Neurological diseases in horses encompass a range of disorders affecting the central and peripheral nervous systems. These conditions can arise from various etiologies, including infectious agents, genetic predispositions, trauma, or metabolic imbalances. Common neurological diseases in horses include equine protozoal myeloencephalitis (EPM), equine herpesvirus myeloencephalopathy (EHM), and cervical vertebral stenotic myelopathy (CVSM), also known as wobbler syndrome. Clinical signs associated with these diseases may include ataxia, weakness, altered gait, and changes in behavior or mental status. Diagnosis typically involves a combination of clinical evaluation, imaging techniques, and laboratory testing. This page compiles peer-reviewed research studies and scholarly articles that investigate the pathophysiology, diagnostic approaches, and treatment options for neurological diseases in equine populations.
Divers TJ, Mongodin EF, Miller CB, Belgrave RL, Gardner RB, Fraser CM, Schutzer SE.Antemortem diagnosis of neuroborreliosis in horses has been hindered by both the low sensitivity of PCR testing for in CSF and the low specificity of serum:CSF ELISA ratios used to determine intrathecal antibody production against the bacterium. PCR testing of the CSF of an adult horse with acute neurologic disease for the flagellin gene was negative. However, we enriched DNA through nucleic acid hybrid capture, followed by next-generation sequencing, and identified in the CSF of the horse, confirming a diagnosis of neuroborreliosis.
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 ...
Toribio RE.Several viruses transmitted by biological vectors or through direct contact, air, or ingestion cause neurologic disease in equids. Of interest are viruses of the Togaviridae, Flaviviridae, Rhabdoviridae, Herpesviridae, Bornaviridae, and Bunyaviridae families. Variable degree of inflammation is present with these viruses but lack of an inflammatory response does not rule out their presence. The goal of this article is to provide an overview on pathophysiologic and clinical aspects of nonarboviral equine encephalitides, specifically on lyssaviruses (rabies) and bornaviruses (Borna disease).
van Spijk JN, Beckmann K, Wehrli Eser M, Boxler M, Stirn M, Rhyner T, Kaelin D, Saleh L, Schoster A.Polymyxin B (PolyB) is used to treat endotoxemia in horses; neurologic and nephrogenic adverse effects occur in humans. Objective: To describe PolyB adverse effects in horses. Methods: Five healthy horses (ataxia 0/5), 1 horse with cervical osteoarthritis (ataxia 1/5). Methods: Prospective blinded randomized cross-over trial; 3-weeks wash out. Horses received PolyB (PolyB 6000 IU/kg IV, 7 doses q12h, n = 6) and PolyB/gentamicin (PolyB 6000 IU/kg IV, q12h 7 doses; gentamicin 10 mg/kg IV q24h 4 doses n = 4, or q12-24 h 5 doses because of an additional erroneous dose, n = 2). Daily n...
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.
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...
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 ...
Finno CJ, Johnson AL.Neuroaxonal degenerative disease in the horse is termed equine neuroaxonal dystrophy (eNAD), when pathologic lesions are localized to the brainstem and equine degenerative myeloencephalopathy (EDM) and degenerative changes extend throughout the spinal cord. Both pathologic conditions result in identical clinical disease, most commonly characterized by the insidious onset of ataxia during early development. However, later onset of clinical signs and additional clinical features, such as behavior changes, is also observed. A definitive diagnosis of eNAD/EDM requires histologic evaluation of the ...
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...
Furr MO.Neurologic disease of foals is a diagnostic and therapeutic challenge for veterinarians. Disease conditions such as neonatal encephalopathy are seen as well as developmental and congenital defects, bacterial infections, and trauma. Neonatal encephalopathy can be considered a "syndrome" with a variety of causes resulting in a similar clinical presentation. These causes can be categorized as maladaptation, hypoxic/ischemic encephalopathy, and metabolic abnormalities, all leading to signs of cerebral and brainstem disease. Spinal cord signs may occasionally be seen, but these signs are usually ov...
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.
