The nervous system in horses is a complex network responsible for transmitting signals between different parts of the body. It consists of the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which comprises nerves that extend throughout the body. The nervous system regulates various physiological processes, including movement, sensation, and the coordination of bodily functions. It plays a critical role in processing sensory information and initiating appropriate responses. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and clinical implications of the equine nervous system, including its role in behavior, response to stimuli, and neurological disorders.
Rasbech NO.Ejaculatory disorders of the stallion seem to occur more frequently than hitherto accepted. The condition is manifested differently in individual stallions from normal copulation without ejaculation to an abnormal pattern of copulation without or with occasional ejaculation. The condition is probably caused by a functional disturbance of the nervous mechanism which controls the ejaculatory process, and may be caused by environmental or other factors. Eleven cases of ejaculatory disorders in normal healthy stallions were investigated and three of these animals recovered after simple correction ...
Irvine CH, Evans MJ.Total tyhroxine (TT4), free thyroxine (FT4), total triiodothyronine (TT3) and free triiodothyronine (FT3) concentrations in foal umbilical cord blood were respectively 14, 5 7 and 3 times the concentrations of these hormones in adult horse blood. The TT4 levels in foals declined rapidly to reach adult concentrations by Day 16 and FT4 levels declined steadily during the first 3 months of life. Foal TT3 levels rose during the first 10 hr after birth and thereafter declined, although they were still X2-5 higher than adult levels at 3 months of age. Levels of FT3 similarly increased after birth be...
Harris WF.Three horses exhibited nervous and cardiopulmonary signs after ingestins small amounts of metaldehyde, and 2 died in 3 to 5 hours. A colt given 0.1 mg/kg was similarly affected and died.
Hayes HM, Priester WA, Pendergrass TW.From 11 North American veterinary university hospitals and clinics, 248 animals were a confirmed diagnosis of nervous-tissue tumor were identified; 7 tumors were found in cattle, 28 in horses, 14 in cats, 199 in dogs, and none in other species. Tumors were divided for analysis into three categories-glial, meningeal, and peripheral nerve. In cattle and horses, all tumors involved peripheral nerves, the risk of which, in horses, reached a plateau at 4-6 years of age and remained constant thereafter. In cats, the tumors were equally distributed among the three tumor categories whereas, in dogs, t...
Hooper PT.Severe spongy degeneration of the central nervous system (CNS) was seen in 11 cattle, 19 sheep, 4 pigs and 1 goat, associated with a variety of hepatic diseases, particularly those caused by hepatotoxic pyrrolizidine alkaloids. It was also seen in a milder form in 2 of 8 horses examined, 1 dog of 5 dogs examined, and in 1 rabbit only of a large number of laboratory animals examined. This paper reports results of experiments which confirmed initially that the CNS disease cold be caused by pyrrolizidine alkaloid intoxication. This was done by poisoning lambs with lasiocarpine. As the disease was...
Tabel H, Charlton KM.A horse showing clinical signs of a neurological disorder was killed and various diagnostic tests for rabies were carried out. Histopathlogy revealed a nonsuppurative encephalitis. Fluorescent antibody test and mouse inoculation test were negative. A positive diagnosis of rabies was based on a high antibody titer (1:10,000) to rabies virus in brain tissue.
Louie EW, Streeter R, Story M, Scrivani PV, Barrett M, Mullen KR.A neonatal Dutch Warmblood colt was evaluated for inability to stand, incoordination and intention tremor. Despite partial improvement in clinical signs during the first 4 days of hospitalization, neurological deficits remained. Magnetic resonance imaging identified a unilateral infratentorial arachnoid cyst-like lesion with ipsilateral compression and displacement of the cerebellar hemisphere, absent corpus collosum, polymicrogyria, suspect leukoencephalopathy, and noncompressive occipitoatlantal malformation. Improvement in clinical signs during the first 6 months of life suggests that ho...
Palmieri G, Panu R, Asole A, Farina V, Sanna L.The various types of sensory nerve endings found in the peroneus tertius muscle in the ass and in the horse have been studied with Ruffini's gold chloride method. Free nerve endings have been described as well as encapsulated receptors. These corpuscles are classified as Pacini-like, Ruffini's terminations and also Golgi's tendon-organs. The authors have pointed out the morphology, topography and structural characteristics of the above named nervous terminations and have hypothesized that a probable functional relation existed between these nervous corpuscles and the considered tendinous struc...
