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.
Kligler EB, Shkap V, Baneth G, Mildenberg Z, Steinman A.Sera from 800 asymptomatic horses were examined for the presence of antibodies to Neospora caninum by immunofluorescence antibody test (IFAT). The presence of antibodies to N. caninum was also tested in sera from 52 mares that had aborted and 40 horses exhibiting neurological signs. A total of 95 (11.9%) of the 800 sera had antibodies for Neospora. Significantly higher seropositivity was obtained from horses that had neurological signs (21.2%) and from aborted mares (37.5%). There was significant linear-by-linear association between age and seropositivity. This is the first serologic survey fo...
Mohammed HO, Divers TJ, Summers BA, de Lahunta A.Equine motor neuron disease (EMND) is a spontaneous neurologic disorder of adult horses which results from the degeneration of motor neurons in the spinal cord and brain stem. Clinical manifestations, pathological findings, and epidemiologic attributes resemble those of human motor neuron disease (MND). As in MND the etiology of the disease is not known. We evaluated the predisposition role of vitamin E deficiency on the risk of EMND. Methods: Eleven horses at risk of EMND were identified and enrolled in a field trial at different times. The horses were maintained on a diet deficient in vitami...
Aleman M, Magdesian KG, Peterson TS, Galey FD.A 4-month-old American Paint filly was evaluated because of sudden onset of ataxia that progressed to recumbency. Five additional horses from the same and neighboring premises developed signs of poor performance, generalized weakness, ataxia, and recumbency; 2 of those horses were also evaluated. A new batch of a commercial feed supplement had been introduced to the horses' diet on each farm within the preceding 3 days. Results: Other than recumbency, findings of physical and neurologic examinations of the foal were unremarkable. The other 2 horses had generalized weakness and mild ataxia, and...
Silkwood-Sherer D, Warmbier H.The purpose of this pilot study was to examine the effectiveness of hippotherapy as an intervention for the treatment of postural instability in individuals with multiple sclerosis (MS). Methods: A sample of convenience of 15 individuals with MS (24-72 years) were recruited from support groups and assessed for balance deficits. Methods: This study was a nonequivalent pretest-posttest comparison group design. Nine individuals (4 males, 5 females) received weekly hippotherapy intervention for 14 weeks. The other 6 individuals (2 males, 4 females) served as a comparison group. All participants we...
Gilliam LL, Holbrook TC, Dechant JE, Johnson BJ.A 6-year-old Quarter Horse stallion was referred to Oklahoma State University Veterinary Medical Teaching Hospital for evaluation of abdominal pain that developed after breeding activity earlier in the day. The horse developed diarrhea and progressively worsening neurologic signs (circling, ataxia, head pressing) within 22 hours of presentation and was subsequently euthanized due to severe self-destructive behavior. Antemortem biochemical and hematologic abnormalities included hypocalcemia but no evidence of hepatic disease. Idiopathic hyperammonemia and encephalopathy were suspected; cerebros...
Berger J, Valdez S, Puschner B, Leutenegger CM, Gardner IA, Madigan JE.Highly reactive horses may pose risks to humans involved in equestrian activities. Among the factors that may affect horses' reactivity to external stimuli are pesticides used for fly control in equine facilities. The organophosphorus (OP) insecticide tetrachlorvinphos (TCVP) is used as a feed-through larvicide to prevent completion of the fly larval life cycle in horse manure. TCVP exerts its effect by inhibiting the enzyme cholinesterase (ChE) leading to the accumulation of the neurotransmitter acetylcholine (AChE) in synapses of the central and peripheral nervous systems. The aim of the pre...
Holbrook TC, Dechant JE, Crowson CL.A 523 kg Quarter Horse was anesthetized for unilateral eye enucleation. The anesthetic period was unremarkable. During anesthetic recovery the cap on the jugular venous catheter became dislodged. Clinical signs of pulmonary edema associated with moderate arterial hypoxemia subsequently developed. Although pulmonary edema resolved with medical therapy, the day following anesthetic recovery, clinical signs of vestibular disease and blindness developed. Treatment included nasal oxygen insufflation, flunixin meglumine, furosemide, dexamethasone, thiamine, dimethylsulfoxide, antimicrobials, and phe...