Kernot N, Butler R, Randle H.Conditions of the equine caudal neck (C5-C7) are thought to be associated with various clinical signs. However, little investigation has been undertaken to isolate clinical indicators associated with specific conditions of the equine caudal cervical spine. This systematic review aimed to evaluate associations of clinical signs with anatomical malformation of caudal cervical vertebrae, spinal cord compression of the caudal cervical spine, and arthropathy of the caudal cervical articular process joints (APJs). A literature search was carried out using Google Scholar in accordance with PRISMA (Pr...
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...
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...
Young KAS, Hepworth-Warren KL, Dembek KA.Cerebrospinal fluid (CSF) is routinely collected from three sites in the horse, the atlanto-occipital (AO), atlantoaxial (AA), and lumbosacral (LS) space. A comparison between fluid analysis parameters [total protein, total nucleated cell count (TNCC), red blood cell (RBC) count, and morphologic analysis] from samples obtained at each of the three sites has not previously been performed. A retrospective analysis was performed to evaluate the differences in fluid analysis of CSF between the AO, AA, and LS sites in equids presented to a referral service for evaluation of suspected neurological d...
Polani S, Dean M, Lichter-Peled A, Hendrickson S, Tsang S, Fang X, Feng Y, Qiao W, Avni G, Kahila Bar-Gal G.Juvenile idiopathic epilepsy (JIE) is a self-limiting neurological disorder with a suspected genetic predisposition affecting young Arabian foals of the Egyptian lineage. The condition is characterized by tonic-clonic seizures with intermittent post-ictal blindness, in which most incidents are sporadic and unrecognized. This study aimed to identify genetic components shared across a local cohort of Arabian foals diagnosed with JIE via a combined whole genome and targeted resequencing approach: Initial whole genome comparisons between a small cohort of nine diagnosed foals (cases) and 27 contro...
Xu M, Hu Y, Qiu H, Wang J, Jiang J. species, which mainly feed on protists and algae, are free-living close relatives of apicomplexans. Recent reports have identified sp. infections in an immunocompromised individual and a suspected case of tick-transmitted infection resulting in neurological symptoms. Our molecular examination of piroplasmosis-infected horses in China identified nearly whole 18S rRNA gene sequences that are closely related to sp. ATCC 50594 isolated from brown woodland soil at Gambrill State Park, located in Frederick, MD, shedding light on an underreported emerging zoonotic pathogen.
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...
Bartak M, Chodkowski M, Słońska A, Grodzik M, Szczepaniak J, Bańbura MW, Cymerys J.Equid alphaherpesvirus 1 (EHV-1) causes respiratory diseases, abortion, and neurological disorders in horses. Recently, the oncolytic potential of this virus and its possible use in anticancer therapy has been reported, but its influence on cytoskeleton was not evaluated yet. In the following study, we have examined disruptions in actin cytoskeleton of glioblastoma multiforme in vitro model-A172 cell line, caused by EHV-1 infection. We used three EHV-1 strains: two non-neuropathogenic (Jan-E and Rac-H) and one neuropathogenic (EHV-1 26). Immunofluorescent labelling, confocal microscopy, real-t...
Ghosh S, Kjöllerström J, Metcalfe L, Reed S, Juras R, Raudsepp T.We present cytogenetic and genotyping analysis of a Thoroughbred foal with congenital neurologic disorders and its phenotypically normal dam. We show that the foal has non-mosaic trisomy for chromosome 26 (ECA26) but normal 2n = 64 diploid number because two copies of ECA26 form a metacentric derivative chromosome der(26q;26q). The dam has normal 64,XX karyotype indicating that der(26q;26q) in the foal originates from errors in parental meiosis or post-fertilization events. Genotyping ECA26 microsatellites in the foal and its dam suggests that trisomy ECA26 is likely of maternal origin and tha...
Berardi A, Di Napoli G, Ernesto M, Fabbrini G, Conte A, Ferrazzano G, Viselli F, Galeoto G.The objective of this study was to evaluate the efficacy of equine therapy (ET) to detect changes in the activities of daily living, quality of life, mood, balance, and gait in individuals with Parkinson's disease (PD). Methods: In the study, 17 participants with PD were recruited to participate in 10 sessions of ET. The inclusion criteria of the study were: second and third stages of the Hoehn and Yahr scale, Mini-Mental State Examination (MMSE) greater than or equal to 24 points, and age up to 85 years. The outcome measures administered at the beginning and the end of treatment relied on mea...