Galeano R, Germanà A, Abbate F, Calvo D, Naves FJ, Hidaka H, Germanà G, Vega JA.Neurocalcin (NC) is a recently characterized EF-hand calcium-binding protein present in a discrete population of sensory neurons and their peripheral mechanoreceptors, but its presence in peripheral nervous system neurons other than in the rat is still unknown. The present study was designed to investigate the occurrence of NC in the dorsal root ganglia (DRG) of several mammalian species (horse, buffalo, cow, sheep, pig, dog, and rat), including humans. DRG were fixed, embedded in paraffin, and processed for immunohistochemistry using a polyclonal antibody against NC. The size of the immunorea...
Gill KK, Kroeger EA.Equine airway smooth muscle is innervated by vagal efferents and, in addition, displays spontaneous mechanical activity. The preparation thus appears to contain at least two discrete excitable components, the cholinergic neural elements and the smooth muscle membrane. Indomethacin (INDO), a cyclooxygenase (CO) inhibitor, exerts a considerable potentiation of function in this preparation. The latter may be effected indirectly, through loss of the inhibitory effect of endogenous prostaglandin E2 (PGE2) on neural acetylcholine release and through direct effects on smooth muscle of the generally a...
Tennent-Brown BS, Morrice AV, Reed S.Neonatal encephalopathy is the most common neurologic condition affecting newborn foals and shares similarities with perinatal asphyxia syndrome of human infants. In many cases of neonatal encephalopathy there is no obvious episode of acute or chronic hypoxia and other mechanisms likely play a role in the pathogenesis. Increased concentrations of neuroactive progestagens are found in affected foals; whether these molecules are protective, as has been suggested, or play a role in the pathogenesis is unknown. Neurologic diseases other than neonatal encephalopathy affect foals occasionally and sh...
Boratyński Z, Flieger S, Eustachiewicz R, Sławomirski J.In this paper, structure and position of the centers of the parasympathetic nervous system in the horse spinal cord were presented. Studies were carried out on 2 horse spinal cordis. After sampling, the material was dehydrated in alcohol, embedded in paraffin and cut into 15 micron thick sections. The sections were stained according to Nissl's method. Every third section was studied. Nucleus intermediomedialis in the horse spinal cord is an intermittent tract of nervous cells passing from the I cervical neuromere to the V sacral segment. The cells of this nucleus form round, horizontally--oval...
Wright JA, Fordyce P, Edington N.Ultrastructural lesions of the cranial nerves and their ganglia and the autonomic nervous system from 5 cases of neuritis of the cauda equina in the horse are described. They include lysosomal inclusions within the semilunar, geniculate and sympathetic chain ganglia, granulomatous involvement of the coeliaco-mesenteric ganglion and accumulation of axonal organelles in unmyelinated fibres of the great splanchnic nerve, sympathetic chain and oesophageal vagus.
Nasu T, Sueishi A, Morimoto M.We used immunohistochemical techniques to analyze the localization and distribution of the catecholamine-synthesizing enzyme tyrosine hydroxylase (TH) and the neuropeptides methionine-endephalin (M-Enk), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), calretinin (Cal), calcitonin gene-related peptide (CGRP), substance P (SP), and galanin (Gal) in the stellate ganglia of two species of domestic animal (cattle and horses). NPY, VIP and Gal immunoreactive neurons (both cell body and nerve fiber) were observed in the stellate ganglia of both animals. M-Enk and CGRP immunoreactive ne...
Peters M, Graf G, Pohlenz J.A 14-year-old standardbred mare with clinically suspected acute bronchitis was killed because of rapidly progressing central nervous disturbances. Necropsy revealed systemic granulomatous inflammation and vasculitis involving the lungs, thoracic lymph nodes, ribs, and liver. In the cerebrum there was a severe subacute bilateral encephalitis and malacia predominately affecting the white matter, and vasculitis with perivascular infiltration of lymphocytes, macrophages, and giant cells. A causative infectious agent could not be detected by Ziehl-Neelsen, Grocott, or Giemsa stains, by periodic aci...
