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.
Seki N, Tochinai R, Sekizawa SI, Márquez MA, Fukuda K, Ohmura H, Kuwahara M.The Criollo is an Argentine horse breed with a calm temperament. Although its temperament is considered to be related to its neurophysiological characteristics, the details of this are unknown. Therefore, we analyzed the heart rate variability in Criollos as a preliminary study to deepen the neurophysiological understanding of their autonomic function. Electrocardiograms were recorded from Criollos and Thoroughbreds, and the power spectrum of heart rate variability was analyzed. Compared with Thoroughbreds, Criollos showed (i) a significantly higher high-frequency component, which is an index ...
Harvey AM, Beausoleil NJ, Ramp D, Mellor DJ.The mental experiences of animals are what characterises their welfare status. The Five Domains Model for assessing welfare aligns with the understanding that physical and mental states are linked. Following measurement of indicators within each of the four physical/functional Domains (1. Nutrition; 2. Physical environment; 3. Health; and 4. Behavioural interactions), the anticipated negative or positive affective consequences (mental experiences) are cautiously inferred and assigned to Domain 5. Those inferences derive credibility from validated knowledge of the underlying systems of physiolo...
Vinardell T, Elestwani S, Jamieson C, Karim E, Robin M, Glynn S, Benini R, Aleman M.A standardized protocol for electroencephalography (EEG) under standing sedation for the investigation of epilepsy in foals is needed. Objective: To evaluate a modified standardized EEG protocol under standing sedation using sublingual detomidine hydrochloride in Egyptian Arabian foals. Methods: Nineteen foals (controls, 9; juvenile idiopathic epilepsy [JIE], 10). Methods: Descriptive clinical study. Foals were classified as controls or epileptic based on history or witnessed seizures and neurological examination. Foals were sedated using sublingual detomidine hydrochloride at a dosage of 0.08...
Phelps S, Chong D, McKenzie E, Kiupel M, Gorman E.Clinical disease caused by infection with Listeria monocytogenes is rare in adult horses, and there is a paucity of ante-mortem clinicopathologic changes for this species reported in the literature. Confirmatory diagnosis is difficult and often requires post-mortem sampling of the brainstem. This report details a case of meningoencephalitis caused by Listeria monocytogenes in an adult American quarter horse gelding presenting with central neurologic signs. Pre-mortem analysis of the cerebrospinal fluid revealed a mononuclear, primarily lymphocytic, pleocytosis, which is a reported finding in o...
Salamanca-Carreño A, Parés-Casanova PM, Crosby-Granados RA, Vélez-Terranova M, Bentez-Molano J.The skull is divided into neurocranium and splanchnocranium, and its variation allows ecomorphological studies to learn about possible evolutionary and adaptive characteristics. The basicranial organization of the neurocranium and splanchnocranium modules was studied in a sample of 31 skulls from adult Araucanian horses by means of 2D geometric morphometric techniques. The neurocranium and splanchnocranium modules on the ventral aspect were analyzed separately using a set of 31 landmarks. The RV coefficient (the multivariate analog of a correlation) was estimated to analyze the independence of...
Trobec T, Žužek MC, Sepčić K, Kladnik J, Turel I, Frangež R.Enzyme butyrylcholinesterase (BChE) shows increased activity in some brain regions after progression of Alzheimer's disease and is therefore one of the therapeutic targets for symptomatic treatment of this neurodegenerative disorder. The organoruthenium(II) complex [(η--cymene)Ru(II)(1-hydroxy-3-methoxypyridine-2(1)-thionato)pta]PF () was designed based on the results of our previous structure-activity studies. Inhibitory activity toward cholinesterase enzymes shows that this complex selectively, competitively, and reversibly inhibits horse serum BChE (hsBChE) with an IC value of 2.88 µM. Wh...