Wang T, Hu L, Liu M, Wang T, Hu X, Li Y, Liu W, Li Y, Wang Y, Ren H, Zhang W, Wang C, Li L.The equine herpesvirus type 8 (EHV-8) can cause significant economic losses in the global horses and donkey industry. The disease has been associated with abortion and respiratory symptoms. However, it is rare for a study to be reported about donkeys with neurological diseases induced by EHV-8 infection. In the present study, one 2-year-old male donkey, from a large-scale donkey farm in China, died with a severe neurological disorder. The causative agent, donkey/Shandong/10/2021 (GenBank accession: OL856098), was identified and isolated from the brain tissue of the dead donkey. Meanwhile, BALB...
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...
Kondo T, Sato F, Tsuzuki N, Chen CJ, Yamada K.Computed tomographic myelography can be a useful tool for evaluating vertebral canal stenosis. However, an index of spinal cord compression is yet to be established. This observational descriptive study aimed to establish an index for spinal cord compression using computed tomography (CT). Twenty-three Thoroughbred horses (age, 155-717 days; weight, 205-523 kg) with suspected cervical vertebral malformation were subjected to computed tomographic myelography in dorsal recumbency using large-bore gantry CT to define the entire cervical vertebrae from C1 to C7. Subsequently, the height of the sp...
Cabral LDR, Sato AP, de Sousa RS, Rossa AP, Sanches AWD, Bortoleto CT, Locatelli Dittrich R.The closely related apicomplexa protozoa, Toxoplasma gondii, Neospora spp., and Sarcocystis neurona, have all been associated with neurological and reproductive diseases in horses. However, there is limited data regarding the presence of these three parasites in equine placental tissues and amniotic fluid. The aim of the present report was to investigate the presence of the DNA of T. gondii, Neospora spp. and S. neurona in placentas and amniotic fluid in mares. Anti-T. gondii, anti- S. neurona and anti- Neospora spp. antibody titers were evaluated in 31 mares in the final third of pregnancy by...
Henker LC, Lorenzett MP, Piva MM, Wronski JG, de Andrade DGA, Borges AS, Driemeier D, Oliveira-Filho JP, Pavarini SP.Holoprosencephaly is a central nervous system malformation, characterized by incomplete or total lack of division of prosencephalon hemispheres, which is commonly accompanied by craniofacial malformations. A 9-month-gestation aborted American Quarter Horse fetus was submitted for postmortem examination. The fetus lacked haircoat and had severe facial malformations including marked shortening/absence of the maxillary, incisive and nasal bones, bilateral anophthalmia, and pre-maxillary agenesis. The prosencephalon was small and nearly spherical, represented by a single lobe, with no visible sepa...
Weese JS, Baird JD, DeLay J, Kenney DG, Staempfli HR, Viel L, Parent J, Smith-Maxie L, Poma R.West Nile virus encephalomyelitis was diagnosed in 28 horses presented to the Ontario Veterinary College Veterinary Teaching Hospital between August 20 and October 15, 2002. The age range of affected horses was 5 months to 20 years (mean 6.9 years, median 6 years). Clinical signs were highly variable. Duration of hospitalization ranged from < 1 to 12 days (mean 5 days, median 5.4 days). Overall, 16 of the 28 (57%) horses were discharged and, of the 14 from which follow-up information was available, 13 (93%) were reported to be clinically normal 4 to 6 weeks following discharge, while the other...
Kaneene JB, Ross WA, Miller R.A prospective study was designed to document the frequencies of equine health problems in the state of Michigan, USA. A total of 2469 horses from a random sample of 138 equine operations were monitored in the study in two 12-month periods: 1992-1993 and 1993-1994. All the major breeds of horses in the state were proportionately represented in the sample. Using weighted annual incidence densities as measures of disease frequencies, the 10 most frequently observed groups of health problems were (from most to least frequent) leg lameness, dermatological problems, respiratory problems, hoof and fo...
