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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.
An eastern equine encephalomyelitis (EEE) outbreak in Quebec in the fall of 2008. Eastern equine encephalomyelitis (EEE) was diagnosed in 19 horses and a flock of emus in the province of Quebec in fall 2008. The EEE virus caused unusual gross lesions in the central nervous system of one horse. This disease is not usually present in Quebec and the relation between the outbreak and favorable environmental conditions that summer are discussed. Une éclosion d’encéphalomyélite équine de l’Est (ÉÉE) s’est produite chez 19 chevaux et dans un troupeau d’émeus au Québec à l’automne de 2008. Un cheval présentait une lésion macroscopique anormale dans le système...
Mapping of equine cerebellar abiotrophy to ECA2 and identification of a potential causative mutation affecting expression of MUTYH. Equine Cerebellar Abiotrophy (CA) is a neurological disease found in Arabian horses. CA is characterized by post-natal degeneration of the Purkinje cells of the cerebellum. Signs of CA include ataxia, head tremors, and a lack of balance equilibrium. We have discovered a linkage of the CA phenotype to a microsatellite marker on ECA2 and identified a region of conserved homozygosity spanning approximately 142 kb. Complete sequencing of the four genes in this region identified one SNP found only in Arabian horses, located in exon 4 of TOE1 and approximately 1200 base pairs upstream of MUTYH, adja...
Fatal epizootic equine herpesvirus 1 infections in new and unnatural hosts. In a zoological collection, four black bears (Ursus americanus) died from neurological disease within six months. Independently in a geographically different zoo, two Thomson's gazelles (Eudorcas thomsoni) and 18 guinea pigs (Cavia porcellus f. dom.) suffered from neurological disorders. In addition, guinea pigs showed abortions and stillbirths. All affected animals displayed a non suppurative meningoencephalitis with intranuclear inclusion bodies. Immunohistology demonstrated equine herpes virus antigen and ultrastructurally herpes viral particles were detected. Virus isolation and molecular ...
Meningitis, cranial neuritis, and radiculoneuritis associated with Borrelia burgdorferi infection in a horse. A 12-year-old Thoroughbred was examined because of signs of depression, neck stiffness, and poor performance. Results: Physical examination revealed that the horse was dull, appeared depressed, was reluctant to raise its neck and head above a horizontal plane, and had a temperature of 38.5°C (101.3°F). No radiographic or scintigraphic abnormalities of the neck were found; however, high plasma fibrinogen concentration and relative lymphopenia were identified and the horse was seropositive for antibodies against Borrelia burgdorferi. Analysis of CSF revealed neutrophilic inflammation, and resu...
Improved detection of equine antibodies against Sarcocystis neurona using polyvalent ELISAs based on the parasite SnSAG surface antigens. Equine protozoal myeloencephalitis (EPM) is a common neurologic disease of horses that is caused by the apicomplexan pathogen Sarcocystis neurona. To help improve serologic diagnosis of S. neurona infection, we have modified existing enzyme-linked immunosorbent assays (ELISAs) based on the immunogenic parasite surface antigens SnSAG2, SnSAG3, and SnSAG4 to make the assays polyvalent, thereby circumventing difficulties associated with parasite antigenic variants and diversity in equine immune responses. Two approaches were utilized to achieve polyvalence: (1) mixtures of the individual recombin...
The 3D anatomy of the cervical articular process joints in the horse and their topographical relationship to the spinal cord. REASONS FOR STUDY: Detailed anatomy of the equine cervical articular process joints (APJs) has received little attention in the literature and yet disorders of this joint have been linked to spinal cord compression resulting in severe clinical signs such as ataxia and weakness. This study aimed to describe the 3D anatomy of the APJ in relation to the spinal cord in the horse. Objective: Artificial distension of the APJ causes the joint pouches to extend into the vertebral canal, with the potential for APJ effusion to cause spinal cord compressive disease. Methods: Six cadaveric necks (C1-C7) o...
Pathological changes caused by Anoplocephala perfoliata in the mucosa/submucosa and in the enteric nervous system of equine ileocecal junction. In this study, pathological changes caused by Anoplocephala perfoliata in the ileocecal junction were investigated in 31 regularly slaughtered mixed-breed horses of both sexes. Our results showed a significant relationship between parasite burden and grading of histopathological lesions in the mucosa and submucosa. Hypertrophy of the circular muscle layer was found in infected horses. Moreover, enteric nervous system evaluation showed a significant injury of intestinal nervous elements in the horses with moderate to high parasitism expressed as an increase of degenerative-regressive changes in...