Donnelly CG, Finno CJ.Phosphorylated neurofilament heavy, a marker of neuroaxonal damage, is increased in horses with equine neuroaxonal dystrophy. However, the temporal dynamics of this biomarker during the post-natal risk period are not understood. Objective: To measure serum and cerebrospinal fluid phosphorylated neurofilament heavy concentrations in juvenile foals across the post-natal window of susceptibility for equine neuroaxonal dystrophy. Methods: Case-control in vivo experimental study. Methods: Concentrations of phosphorylated neurofilament heavy were measured using frozen serum and cerebrospinal fluid c...
Hansen S, Olsen E, Raundal M, Agerholm JS.Cerebellar abiotrophy (CA) is an uncommon hereditary neurodegenerative disorder affecting the cerebellar Purkinje cells. Equine CA has been reported in several breeds, but a genetic etiology has only been confirmed in the Arabian breed, where CA is caused by an autosomal recessive mutation. Methods: Clinical and histological findings consistent with CA are reported in an 8.5-month-old Icelandic filly. The filly showed a perceived sudden onset of marked head tremor, incoordination, ataxia, lack of menace response and a broad-based stance. Cerebrospinal fluid, hematological and biochemical findi...
Murillo C, Weng HY, Weil AB, Kreuzer M, Ko JC.This study aimed to investigate the use of electroencephalography (EEG) for detecting brain activity changes perioperatively in anesthetized horses subjected to surgery. Twelve adult horses undergoing various surgeries were evaluated after premedication with xylazine and butorphanol, induction with ketamine, midazolam, and guaifenesin, and maintenance with isoflurane. The frontal EEG electrodes were placed after the horse was intubated and mechanically ventilated. The EEG data were collected continuously from Stage (S)1-transition from induction to isoflurane maintenance, S2-during surgery, S3...
Repac J, Mangan E, Xie H.Acupuncture is an inexpensive nonpharmacological modality that has a variety of musculoskeletal, neurologic, and internal medicine applications for the equine practitioner. Common uses include back pain colic, laminitis, laryngeal hemiplegia, and suprascapular neuropathy. Although there is a growing body of literature supporting the use of acupuncture in equids, there remains a need for further robust, double-blinded, placebo-controlled clinical efficacy trials.
Cahalan SD, Perkins JD, Boehm I, Jones RA, Gillingwater TH, Piercy RJ.Morphological study of the neuromuscular junction (NMJ), a specialised peripheral synapse formed between a lower motor neuron and skeletal muscle fibre, has significantly contributed to the understanding of synaptic biology and neuromuscular disease pathogenesis. Rodent NMJs are readily accessible, and research into conditions such as amyotrophic lateral sclerosis (ALS), Charcot-Marie-Tooth disease (CMT), and spinal muscular atrophy (SMA) has relied heavily on experimental work in these small mammals. However, given that nerve length dependency is an important feature of many peripheral neurop...
Hahn C.The neurological examination is undertaken to determine whether any deficit is due to a lesion in the nervous system and, if so, where within the nervous system any possible lesion or lesions are located. The examination of horses has challenges not encountered when doing the equivalent examination in dogs and cats, principally that spinal reflexes and postural reactions are impossible/difficult to assess in most animals. The anatomy book can be consulted later but at the end of the neurological examination the clinician then should be able to determine broadly which area of the neuromuscular ...
Schils S, Ober T.When diagnosing neuromuscular injury and pain, the use of biomechanical evaluations to assess the mechanics of movement patterns has been useful in the human population. Functional electrical stimulation (FES) is a technology that can create action potentials to produce musculoskeletal movement that is almost indistinguishable from the voluntary kinematics produced by the nervous system. To create controlled and precise musculoskeletal movements in humans and in horses, FES has been shown to be effective. In humans, the kinematic information obtained from FES data has been utilized to direct f...
Nout-Lomas YS.Mechanisms of traumatic nervous system injury to a degree are similar, but differences exist in etiology, pathophysiology, and treatment of brain, spinal cord, and peripheral nerve injury. The most common clinical abnormalities seen in the horse are abnormal level of consciousness, abnormal behavior, seizures, cranial nerve deficits, vestibular disease, tetra- and paraparesis or paraplegia, cauda equina syndrome, specific gait deficits, and muscle atrophy. Treatments are directed toward reducing inflammation and swelling, halting secondary injury, and promoting mechanisms of neuroregeneration ...