Fortin JS, Hetak AA, Duggan KE, Burglass CM, Penticoff HB, Schott HC.Equine pituitary pars intermedia dysfunction (PPID) is a common endocrine disease of aged horses that shows a similar pathophysiology as Parkinson's Disease (PD) with increased levels of α-synuclein (α-syn). While α-syn is thought to play a pathogenic role in horses with PPID, it is unclear if α-syn is also misfolded in the pars intermedia and could similarly promote self-aggregation and propagation. Consequently, α-syn was isolated from the pars intermedia from groups of healthy young and aged horses, and aged PPID-afflicted horses. Seeding experiments confirmed the prion-like properties...
Furr M, Kennedy T, MacKay R, Reed S, Andrews F, Bernard B, Bain F, Byars D.Equine protozoal myeloencephalitis (EPM) is a neurologic disease of horses most commonly caused by the protozoan parasite Sarcocystis neurona. Until recently the only treatment option was the combination of a sulfonamide with pyrimethamine. The present study was performed to assess the efficacy of ponazuril, an anticoccidial triazine-based compound, as a treatment for naturally occurring EPM. One hundred one horses with EPM were randomly allocated to treatment with ponazuril 15% oral paste at either 5 or 10 mg/kg body weight for 28 consecutive days. Horses were evaluated clinically and by anal...
Hippotherapy (HT) is a rehabilitative tool inducing psychological and motor improvements using human-horse interaction. HT provides sensory stimulation to the rider through the rhythmic and repetitive movements of the horse, facilitating communication between patients and healthcare professionals, favoring the establishment of a therapeutic alliance. The purpose of this review is to evaluate the effects of HT treatment on cognitive-behavioral processes in neurodevelopmental disorders. We screened studies published between 2002 and 2020 on PubMed, Scopus, Cochrane, and Web of Sciences databases...
Franklin RP, Kinde H, Jay MT, Kramer LD, Green EG, Chiles RE, Ostlund E, Husted S, Smith J, Parker MD.A yearling quarter horse, which was raised in southern California, received routine vaccinations for prevention of infection by Eastern equine encephalomyelitis virus (EEEV). One week later, severe neurologic signs developed, and the horse was humanely destroyed. A vaccine-related encephalomyelitis was later suspected. A final diagnosis of EEEV infection was established on the basis of acute onset of the neurologic signs, histopathologic and serologic testing, and isolation and molecular characterization of EEEV from brain tissue. The vaccine was extensively tested for viral inactivation. Nucl...
Won SY, Kim YC, Kim SK, Jeong BH.Prion diseases are fatal neurodegenerative diseases and are characterized by the accumulation of abnormal prion protein (PrP) in the brain. During the outbreak of the bovine spongiform encephalopathy (BSE) epidemic in the United Kingdom, prion diseases in several species were reported; however, horse prion disease has not been reported thus far. In previous studies, the shadow of prion protein (Sho) has contributed to an acceleration of conversion from normal prion protein (PrP) to PrP, and the shadow of prion protein gene () polymorphisms have been significantly associated with the susceptibi...
Petter-Puchner AH, Froetscher W, Krametter-Froetscher R, Lorinson D, Redl H, van Griensven M.While fibrin sealant (FS) and equine collagen (EC) have been used as scaffold materials in experimental spinal cord injury (SCI), questions concerning neurocompatibility still remain. In this study, we assessed potential adverse effects, as well as functional and histological impact of FS and EC in subtotal hemisection of the thoracic spinal cord (SC) in rats. Methods: 124 male rats were randomly assigned to four main groups (n=31): Sham (SH), Lesion only (L), fibrin sealant (GFS) and equine collagen group (GEC). SH animals received laminectomy only; all other animals underwent subtotal latera...
Olsen E, Dunkel B, Barker WH, Finding EJ, Perkins JD, Witte TH, Yates LJ, Andersen PH, Baiker K, Piercy RJ.Reproducible and accurate recognition of presence and severity of ataxia in horses with neurologic disease is important when establishing a diagnosis, assessing response to treatment, and making recommendations that might influence rider safety or a decision for euthanasia. Objective: To determine the reproducibility and validity of the gait assessment component in the neurologic examination of horses. Methods: Twenty-five horses referred to the Royal Veterinary College Equine Referral Hospital for neurological assessment (n = 15), purchased (without a history of gait abnormalities) for an u...
