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.
Mayhew IG, deLahunta A, Whitlock RH, Geary JC.Five horses of mixed breeding and 1 zebra with symmetric tetraparesis and ataxia were studied. There were 2 females and 4 males. Signs of illness were first noticed from birth to 12 months of age. Clinical and pathologic studies were performed when the animals were 4 to 24 months old. Two of the horses were related. All of the subjects had diffuse degenerative myeloencephalopathy. The degeneration was most pronounced in thoracic segments of the spinal cord. Ventral and dorsolateral funiculi were most severely affected. Axonal swelling and abnormal neuronal cell bodies were seen in the gray mat...
Mayhew IG, deLahunta A, Whitlock RH, Geary JC.Five horses of mixed breeding and 1 zebra with symmetric tetraparesis and ataxia were studied. There were 2 females and 4 males. Signs of illness were first noticed from birth to 12 months of age. Clinical and pathologic studies were performed when the animals were 4 to 24 months old. Two of the horses were related. All of the subjects had diffuse degenerative myeloencephalopathy. The degeneration was most pronounced in thoracic segments of the spinal cord. Ventral and dorsolateral funiculi were most severely affected. Axonal swelling and abnormal neuronal cell bodies were seen in the gray mat...
Kitchell RL, Stromberg MW, Davis LH.Quantitative studies were made of cells in the dorsal motor nucleus of the vagus nerve in the horse, dog, cat, pig, sheep, goat, and calf. This nucleus was larger in ruminants than in nonruminants. Some cells in all parts of the nucleus supplied visceral structures in the head, cervical, thoracic, and abdominal regions; however, a definite topographic localization did exist within the nucleus. Eighty percent of the cells which supplied the abdominal viscera were in the rostral and rostral-middle regions. The cells which supplied the thoracic viscera were distributed almost equally within the r...
Science (New York, N.Y.)November 5, 1976
Volume 194, Issue 4265 626-627 doi: 10.1126/science.790567
Radinsky L.Previous interpretations of early horse brains were based on an incorrectly identified fossil endocast, now believed to be from a condylarth. Newly prepared endocasts of Hyracotherium, the oldest horse and one of the earliest perissodactyls, reveal a relatively larger brain, with a more expanded neocortex, than existed in the condylarth ancestors of perissodactyls. Fifty million years ago, horse brains had suprasylvian, ectolateral, and lateral sulci, but the frontal lobe was undeveloped.
Rankin JS, Diesem CD.The hindlimbs of 3 ponies and 3 horses were dissected. The hip joint capsule was found to receive articular nerve fibers from the femoral, obturator, cranial gluteal, and sciatic nerves. The nerve fibers were distributed to the fibrous joint capsule and associated capsular ligaments. The stifle joint capsule was found to receive articular branches from the femoral, saphenous, obturator, common peroneal, and tibial nerves. The fibers terminated in the joint capsule, fat pad, patellar and collateral ligaments, and the internally situated meniscal and cruciate ligaments.
Timoney PJ, Donnelly WJ, Clements LO, Fenlon M.An outbreak of LI infection in a group of free range horses is described. Three of 4 horses displayed signs of CNS disturbance and 2 of these died after illnesses ranging from 2-12 days duration. In both cases a variable degree of viral polioencephalomyelitis was observed. A virus antigenically indistinguishable from a reference strain of LI virus was isolated from the brain and cervical cord of a 3 y.o. draft mare. Serum samples obtained from 3 of the horses contained HI, CF, precipitating and neutralising antibodies to LI virus, with a rise in antibody titre being demonstrated in 2 animals.
Kelly DF, Watson WJ.An aged Connemara mare had a neurological illness lasting 3 weeks and characterised by episodes of dullness, head-pressing, staggering gait and hyperexcitability. The signs recurred at intervals of 3 to 4 days, with intervening periods of apparent normality. Post-mortem examination revealed an epidermoid cyst on the dorsal surface of the occipital lobe of the left cerebral hemisphere. The cyst was lined by stratified squamous epithelium and contained desquamated keratinised material and blood. The lesion is considered to be a congenital malformation which enlarges and produces space-occupying ...