Valberg SJ.Movement disorders are defined as involuntary movements that are not due to a painful stimulus or associated with changes in consciousness or proprioception. Diagnosis involves ruling out any lameness and neurologic disease and characterizing the gait during walking backward and forward and trotting. Shivers causes abnormal hindlimb hypertonicity during walking backward and, when advanced, a few strides walking forward. Stringhalt causes consistent hyperflexion during walking forward and trotting and variable difficulty when walking backward. Classification and potential causes are discussed a...
Garrett KS.Diagnostic imaging is often an important part of the diagnostic approach to neurologic disease. Advanced imaging techniques such as myelography, computed tomography (CT), and magnetic resonance imaging (MRI) provide more information than radiography and ultrasonography but are more limited in their availability. The clinician should be cognizant of the findings of the clinical examination when interpreting diagnostic imaging findings.
Aleman M.The vestibular system (VS) is the primary specialized sensory system responsible for maintaining balance (equilibrium) and orientation of the eyes, neck, trunk, and limbs during rest and movement. Two important reflexes are responsible for maintaining balance: vestibulo-ocular and vestibulospinal reflexes. These reflexes involve peripheral and central components of the VS. Whether central or peripheral disease, most of the disorders of the VS result in ipsilateral neurologic deficits. A few uncommon exceptions present with contralateral signs to the site of the lesion. This article provides a ...
Journée HL, Journée SL.Depending on the localization of the lesion, spinal cord ataxia is the most common type of ataxia in horses. Most prevalent diagnoses include cervical vertebral stenotic myelopathy (CVSM), equine protozoal myeloencephalitis (EPM), trauma and equine degenerative myeloencephalopathy (EDM). Other causes of ataxia and weakness are associated with infectious causes, trauma and neoplasia. A neurologic examination is indispensable to identify the type of ataxia. In addition, clinical neurophysiology offers tools to locate functional abnormalities in the central and peripheral nervous system. Clinical...
MacKay RJ, Howe DK.Advances in the understanding of equine protozoal myeloencephalitis (EPM) are reviewed. It is now apparent that EPM can be caused by either of 2 related protozoan parasites, Sarcocystis neurona and Neospora hughesi, although S neurona is the most common etiologic pathogen. Horses are commonly infected, but clinical disease occurs only infrequently; the factors influencing disease occurrence are not well understood. Epidemiologic studies have identified risk factors for the development of EPM, including the presence of opossums and prior stressful health-related events. Attempts to reproduce EP...
Johnson SA.Rehabilitation of the neurologic horse represents a unique challenge for the equine practitioner. Improving postural stability and balance control through improving the strength of the spinal stabilizer muscle multifidus remains one of the most promising rehabilitative targets. This muscle can be targeted through the use of physiotherapeutic exercises, various forms of perturbation, and even whole-body vibration. Neuroanatomic localization and diagnosis specificity enable the practitioner to determine suitability for such rehabilitative tasks, and with the advent of evolving strategies and com...
Ruby RE, Janes JG.The variety of neurologic diseases which affect horses makes pathologic examination of the nervous system a complex and lengthy process. An understanding of the common causes of neurologic disease, antemortem neurolocalization, and supplementation of the necropsy examination with ancillary testing will help to diagnose a large number of causes of neurologic disease. A general understanding of neuropathology and collaborative relationship with your local pathologists will aid in the definitive diagnosis of neurologic diseases.
Rojas-Núñez I, Gomez AM, Palmer S, Mohammed HO.Neurofilaments are structural proteins that are concentrated in the body and axons of neurons. Damage to the neurons or axons as a result of trauma or infectious diseases leads to the release of neurofilaments into blood and cerebrospinal fluid (CSF). This case-control study was carried out to compare serum levels of phosphorylated neurofilament heavy chain (pNF-H) between clinically healthy Thoroughbred (TB) horses and TB horses that suffered catastrophic musculoskeletal injuries (cMSI), and to investigate the correlation between putative risk factors and serum concentrations of pNF-H in inju...