Dursun E, Dursun N, Alican D.In this study our aim was to evaluate the effectiveness of Ankle-Foot Orthoses (AFOs) on gait function in patients with spastic cerebral palsy for whom orthoses were indicated to control dynamic equines deformity. Methods: Twenty-four spastic cerebral palsied patients with dynamic equines deformity were included in the study. Videotape recordings were performed to each patient on the same day with barefoot and AFOs. Temporal distance factors including velocity, cadence, stride length, stride width and Clinical Gait Assessment Score (CGAS) were compared across two conditions. Results: The use o...
Pusterla N, Mapes S, Akana N, Barnett C, MacKenzie C, Gaughan E, Craig B, Chappell D, Vaala W.The objective of the present case-control study was to determine prevalence factors associated with the detection of equine herpesvirus type 1 (EHV-1) by quantitative PCR (qPCR) in horses presented to veterinarians with clinical signs related to an upper respiratory tract infection and/or acute onset of neurological disease from March 2008 to December 2014. Nasal secretions and whole blood from 4228 equids with acute onset of fever, respiratory signs and/or neurological deficits were tested by qPCR for EHV-1. Categorical analyses were performed to determine the association between observations...
Aleman M, Pickles KJ, Conley AJ, Stanley S, Haggett E, Toth B, Madigan JE.Increased levels of pregnanes have been reported in foals with neonatal maladjustment syndrome (NMS). These steroids may cross the blood-brain barrier and have depressive effects in the central nervous system leading to behavioural abnormalities and altered states of consciousness in affected foals. Objective: The aim of this study was to determine the pregnane profile of foals with NMS and compare it with that of healthy controls and sick, non-NMS foals. Methods: Prospective-clinical study. Methods: Thirty-two foals with a clinical diagnosis of NMS, 12 foals with other neonatal disorders and ...
Pusterla N, Mapes S, Wilson WD.The objective of this study was to detect and characterise the biovar of equine herpesvirus type 1 (EHV-1) from submandibular lymph nodes (SMLNs) and trigeminal ganglia from 153 equids undergoing routine postmortem examination for various medical and surgical reasons. A combination of nucleic acid precipitation and preamplification steps was used to increase the analytical sensitivity of the analysis. The presence of latent EHV-1 was determined when tissue samples were PCR-positive for the glycoprotein B (gB) gene and the DNA polymerase (ORF 30) gene of EHV-1 in the absence of detectable late ...
Charlton KM, Mitchell D, Girard A, Corner AH.During an outbreak of abortion caused by equine herpesvirus 1, a neurologic disease characterized clinically by dullness and ataxia occurred in several mares. Equine herpesvirus 1 was isolated from brain and lung of two severely affected mares. Histologically, both mares had disseminated meningoencephalomyelitis characterized by necrotizing arteritis, focal malacia in grey and white matter of brain and spinal cord, and accumulation of lymphocytes and neutrophils in paravertebral ganglia. Eosinophilic intranuclear inclusion bodies occurred in foci of necrosis in thyroid adenomas of both mares.
Taniguchi A, Fukushi H, Matsumura T, Yanai T, Masegi T, Hirai K.Pathogenicity of equine herpesvirus 9 (EHV-9), a new type of equine herpesvirus isolated from Gazella thomsoni, in horses was investigated by intranasal inoculation of EHV-9 (10(7) pfu) to two conventionally reared 8-months old half-bred weanling horses. Fever higher than 39 degrees C was recorded. Virus was recovered from nasal swabs and peripheral blood mononuclear cells. Both horses developed neutralizing antibody to EHV-9. Perivascular infiltration of mononuclear cells and glial reaction were found in the olfactory and limbic systems. The results suggested that EHV-9 has a pathogenicity in...
Leblond A, Villard I, Leblond L, Sabatier P, Sasco AJ.Epidemiological studies should allow comparisons to be made of the prevalence of disease in populations from different countries, but the population characteristics and health problems in French horses are not well established. We have conducted a retrospective evaluation of the causes of death and vital characteristics of insured horses in France for the year 1995, with a view to comparison with published data from other countries. Files on 448 deceased horses were provided by nine insurance companies. Most of the animals were used for breeding (60%), followed by leisure (20%), eventing and r...