Haughey KG, Jones RT.A high frequency of meningeal lesions was found at autopsy in foals dying perinatally. Such lesions are considered an index of injury to the fetal central nervous system, from trauma and/or hypoxia during birth. Their incidence in the sample examined (26 foals) is similar to that observed in the perinatal mortality of lambs and calves.
Mayhew IG.Methods for atlanto-occipital and lumbosacral collection of cerebrospinal fluid from the horse are described in detail, and the techniques and complications discussed.
Johnson P, Rossdale PD.This paper describes preliminary experiments designed to test the hypothesis that cerebral damage is caused by cardiovascular events involving explosive changes in cerebral blood flow during birth. These events may be responsible for the convulsive episodes of foals suffering from the neonatal maladjustment syndrome.
The Journal of physiologySeptember 1, 1975
Volume 250, Issue 3 633-649 doi: 10.1113/jphysiol.1975.sp011074
Johnson KG.1. A technique for perfusion of skin has been used to investigate a possible neurochemical basis for the different patterns of sweating in domestic animals. Evaporative water loss was measured from excised trunk skin, ears or tails perfused with a nutrient Krebs solution, to which drugs were added as required. Perfused skin was observed to sweat in response to administration of sudorific drugs, and some features of the patterns of sweating were similar to those which could be induced by heating or by drugs in conscious animals. 2. In sheep and goat skin, injections of adrenaline, and to a less...
Hatziolos BC, Sass B, Albert TF, Stevenson MC.Recurrent epistaxis and locomotor and visual disturbances leading to blindness in a 7-year-old gelding appeared to have resulted from a spreading fungal granuloma of the guttural pouch. The inflammatory area extended to the intracranial segment of the right optic nerve and to the region adjacent to the optic chiasma. Microscopically, changes indicative of multiple foci of ischemic infarction were noticed in the retina, optic nerves, optic chiasma, and optic lobe. The profusely growing fungal elements in the guttural granuloma had the morphologic characteristics of an Aspergillus sp.
Cavasin JP, Miller AD, Duhamel GE.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...
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...
Kyles KW, McGorum BC, Fintl C, Hahn CN, Mauchline S, Mayhew IG.Electromyography was used as an aid to the diagnosis of equine motor neuron disease in a conscious horse while it was under caudal epidural anaesthesia. A muscle biopsy was taken to confirm the diagnosis which was then supported by a postmortem examination.
Freeman DE, Donawick WJ, Klein LV.The effect of a single ligature on back pressure in the internal carotid artery was studied in nine horses. In six anesthetized horses, one internal carotid artery was catheterized 2 cm from its origin and blood pressure was recorded continuously. Then the artery was ligated, pressure was recorded again, and the horses were euthanatized. In another three anesthetized horses, indwelling catheters were placed in both internal carotid arteries and a loose ligature was placed proximal to one catheter. After horses recovered from anesthesia, the ligature was tied and blood pressure was recorded in ...
Cornelissen BP.Sesamoiditis is characterized clinically by repeated lameness and radiologically by changes in the proximal sesamoid bones. This thesis, which was defended in June 1997, investigated two characteristics of sesamoiditis, namely the arterial blood supply and the innervation of the proximal sesamoid bones, in order to gain more insight into the etiopathogenesis of sesamoiditis. Experiments with patient material showed that the proximal sesamoid bones have an enormous arterial reserve, due in part to the formation of an arterial shift. Moreover, the sesamoid bones have their own sensory innervatio...
Melrose PA, Knigge KM.The present study describes and compares the topography of alpha-melanocyte-stimulating hormone (alpha-MSH)-immunoreactive neurons in the forebrain of rats and horses. Two groups of immunoreactive cells were present in both species. These groups were distinguished by their cross-immunoreactivity and topography. The topography of cell bodies with cross-immunoreactivity for peptides derived from pro-opiomelanocortin (POMC) including adrenocorticotropin, 16K, alpha-MSH and beta-endorphin was similar in both species. However, the topography of perikarya which stained only for alpha-MSH, and not fo...