Ocular manifestations of systemic disease in horses. Ocular manifestations may develop in many systemic diseases of horses; however, signs may not be observed unless ophthalmological examination is specifically undertaken. Recognition and assessment of ocular lesions in horses with systemic disease is desirable to facilitate diagnosis and determination of treatment options and diagnosis for both the underlying systemic disease and ocular manifestations. The purpose of this article is to review systemic diseases of horses that may have ocular signs as part of the disease process. Systemic diseases are discussed in categories of pathways for devel...
Neuro-ophthalmology: a review. Evaluation of horses for eye problems and for suspected impairment of visual acuity often requires a thorough neuroophthalmic examination to be conducted. Along with a full ophthalmic evaluation, the results of such an examination should indicate the likely site of any lesion(s) accounting for blindness, miosis, mydriasis, anisocoria, Horner's syndrome, strabismus, facial paralysis and facial spasm, nystagmus and other signs of vestibular disease, and cerebellar disorders, that may be present. Such a thorough examination with guidance for correct interpretation of findings is given here.
Posterior segment diseases. Diseases of the vitreous, fundus and optic nerve are described and illustrated according to their ophthalmological appearance. Vitreal alterations are commonly of developmental, degenerative, age related, traumatic or inflammatory origin and of minor clinical relevance. In contrast, those affecting the fundus, may be accompanied by visual deficits or blindness. Fundic lesions of inflammatory (multifocal or peripapillary chorioretinitis, haemorrhage, retinal detachment) and traumatic origin have to be differentiated from congenital (congenital stationary night blindness, colobomatous defects, r...
Bilateral internal carotid and vertebral artery dissection after a horse-riding injury. 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...
West Nile virus lineage 2 as a cause of zoonotic neurological disease in humans and horses in southern Africa. West Nile virus (WNV) is widely distributed in South Africa, but since a few cases of neurological disease have been reported from this region, endemic lineage 2 strains were postulated to be of low virulence. Several cases of nonfatal encephalitis in humans as well as fatal cases in a foal, dog, and ostrich chicks have, however, been associated with lineage 2 WNV in South Africa. The pathogenesis of lineage 2 WNV strains was investigated using mouse neuroinvasive experiments, gene expression experiments, and genome sequence comparisons which indicated that lineage 2 strains that are highly pa...
Prevalence of equine herpesvirus type 1 in trigeminal ganglia and submandibular lymph nodes of equids examined postmortem. 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 ...
Trema micrantha toxicity in horses in Brazil. After ingesting green leaves of T. micrantha, 2 horses showed apathy, locomotor deficit, blindness, recumbency, paddling, coma and death. The main gross findings were scattered haemorrhages, enhanced lobular pattern of the liver, and cerebral oedema. Histological changes included disseminated haemorrhages, massive hepatocellular necrosis, neuronal degeneration, Alzheimer type II astrocytes and cerebral perivascular oedema. Clinicopathological findings which were comparable with those observed in Trema micrantha poisoned ruminants, associated with epidemiological evidence suggested the diagnosi...
Diagnostic utility of computed tomography imaging in equine intracranial conditions. 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...
Equine protozoal myeloencephalitis due to Neospora hughesi and equine motor neuron disease in a mule. A 23-year-old female mule was presented for bilateral ocular abnormalities and an abnormal pelvic limb gait. Results: Anisocoria, unilateral enophthalmos, medial strabismus, ptosis, pupillary light reflex deficits, and bilateral reticulated pigmentary retinopathy were observed on ophthalmic examination. Neurologic abnormalities included right-sided facial nerve paralysis, extensive symmetric muscle atrophy, and asymmetric pelvic limb ataxia with an abnormal pelvic limb gait. A positive titer (1:40) for equine protozoal myeloencephalitis (EPM) associated with Neospora hughesi was obtained from ...
West Nile virus activity – United States, 2009. 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...
Detection of neuropathogenic strains of Equid Herpesvirus 1 (EHV-1) associated with abortions in Germany. A single nucleotide polymorphism within EHV-1 gene ORF 30, which encodes for the viral DNA polymerase, allows the differentiation of the neuropathogenic (G2254) from non-neuropathogenic genotype (A2254). The aim of our study was to investigate the distribution of the neuropathogenic and non-neuropathogenic genotype of EHV-1 isolates associated with abortions in Germany. To determine the nucleotide sequence at the polymorphic site the amplification product of ORF 30 gene specific nested PCR was digested with restriction enzyme SalI and sequenced. Thirty-two EHV-1 isolates from six abortion outb...