McBride SD, Roberts K, Hemmings AJ, Ninomiya S, Parker MO.Stress and genotype elicit changes in impulse control in a range of species that are attributable to adaptations in both the central and peripheral nervous system. We examined aspects of this mechanism in the horse by assessing the effect of a dopamine receptor genotype (DRD4) and central dopaminergic tone (measured via spontaneous blink rate [SBR] and behavioral initiation rate [BIR]), on measures of impulsivity, compulsivity (3-choice serial reaction time task) and sympathetic/ parasympathetic system balance (heart rate variability [HRV]). Genotype did not have a significant effect on any of...
Adalbert R, Cahalan S, Hopkins EL, Almuhanna A, Loreto A, Pór E, Körmöczy L, Perkins J, Coleman MP, Piercy RJ.Neurological disorders are prevalent in horses, but their study is challenging due to anatomic constraints and the large body size; very few host-specific in vitro models have been established to study these types of diseases, particularly from adult donor tissue. Here we report the generation of primary neuronal dorsal root ganglia (DRG) cultures from adult horses: the mixed, dissociated cultures, containing neurons and glial cells, remained viable for at least 90 days. Similar to DRG neurons in vivo, cultured neurons varied in size, and they developed long neurites. The mitochondrial movem...
Landa L, Trojan V, Demlova R, Jurica J, Hrib R.In connection with the use of cannabinoids for therapeutic purposes in human medicine, there is increased attention for their use in veterinary medicine, particularly by the owners of companion animals and horses. Therefore, veterinarians are expected to face this interest and have the corresponding knowledge on these substances. Presently, it is not possible to use medical marijuana (in terms of the dried cannabis flowers) for veterinary purposes in many countries, but there is increasing evidence that isolated cannabinoids also have beneficial effects (namely cannabidiol - CBD)...
Cantatore F, Marcatili M, Withers J.Stiff-person syndrome is a well-recognised disease in humans, whilst cases of stiff-horse syndrome (SHS) have been rarely reported in the veterinary medicine literature. SHS is a progressive immunomediated disorder of the central nervous system leading to a disturbance of gamma amino butyric acid transmission at the neuromuscular junction in which antibodies are produced against the enzyme glutamic acid decarboxylase. A 6 year-old Irish Sport Horse was presented for investigation of involuntary violent contraction of hindlimb and back muscles triggered by stress. The diagnosis of SHS was made ...
Journée SL, Journée HL, Berends HI, Reed SM, Bergmann W, de Bruijn CM, Delesalle CJG.So far, only transcranial motor evoked potentials (MEP) of the extensor carpi radialis and tibialis cranialis have been documented for diagnostic evaluation in horses. These allow for differentiating whether lesions are located in either the thoraco-lumbar region or in the cervical myelum and/or brain. Transcranial trapezius MEPs further enable to distinguish between spinal and supraspinal located lesions. No normative data are available. It is unclear whether transcranial electrical stimulation (TES) and transcranial magnetic stimulation (TMS) are interchangeable modalities. Unassigned: To pr...
de Melo UP, Ferreira C.Tetanus is a distressing and often fatal disease caused by exotoxins released by the bacterium . is a commensal of the gastrointestinal tract of humans and domestic animals, and its spores are highly resistant to environmental changes, acid, and alkali and may persist in the soil for many years. The disease is characterized by generalized muscular rigidity and spasms, hyperesthesia, convulsions, respiratory arrest, and death. Horses are the most susceptible domestic animals. Treatment is typically directed towards elimination of the source of the toxin, neutralization of any unbound toxin, es...
Walendy L, Goehring LS, Zablotski Y, Weyh T, Matiasek K, May A.Transcranial magnetic stimulation (TMS) has been successfully used in horses to evaluate function and integrity of descending motor pathways in patients affected by neurological gait abnormalities. In preceding studies, lengthening latency times (LT) of cranially evoked limb muscle potentials have been considered a reliable diagnostic parameter. Standardized settings use device output signal intensities of 100%. The aim of this study was to determine the effect of submaximal stimulation intensities (SI) and to determine the minimum coil output necessary to evoke motor unit potentials. As an ad...
