Topic:Neurological Diseases
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.
Variation in MUTYH expression in Arabian horses with Cerebellar Abiotrophy. 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...
Neuro-ophthalmology in the Horse. This article provides a brief, clinically relevant review of neurologic disorders of the eye. A description of the neuro-ophthalmic examination is provided. Stepwise descriptions of the most common neuro-ophthalmic abnormalities are provided along with common rule outs.
Computed tomography and magnetic resonance imaging findings for the initial stage of equine temporohyoid osteoarthropathy in a Thoroughbred foal. Temporohyoid osteoarthropathy (THO) is characterized by progressive osseous proliferation of the stylohyoid and petrous temporal bones. Generally, diagnosis is confirmed by guttural pouch endoscopy and skull radiography. In the present case, computed tomography (CT) and magnetic resonance imaging (MRI) were performed in a 6-month-old Thoroughbred foal showing signs of head tilt and unilateral ear droop, consistent with the presence of a vestibular disease and unilateral facial paralysis. CT revealed bony fusion and proliferation of the right temporohyoid joint, while MRI revealed that otitis m...
Kinematic discrimination of ataxia in horses is facilitated by blindfolding. Agreement among experienced clinicians is poor when assessing the presence and severity of ataxia, especially when signs are mild. Consequently, objective gait measurements might be beneficial for assessment of horses with neurological diseases. Objective: To assess diagnostic criteria using motion capture to measure variability in spatial gait-characteristics and swing duration derived from ataxic and non-ataxic horses, and to assess if variability increases with blindfolding. Methods: Cross-sectional. Methods: A total of 21 horses underwent measurements in a gait laboratory and live neurolog...
Testing the Sarcocystis neurona vaccine using an equine protozoal myeloencephalitis challenge model. Equine protozoal myeloencephalitis (EPM) is an important equine neurologic disorder, and treatments for the disease are often unrewarding. Prevention of the disease is the most important aspect for EPM, and a killed vaccine was previously developed for just that purpose. Evaluation of the vaccine had been hampered by lack of post vaccination challenge. The purpose of this study was to determine if the vaccine could prevent development of clinical signs after challenge with Sarcocystis neurona sporocysts in an equine challenge model. Seventy horses that were negative for antibodies to S. neuron...
Interobserver Variation in the Diagnosis of Neurologic Abnormalities in the Horse. The diagnosis of equine protozoal myeloencephalitis (EPM) relies heavily on the clinical examination. The accurate identification of neurologic signs during a clinical examination is critical to the interpretation of laboratory results. Objective: To investigate the level of agreement between board-certified veterinary internists when performing neurologic examinations in horses. Methods: Ninety-seven horses admitted to the Veterinary Teaching Hospital at The Ohio State University from December 1997 to June 1998. Methods: A prospective epidemiologic research design was used. Horses enrolled in...
Atlanto-axial malformation in an adult Quarter horse gelding. An adult gelding was evaluated for bilateral intermittent forelimb lameness of approximately 2 years duration. The horse was found to have grade 2/5 upper motor neuron-general proprioception ataxia with no cranial nerve deficits. During radiographic and gross necropsy examinations a novel atlanto-axial malformation of possible congenital etiology was found. Un hongre adulte a été évalué pour une boiterie intermittente de la jambe avant présente depuis environ 2 ans. On a constaté que le cheval avait une ataxie de proprioception générale des motoneurones supérieurs de grade 2/5 sans d...
Neurotoxicosis in horses associated with consumption of Trema micrantha. Trema micrantha is a tree widely distributed throughout the Americas. The tree produces highly palatable leaves that have been associated with natural poisoning in goats, sheep and horses, in which hepatic necrosis and hepatic encephalopathy have been observed. Objective: This study describes malacia and haemorrhage in the central nervous system (CNS) due to T. micrantha consumption, with minimal to absent hepatic lesions. Methods: Retrospective case series. Methods: A total of 14 horses with a history of neurological signs and spontaneous consumption of T. micrantha leaves were submitted to...
Survey of Veterinarians Using a Novel Physical Compression Squeeze Procedure in the Management of Neonatal Maladjustment Syndrome in Foals. Horses are a precocious species that must accomplish several milestones that are critical to survival in the immediate post-birth period for their survival. One essential milestone is the successful transition from the intrauterine unconsciousness to an extrauterine state of consciousness or awareness. This transition involves a complex withdrawal of consciousness inhibitors and an increase in neuroactivating factors that support awareness. This process involves neuroactive hormones as well as inputs related to factors such as cold, visual, olfactory, and auditory stimuli. One factor not previ...