Loynachan AT, Williams NM, Freestone JF.A 5-day-old Thoroughbred foal was submitted to the necropsy service at the University of Kentucky Livestock Disease Diagnostic Center. The foal had a clinical history of seizure activity and severe icterus. A complete blood count and serum chemistry analysis indicated that the foal was anemic (hematocrit, 16%), hyperbilirubinemic (45 mg/dl), and hypoglycemic. At necropsy, all tissues were discolored various shades of yellow. Microscopically, there was degeneration and necrosis of cerebral neurons and cerebellar Purkinje cells; severe hepatocellular degeneration and necrosis; and deposition of ...
Strobach A, Kotschwar A, Mayhew IG, Peham C, Licka T.Equine ataxia is routinely evaluated subjectively by clinicians; however, objective measurements of the movement and coordination of ataxic horses have not been reported. Objective: To document the movement pattern of ataxic horses and compare the results to the movement of neurologically sound horses with, and without, sedation. Methods: Seventeen ataxic horses were evaluated walking and trotting on a treadmill using a 3D high speed video system. From the horizontal movement of hoof markers the autocorrelation function (ACF) of the left forelimb and the cross correlation function (CCF) betwee...
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...
Henninger RW, Reed SM, Saville WJ, Allen GP, Hass GF, Kohn CW, Sofaly C.Equine herpesvirus type 1 (EHV-1) infection causes neurologic disease in horses. However, risk factors for the disease and long-term prognosis are poorly characterized. Objective: There are identifiable risk factors for equine herpes-1 myeloencephalopathy. Methods: The entire population of 135 horses housed within the equestrian facility. Methods: A descriptive study investigated the clinical, serologic, virologic, and management aspects of an outbreak of EHV-1 myeloencephalopathy. Results: Out of 135 horses at the facility, 117 displayed signs of EHV-1 infection. Forty-six horses developed ne...
Bell C.A 2-month-old warmblood filly was presented for a 1-week history of a large, nonpainful, fluctuant swelling of the parotid and laryngeal area. Bilateral guttural pouch tympany was diagnosed. Surgical correction resolved the guttural pouch tympany; however, postoperative pharyngeal neuromuscular dysfunction developed. Dysfonction pharyngée neuromusculaire associée à un tympanisme bilatéral des poches gutturales chez un poulain. Une pouliche de race Warmblood a été présentée pour examen d’une enflure marquée non-douloureuse et fluctuante, localisée dans la région laryngée et paroti...
McFarlane D.Parkinson's disease (PD) is a leading cause of neurologic disability in the aged population. Remarkable progress has been made in the past decade to understand the cellular and molecular events that occur in PD. However attempts to unravel the early, initiating factors in the pathogenesis of dopaminergic neurodegeneration and PD have been limited by the lack of a suitable animal model. Models in which there has been genetic or environmental manipulation are not of use in determining the natural cause of a disease. While a large scale prospective human study would be ideal, the relatively low p...
Aleman M, Borchers A, Kass PH, Puchalski SM.To describe ultrasonographic landmarks for use in collection of CSF from the lumbosacral region in equids. Methods: Prospective study. Methods: 37 equids (27 with neurologic disease and 10 with nonneurologic disease). Methods: Standing equids (n = 17) were sedated with detomidine hydrochloride (0.006 to 0.01 mg/kg [0.003 to 0.005 mg/lb], IV) followed by butorphanol tartrate (0.01 mg/kg, IV) and restrained with a nose twitch for collection of CSF. The CSF was collected from 20 laterally recumbent equids (10 sedated and 10 immediately after euthanasia). Anatomic landmarks were identified ultraso...
Sasaki N, Yamada M, Morita Y, Furuoka H, Itoh M, Satoh M, Yamada H.We report a case of EMND in a heavy horse that was bred and trained in Hokkaido, Japan. Clinical symptoms included severe ataxia of all four limbs, tilted head, lethargy, and flaccid lips. Numerous axonal degenerations and swellings were observed in nuclei, mostly in the cerebellar dentate nucleus and the nucleus of the hypoglossal nerve, and in the ventral horn of the spinal cord. In the ventral horn of the spinal cord, neuronal degeneration, swelling, and/or necrosis were observed sporadically. The case was diagnosed as EMND from the clinical symptoms and pathological findings.
