Topic:Neurology
Neurology in horses encompasses the study of the equine nervous system, including its structure, function, and associated disorders. The equine nervous system is divided into the central nervous system (CNS), consisting of the brain and spinal cord, and the peripheral nervous system (PNS), which includes nerves extending throughout the body. Neurological conditions in horses can manifest as gait abnormalities, behavioral changes, or sensory deficits. Common neurological disorders include equine protozoal myeloencephalitis (EPM), cervical vertebral stenotic myelopathy (CVSM), and equine herpesvirus myeloencephalopathy (EHM). Diagnostic approaches may involve clinical evaluation, imaging techniques, and laboratory tests. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, pathophysiology, diagnosis, and management of neurological disorders in horses.
Comparison of Muscle MEPs From Transcranial Magnetic and Electrical Stimulation and Appearance of Reflexes in Horses. Transcranial electrical (TES) and magnetic stimulation (TMS) are both used for assessment of the motor function of the spinal cord in horses. Muscular motor evoked potentials (mMEP) were compared intra-individually for both techniques in five healthy horses. mMEPs were measured twice at increasing stimulation intensity steps over the extensor carpi radialis (ECR), tibialis cranialis (TC), and caninus muscles. Significance was set at < 0.05. To support the hypothesis that both techniques induce extracranially elicited mMEPs, literature was also reviewed. Results: Both techniques show the pr...
Persistent Intracranial Hypertension in a Cranial Vault Remodeling Patient With Open Skull Fractures From Horse Kick. A 4-year-old female with prior cranial vault remodeling for nonsyndromic bilateral coronal craniosynostosis sustained a severe traumatic brain injury with open skull fractures from a horse kick. Her post-traumatic course was complicated by persistently elevated intracranial pressure despite neurosurgical decompressions, maximum medical therapy, and trial of multiple pressure monitoring devices. She eventually had improvement in her intracranial pressures and made a full neurologic recovery. This case highlights the potential severity of horse kick injuries, the possible etiology of persistent ...
Viral Load and Cell Tropism During Early Latent Equid Herpesvirus 1 Infection Differ Over Time in Lymphoid and Neural Tissue Samples From Experimentally Infected Horses. Upper respiratory tract infections with Equid Herpesvirus 1 (EHV-1) typically result in a peripheral blood mononuclear cell-associated viremia, which can lead to vasculopathy in the central nervous system. Primary EHV-1 infection also likely establishes latency in trigeminal ganglia (TG) via retrograde axonal transport and in respiratory tract-associated lymphatic tissue. However, latency establishment and reactivation are poorly understood. To characterize the pathogenesis of EHV-1 latency establishment and maintenance, two separate groups of yearling horses were experimentally infected intra...
Sidewinder gait in horses. Sidewinder gait in horses is poorly understood and characterized by walking with the trunk and pelvic limbs drifting to 1 side. Objective: To report causes, clinical and diagnostic features. Methods: Horses examined at 2 institutions. Methods: Retrospective study (2000-2019). Cases with sidewinder gait, neurological and orthopedic examination, and diagnostic work up or postmortem evaluation were included. Descriptive statistics were performed. Results: Twenty-four horses (mean age 18.9 years) of various breeds and both sexes were included. Onset was acute (N = 10), subacute (N = 6), and insi...
Diffusion Tensor Imaging Tractography of White Matter Tracts in the Equine Brain. Tractography, a noninvasive technique tracing brain pathways from diffusion tensor magnetic resonance imaging (DTI) data, is increasingly being used for brain investigation of domestic mammals. In the equine species, such a technique could be useful to improve our knowledge about structural connectivity or to assess structural changes of white matter tracts potentially associated with neurodegenerative diseases. The goals of the present study were to establish the feasibility of DTI tractography in the equine brain and to provide a morphologic description of the most representative tracts in t...
Variability, repeatability and test-retest reliability of equine flash visual evoked potentials (FVEPs). Visual evoked potentials (VEPs) are electrical potentials generated by neurons in the central nervous system in response to visual stimuli. A series of positive and negative wavelets in response to flash-stimuli (flash-VEP; FVEP) or reversing, iso-luminant patterns (pattern-VEP; PVEP) are recorded. Pathological conditions affecting the post-retinal pathways can alter overall waveform morphology, and also affect wavelet peak times and amplitudes. FVEPs have recently been described in horses, but more data on the variability within and between subjects is required, to adequately interpret result...