Mayhew IG, Watson AG, Heissan JA.From a clinical, radiological and morphological study of 9 horses with congenital malformations of the occiput, atlas and axis, and from a study of 2 reported cases, 3 diseases were defined: A. Familial occipitalisation of the atlas with atlantalisation of the axis in Arabian horses (7 cases in this report and the case reported by Leipold, et al., 1974). These horses had congenital atlantooccipital fusion, hypoplasia of the atlas and dens, malformation of the axis and modification of the atlantoaxial joint. B. Congenital asymmetrical occipitoatlantoaxial malformation (2 cases in this report). ...
Jackson TA, Osburn BI, Cordy DR, Kendrick JW.Experimental infection with equine herpesvirus 1 (rhinopneumonitis) resulted in neurologic disease in 8 of 15 inoculated horses. Nonpregnant animals did not develop clinical disease, and microscopic examination of tissues revealed no changes. In all mares between 3 and 9 months of gestation, a neurologic syndrome appeared 6 to 8 days after inoculation. Mares inoculated when 10 months pregnant did not develop neurologic disorders, but several aborted. The histopathologic change common to both sequelae was vasculitis, involving smaller arteries and veins. Although blood vessel changes were detec...
Wensman JJ, Thorén P, Hakhverdyan M, Belák S, Berg M.Borna disease virus (BDV) is a non-segmented, negative-stranded RNA virus, which infects cells of the central nervous system (CNS) in many different species. BDV is the causative agent of the neurological disorders in horses and sheep termed classical Borna disease (BD), as well as staggering disease in cats. At present, the diagnosis staggering disease or feline BD is made by histopathology or immunohistochemistry of the CNS. In order to obtain a better clinical diagnostic tool, a duplex real-time RT-PCR assay (rRT-PCR) was developed. TaqMan probes and primers specific for the BDV P and BDV L...
West Nile virus (WNV) was first detected in the Western Hemisphere in 1999 in New York City and has since caused seasonal epidemics of febrile illness and neurologic disease across the United States, where it is now the leading cause of arboviral encephalitis. This report updates a previous report and summarizes WNV activity in the United States reported to CDC in 2009. A total of 38 states and the District of Columbia (DC) reported 720 cases of WNV disease. Of these, 33 states and DC reported 386 cases of WNV neuroinvasive disease, for an incidence of 0.13 per 100,000 population. The five sta...
Lacombe VA, Sogaro-Robinson C, Reed SM.The use of computer tomography (CT) and contrast-enhanced CT (CCT) to image the head is common. However, the validity of CT as a neurodiagnostic indicator of intracranial diseases in horses is unknown. Objective: To define the validity of CT and CCT in horses with suspected intracranial disorders. Methods: The validity of CT imaging was estimated by comparing clinical, clinicopathological and histopathological findings to CT findings in 15 horses presented for intracranial disorders, for which pre- and post contrast CT images and post mortem examination of the brain and skull were reviewed. Po...
McFadden AM, Hanlon D, McKenzie RK, Gibson I, Bueno IM, Pulford DJ, Orr D, Dunowska M, Stanislawek WL, Spence RP, McDonald WL, Munro G, Mayhew IG.On 9 January 2014 (Day 0) a mare from a stud farm in the Waikato region presented with urinary incontinence without pyrexia. Over the following 33 days 15 mares were clinically affected with neurological signs. All but one mare had a foal at foot. The most commonly observed clinical signs were hind limb paresis and ataxia. In some cases recumbency occurred very early in the course of disease and seven mares were subject to euthanasia for humane reasons. Results: Equid herpesvirus (EHV) type 1 was detected using PCR in various tissues collected post mortem from two mares with neurological signs...
Saegerman C, Alba-Casals A, García-Bocanegra I, Dal Pozzo F, van Galen G.West Nile fever (WNF) is a viral zoonotic infection caused by a mosquito-borne flavivirus of the Flaviviridae family. According to a comparative study, the passive surveillance of horses by equine veterinarians appeared to be the most cost-effective system in the European context of WNF. Clinical data issued from a passive epidemiosurveillance network from September 2010 to December 2011 on horses in Spain were statistically compared and used to develop a predictive diagnostic decision tree, both with the aim to improve the early clinical detection of WNF in horses. Although clinical signs wer...