Bröjer JT, Parsons DA, Linder KE, Peregrine AS, Dobson H.An 8-year-old, Arabian mare presented with acute progressive ataxia and a firm swelling over the right mandible. Radiographs revealed multiple radiolucent areas on the mandibles. The mare's neurological signs progressed, she was consequently euthanized. Postmortem examination revealed mandibular granulomatous reactions and meningoencephalitis due to the nematode Halicephalobus gingivalis.
Wickens C, Brooks SA.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...
Foreman JH, Constable PD, Waggoner AL, Levy M, Eppley RM, Smith GW, Tumbleson ME, Haschek WM.The objective of this experiment was to characterize a dose-dependent toxic effect of fumonisin B1 (FB1) and to document initial neurologic signs, clinical progression, and terminal cerebrospinal fluid (CSF) changes in horses administered FB1 IV. Seventeen healthy horses were administered 0.00 (n = 4), 0.01 (n = 3), 0.05 (n = 3), 0.10 (n = 3), or 0.20 mg (n = 4) of purified FB1 IV q24h. When neurologic abnormalities observed by a masked observer became severe, atlanto-occipital CSF taps were performed and CSF pressure, cell count, cytology, protein, albumin and glucose concentrations, and crea...
Williams DC, Brosnan RJ, Fletcher DJ, Aleman M, Holliday TA, Tharp B, Kass PH, LeCouteur RA, Steffey EP.The effects of anesthesia on the equine electroencephalogram (EEG) after administration of various drugs for sedation, induction, and maintenance are known, but not that the effect of inhaled anesthetics alone for EEG recording. Objective: To determine the effects of isoflurane and halothane, administered as single agents at multiple levels, on the EEG and quantitative EEG (qEEG) of normal horses. Methods: Six healthy horses. Methods: Prospective study. Digital EEG with video and quantitative EEG (qEEG) were recorded after the administration of one of the 2 anesthetics, isoflurane or halothane...
Sleutjens J, Voorhout G, Van Der Kolk JH, Wijnberg ID, Back W.In dressage, the head and neck position has become an issue of concern as certain extreme positions may imply a welfare risk for the horse. In man, extension and flexion of the cervical spine cause a decrease and increase in intervertebral foramina dimensions, respectively. However, in horses, the influence of flexion and extension on foramina dimensions and its possible interference with peripheral nerve functioning remains unknown. Objective: To determine the effect of ex vivo flexion and extension on intervertebral foramina dimensions in the equine cervical spine. Methods: Computed tomograp...
Parker M, Redhead ES, Goodwin D, McBride SD.Horses displaying an oral stereotypy were tested on an instrumental choice paradigm to examine differences in learning from non-stereotypic counterparts. Stereotypic horses are known to have dysfunction of the dorsomedial striatum, and lesion studies have shown that this region may mediate response-outcome learning. The paradigm was specifically applied in order to examine learning that requires maintenance of response-outcome judgements. The non-stereotypic horses learned, over three sessions, to choose a more immediate reinforcer, whereas the stereotypic horses failed to do so. This suggests...
Marcinkowska M, Bucki A, Panek D, Siwek A, Fajkis N, Bednarski M, Zygmunt M, Godyń J, Del Rio Valdivieso A, Kotańska M, Kołaczkowski M....Serotonin 5-HT receptors, butyrylcholinesterase (BuChE) and oxidative stress are related to the pathophysiology of Alzheimer's disease. Inhibition of BuChE provides symptomatic treatment of the disease and the same effect was demonstrated for 5-HT antagonists in clinical trials. Oxidative stress is regarded as a major and primary factor contributing to the development of Alzheimer's disease; therefore, antioxidant agents may provide a disease-modifying effect. Combining BuChE inhibition, 5-HT antagonism, and antioxidant properties may result in multitarget-directed ligands providing cognitio...