Tanabe M, Kelly R, de Lahunta A, Duffy MS, Wade SE, Divers TJ.Parasitic granulomatous eosinophilic inflammation was observed in the central nervous system (CNS) of a 6-month-old Arabian colt from New York state. Inflammation was associated with eggs, larvae, and adult nematodes in the cerebellum. Nematodes had histological characteristics of the superfamily Metastrongyloidea. The presence of dorsal-spined larvae in the CNS was further indicative of infection with a nematode in the family Protostrongylidae. Infections were most compatible with Parelaphostrongylus tenuis but specific diagnosis was not possible. This is the first definitive report of a prot...
Dietzel J, Kuhrt H, Stahl T, Kacza J, Seeger J, Weber M, Uhlig A, Reichenbach A, Grosche A, Pannicke T.Borna disease (BD) is a fatal disorder of horses, often characterized by blindness. Although degeneration of retinal neurons has been demonstrated in a rat model, there are controversial data concerning whether a similar degeneration occurs in the retina of infected horses. To investigate whether BD may cause degeneration of photoreceptors and possibly of other neuronal cells at least at later stages of the disease, we performed a detailed quantitative morphologic study of retinal tissue from Borna-diseased horses. BD was diagnosed by detection of pathognomonic Joest-Degen inclusion bodies in ...
Morales MA, Barrandeguy M, Fabbri C, Garcia JB, Vissani A, Trono K, Gutierrez G, Pigretti S, Menchaca H, Garrido N, Taylor N, Fernandez F, Levis S....West Nile virus (WNV) was isolated from the brains of 3 horses that died from encephalitis in February 2006. The horses were from different farms in central Argentina and had not traveled outside the country. This is the first isolation of WNV in South America.
Franci P, Leece EA, Brearley JC.Patient positioning and long anaesthetic duration required for magnetic resonance imaging (MRI) may result in a higher frequency of post anaesthetic myopathy/neuropathy syndrome (PAMNS) as compared to horses undergoing anaesthesia for surgery. Objective: Equine anaesthesia for MRI is associated with a higher frequency of PAMNS than anaesthesia for nonemergency, nonabdominal surgery. Methods: Anaesthetic and medical records of horses (n = 633) undergoing MRI or surgery between January 2001 and January 2005 (inclusive), were reviewed. Information obtained included patient details (breed, sex, ag...
Bryant UK, Lyons ET, Bain FT, Hong CB.A 13-week-old Thoroughbred colt from central Kentucky was euthanized after an acute onset of ataxia, blindness, head tremors, leaning to the right, recumbency, and seizures. Microscopically, there was a verminous meningoencephalitis characterized by an eosinophilic and granulomatous inflammatory reaction primarily affecting the cerebellum. Dispersed within regions of inflammation were numerous cross and longitudinal sections of intact and degenerative small nematodes. The nematodes had dorsoflexed ovaries and ventroflexed vulvas, which are distinguishing features of Halicephalobus gingivalis. ...
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...
Snowden NJ, Helyar CV, Platt SR, Penderis J.Moxidectin is a macrocyclic lactone related to ivermectin used in horses and dogs for endoparasite treatment and prophylaxis. The clinical and neurological presentation of moxidectin toxicity in two dogs following inadvertent poisoning with a moxidectin-containing equine de-worming medication is reported here. In both the dogs, the predominant clinical signs were generalised tremors and ataxia. Moxidectin exerts its neurotoxic effects in mammals by potentiating the effect of gamma-aminobutyric acid and, consistent with this, both the dogs demonstrated a poor response to treatment with diazepam...
Jahns H, Callanan JJ, McElroy MC, Sammin DJ, Bassett HF.Brains from 100 horses, aged 2-25 years, were systematically examined by histopathology at 46 different neuroanatomical sites. The horses were sourced from a slaughterhouse (group A, n = 57), from a kennel that collected dead animals, and from 2 diagnostic laboratories (group B, n = 43). All horses from group A and 26 horses from group B were examined by a veterinarian in the period before death. None of the horses were known to exhibit clinical signs suggestive of neurologic disease. Among the main changes identified were vacuolation in the neuropil (n = 73), neurons (n = 32), white matter (n...
Finno C, Pusterla N, Aleman M, Mohr FC, Price T, George J, Holmberg T.A 4-month-old American Paint Horse colt was evaluated because of acute onset of ataxia, left-sided head tilt, and fever and a recently noticed heart murmur. Upper respiratory tract infection caused by Streptococcus equi subsp equi had been diagnosed at 3 months of age. Results: Hematologic abnormalities included leukocytosis, mature neutrophilia, monocytosis, and mild anemia. Analysis of a CSF sample revealed high total protein concentration and total nucleated cell count; nucleated cells consisted mainly of degenerate neutrophils. Results of a real-time PCR assay were positive for S equi subs...