Resolution of cauda equina syndrome after surgical extraction of lumbar intrathecal bullet. Gunshot wound (GSW) injuries to the spinal column are correlated with potentially severe neurological damage. Here, we describe a GSW to the thoracolumbar junction (e.g., T12/L1 level) which resulted in a cauda equina syndrome that resolved once the bullet was removed. Methods: A 29-year-old male presented with a T12-L1 GSW; the bullet traversed the right chest and liver, entered the spinal canal at T12, and then settled at L1. He experienced excruciating burning pain in the right lower extremity/perineum and had urinary retention. On neurological examination, he exhibited severe weakness of t...
Quantitative analysis of astrocyte and axonal density relationships: Glia to neuron ratio in the optic nerve laminar regions. Astrocytes are critical for the maintenance of retinal ganglion cell (RGC) axonal function and viability, and form a key component of the functional neurovascular unit. Recently, we described the quantitative properties of astrocytes in relation to the capillary distributions in optic nerve laminar regions. Here, we provide a quantitative analysis of astrocytes and RGC axons in longitudinal sections of optic nerve tissue. Histological and immunocytochemical techniques are used to demonstrate the density of astrocytes, RGC axons and glia-neuron ratios across the pre laminar, lamina cribrosa and...
Degenerative Lumbar Spinal Stenosis. Degenerative lumbar spinal stenosis is the most frequent cause of low back pain and/or sciatica in the elderly patient. Epidemiology, pathophysiology, clinical manifestations and testing are reviewed in a wide current bibliographic investigation. The importance of the relationship between clinical presentation and imaging study, especially magnetic resonance imaging (MRI), is emphasized. Prior to treatment indication, it is necessary to identify the precise location of pain, as well as the differential diagnosis between neurological and vascular lameness. Conservative treatment combining medic...
Extramuscular Recording of Spontaneous EMG Activity and Transcranial Electrical Elicited Motor Potentials in Horses: Characteristics of Different Subcutaneous and Surface Electrode Types and Practical Guidelines. Adhesive surface electrodes are worthwhile to explore in detail as alternative to subcutaneous needle electrodes to assess myogenic evoked potentials (MEP) in human and horses. Extramuscular characteristics of both electrode types and different brands are compared in simultaneous recordings by also considering electrode impedances and background noise under not mechanically secured (not taped) and taped conditions. Methods: In five ataxic and one non-ataxic horses, transcranial electrical MEPs, myographic activity, and noise were simultaneously recorded from subcutaneous needle (three brands) ...
The contribution of the middle cerebral artery and callosal artery to the vascularisation of the Facies convexa of the brain in horses with reference to the equine-specific cartographic pattern of the neopallium. The extremely complex surface architecture of the equine brain does not allow a uniform transfer of anatomical data from other mammalian species, e.g., dog or cat. Rather, a special approach is required to elucidate the equine-specific patterns of cerebral vascular ramifications. Therefore, a novel cartographic system was applied. Prior attention was paid to the A. cerebri media (MCA) and to the A. corporis callosi (CA), as they spread over the widest part of the neopallium's Facies convexa (i.e. the lateral and dorsal surface), thus being of particular interest in terms of surgical treatment ...
Localisation of cannabinoid and cannabinoid-related receptors in the equine dorsal root ganglia. Growing evidence recognises cannabinoid receptors as potential therapeutic targets for pain. Consequently, there is increasing interest in developing cannabinoid receptor agonists for treating pain. As a general rule, to better understand the actions of a drug, it would be of extreme importance to know the cellular distribution of its specific receptors. The localisation of cannabinoid receptors in the dorsal root ganglia of the horse has not yet been investigated. Objective: To localise the cellular distribution of canonical and putative cannabinoid receptors in the equine cervical dorsal roo...
Histologic Evaluation of Palmar Digital Nerves after Perineural Injection of 2% Ammonium Chloride in Miniature Horses. Neurolytic compounds are widely used by equine practitioners for the management of lameness, mostly related to the foot. The present study aimed to evaluate the neurotoxicity of 2% ammonium chloride (2% AC) applied adjacent to the palmar digital nerves in six miniature horses. The 2% AC and 0.9% saline solution were randomly injected into three and one palmar digital nerve of each horse, respectively. Nerve samples were collected by neurectomy performed under general anesthesia at 5, 12, 19, 35, 47, and 62 days after treatment, with one horse per day of surgery. The inflammatory reaction to p...
Genetics of Equine Behavioral Traits. Behavior is a valuable quantitative trait in the horse because of its impact on performance, work, recreation, and prerequisite close interactions with humans. This article reviews what is known about the genetics of behavior in horses with an emphasis on the genetic basis for temperament traits, neuroendocrine function, and stereotypic behavior. The importance of using modern molecular genetic techniques to the study of equine behavior and recommendations for future research are also discussed. Ultimately, these studies enhance the understanding of the biology of behavior in the horse, improv...
