observers experience: Spearman's Rho = 0.946, p < 0.001 (intraobserver reliability) and intraclass correlation coefficient = 0.98, p < 0.001 (interobserver reliability). Interobserver reliability for intuitive global-type-scale was fair to substantial: Fleiss' ?appa = 0.48 (R-S) -0.63 (E-S). Groups created by intuitive global-type-scale had significantly different R-S and E-S (p < 0.05), demonstrating discriminant validity. Convergent validity was proven as horses with grade 3/3 had significantly higher average E-S and total scores compared with an existing score than those with grade 0/3 or 1/3 (p < 0.001).Main limitations: Retrospective nature, video recordings, sample size.Conclusions: HRE-S is a valid and reliable score evaluating disease severity in TMHS, independent of observers' experience.

Summary Background The majority of horses presenting to a hospital with signs of headshaking receive a diagnosis of trigeminal‐mediated headshaking. This diagnosis is one of exclusion, so ruling out other possible causes of headshaking is essential. Objectives The aims of this study were to describe the computed tomographic (CT) findings in horses that were presented for investigation of headshaking and underwent CT examination of the head under standing sedation. A secondary aim was to establish whether the proximity of the apices of the caudal maxillary cheek teeth to the infra‐orbital canal varied between age‐matched groups of horses presented for CT examination for investigation of headshaking and those presented for investigation of other conditions. Study design Retrospective case series of horses undergoing CT examination of the head as part of the investigation of headshaking at the Equine Centre, University of Bristol. Methods Case records of horses that had standing CT images of the head obtained, reviewed and reported at the Equine Centre, University of Bristol over a 5‐year period (February 2012–March 2017) were reviewed. Cases that had presented for investigation of headshaking were included. The proximity of the apices of the maxillary cheek teeth to the infra‐orbital canal was assessed in age‐matched horses presenting for CT for investigation of headshaking and other reasons. Results A total of 101 horses presented for investigation of headshaking were included. There were four horses in which CT detected likely causative pathology for the headshaking which had not been identified by other diagnostic tests; however, radiographs had not been obtained in two of these horses. Three horses had periapical infection of the maxillary cheek teeth, and one horse had a fracture of the paracondylar process of the occipital bone. Clinical signs resolved following treatment in three horses; two with periapical infection and one with a paracondylar process fracture. One horse with periapical infection was lost to follow‐up. There was no significant difference in the proximity of the apices of the maxillary cheek teeth to the infra‐orbital canal between the head‐shaking and non‐head‐shaking groups. Main limitations Retrospective study; pre‐selection of cases through discussion of the case and, in some instances assessment of videos of the behaviour, by the last author, prior to referral; lack of radiographs. Conclusions Whilst trigeminal‐mediated headshaking is the most common cause of headshaking in horses, it is a diagnosis of exclusion so thorough investigation to rule out other possible causes is essential. We consider CT examination of the head to be a valuable tool in this investigation, although the diagnostic yield is likely to be low.

Standing computed tomographic (CT) examination of the equine guttural pouch frequently reveals deviation of the midline septum. The significance of deviation is currently unknown. The aims of this retrospective, single-centre study were to determine the prevalence of deviation of the midline septum of the guttural pouch and determine whether there was an association between the presence and degree of deviation of the septum, and guttural pouch disease. Case records were reviewed, identifying 95 horses that had undergone a standing, sedated, head CT and guttural pouch endoscopy. The presence, laterality, subjective degree and angle of deviation of the midline septum on CT was recorded. A total of 69 (72.6%) horses were identified with deviation of the midline septum, with the mean angle of deviation 13.4 degrees and a maximum deviation of 52.6 degrees. No significant association between the presence of deviation of the midline septum (P = .722) or severity of deviation (P = .428) and an endoscopic abnormality within the guttural pouch was found. The laterality of deviation and guttural pouch abnormalities were also not associated (P = .000). Deviation of the midline septum of the guttural pouch is a common finding on CT examination, and does not have clinical significance in this study. (C) 2021 Elsevier Inc. All rights reserved.