Blanco A, Moyano R, Vivo J, Flores-Acuña R, Molina A, Blanco C, Monterde JG.Purkinje cerebellar cells were studied in three Arabian horses aged between 6 and 8 months with clinical disorders in their movements, tremors and ataxia; the occurrence of apoptosis in this cell population was investigated by the (terminal deoxynucleotidyl transferase biotin-dUTP nick-end labelling (TUNEL) method. Both optical and electron microscopical images showed a scant number of Purkinje cells, most of them with morphological features of apoptosis such as condensation of the nucleus and cytoplasm as well as segregation and fragmentation of the nucleus into apoptotic bodies. The TUNEL te...
The Journal of parasitologyAugust 4, 2006
Volume 92, Issue 3 637-643 doi: 10.1645/0022-3395(2006)92[637:PAOPRC]2.0.CO;2
Furr M, McKenzie H, Saville WJ, Dubey JP, Reed SM, Davis W.The ability of ponazuril to prevent or limit clinical signs of equine protozoal myeloencephalitis (EPM) after infection with Sarcocystis neurona was evaluated. Eighteen horses were assigned to 1 of 3 groups: no treatment, 2.5 mg/kg ponazuril, or 5.0 mg/kg ponazuril. Horses were administered ponazuril, once per day, beginning 7 days before infection (study day 0) and continuing for 28 days postinfection. On day 0, horses were stressed by transport and challenged with 1 million S. neurona sporocysts per horse. Sequential neurologic examinations were performed, and serum and cerebrospinal fluid w...
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...
Pellegrini-Masini A, Livesey LC.This article provides an overview of meningitis and encephalomyelitis in horses, including diagnostic tests, treatment developments, and preventative measures reported in the equine and human medical literature of the past few years.
Pusterla N, Wilson WD, Conrad PA, Mapes S, Leutenegger CM.To determine gene transcription for cytokines in nucleated cells in CSF of horses without neurologic signs or with cervical stenotic myelopathy (CSM), West Nile virus (WNV) encephalitis, equine protozoal myeloencephalitis (EPM), or spinal cord trauma. Methods: 41 horses (no neurologic signs [n = 12], CSM [8], WNV encephalitis [9], EPM [6], and spinal cord trauma [6]). Methods: Total RNA was extracted from nucleated cells and converted into cDNA. Gene expression was measured by use of real-time PCR assay and final quantitation via the comparative threshold cycle method. Results: Cytokine genes ...
Patton KM, Peek SF, Valentine BA.A 17-year-old Quarter horse mare was referred to Cornell University for postmortem examination after 72 hours of encephalopathy that consisted of depression, mania, and blindness. A plasma sample and cerebral spinal fluid demonstrated hyperammonemia. Gross necropsy examination findings included the following: mild icterus, a transmural mass in the glandular portion of the gastric fundus, multiple masses throughout the liver, and a large tumor thrombus in the portal vein. Microscopically, the gastric mass, hepatic masses, and portal vein thrombus were composed of similar neoplastic epithelial c...
Cymerys J, Słońska A, Brzezicka J, Tucholska A, Chmielewska A, Rola J, Malik P, Bańbura MW.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) ...
Noiva R, Ruivo P, de Carvalho LM, Fonseca C, Fevereiro M, Carvalho P, Orge L, Monteiro M, Peleteiro MC.Halicephalobus gingivalis is a small saprophytic rhabditid nematode, represented only by females with a typical rhabditoid oesophagus and one egg in the uterus, capable of infecting vertebrates. This opportunistic parasite present in the soil, manure and decaying humus, is thought to penetrate through previous injuries to the mouth, eyes and skin of horses and migrate to various organs. The brain is one such organ, where the females lay their eggs, leading to malacia and causing a sudden onset of neurological signs, such as anorexia, ataxia, urinary incontinence, blindness, decreased menace an...
Doxey DL, Milne EM, Woodman MP, Gilmour JS, Chisholm HK.The number of neurons in the coeliacomesenteric ganglia and the myenteric and submucosal plexuses of the jejunum, ileum and small colon, and the pathological changes induced in them, were studied in various types of equine dysautonomia. In all forms of dysautonomia, severe and extensive neuron loss and damage occurred in the ileum. In acute and subacute dysautonomia, jejunal neuron loss and damage were severe, but in chronic cases significantly less loss or damage occurred. The damage followed the same pattern in the small colon but it was always less obvious than in the jejunum. The distribut...