Evaluation of a portable media device for use in determining postural stability in standing horses. OBJECTIVE To determine the ability of an accelerometer within a commercially available portable media device (PMD) to measure changes in postural stability of standing horses during various stance conditions and to compare these results with data obtained by use of a stationary force platform. ANIMALS 7 clinically normal horses. PROCEDURES A PMD was mounted on a surcingle; the surcingle was placed immediately caudal to the highest point of the shoulders (withers). Each horse was examined while standing on a stationary force platform system in a normal square stance, forelimb base-narrow stance...
Differential Expression of Tubulin Acetylase and Deacetylase Between the Damaged Central and Peripheral Branch of Dorsal Root Ganglion Neurons. BACKGROUND The differences between the peripheral and central branches of the dorsal root ganglion (DRG) have not been fully elucidated. This study aimed to explore the expression of tubulin post-translational modifications (acetylation and deacetylation) between damaged peripheral and central branches of DRG neurons. MATERIAL AND METHODS Fifty Sprague-Dawley rats were randomly assigned to five groups with 10 rats in each group. These five groups consisted of spinal nerve ligation (SNL) at 24 hour and 48 hour, and cauda equina compression (CEC) at 24 hour and 48 hour, and a sham group. SNL inj...
Phosphorylated neurofilament H (pNF-H) as a potential diagnostic marker for neurological disorders in horses. The current study aimed at the investigating the potential use of phosphorylated neurofilament H (pNF-H) as a diagnostic biomarker for neurologic disorders in the horse. Paired serum and cerebrospinal fluid (CSF) samples (n=88) and serum only (n=30) were obtained from horses diagnosed with neurologic disorders and clinically healthy horses as control. The neurologic horses consisted of equine protozoal myeloencephalitis (EPM) (38 cases) and cervical vertebral malformation (CVM) (23 cases). Levels of pNF-H were determined using an ELISA. The correlation between CSF and serum concentrations of p...
Sarcocystis neurona and Neospora caninum in Brazilian opossums (Didelphis spp.): Molecular investigation and in vitro isolation of Sarcocystis spp. Sarcocystis neurona and Neospora spp. are protozoan parasites that induce neurological diseases in horses and other animal species. Opossums (Didelphis albiventris and Didelphis virginiana) are definitive hosts of S. neurona, which is the major cause of equine protozoal myeloencephalitis (EPM). Neospora caninum causes abortion in cattle and infects a wide range of animal species, while N. hughesi is known to induce neurologic disease in equids. The aims of this study were to investigate S. neurona and N. caninum in tissues from opossums in the northeastern Brazil, and to isolate Brazilian stra...
Outcomes after medical and surgical interventions in horses with temporohyoid osteoarthropathy. Temporohyoid osteoarthropathy (THO) is a cause of neurological disease in horses that is characterised by facial and vestibulocochlear nerve deficits. Studies reporting and comparing survival following medical or surgical treatment of THO are lacking. Objective: To compare survival and prognosis in horses with THO treated medically or surgically, and to report surgical complications. Methods: Retrospective study. Methods: The medical records of horses diagnosed with THO were retrieved, and data on signalment, clinical signs and duration, corneal ulceration and bilateral occurrence were recorde...
Acquired equine polyneuropathy of Nordic horses: A conspicuous inclusion body schwannopathy. Acquired equine polyneuropathy (AEP), formerly also known as Scandinavian knuckling syndrome, is one of the most prevalent polyneuropathies in equids in Norway and Sweden, with more than 400 cases registered since first observations in 1995. Despite geographical clustering and an association to forage feeding, its aetiology remains unknown. Clinically AEP is characterized by knuckling due to dysfunction of metatarsophalangeal extensor muscles. This neuropathological study aimed to gain further insights in the pathobiology of AEP and its underlying aetiopathogenesis. We thereby confirmed that a...
Phenotypic characterisation of cell populations in the brains of horses experimentally infected with West Nile virus. West Nile virus (WNV), a mosquito borne member of the Flaviviridae, is one of the most commonly diagnosed agents of viral encephalitis in horses and people worldwide. Objective: A cassette of markers for formalin-fixed paraffin-embedded tissue and an archive of tissues from experimental infections in the horse were used to investigate the equine neuroimmune response to WNV meningoencephalomyelitis to phenotype the early response to WNV infection in the horse. Methods: Quantitative analysis using archived tissue from experimentally infected horses. Methods: The thalamus and hindbrain from 2 gro...