Background Early results from the use of neuromodulation by percutaneous electrical nerve stimulation for the management of trigeminal-mediated headshaking in horses were promising but lacked sufficient case numbers and long-term follow-up. The neuromodulatory procedure has since been established as EquiPENS (TM). Objectives The aim of this study was to report long-term results from a larger number of cases and to investigate for predictors of outcome. Study design Prospective case series using international, multi-centre data. Methods Eligible cases were horses with a veterinary diagnosis of trigeminal-mediated headshaking, which received EquiPENS (TM) neuromodulation at trained centres between August 2013 and November 2017. The standard protocol was an initial three-procedure course, with additional procedures should a horse go into remission but then relapse. Data collected included signalment, history, diagnostic tests performed, details of any complications, whether horses had gone into remission and the length of remission. Results Results were obtained from 168 horses, with 530 procedures. The complication rate was 8.8% of procedures. In all but one case, complications were mild and transient, without self-trauma. Remission of headshaking following the initial course occurred in 53% (72/136) of horses. Median length of time recorded in remission was 9.5 weeks (range 2 days to 156 weeks ongoing). Where signs recurred, most horses went back into remission following additional procedures, usually for longer than from the previous procedure. No predictors for outcome were determined. Main limitations No placebo or control group, owner-assessed results. Conclusions EquiPENS (TM) neuromodulation can be an effective and safe treatment for the management of trigeminal-mediated headshaking in some horses. An increased understanding of neuromodulation could help optimise the technique. Advances in treatment for trigeminal-mediated headshaking will remain limited until there is a greater understanding of the aetiopathogenesis of the condition.

Trigeminal-mediated headshaking is a little-understood neuropathic facial pain condition of the horse. The condition may affect around 1% of the equine population to a degree of severity sufficient to require veterinary attention. As a pain condition, this represents a significant welfare issue. Horses are usually more severely affected at exercise which can leave them unable to perform, or even dangerous to ride and handle. With little known about the condition and variable response to treatments, severely affected horses are often euthanized. This review article considers the literature on trigeminal-mediated headshaking, focusing on what is known, and indeed not known, about the prevalence of the condition and its impact. The current published management options are considered, along with their challenges and limitations.

It is not uncommon for equine vets to be asked to examine a horse which is exhibiting headshaking. This article covers my approach to reaching a diagnosis in these cases. I find that trigeminal-mediated headshaking is often the definitive diagnosis, and the article covers the current published treatment options, highlighting the latest advances.

REASON FOR PERFORMING STUDY Headshaking in horses has been reported to be most commonly due to idiopathic neuropathic facial pain (trigeminal-mediated headshaking). The prevalence of headshaking in horses in the UK is unknown. OBJECTIVES To estimate owner-reported prevalence of headshaking in horses in the UK and to report their case background and disease characteristics, as reported by owners. STUDY DESIGN Cross-sectional web based owner questionnaire. METHODS The questionnaire was advertised online via social media, horse forums, veterinary websites and equestrian magazines from 17th June 2016, until >1000 responses had been obtained. All UK horse owners were eligible to complete the questionnaire, however only one questionnaire could be completed per owner. RESULTS The estimated prevalence of owner-reported headshaking in the sample population of horses (n = 1014), within the last year, was 4.6% (95% confidence interval 3.5-6.1), whereas 6.2% (95% confidence interval 4.9-7.9) of horses were reported by their owners to have shown signs of headshaking at any time-point since ownership. There was no association of sex or breed. Nineteen percent of headshaking horses were reported to show headshaking at rest. Fewer than one-third (30.2%, n = 19) of headshaking horses had been examined by a veterinarian for headshaking. Of horses seen by a veterinarian, the cause for headshaking remained unknown in the majority of cases (57.9% responses) and trigeminal-mediated headshaking was reported as a diagnosis in just one case. MAIN LIMITATIONS The accuracy in data reporting by horse owners was not verified in this study. There may be a potential for bias towards over-reporting due to the nature of survey participation. CONCLUSIONS Within this sample, owner-reported prevalence of signs of headshaking within the last year, in horses in the UK was 4.6%. Over two-thirds of owners of headshaking horses did not seek veterinary intervention for headshaking. Trigeminal-mediated headshaking was rarely reported by owners as a diagnosis.

Trigeminal-mediated headshaking is an idiopathic neuropathic facial pain syndrome in horses. There are clinical similarities to trigeminal neuralgia, a neuropathic facial pain syndrome in man, which is usually caused by demyelination of trigeminal sensory fibers within either the nerve root or, less commonly, the brainstem. Our hypothesis was that the neuropathological substrate of headshaking in horses is similar to that of trigeminal neuralgia in man. Trigeminal nerves, nerve roots, ganglia, infraorbital, and caudal nasal nerves from horse abattoir specimens and from horses euthanized due to trigeminal-mediated headshaking were removed, fixed, and processed for histological assessment by a veterinary pathologist and a neuropathologist with particular experience of trigeminal neuralgia histology. No histological differences were detected between samples from horses with headshaking and those from normal horses. These results suggest that trigeminal-mediated headshaking may have a different pathological substrate from trigeminal neuralgia in man.