Wheeler SJ.This study aimed to establish a clinically reproducible method of evaluation of sensory nerve conduction in the horse and to provide reference values in a group of normal horses. Age-related changes in the sensory nerve conduction velocity were of particular interest. Sensory nerve conduction was performed in the lateral palmar nerve. The results revealed an increase in velocity over the first year of life and a subsequent decrease in velocity in older horses. The effect of age must be considered if results from horses in which peripheral nerve disease is suspected are to be interpreted correc...
Smith JS, Mayhew IG.The sympathetic nervous innervation of the head was surgically transected in the horse, cow, sheep and goat. The site of transection was preganglionic in all 4 species and ganglionic-postganglionic in 2 additional horses. The Horner's syndrome, manifested as a result of the iatrogenic lesion, varied with the species. Ptosis was the most constant sign in all species. Unilateral sweating over the face and proximal neck, particularly at the base of the ear, was the most prominent feature in the horse. The cow revealed distension of vasculature and cutaneous heat of the pinna, and a reduced produc...
Slone DE, Bergfeld WA, Walker TL.A filly with ataxia and splinting and crepitation in the neck was found to have atlantoaxial subluxation. Radiographic diagnosis was based on the same criteria as those used in other species, ie, increased distance between the atlas and spine of the axis and increased distance between the dens and floor of the atlas. Extensive hemilaminectomy was performed to decompress the spinal cord. Stabilization was not attempted. Immediate postoperative response was encouraging, but the untimely death of the filly prevented further evaluation of the procedure.
Langsjoen RM, Key A, Shariatzadeh N, Jackson CR, Mahmood F, Arkun K, Alexandrescu S, Solomon IH, Piantadosi A.Eastern equine encephalitis virus (EEEV) is a relatively little-studied alphavirus that can cause devastating viral encephalitis, potentially leading to severe neurological sequelae or death. Although case numbers have historically been low, outbreaks have been increasing in frequency and scale since the 2000 s. It is critical to investigate EEEV evolutionary patterns, especially within human hosts, to understand patterns of emergence, host adaptation, and within-host evolution. To this end, we obtained formalin-fixed paraffin-embedded tissue blocks from discrete brain regions from five contem...
Wilson WD, Hughes SJ, Ghoshal NG, McNeel SV.Occipitoatlantoaxial malformation was diagnosed in a 19-month-old mare of Appaloosa breeding and in a 3-year-old Quarter Horse gelding. Both horses had abnormal head and neck carriage since birth, but neurologic deficits did not become evident clinically until the horses reached 2 and 3 years of age, respectively. Palpation and manipulation of the base of the skull and cervical area proved to be useful diagnostically. Movement could not be elicited at the atlantooccipital joint but, in comparison with clinically normal horses, the range of dorsoventral motion at the atlantoaxial joint was incr...
Lewis SR, Ellison SP, Dascanio JJ, Lindsay DS, Gogal RM, Werre SR, Surendran N, Breen ME, Heid BM, Andrews FM, Buechner-Maxwell VA, Witonsky SG.Sarcocystis neurona is the most common cause of Equine Protozoal Myeloencephalitis (EPM), affecting 0.5-1% horses in the United States during their lifetimes. The objective of this study was to evaluate the equine immune responses in an experimentally induced Sarcocystis neurona infection model. Neurologic parameters were recorded prior to and throughout the 70-day study by blinded investigators. Recombinant SnSAG1 ELISA for serum and CSF were used to confirm and track disease progression. All experimentally infected horses displayed neurologic signs after infection. Neutrophils, monocytes, an...
Keane DP, Little PB, Wilkie BN, Artsob H, Thorsen J.A survey was conducted by testing 115 paired equine serum and cerebrospinal fluid samples by hemagglutination-inhibition for antibodies to Powassan and snowshoe hare viruses, and by virus neutralization for antibodies to equine herpesvirus type 1. Twenty-five samples were from horses with spontaneous neurological disease and the remainder from horses euthanized because of various nonneurological disorders. All sera and cerebrospinal fluids were negative for antibodies to Powassan virus. Fifty-one sera (44.3%) and 15 cerebrospinal fluids (13.0%) had antibodies to snowshoe hare virus. Ninety-eig...