Heun F, Böing L, Theunert J, Gasse H.This basically anatomical study focuses on two items; firstly, the establishment of a system for the cartographic subdivision of the neopallium; secondly, the topographical correlation of extracranial landmarks and intracranial sites on the neopallium. Methods: The surface of the neopallium was subdivided into 15 sectors with reference to a newly introduced pattern of Primary Sulci. The topographical link between extracranial landmarks and certain intracranial sites (i.e. neopallium sectors) was elaborated by using a simple stereotactic device and a computer-assisted measurement device. Measur...
Kurz JP, Schoenhals KE, Hullinger GA, Van Wettere AJ.Syringomyelia is a form of myelodysplasia defined by the formation of one or more fluid-filled cavities within the spinal cord that do not communicate with the central canal. The defect may be congenital or acquired. Clinical signs correlate to the segment of spinal cord affected and include pain, paresis, proprioceptive deficits, alterations in sensation, scoliosis, and autonomic dysfunction. This report describes the clinical and pathologic changes in a case of acquired syringomyelia in a 10-year-old American Paint Horse mare. The horse had a six-week history of progressive proprioceptive de...
Melrose PA, Douglas RH.Scanning electron microscopy showed that cells in the infundibular recess of prepubertal female horses were devoid of cilia and sparsely covered with stubby microvilli and small blebs, whereas superior ventricular areas were covered with cilia. Ciliated ependymal cells in supraoptic-suprachiasmatic areas were associated with extensive blebbing, and folded tissue adjacent to the inferior borders of the mamillary body displayed distinct bands of cilia regularly interrupted by areas of sparsely ciliated cells which appeared to be undergoing ciliogenesis. Arcuate ependymal areas had well developed...
Böing L, Heun F, Gasse H.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 ...
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...
Acone F, Botti M, Gazza F, Sanna M, Cappai MG, Bo Minelli L.The sensitive and autonomic innervation of the prostate was studied in some mammals (rat, rabbit, horse, donkey and bull) using gold chloride impregnation. In all the species considered the gland was supplied with conspicuous innervation located in the thickness of the capsule and in trabeculae. The autonomic innervation was constituted by ganglion cells of different sizes (small, medium and large), isolated or in groups of large ganglia also, always located along the course of nerve bundles. The sensitive nervous component, placed more frequently in the most superficial layer of the capsule, ...
Furr M, Chickering WR, Robertson J.To determine normal CSF electrophoresis patterns in horses, and to determine whether the electrophoretic scans from horses with cervical compression differ from those of neurologically normal horses. Methods: 32 horses assigned to 1 of 2 groups: neurologically normal (n = 18) or cervical compression (n = 14). Methods: CSF was collected from 18 neurologically normal horses referred to the Marion duPont Scott Equine Medical Center, and protein electrophoresis was performed to describe the normal equine CSF electrophoretogram. Results of CSF electrophoresis from 14 horses with cervical compressio...
Rousselle JC, Gillet G, Fillion G.The solubilization of the serotonergic 5HT1 and 5HT3 sites was performed with digitonin and sodium cholate at 1% (final concentration). Two binding sites for [3H]5HT were observed on rat or horse brain synaptosomal membranes solubilized with these detergents. The corresponding dissociation constants (KD) were 1-3 nM and 13-30 nM respectively. These values were closely similar to those corresponding to 5HT1 and 5HT3 sites located in intact membranes. The solubilized sites specifically bound 5HT. The effect of GTP decreasing the binding to 5HT1 sites was lost on solubilized 5HT1 sites; it was re...
Nemeth F.Within the framework of the series 'Papers of yesterday and today', two articles on neurotomy by Moubis (1876 and 1878) are used to evaluate the present status of neurectomy. In 1800 neurotomy was replaced by neurectomy because of the reinnervation which occurred after several weeks. On the basis of a literature review and clinical experience in the Department of Large Animal Surgery the indications, conditions, anatomy, operative techniques, complications and results of neurectomy are discussed. Post-operative neuroma formation is the most important complication following palmar digital neure...