Chaetomiaceae Fungi, Novel Pathogens of Equine Neurotropic Phaeohyphomycosis. Many previously unrecognized fungi are emerging as potential pathogens. One such group is dematiaceous fungi of the Chaetomiaceae family (phylum Ascomycota, class Sordariomycetes). These fungi are rare causes of opportunistic, neurotropic phaeohyphomycosis in humans but are not known to cause similar infections in animals. The aims of this study were to investigate equine hyphal mycotic encephalitis, characterize key histopathologic features, and classify causative organisms with molecular diagnostic techniques. Seven cases were evaluated by histopathology. Panfungal PCR targeting the ribosoma...
Toxoplasma gondii seroprevalence and association with equine protozoal myeloencephalitis: A case-control study of Californian horses. While toxoplasmosis is not commonly considered a clinical disease of equines, previous seroprevalence studies have reported differing background rates of Toxoplasma gondii infection in horses globally. The objective of this study was to evaluate possible associations between T. gondii seroprevalence and clinical signs of equine protozoal myeloencephalitis (EPM) in horses. Using a case-control study design, 720 Californian horses with neurologic signs compatible with EPM were compared to healthy, non-neurologic horses for the presence of T. gondii antibodies (using indirect fluorescent antibody...
Trigeminal Nerve Root Demyelination Not Seen in Six Horses Diagnosed with Trigeminal-Mediated Headshaking. Trigeminal-mediated headshaking is an idiopathic neuropathic facial pain syndrome in horses. There are clinical similarities to trigeminal neuralgia, a neuropathic facial pain syndrome in man, which is usually caused by demyelination of trigeminal sensory fibers within either the nerve root or, less commonly, the brainstem. Our hypothesis was that the neuropathological substrate of headshaking in horses is similar to that of trigeminal neuralgia in man. Trigeminal nerves, nerve roots, ganglia, infraorbital, and caudal nasal nerves from horse abattoir specimens and from horses euthanized due to...
Eosinophilic encephalomyelitis in horses caused by protostrongylid parasites. Four thoroughbred horses showing lameness, ataxia, circling, depression, recumbency, and seizures, were examined. The horses had gross, pale- to dark-red manifestations and foci in the central nervous system (CNS). Multifocal to coalescing eosinophilic necrotizing encephalomyelitis was observed histologically in the CNS along with intact or degenerated nematodes. Nematodes had polymyarian-coelomyarian musculature, a smooth thin cuticle, and intestines lined by multinucleated cells with microvilli. These traits suggested the nematodes belonged to the family Protostrongylidae, which includes Par...
The 5-HT4 receptor agonist prucalopride does not facilitate cholinergic neurotransmission in circular and longitudinal smooth muscle preparations of equine mid-jejunum. Postoperative ileus (POI) remains an important cause of death in horses. The recently developed selective 5-HT receptor agonists such as prucalopride target 5-HT receptors on myenteric cholinergic neurons to enhance acetylcholine release and GI motility. No clearcut in vitro evaluation whether highly selective 5-HT receptor agonists enhance submaximal cholinergic neurotransmission towards the muscle layer has been performed in horses. Objective: To identify functional 5-HT receptors in equine jejunum. Methods: In vitro experimental study. Methods: Circular and longitudinal smooth muscle strips...
Parelaphostrongylus tenuis Cerebrospinal Nematodiasis in a Horse with Cervical Scoliosis and Meningomyelitis. There are reports of horses with acute onset acquired cervical scoliosis and cutaneous analgesia. The underlying dorsal gray column myelitis that produces these neurologic signs has been only presumptively attributed to migration of Parelaphostrongylus tenuis within the spinal cord. Despite previous confirmation brain by polymerase chain reaction testing, of P. tenuis within the brain of horses by polymerase chain reaction testing, genetic testing has failed to definitively identify the presence of this parasite in cases of equine myelitis. This case report provides molecular confirmation via ...
Sarcocystis neurona manipulation using culture-derived merozoites for bradyzoite and sporocyst production. Equine protozoal myeloencephalitis (EPM) remains a significant central nervous system disease of horses in the American continents. Sarcocystis neurona is considered the primary causative agent and its intermediate life stages are carried by a wide host-range including raccoons (Procyon lotor) in North America. S. neurona sarcocysts mature in raccoon skeletal muscle and can produce central nervous system disease in raccoons, mirroring the clinical presentation in horses. The study aimed to develop laboratory tools whereby the life cycle and various life stages of S. neurona could be better stu...