Divers TJ, Mohammed HO, Cummings JF.This article reviews the subject of equine motor neuron disease, a neurodegenerative disease of horses. The authors discuss various topics, including epidemiology, pathophysiology, clinical signs, laboratory findings, diagnosis, and treatment.
Tuthill RJ, Clark WH, Levene A.A unique pigmented lesion, judged to be a hamartoma of neural crest origin, occurring in a female patient, is compared with equine melanotic disease, The characteristic perifollicular arrangement of pigment-laden spindle cells is remarkably similar in both. Previously described patch- and plaque-like blue nevi in humans are also closely related. Light and ultrastructural features showed differentiation toward both nevus cells and Schwann cells, and it is proposed that the lesion be termed pilar neurocristic hamartoma.
Nollet H, Van Ham L, Dewulf J, Vanderstraeten G, Deprez P.The influence of coil position on the peak-to-peak amplitude and onset latency of transcranial magnetic motor evoked potentials (MMEPs) in the extensor carpi radialis and cranial tibial muscles of horses was evaluated. Seven different stimulating coil positions were obtained by constructing a frame on the forehead. Two stimulation intensities (80% and 100% of maximal stimulator output) and two different coil currents (clockwise and counter-clockwise) were tested. For both recording sites MMEPs with the shortest onset latency and the largest peak-to-peak amplitude were detected when the coil wa...
Solbrig MV.Borna disease (BD), caused by the neurotropic RNA virus, Borna Disease virus, is an affliction ranging from asymptomatic to fatal meningoencephalitis across naturally and experimentally infected warmblooded (mammalian and bird) species. More than 100 years after the first clinical descriptions of Borna disease in horses and studies beginning in the 1980's linking Borna disease virus to human neuropsychiatric diseases, experimentally infected rodents have been used as models for examining behavioral, neuropharmacological, and neurochemical responses to viral challenge at different stages of lif...
Montinaro A, Gianfreda CD, Proto P.Serous sheets are currently used in Neurosurgery as dural substitute. The aim of this study is to demonstrate that the horse pericardium, which has the essential charasteristics of reabsorbable membranes and moreover is BSE-free, is an excellent dural substitute. Methods: 200 patients, 53 suffering from cranial traumatic conditions and 97 from cranial and craniospinal neoplastic pathologies, underwent a surgical procedure with the application of horse pericardium as a dural prosthesis. Results: The follow-up controls of the patients included a neurosurgical visit and advanced diagnostic imagin...
Aleman M, Williams DC, Guedes A, Madigan JE.An overdose of pentobarbital sodium administered i.v. is the most commonly used method of euthanasia in veterinary medicine. Determining death after the infusion relies on the observation of physical variables. However, it is unknown when cortical electrical activity and brainstem function are lost in a sequence of events before death. Objective: To examine changes in the electrical activity of the cerebral cortex and brainstem during an overdose of pentobarbital sodium solution for euthanasia. Our testing hypothesis is that isoelectric pattern of the brain in support of brain death occurs bef...
Finno CJ, Estell KE, Winfield L, Katzman S, Bordbari MH, Burns EN, Miller AD, Puschner B, Tran CK, Xu L.Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disorder affecting genetically predisposed foals maintained on an α-tocopherol (α-TOH) deficient diet. Currently no antemortem diagnostic test for eNAD/EDM is available. Objective: Because α-TOH deficiency is associated with increased lipid peroxidation, it was hypothesized that F2 -isoprostanes (F2 IsoP), F4 -neuroprostanes (F4 NP) and oxysterols derived from free radical oxidation would be increased in the cerebrospinal fluid (CSF) and neural tissue of eNAD/EDM affected horses and could ...
Freytag C, Seeger J, Siegemund T, Grosche J, Grosche A, Freeman DE, Schusser GF, Härtig W.The present study was performed on whole-mount preparations to investigate the chemical neuroanatomy of the equine myenteric plexus throughout its distribution in the intestinal wall. The objective was to quantify neurons of the myenteric plexus, especially the predominant cholinergic and nitrergic subpopulations. Furthermore, we investigated the distribution of vasoactive intestinal polypeptide and the calcium-binding protein calretinin. Samples from different defined areas of the small intestine and the flexura pelvina were taken from 15 adult horses. After fixation and preparation of the ti...