EEG based assessment of stress in horses: a pilot study. As has been hypothesized more than 20 years ago, data derived from Electroencephalography (EEG) measurements can be used to distinguish between behavioral states associated with animal welfare. In our current study we found a high degree of correlation between the modulation index of phase related amplitude changes in the EEG of horses ( = 6 measurements with three different horses, mare and gelding) and their facial expression, measured by the use of the horse grimace scale. Furthermore, the pattern of phase amplitude coupling (PAC) was significantly different between a rest condition and a s...
Intracerebral Astrocytoma in a Horse. An 8-year-old Anglo-European gelding with progressive neurological signs was humanely destroyed and submitted for necropsy examination. The right parietal cortex was disrupted by a well-demarcated, intraparenchymal, 1.5 cm diameter, tan, homogeneous, dense mass. Microscopical examination was consistent with an astrocytoma, which was confirmed on the basis of strong immunohistochemical labelling for glial fibrillary acidic protein. The neoplastic population lacked immunolabelling for oligodendrocyte transcription factor 2. Labelling for ionized calcium binding adaptor molecule 1 highlighted la...
Equine-Assisted Intervention to Improve Perceived Value of Everyday Occupations and Quality of Life in People with Lifelong Neurological Disorders: A Prospective Controlled Study. People with neurological disorders suffer from poor mobility, poor balance, fatigue, isolation and monotonous everyday activities. Studies show that equine-assisted interventions can improve their mobility and balance, but could these kinds of interventions also increase participants' activity repertoire and self-assessed health, and reduce their fatigue? The study was conducted as a prospective, controlled study with three cohorts followed for one year: intervention group ( = 14), control group Passive ( = 29), and control group Active ( = 147). Participants in the study were affected by neur...
Presumed cholesterinic granulomas detected on CT in horses are associated with increased lateral ventricle height and age. Cholesterinic granulomas are mass-like lesions that form at the choroid plexus of the ventricular system. Large cholesterinic granulomas within the lateral ventricles have been reported to cause severe neurological signs. However, little data are available about their prevalence or appearance in the overall population. The objective was to report the prevalence of presumed cholesterinic granulomas on CT in a population of horses, and investigate associations between presumed cholesterinic granuloma presence, lateral ventricle size, age, and neurological signs. The study was cross sectional, CT...
Comparison of 2 collection methods for cerebrospinal fluid analysis from standing, sedate adult horses. Cerebrospinal fluid (CSF) analysis is an important component of the evaluation of horses with neurologic disease. Lumbosacral (LS) centesis is routine, but CSF is also collected from the space between the first and second cervical vertebrae (C1-C2). Objective: To compare collection times, CSF cytology results, and equine protozoal myelitis (EPM) titers of CSF collected from the C1-C2 and LS sites. Methods: Fifteen university-owned adult horses with no evidence of neurologic disease, and 9 horses with signs of neurologic disease: 3 university-owned and 6 client-owned. Methods: Prospective study...
Susceptibility of rat immortalized neuronal cell line Rn33B expressing equine major histocompatibility class 1 to equine herpesvirus-1 infection is differentiation dependent. Equine herpesvirus-1 (EHV-1), which causes encephalomyelitis in horses, shows endotheliotropism in the central nervous system of horses, and generally does not infect neurons. However, little is known about the mechanism underlying the resistance of neuron to EHV-1, due to the lack of convenient cell culture systems. In this study, we examined EHV-1 infection in immortalized Rn33B rat neuronal cells, which differentiate into neurons when cultured under nonpermissive conditions. Because murine cell lines are resistant to EHV-1 infections due to the lack of functional entry receptors for EHV-1, ...
Genome-Wide Association Study and Subsequent Exclusion of ATCAY as a Candidate Gene Involved in Equine Neuroaxonal Dystrophy Using Two Animal Models. Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disorder of unknown etiology. Clinical signs of neurological deficits develop within the first year of life in vitamin E (vitE) deficient horses. A genome-wide association study (GWAS) was carried out using 670,000 SNP markers in 27 case and 42 control Quarter Horses. Two markers, encompassing a 2.5 Mb region on ECA7, were associated with the phenotype (p = 2.05 × 10-7 and 4.72 × 10-6). Within this region, caytaxin (ATCAY) was identified as a candidate gene due to its known role ...
Neurosurgical management of head injuries incurred during sports: a single centre experience. Accidents during sporting activities are a common cause of head injury, particularly in children and young adults. Whilst most sporting head injuries are minor, there remains a proportion which is associated with high morbidity and mortality. The epidemiology of sports associated head injuries is variable based on geographical region so the aim of this study was to review the management and outcomes of sporting head injuries managed by a single neurosurgical unit in the South of England. A retrospective review of the Trauma Audit and Research Network database was conducted for all patients ad...