Shchurova EN, Khudiaev AT.Temperature sense and pain appreciation has been studied in the dermatomes of cauda equine roots in patients with lumbar intervertebral disc hernia before treatment, in the immediate and long-term periods of observation after disc hernia elimination. Temperature sense and pain appreciation has been determined to be disordered not only in the dermatome of compressed root, but in the dermatomes located proximally and distally as well. The manifestation of negative changes was observed to a greater extent during temperature sense examination. After disc hernia elimination the recovery of temperat...
Matters of physical and medical rehabilitation of children with organic lesions of the nervous system, in particular, with cerebral palsy, are actual in countries around the world. Hippotherapy is neurophysiologically oriented therapy using horses. Determine whether a combination of hippotherapy as a method of rehabilitation in the aftermath of outpatient comprehensive impact on MS on a stationary phase; Study of the effect of hippotherapy as securing and preparation method for learning new postures and movements in children with spastic cerebral palsy forms; The study of the possible optimiza...
Delesalle CJ, Callens C, Van Colen I, Lefebvre RA.Selective 5-HT4 receptor agonists such as prucalopride are used as human prokinetics, since activation of 5-HT4 receptors on intestinal cholinergic neurons facilitates acetylcholine release. 5-HT4 receptors, linked to adenylyl cyclase, act via generation of cAMP. None of the 4 in vitro studies on 5-HT in horses provided evidence for neuronal 5-HT4 receptors, but none used the protocol as described in human studies [1-4]. Objective: To investigate whether functional 5-HT4 receptors are present in the equine small intestine. Methods: In vitro organ bath set up, applying electrical field stimulat...
Palmieri G, Asole A, Panu R, Farina V, Sanna L.A vegetative innervation is described for the first time in this district. On the contrary, the finding of Pacini and pacini-like corpuscles, of Golgi Mazzoni's receptors, of muscle spindles and Golgi's tendon-organs testifies the existence of a sensitive innervation in this anatomical territory. According to Karamanlidis free nervous endings are not present. All the above recorded receptors show the typical structure and can be found isolated, grouped to constitute flower-sprays, organized to form opposito-polar corpuscles or associated to originate pecilomorphic fibers. These two last findin...
Hunt RJ, Allen D, Mueller PO.Heterotopic polyodontia is typically associated with a sinus and a fistulous tract with a secreting membrane which extends to an ectopic tooth attached to the temporal bone. Recommendations for treatment include complete excision of the tract, the dental component, and the lining of the alveolar socket. Iatrogenic cerebral trauma was encountered during surgical extraction of an ectopic tooth. At post-mortem examination a second ectopic tooth was found compressing the right side of the cerebellum.
Berardinelli P, Barazzoni AM, Russo V, Brunetti O, Della Torre G, Scapolo PA, Muttini A, Bortolami R.Based on previous observations that capsaicin can selectively damage group III and IV afferents and induce muscle fibre transformation, we hypothesized that eliminating, by means of capsaicin, the group III and IV afferents of a peripheral territory it could lead to a fibre transformation in a muscle involved in the flexor reflexes of the same peripheral territory. Therefore, capsaicin was injected into the palmar nerves of the forelimb of the horse to investigate if eliminating group III and IV afferents from the hand of the horse a muscle fibre transition would occur in the flexor carpi radi...
Newton-Clarke MJ, Divers TJ, Delahunta A, Mohammed HO.A study was conducted over a 12 month period to assess the specificity and sensitivity of the 'slap test', using endoscopic evaluation, in the detection of cervical spinal cord and caudal brainstem lesions in horses. Fifteen ataxic horses were subjected to the 'slap test' and subsequently examined post mortem. Twelve out of the 15 had histopathological lesions consistent with their clinical signs. Thirteen horses with no history of neurological dysfunction and no histopathological evidence of cervical spinal cord or brainstem disease were used as controls. The laryngeal adductory responses exh...