Whalen LR, Wheeler DW, LeCouteur RA, Yovich JV, Boggie LC, Grandy JL, Kainer RA.Maximal conduction velocities of compound action potentials evoked by stimuli of 2 times threshold in the caudal cutaneous sural (CCSN) and medial cutaneous antebrachial (MCAN) nerves were determined by averaging potentials evoked and recorded through percutaneous needle electrodes. Mean maximal conduction velocities of compound action potentials were: CCSN = 61.3 +/- 2.0 meters/second (m/s) and MCAN = 56.4 +/- 2.8 m/s. To confirm accuracy of our percutaneous recordings, compound action potentials were recorded through bipolar chlorided silver electrodes from the exposed surfaces of fascicles ...
Scott EY, Woolard KD, Finno CJ, Penedo MCT, Murray JD.Cerebellar Abiotrophy (CA) is a neurodegenerative disease in Arabian horses affecting the cerebellum, more specifically the Purkinje neurons. Although CA occurs in several domestic species, CA in Arabian horses is unique in that a single nucleotide polymorphism (SNP) has been associated with the disease. Total RNA sequencing (RNA-seq) was performed on CA-affected horses to address the molecular mechanism underlying the disease. This research expands upon the RNA-seq work by measuring the impact of the CA-associated SNP on the candidate gene MutY homolog (MUTYH) and its regulation, isoform-spec...
Koh RB, Harrison TM.Over the past years, the concept of pain management in veterinary medicine has evolved and led to the establishment of a new concept of multimodal approach to pain management, as the current standard of care. The use of multimodal analgesia combining pharmacologic and nonpharmacologic techniques not only helps optimize the quality and efficacy of analgesia but also may prevent the development of chronic or persistent pain. During the past decade, acupuncture has become more popular and evolved into one of the most used forms of integrative medicine interventions and nonpharmacologic therapeuti...
Mello GW, Riet-Correa F, Batista MC, Carvalho CJ, Dias AC, Franklin FL, Silva SM, Dias A.Farmers in the State of Piauí in northeastern Brazil reported nervous signs in ruminants and donkeys after ingestion of Brunfelsia uniflora at the start of the rainy season when the plant is flowering. Leaves of the plant, collected at the start or at the end of the rainy season, were administered in single doses of 5-20 g/kg body weight to 8 sheep and 3 donkeys. Two sheep and 1 donkey that ingested 10 g/kg of the plant in November at the start of the rainy season, when the plant was flowering, developed severe convulsions and diarrhea. One sheep was euthanized and autopsied, and no significa...
Martin-Giménez T, Cruz AM, Barragán A, Montero E, Sanchez PG, Caballero G, Corradini I.Occipital condylar fractures (OCFs) causing delayed onset lower cranial nerve paralysis (LCNPs) are rare. We present a 7-year-old Friesian horse with delayed onset dysphagia caused by vagus nerve (CNX) paralysis and suspicion of glossopharyngeal nerve (CNIX) paralysis developed several days after a minor head injury. Endoscopic examination revealed right laryngeal hemiplegia and intermittent dorsal displacement of the soft palate. An area of submucosal hemorrhage and bulging was appreciated over the dorsal aspect of the medial compartment of the right guttural pouch. Radiological examination o...
Donnelly CG, Johnson AL, Reed S, Finno CJ.Cervical vertebral compressive myelopathy (CVCM) and equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) are leading causes of spinal ataxia in horses. The conditions can be difficult to differentiate, and there is currently no diagnostic modality that offers a definitive antemortem diagnosis. Objective: Evaluate novel proteomic techniques and machine learning algorithms to predict biomarkers that can aid in the antemortem diagnosis of noninfectious spinal ataxia in horses. Methods: Banked serum and cerebrospinal fluid (CSF) samples from necropsy-confirmed adult eNAD/EDM (...