SummaryDiagnostic laparotomy and laparoscopy are surgical techniques commonly used for the investigation of chronic abdominal disease and weight loss. They can both be usefully carried out in the standing sedated horse, allowing a thorough examination of the dorsal abdominal cavity and biopsies to be harvested. Small intestinal disease is an important cause of weight loss and recurrent colic. Inflammatory or neoplastic bowel disease may not always be apparent grossly and histopathological assessment of full thickness biopsies may be required to provide a definitive diagnosis. Details of cases of 15 horses that underwent small intestinal biopsy or enterectomy while sedated and standing are presented. Three incisional infections occurred causing delayed wound healing. Three horses were subjected to euthanasia before hospital discharge: two had persistent gastric reflux and one had colitis. A further six were subjected to euthanasia in the first 4 months due to their underlying inflammatory bowel condition. One horse was subjected to euthanasia for severe laminitis that was presumed to be caused by treatment with a corticosteroid 4 years later, and one died of acute colic 2.3 years after successful resection and anastomosis. Five horses were alive at the time of review, median 2.7, range 1.2–4.3 years. Overall therefore, 3 (20%) horses died during hospitalisation and 5 (33%) were still alive at the end of the study. Results from this series suggest that minimising the number of intestinal biopsies may reduce morbidity, but the underlying pathological process appears to be the most important prognostic factor for survival. Resection and anastomosis in the standing sedated horse proved feasible.

REASONS FOR PERFORMING STUDY:There are no consistently safe and effective methods for the treatment of trigeminal-mediated headshaking in horses. In affected horses, the trigeminal nerve is sensitised, appearing to result in neuropathic pain. Percutaneous electrical nerve stimulation (PENS) therapy is a minimally invasive neuromodulatory treatment used in people to manage neuropathic pain.OBJECTIVES:To determine whether PENS therapy is safe, tolerated and effective for the management of trigeminal-mediated headshaking in horses.STUDY DESIGN:Descriptive case series.METHODS:Seven horses diagnosed with trigeminal-mediated headshaking and currently showing clinical signs were studied. All procedures were carried out in sedated horses with a needle-prick sized area of skin desensitised with local anaesthetic to facilitate probe insertion. A disposable PENS probe was advanced subcutaneously adjacent to the nerve, rostral to the infraorbital foramen under ultrasonographic guidance. The nerve was stimulated for 25 min following a protocol of alternating frequencies and a perception threshold based on human clinical data. The probe was removed and the procedure repeated on the contralateral side. The protocol used comprised a series of 3 or 4 treatments, with treatments being repeated when signs of headshaking recurred.RESULTS:All horses tolerated the procedure well. Three horses developed a haematoma at the site on one occasion and 2 had increased clinical signs for up to 3 days following first treatment. Six horses demonstrated a positive response to their first treatment, returning to ridden work at the same level as prior to onset of headshaking, with 5 continuing to respond. Median remission time for first treatment was 3.8 days (range 0-8 days, n = 7), second treatment 2.5 weeks (0-8 weeks, n = 7), third treatment 15.5 weeks (0-24 weeks, n = 5) and fourth treatment 20 weeks (12-28 weeks ongoing, n = 2).CONCLUSIONS:Percutaneous electrical nerve stimulation therapy is a safe, well tolerated, minimally invasive, repeatable management option for trigeminal-mediated headshaking, with encouraging efficacy for amelioration of clinical signs in the short- to medium term.

Equine HealthVol. 2015, No. 24 VeterinaryHeadshaking - harmless irritation or silent agony?Veronica RobertsVeronica RobertsSearch for more papers by this authorVeronica RobertsPublished Online:7 Jul 2015https://doi.org/10.12968/eqhe.2015.24.26AboutSectionsView articleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InEmail View articleFurther readingRoberts VHL, Patel NK, Tremaine WH (2015) 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 Article first published online: 8 APR 2015. DOI: https://doi.org/10.1111/evj.12394 Google Scholar FiguresReferencesRelatedDetails 2 July 2015Volume 2015Issue 24ISSN (print): 2047-9867ISSN (online): 2052-2967 Metrics History Published online 7 July 2015 Published in print 2 July 2015 Information© MA Healthcare LimitedPDF download

SummaryA 13‐year‐old Swedish Warmblood mare was presented for evaluation of a mass on the medial aspect of the left vertical ear canal. The mass was initially resected using monopolar loop diathermy. Histopathological diagnosis of the excisional biopsy was a low‐grade malignant ceruminous adenocarcinoma. The clinical and histopathological features of this previously unreported neoplasm in the horse are described. A modified vertical ear canal ablation was performed in order to remove the base of the neoplasm with adequate free margins. The surgical technique is described. No recurrence was noted 2 years after surgery and the appearance and function of the pinna were retained.