Chang HT, Rumbeiha WK, Patterson JS, Puschner B, Knight AP.Chronic ingestion of yellow star thistle (Centaurea solstitialis) or Russian knapweed (Acroptilon repens) causes nigropallidal encephalomalacia (NPE) in horses with an abrupt onset of neurologic signs characterized by dystonia of lips and tongue, inability to prehend food, depression, and locomotor deficits. The objectives of this study were to reexamine the pathologic alterations of NPE and to conduct an immunohistochemistry study using antibodies to tyrosine hydroxylase and α-synuclein, to determine whether NPE brains show histopathologic features resembling those in human Parkinson disease...
Duncan ID, Hammang JP.The left recurrent laryngeal nerves from five horses with sub-clinical neuropathy were examined by light and electron microscopy in a study designed to examine accumulation of axonal organelles at paranodal and internodal locations. Transverse sections of the nerve showed scattered fibres with split myelin sheaths and axonal accumulation of organelles. On longitudinal sections these collections were seen to result from an axonal outpouching in which dense lamellar bodies and mitochondria had accumulated. These paranodal collections, which could be found on both sides of the node, were often as...
Ohba T, Ebata S, Ando T, Ichikawa J, Clinton D, Haro H.Hematoma of the ligamentum flavum is a rare cause of neural compression, for which treatment has consisted of excising the hematoma via open surgical approaches, including total laminectomy or bilateral partial laminectomy. This article presents the first report of a microscope-assisted endoscopic decompression to resect a hematoma of the ligamentum flavum.A 52-year-old man presented with back and leg pain, as well as difficulty initiating micturation. Magnetic resonance imaging demonstrated an epidural mass at L5/S1 that was continuous with the facet joint. Visualization was obtained via an e...
Toribio RE.Neonatal encephalopathy (NE) and neonatal maladjustment syndrome (NMS) are terms used for newborn foals that develop noninfectious neurologic signs in the immediate postpartum period. Cerebral ischemia, hypoxia, and inflammation leading to neuronal and glial dysfunction and excitotoxicity are considered key mechanisms behind NE/NMS. Attention has been placed on endocrine and paracrine factors that alter brain cell function. Abnormal steroid concentrations (progestogens, neurosteroids) have been measured in critically ill and NE foals. In addition to supportive treatment, antimicrobials should ...
McBride SD, Hemmings A.Stress-induced changes in mesoaccumbens dopamine neurophysiology have been associated with the development of stereotypic behaviour in in-bred strains of laboratory rodents. This experiment evaluated whether similar changes are associated with environmentally-induced stereotypic behaviour in a higher-vertebrate species, the horse. D1- and D2-like dopamine receptor densities (B(max)) and dissociation constants (K(d)) were measured in control (n=9) and stereotypy (n=9) horses in the nucleus accumbens, caudate nucleus, putamen, substantia nigra and ventral tegmentum brain regions. Results reveale...
Pascalau R, Aldea CC, Padurean VA, Szabo B.The spatial anatomy of the white matter tracts is a subject of growing interest not only for researchers but also for clinicians. Imagistic methods have some limitations so that they should be confronted with dissection studies. The aim of this paper was to provide a three-dimensional view of the major white matter tracts in equine, feline and canine brains by use of the fibre dissection technique. Twenty cerebral hemispheres (six equine, four feline and 10 canine brains) were prepared according to the Klingler method. Stepwise mediolateral and lateromedial blunt dissections were performed usi...
Takeuchi K, Hagiwara Y, Kanaya K, Wada K, Shiba M, Kato Y.The diagnosis of pituitary carcinoma cannot be made easily histologically, and most cases of pituitary carcinoma are diagnosed only after the clinical detection of metastasis. Distant metastasis of pituitary tumor occurs in 0.1% to 0.2% of cases and has been reported in the liver, bone and central nervous system, with only one case of metastasis to the cauda equine reported. This study describes a rare case of the drop metastasis of adrenocorticotropic hormone-producing pituitary adenocarcinoma to the cauda equina, causing cauda equina syndrome.