Mayhew IG.A technique for the subarachnoid perfusion-fixation of the central nervous system was developed to help identify various significant vascular accidents (SVAs) in the central nervous system (CNS) of 24 neonatal foals submitted for necropsy. SVAs, comprising subarachnoid, parenchymal and nerve root haemorrhages, and oedema and necrosis, occurred in 17 foals, more frequently in the spinal cord than the brain. They occurred as frequently in premature foals as in those born at full term, in foals born dead as in foals born alive, and in foals born following dystocia with an assisted delivery as in ...
McGorum BC, Jago RC, Cillan-Garcia E, Pirie RS, Keen JA, Reardon RJM, Saffu PY, Miller NJ.The aetiology of equine grass sickness (EGS) is currently unknown. We hypothesised that an acute deficiency of niacin (vitamin B3), which plays a key role in neural homeostasis, may contribute to neurodegeneration in EGS. Niacin deficiency can potentially result from ingestion of niacin antagonists produced by pasture mycotoxigenic fungi. Objective: To compare the niacin status of EGS and control grazing horses. A secondary objective was to compare blood concentrations of vitamins B1, B2 and B6 in EGS and control grazing horses to determine if the status of these vitamins was altered in EGS. M...
Scrivani PV.Neuroimaging underwent a dramatic revolution during the past few decades due to the development of new technologies that produce exquisite images of patient morphology and function, new technologies that store and distribute information more efficiently, and research that has improved understanding of pathogenesis and effective clinical use of new imaging methods. Advanced equine neuroimaging is a specialized field with unique challenges associated with patient size, availability of equipment, using equipment designed for humans, small sample size for various diseases, and issues associated wi...
Taylor KR, MacKay RJ, Nelson EA, Stieler AL, Roberts JF, Castleman WL.Two horses euthanized for neurologic deficits were diagnosed with hamartomatous myelodysplasia of the spinal cord. One was a 5-week-old Holsteiner colt exhibiting spasms of muscle rigidity in the extensor muscles of the limbs and epaxial muscles, and the other was a 3-year-old Thoroughbred colt exhibiting progressive ataxia and hypermetria in the pelvic limbs. Each had focal disorganization of the white and gray matter of the spinal cord forming a mass interspersed with neurons, glial cells, and disoriented axon bundles. In the Holsteiner colt, the mass was at the level of C5 and included isla...
Zhang XY, Zhu FX, Robinson NE.To investigate the effects of changes in intracellular cAMP on alpha 2-adrenoceptor (AR)-induced inhibition of airway acetylcholine (ACh) release, we examined the effects of the alpha 2-AR agonist clonidine on electrical field stimulation-evoked ACh release from equine tracheal parasympathetic nerves before and after treatment with 8-bromo-cAMP or forskolin. We also tested whether charybdotoxin (ChTX)- or iberiotoxin (IBTX)-sensitive Ca(2+)-activated K+ channels mediate alpha 2-AR-induced inhibition by examining the effect of clonidine in the absence and presence of ChTX or IBTX on ACh release...
Wong D, Wilkins PA, Bain FT, Brockus C.Neonatal encephalopathy is a common central nervous system disorder of neonatal foals and human infants, resulting in clinical signs such as lethargy, inappropriate behavior, seizures, and other neurologic deficits. Although neonatal encephalopathy is frequently seen in equine practice, a paucity of veterinary clinical and basic science research data is available. Therefore, the pathophysiologic mechanisms of this disorder in equids, such as energy deprivation, excess excitatory amino acids, and free radical injury, have been extrapolated from human medicine. Equine veterinarians have used var...
Hales EN, Esparza C, Peng S, Dahlgren AR, Peterson JM, Miller AD, Finno CJ.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 ...
Shrauner B, Blikslager A, Davis J, Campbell N, Law M, Lustgarten M, Prange T.The large size of the adult horse prevents the use of advanced imaging modalities in most areas of the axial skeleton, including the lumbosacral vertebral column. Traditional imaging techniques are frequently unable to pinpoint the underlying pathology in horses with caudal back pain. In man, lumbosacral epiduroscopy is used to diagnose and treat subjects with chronic back and leg pain. This technique may close the diagnostic gap in horses with similar clinical signs. Objective: To evaluate the safety and feasibility of lumbosacral epiduroscopy in the standing adult horse. Methods: Descriptive...