Equine herpesvirus type 1 induces both neurological and respiratory disease in Syrian hamsters. The equine herpesvirus type 1 (EHV-1) is an important cause of myeloencephalopathy and respiratory disease in horses. Animal models for EHV-1 infection have been specially developed using mice and Syrian hamsters (Mesocricetus auratus). However, few studies have attempted to evaluate the pathogenesis of EHV-1 infection in the central nervous system (CNS) and respiratory system of hamsters. Therefore, the aim of this study was to evaluate the pathogenesis of four Brazilian EHV-1 strains within the CNS and lungs of Syrian hamsters. Hamsters intranasally infected with A4/72, A9/92, A3/97, and Iso...
Isolation and molecular characterisation of Halicephalobus gingivalis in the brain of a horse in Piedmont, Italy. A fatal case of meningoencephalitis was reported in a 13-year-old Koninklijk Warmbloed Paard Nederland stallion, suspected of West Nile virus (WNV) infection, in the Piedmont region of Italy. Clinical signs included right head tilt and circling, depression alternated with excitability, fever and lateral strabismus. Combined treatment consisting of dimethylsulfoxide, dexamethasone, sulphonamides and sedative was administered, but because of the poor conditions the horse was euthanatized and submitted for necropsy. At post-mortem examination no skin lesions were observed, all organs appeared nor...
Long-term follow-up of Norwegian horses affected with acquired equine polyneuropathy. Acquired equine polyneuropathy (AEP), a neurological disease clinically characterised by knuckling of metatarsophalangeal joints, has been described in numerous Nordic horses during the last 20 years. Although clinical recovery has been reported, large-scale data on long-term follow-up of survivors have been lacking. Objective: To describe long-term survival of AEP affected horses registered in Norway, with a focus on athletic performance and possible residual clinical signs connected to the disease. Methods: A retrospective cohort study. Methods: The study includes 143 horses recorded with A...
CCL2 and CCL5 driven attraction of CD172a+ monocytic cells during an equine herpesvirus type 1 (EHV-1) infection in equine nasal mucosa and the impact of two migration inhibitors, rosiglitazone (RSG) and quinacrine (QC). Equine herpesvirus type 1 (EHV-1) causes respiratory disease, abortion and neurological disorders in horses. Besides epithelial cells, CD172a monocytic cells become infected with EHV-1 in the respiratory mucosa and transport the virus from the apical side of the epithelium to the lamina propria en route to the lymph and blood circulation. Whether CD172a monocytic cells are specifically recruited to the infection sites in order to pick up virus is unknown. In our study, equine nasal mucosa explants were inoculated with EHV-1 neurological strains 03P37 and 95P105 or the non-neurological strains ...
Developing a 3-choice serial reaction time task for examining neural and cognitive function in an equine model. Large animal models of human neurological disorders are advantageous compared to rodent models due to their neuroanatomical complexity, longevity and their ability to be maintained in naturalised environments. Some large animal models spontaneously develop behaviours that closely resemble the symptoms of neural and psychiatric disorders. The horse is an example of this; the domestic form of this species consistently develops spontaneous stereotypic behaviours akin to the compulsive and impulsive behaviours observed in human neurological disorders such as Tourette's syndrome. The ability to non...
Therapeutics for Equine Protozoal Myeloencephalitis. Equine protozoal myeloencephalitis is an infectious disease of the central nervous system caused by Sarcocystis neurona or Neospora hughesi. Affected horses routinely present with progressive and asymmetrical neurologic deficits. The diagnosis relies on the presence of neurologic signs, ruling out other neurologic disorders, and the detection of intrathecally derived antibodies to either S neurona and/or N hughesi. Recommended treatment is use of an FDA-approved anticoccidial drug formulation. Medical and supportive treatment is provided based on the severity of neurologic deficits and complic...
Replication kinetics of neuropathogenic and non-neuropathogenic equine herpesvirus type 1 (EHV-1) strains in primary murine neurons and ED cell line. Equine herpesvirus type 1 (EHV-1) causes respiratory infections, abortion and neurological disorders in horses. Molecular epidemiology studies have demonstrated that a single-point mutation in DNA polymerase gene, resulting in an amino acid variation (N752/D752), is significantly associated with the neuropathogenic potential of EHV-1 strains. The aim of the study was to elucidate if there are any differences between neuropathogenic (EHV-1 26) and non-neuropathogenic (Jan-E and Rac-H) EHV-1 strains in their ability to infect neuronal cells. For the tested EHV-1 strains, cytopathic effect (CPE) ...