Annual ryegrass toxicity in Thoroughbred horses in Ceres in the Western Cape Province, South Africa. An outbreak of annual ryegrass toxicity occurred on a Thoroughbred stud in Ceres in the Western Cape Province of South Africa. This is the 1st report of annual ryegrass toxicity in horses in South Africa, although the condition has been reported in cattle and sheep populations in the past. Annual ryegrass toxicity is characterised by a variety of neurological signs including tremors, convulsions, recumbency and in many cases death. The description of the outbreak includes the history, clinical presentation and treatment protocol administered during the outbreak. Various epidemiological variabl...
Horse prion protein NMR structure and comparisons with related variants of the mouse prion protein. The NMR structure of the horse (Equus caballus) cellular prion protein at 25 degrees C exhibits the typical PrP(C) [cellular form of prion protein (PrP)] global architecture, but in contrast to most other mammalian PrP(C)s, it contains a well-structured loop connecting the beta2 strand with the alpha2 helix. Comparison with designed variants of the mouse prion protein resulted in the identification of a single amino acid exchange within the loop, D167S, which correlates with the high structural order of this loop in the solution structure at 25 degrees C and is unique to the PrP sequences of e...
Post-anaesthetic myelopathy in a 3-year-old Friesian gelding. A 3-year-old Friesian stallion was referred to the Department of Equine Sciences at Utrecht University with signs of colic. Laparotomy was performed and the stallion was castrated bilaterally because of an incarcerated inguinal hernia. Intestinal resection was not performed. Eight days postoperatively, the horse showed signs of severe colic and was admitted for re-laparotomy. After resection of 1.5 m of strangulated jejunum and severe intraoperative hypotension, bradycardia, and electrolyte disorders, the horse showed problems during recovery with signs of hindquarter paralysis. There was no p...
Whole-genome SNP association in the horse: identification of a deletion in myosin Va responsible for Lavender Foal Syndrome. Lavender Foal Syndrome (LFS) is a lethal inherited disease of horses with a suspected autosomal recessive mode of inheritance. LFS has been primarily diagnosed in a subgroup of the Arabian breed, the Egyptian Arabian horse. The condition is characterized by multiple neurological abnormalities and a dilute coat color. Candidate genes based on comparative phenotypes in mice and humans include the ras-associated protein RAB27a (RAB27A) and myosin Va (MYO5A). Here we report mapping of the locus responsible for LFS using a small set of 36 horses segregating for LFS. These horses were genotyped usin...
Study of laryngopharyngeal pathology in Thoroughbred horses in southern California. There is increasing anecdotal evidence among horse owners, trainers and equine clinicians of a high prevalence of subepiglottic ulcers, suggested to have a negative effect on racing performance. Objective: To provide a prevalence study and pathological characterisation of laryngopharyngeal lesions with emphasis in the subepiglottic area and, in particular, subepiglottic ulcers. Methods: The study was carried out on 91 Thoroughbred racehorses received for post mortem examination from 4 major Southern California racetracks. The most common reason for submission was catastrophic musculoskeletal i...
Neuropathogenic and non-neuropathogenic variants of equine herpesvirus 1 in France. Equine herpesvirus 1 (EHV-1) is a common pathogen of the horse which may induce mild respiratory distress, abortion, neonatal death and neurological disease. A single nucleotide polymorphism in the EHV-1 DNA polymerase (ORF30 A(2254) to G(2254)) has been associated with clinical signs of Equine herpes myeloencephalopathy (EHM). The aim of this work was to analyze the ORF30 genomic region among a panel of EHV-1 DNA extract in order to estimate the prevalence of the EHV-1 neuropathogenic genotype in France. Samples coming from cases associated with EHM, horses with respiratory symptoms and abort...
Animal models of CNS viral disease: examples from borna disease virus models. Borna disease (BD), caused by the neurotropic RNA virus, Borna Disease virus, is an affliction ranging from asymptomatic to fatal meningoencephalitis across naturally and experimentally infected warmblooded (mammalian and bird) species. More than 100 years after the first clinical descriptions of Borna disease in horses and studies beginning in the 1980's linking Borna disease virus to human neuropsychiatric diseases, experimentally infected rodents have been used as models for examining behavioral, neuropharmacological, and neurochemical responses to viral challenge at different stages of lif...