Valberg SJ, Lewis SS, Shivers JL, Barnes NE, Konczak J, Draper AC, Armién AG."Shivers" is a progressive equine movement disorder of unknown etiology. Clinically, horses with shivers show difficulty walking backward, assume hyperflexed limb postures, and have hind limb tremors during backward movement that resembles shivering. At least initially, forward movements are normal. Given that neither the neurophysiologic nor the pathologic mechanisms of the disease is known, nor has a neuroanatomic locus been identified, we undertook a detailed neuroanatomic and neuropathologic analysis of the complete sensorimotor system in horses with shivers and clinically normal control h...
Simonsen U, Prieto D, Hernández M, Sáenz de Tejada I, García-Sacristán A.To study the influence of alpha-adrenergic stimuli on non-adrenergic non-cholinergic (NANC) neurogenic relaxation in isolated horse penile resistance arteries. Methods: Deep intracavernous penile arteries with an internal lumen diameter of 200-500 microns., isolated from the corpus cavernosum of young horses, were mounted in microvascular myographs for isometric tension recording and electrical field stimulation (EFS) of autonomic nerve terminals. Results: In the presence of guanethidine (10(-5) M) and atropine (10(-7) M) tone of the arteries was raised by the thromboxane analogue, U46619. EFS...
Lacombe VA, Podell M, Furr M, Reed SM, Oglesbee MJ, Hinchcliff KW, Kohn CW.Electroencephalography (EEG) is a valuable diagnostic test to identify functional disturbances in brain activity. The purpose of this study was to assess the validity of EEG as a diagnostic indicator of intracranial diseases in horses. The validity of EEG was estimated by comparing clinical, clinicopathologic, and histopathologic findings to EEG findings in 20 horses examined for seizures. collapse, or abnormal behavior between 1984 and 1997. A bipolar left-to-right, back-to-front montage and a bipolar circular montage were recorded from sedated (4) and anesthetized (16) horses. Visual and sem...
Tanabe M, Kelly R, de Lahunta A, Duffy MS, Wade SE, Divers TJ.Parasitic granulomatous eosinophilic inflammation was observed in the central nervous system (CNS) of a 6-month-old Arabian colt from New York state. Inflammation was associated with eggs, larvae, and adult nematodes in the cerebellum. Nematodes had histological characteristics of the superfamily Metastrongyloidea. The presence of dorsal-spined larvae in the CNS was further indicative of infection with a nematode in the family Protostrongylidae. Infections were most compatible with Parelaphostrongylus tenuis but specific diagnosis was not possible. This is the first definitive report of a prot...
Jahns H, Callanan JJ, McElroy MC, Sammin DJ, Bassett HF.Brains from 100 horses, aged 2-25 years, were systematically examined by histopathology at 46 different neuroanatomical sites. The horses were sourced from a slaughterhouse (group A, n = 57), from a kennel that collected dead animals, and from 2 diagnostic laboratories (group B, n = 43). All horses from group A and 26 horses from group B were examined by a veterinarian in the period before death. None of the horses were known to exhibit clinical signs suggestive of neurologic disease. Among the main changes identified were vacuolation in the neuropil (n = 73), neurons (n = 32), white matter (n...
Chiocchetti R, Giancola F, Mazzoni M, Sorteni C, Romagnoli N, Pietra M.The lower esophageal sphincter (LES) is a specialized, thickened muscle region with a high resting tone mediated by myogenic and neurogenic mechanisms. During swallowing or belching, the LES undergoes strong inhibitory innervation. In the horse, the LES seems to be organized as a "one-way" structure, enabling only the oral-anal progression of food. We characterized the esophageal and gastric pericardial inhibitory and excitatory intramural neurons immunoreactive (IR) for the enzymes neuronal nitric oxide synthase (nNOS) and choline acetyltransferase. Large percentages of myenteric plexus (MP) ...