Vitale V, Bindi F, Velloso Alvarez A, de la Cuesta-Torrado M, Sala G, Sgorbini M.This study aimed to evaluate the feasibility of transcutaneous auricular vagal nerve stimulation (tAVNS) in healthy horses and its effect on heart rate variability (HRV). The study comprised three phases: the selection of mares, their acclimatization to the tAVNS, and the stimulation phase. Stimulation was performed with two electrodes positioned on the right pinna. The settings were 0.5 mA, 250 μs, and 25 Hz for pulse amplitude, pulse width, and pulse frequency, respectively. HRV was analysed before (B1), during (T), and after (B2) the tAVNS. From the 44 mares initially included, only 7 comp...
Pickles KJ, Marlin DJ, Williams JM, Roberts VLH.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. Objective: To develop and validate an objective measure of TGMHS. Methods: 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 co...
Beldeanu S, Tay MCA, Daniel C, Dosi MCM, Hahn CN, James O, Townsend NB, Liuti T, Schwarz T, Parkinson NJ.Fractures of the paracondylar process of the occipital bone may cause headshaking, neck pain and neurologic deficits. The condition is being recognised more frequently with increasing availability of computed tomography. However, to date only limited information is available as to presentation, treatment, surgical approach and outcome. Objective: To describe the clinical signs, imaging findings, treatment, surgical approach and outcome in three horses diagnosed with paracondylar process fracture. Methods: Retrospective case series. Methods: Clinical records and diagnostic images of affected ca...
Wolschrijn CF, Smit IH, Schouten J, Moller Te NCR.Facial expressions are important in pain recognition in horses, but current observation-based pain scales remain subjective. A promising technique to quantitatively measure subtle changes in expression patterns, including changes invisible to the human eye, is surface electromyography (sEMG). To achieve high-quality and reliable sEMG signals, unilateral placement of bipolar electrodes is required in relation to the motor endplates (MEP). We aimed to localize the nerve entry points (NEPs; where the nerve branch first pierced the muscle belly) and the direction of the terminal nerve endings to e...
Crawford AE, Picken LK, Gabriel FD, Quade J, Gould S.Equestrian sports continue to gain popularity in the United States and are associated with a high injury rate, especially involving the central nervous system and thorax. Due to this high rate of injury and the potential for long-term consequences associated with participation, an understanding of the unique risks of this sport is needed. Unassigned: To describe severe injury in equestrian sports and review the role that protective gear plays in injury mitigation. Unassigned: The PubMed Database was searched using the search terms "equestrian" and "horse" combined with "spinal cord injury," "h...
Lee J, Mordoh S, Mirza M, Carossino M, Del Piero F.An 18-y-old American Saddlebred mare was admitted with fever and acute onset of neurologic signs including grade 3 of 5 ataxia, difficulty in prehension, and dull mentation. Because of financial restraints, desired testing could not be performed; the horse's condition declined despite supportive treatment, and euthanasia was elected. Postmortem examination revealed petechiae and ecchymoses in the meninges and neuroparenchyma of the encephalon. Blast-like neoplastic round cells were identified within the vasculature and areas of hemorrhage in the neuroparenchyma, the intestinal submucosa, and o...
Franzen V, Gruber NA, Klußmann S, Schoster A, May A.Trigeminal-mediated headshaking is a neuropathic facial pain condition in horses. No treatment has been entirely successful. Repetitive transcranial magnetic stimulation (rTMS) is used in human medicine as a treatment for various neuropathic pain conditions, and good results have been achieved in cases of trigeminal neuralgia. Objective: Apply rTMS to horses with trigeminal-mediated headshaking (TMHS) and to evaluate tolerability, application of the setting, and success rate. Methods: Seventeen horses with nonseasonal signs of TMHS. Methods: Other underlying causes of headshaking were ruled ou...
Knych HK, Steinmetz SJ, Traynham ML, McKemie DS, Kass PH.Morphine is an effective analgesic in horses, however, IV administration at therapeutic doses has been shown to produce dose-dependent neuroexcitation and unwanted gastrointestinal effects. The analgesic effects of morphine have, at least in part, been attributed to the morphine-6-glucuronide (M6G) metabolite. Oral administration to horses results in comparable M6G concentrations to that achieved following IV administration of a therapeutic dose without the adverse effects. The anti-nociceptive effects have not yet been reported. In the current study the thermal anti-nociceptive effects of sin...