Sonea IM, Bowker RM, Broadstone RV, Robinson NE.The tone of respiratory smooth muscle is largely determined by the input from autonomic nerves. The distribution of adrenergic and selected nonadrenergic, non-cholinergic (NANC) nerves in the normal equine trachealis muscle was investigated using immunohistochemistry. The smooth muscle of the trachealis was found to contain numerous nerves immunoreactive for an enzymatic marker of adrenergic nerves, as well as many nerves immunoreactive for a putative NANC neurotransmitter, peptide histidine isoleucine, a potent bronchodilator. The tissue surrounding the respiratory smooth muscle contained num...
Melrose PA, Walker RF, Douglas RH.Catecholamine concentrations (pg/ml) in the cerebrospinal fluid (CSF) of prepubertal (n = 9) and adult (n = 18) horses were determined by radioenzymatic assay. Norepinephrine was low or non detectable in all CSF samples. In contrast, measurable CSF dopamine concentrations were effected by age, reproductive status and exogenous steroid treatments. The concentration of dopamine in the CSF of prepubertal females (733 +/- 92) was greater (p less than 0.05) than the concentration in the CSF of prepubertal males (117 +/- 67). Prepubertal male horses which were treated with testosterone for 5 days (5...
McElroy A, Klinge PM, Sledge D, Donahue JE, Glabman RA, Rashmir A.The objectives of this study were to describe the anatomy, histology, and ultrastructure of the equine filum terminale (FT) and to describe the FT in hereditary equine regional dermal asthenia (HERDA), a model of human Ehlers-Danlos syndromes (EDS). Those humans suffer from tethered cord syndrome (TCS) caused by an abnormally structured FT wherein its attachment at the base of the vertebral column leads to long-term stretch-induced injury to the spinal cord. The pathophysiology of TCS in EDS is poorly understood, and there is a need for an animal model of the condition. Histopathologic and ult...
Bengtsdotter EA, Ekman S, Andersen PH.Inguinal pain, unexplained hind limb lameness, back pain or behavioural problems in geldings could be attributable to painful neuromas that develop as a consequence of crushing and severing the testicular nerves during castration. The presence of neuroma in this anatomical location has never been reported, hence the knowledge of possible clinical relevance is limited. The aim of this study was to histologically investigate the testicular nerves at the castration site in geldings for the presence of neuromas. Proximal spermatic cord remnants were collected from 20 geldings admitted to routine p...
Rijckaert J, Pardon B, Van Ham L, Joosten P, van Loon G, Deprez P.When surgical treatment of cervical vertebral malformation is considered, precise localization of compression sites is essential, but remains challenging. Magnetic motor evoked potentials (mMEP) from paravertebral muscles are useful in localizing spinal cord lesions, but no information about cervical muscle mMEP in horses is available yet. Therefore, the aim of this study was to determine the possibility, normal values, inter- and intra-observer agreement and factors that have an effect on cervical mMEP in healthy horses. Methods: Transcranial magnetic stimulation was performed on 50 normal ho...
Erickson HH, Kitchell RL.In the last 2 decades there have been substantial advances in our knowledge of the scientific basis of the mechanisms of pain. Nociceptors or pain receptors are widespread in the skin and tissues of animals; chemical mediation of nociceptor excitation may provide a key for understanding the peripheral phenomena related to pain. The expression of pain in animals involves multiple ascending and descending branches, as well as specialized pain-signaling mechanisms in the spinal cord. The importance of these different pathways varies with species and circumstances. Endogenous neural systems in the...
Rizvi SM, Slater JD, Wolfinger U, Borchers K, Field HJ, Slade AJ.The distribution of equine herpesvirus 2 (EHV-2) DNA within neurological and lymphoid tissues from 12 EHV-2 seropositive Welsh mountain ponies was determined by PCR. The lymphoid sites sampled in this study were almost universally PCR positive, thus confirming the existing virus co-cultivation data which suggest that the lymph nodes draining the respiratory tract are the main reservoirs of EHV-2 DNA. In addition, EHV-2 DNA was also detected, albeit with lower frequency, within both the peripheral and central nervous systems (PNS and CNS) of these animals. Of the CNS sites sampled 11% were PCR-...