Keilani ZM, Berne JD, Agko M.Blunt cerebrovascular injuries, defined as blunt injuries to the internal carotid or vertebral arteries, are uncommon and usually occur in victims of high-speed deceleration motor vehicle crashes. A blunt cerebrovascular injury after an equestrian accident is an extremely unusual presentation. In recent years, advances in screening and treatment with pharmacologic anticoagulation before the onset of neurologic symptoms have improved outcomes for these patients. Endovascular stenting and embolization, although unproven, offer a new potential approach for these complex injuries. We present a uni...
Hahn CN, Handel I, Green SL, Bronsvoort MB, Mayhew IG.Cervical vertebral malformation is one of the most common causes of ataxia in horses. The most important factor in the diagnosis of cervical vertebral malformation is the identification of cervical vertebral canal stenosis, but published data for minimum sagittal diameter ratios in adult horses are only available for C4-C7 intravertebral sites. Intra- and intervertebral sagittal diameter ratios at C2-C7 were evaluated in 26 ataxic horses, for which a complete clinical and neuropathological evaluation was undertaken. Eight of these horses were diagnosed with cervical vertebral malformation. In ...
Finno CJ, Valberg SJ, Shivers J, D'Almeida E, Armién AG.Equine degenerative myeloencephalopathy (EDM) is characterized by a symmetric general proprioceptive ataxia in young horses, and is likely underdiagnosed for 2 reasons: first, clinical signs overlap those of cervical vertebral compressive myelopathy; second, histologic lesions--including axonal spheroids in specific tracts of the somatosensory and motor systems--may be subtle. The purpose of this study was (1) to utilize immunohistochemical (IHC) markers to trace axons in the spinocuneocerebellar, dorsal column-medial lemniscal, and dorsospinocerebellar tracts in healthy horses and (2) to dete...
Sandmeyer LS, Bellone RR, Archer S, Bauer BS, Nelson J, Forsyth G, Grahn BH. To determine if congenital stationary night blindness (CSNB) exists in the Miniature Horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the Miniature Horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Methods: Three groups of Miniature Horses were studied based on coat patterns suggestive of LP/LP (n=3), LP/lp (n=4), and lp/lp genotype (n=4). Methods: Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp,...
Stitz L, Bilzer T, Richt JA, Rott R.Borna disease represents a unique model of a virus-induced immunological disease of the brain. Naturally occurring in horses and sheep, the mechanisms of pathogenesis have been studied in experimental animals, namely in the rat. Many investigations have revealed that the infection of the natural hosts principally follows the same pathogenic pathways as observed in rats, leading to a severe encephalomyelitis. This affliction of the central nervous system results in severe neurological disorders that again, are fully comparable in laboratory animals to those in the natural and the different expe...
Dunowska M.Equid herpesvirus (EHV) type 1 is a common pathogen of horses with worldwide distribution. Infection with EHV-1 can be subclinical, or can result in sociologically and economically important outcomes such as abortion, neonatal death or neurological disease. The perceived recent increase in the reported cases of EHV-1 neurological disease in the United States of America and Europe over the past decade has caused concerns amongst veterinarians and horse owners worldwide. This review provides an update on the recent developments in our understanding of the pathogenesis and epidemiology of EHV-1 a...
Allen GP.To evaluate a technique for identifying horses latently infected with neuropathogenic strains of equine herpesvirus-1 (EHV-1). Methods: 36 adult mares, 24 of which were experimentally infected as weanlings with neuropathogenic or nonneuropathogenic EHV-1. Methods: Mandibular lymph node (MLN) tissue was obtained from each horse via biopsy during general anesthesia. Purified DNA from MLNs was tested for EHV-1 DNA by use of a magnetic bead, sequencecapture, nested PCR assay. For MLNs that contained EHV-1 DNA, the 256-bp DNA fragments amplified via sequence-capture nested PCR were sequenced to det...