Biofluid Markers of Equine Neurological Disorders Reviewed From Human Perspectives. Neurological disorders (NDs) are often fatal to horses. Thus, symptoms of equine NDs commonly indicate euthanasia. Current diagnostic approaches for equine NDs is based on clinical signs, differential diagnoses, analysis of cerebrospinal fluid (CSF), assessment of histopathological lesions, and imaging. However, advances in biofluid biomarkers in the diagnosis of human neurological diseases can potentially be applied to equine NDs. In this review, we described the established human blood and CSF neurobiomarkers that could potentially be used to diagnose equine NDs.
The neurocognitive gains of diagnostic reasoning training using simulated interactive veterinary cases. The present longitudinal study ascertained training-associated transformations in the neural underpinnings of diagnostic reasoning, using a simulation game named "Equine Virtual Farm" (EVF). Twenty participants underwent structural, EVF/task-based and resting-state MRI and diffusion tensor imaging (DTI) before and after completing their training on diagnosing simulated veterinary cases. Comparing playing veterinarian versus seeing a colorful image across training sessions revealed the transition of brain activity from scientific creativity regions pre-training (left middle frontal and temporal...
Retrospective evaluation of the association between hyponatremia and neurological dysfunction in hospitalized foals (2012-2016): 109 cases. Hyponatremia and rapid correction of hyponatremia can lead to neurological abnormalities. The objective of the study was to determine whether plasma sodium concentrations (Na ) and speed of correction of hyponatremia are significantly associated with neurological abnormalities in foals. Methods: Retrospective cohort study 2012 to 2016. Methods: Equine hospital. Methods: One hundred and nine foals <6 months old with hyponatremia (Na concentration ≤125 mmol/L). Methods: Case records were reviewed for any foal with hyponatremia. Clinicopathological findings, presence or absence of neurologi...
Persistent Bilateral Mydriasis Associated With a Pituitary Adenoma in a Horse. Severe bilateral mydriasis and bilaterally decreased vision were observed in a 23-year-old crossbred warmblood gelding with a history of pituitary pars intermedia dysfunction. Ten years after the onset of clinical signs, it was killed humanely because of worsening of clinical signs and loss of therapeutic responsiveness. Postmortem examination of the head was performed to confirm the suspected pituitary neoplasm and to investigate secondary oculomotor lesions. Pathomorphologic examination revealed an expansile space-occupying pituitary adenoma and degenerative changes in the preganglionic ocul...
Cauda equina syndrome in an ovarian malignant-mixed müllerian tumor with leptomeningeal spread. Leptomeningeal metastasis is extremely rare in patients with ovarian cancer, but should be considered in patients presenting with neurologic deficits such as cauda equine syndrome. Given its poor prognosis and lack of data currently on management, additional studies are needed to optimize treatment regimens and improve outcomes.
Equine Stereotaxtic Population Average Brain Atlas With Neuroanatomic Correlation. There is growing interest in the horse for behavioral, neuroanatomic and neuroscientific research due to its large and complex brain, cognitive abilities and long lifespan making it neurologically interesting and a potential large animal model for several neuropsychological diseases. Magnetic resonance imaging (MRI) is a powerful neuroscientific research tool that can be performed , with adapted equine facilities, or in the research setting. The brain atlas is a fundamental resource for neuroimaging research, and have been created for a multitude animal models, however, none currently exist f...
Determination of magnetic motor evoked potential latency time cutoff values for detection of spinal cord dysfunction in horses. Transcranial magnetic stimulation (TMS) and recording of magnetic motor evoked potentials (MMEP) can detect neurological dysfunction in horses but cutoff values based on confirmed spinal cord dysfunction are lacking. Objective: To determine latency time cutoff for neurological dysfunction. Methods: Five control horses and 17 horses with proprioceptive ataxia. Methods: Case-control study with receiver operating characteristic curve analysis, based on diagnostic imaging, TMS, and histopathological findings. Horses were included if all 3 examinations were performed. Results: Diagnostic imaging an...
Heterogeneity among traumatic spinal cord injuries at the thoracolumbar junction: helping select patients for clinical trials. Retrospective analysis. Methods: China Rehabilitation Research Center, Beijing, China. Objective: A retrospective study that documents the modalities and clarifies the heterogeneity among spinal cord injuries (SCIs) caused by trauma to the thoracolumbar vertebral junction. Methods: X-ray and MRI imaging, neurological records, and the urodynamics results of 190 patients were reviewed and used to categorize different SCI modalities. First, injuries were divided into complete and incomplete injuries using the International Standard for Neurological Classification of Spinal Cord Injury. Next, the ...