Holt PE, Mair TS.Bladder paralysis and sabulous urolithiasis were diagnosed in 10 horses with urinary incontinence. Additional neurological deficits in the hindquarters were detected in five of them. Treatment by catheter drainage and bladder lavage was unsuccessful, and all the horses were destroyed within 14 months of presentation. Neuritis of the cauda equina was diagnosed post mortem in one horse, but the cause of the paralysis was not identified in the others, although radiography revealed abnormal lumbosacral vertebral angulation in one case.
Hamir AN, Moser G, Rupprecht CE.A retrospective study of horses necropsied between 1985 and 1989 at a diagnostic laboratory of a veterinary school in North America is documented. In this investigation over 20 per cent of the horses had clinical neurological signs. Equine protozoal myeloencephalitis (caused by Sarcocystis neurona) and cervical stenotic myelopathy (wobbler syndrome) were the most common of these disorders. The veterinary school is located in the midst of a raccoon rabies enzootic area. However, only four cases of equine rabies were diagnosed during the 5-year study. The gross microscopical and immunohistochemi...
Witonsky S, Morrow JK, Leger C, Dascanio J, Buechner-Maxwell V, Palmer W, Kline K, Cook A.A vaccine against Sarcocystis neurona, which induces equine protozoal myeloencephalitis (EPM), has received conditional licensure in the United States. A major concern is whether the immunoglobulin G (IgG) response elicited by the vaccine will compromise the use of Western blotting (WB) as a diagnostic tool in vaccinated horses with neurologic disease. Our goals were to determine if vaccination (1) causes seroconversion: (2) causes at least a transient increase in S neurona-specific IgG in the cerebrospinal fluid (CSF); and (3) induces an IgG response that can be differentiated from that induc...
Gray LC, Magdesian KG, Sturges BK, Madigan JE.A two-month-old Appaloosa colt developed neurological signs shortly after birth involving deficits affecting cranial nerves IV, VII, VIII, IX, X and XII, and possibly nerve VI. The most likely differential diagnoses were congenital anomalies, meningoencephalitides, trauma or nutritional causes. The foal was investigated by the analysis of cerebrospinal fluid (CSF), electromyelography (EMG), brain auditory evoked responses, magnetic resonance imaging (MRI), peripheral nerve biopsy, and Western blot analysis for the presence of intrathecal antibodies to Sarcocystis neurona, the causative agent o...
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...
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-...
Saville WJ, Morley PS, Reed SM, Granstrom DE, Kohn CW, Hinchcliff KW, Wittum TE.To investigate risk factors for use in predicting clinical improvement and survival of horses with equine protozoal myeloencephalitis (EPM). Methods: Longitudinal epidemiologic study. Methods: 251 horses with EPM. Methods: Between 1992 and 1995, 251 horses with EPM were admitted to our facility. A diagnosis of EPM was made on the basis of neurologic abnormalities and detection of antibody to Sarcocystis neurona or S neurona DNA in CSF. Data were obtained from hospital records and through telephone follow-up interviews. Factors associated with clinical improvement and survival were analyzed, us...
Intan-Shameha AR, Divers TJ, Morrow JK, Graves A, Olsen E, Johnson AL, Mohammed HO.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...
Liu SK, Dolensek EP, Adams CR, Tappe JP.Degenerative myelopathy was diagnosed in six Mongolian wild horses. Three of the horses had a history of ataxia dating from birth to 3 months of age. The clinical signs were uncoordinated movement of the hindlimbs and an abnormally wide-based gait and stance. The other 3 horses had mild ataxia. There were no gross lesions in the brain, vertebrae, or spinal cord. Histologic examination revealed degeneration of the neural processes in the ventral and lateral funiculi of all 6 horses. Myelin sheaths were dilated and vacuolated, and there were swollen, fragmented, or lysed axons. Neuronal degenera...
Hayes TE.The examination of cerebrospinal fluid (CSF) is often part of the diagnostic work-up of a patient exhibiting signs of disease involving the central nervous system. Awareness of the capabilities and limitations of these laboratory tests is important in assessing the benefit-to-risk ratio of performing such procedures. Collection of CSF is a relatively simple procedure, and together with a thorough history, physical examination, and other diagnostic tests, may be a valuable aid in arriving at a diagnosis or prognosis.
Barton AJ, Prow NA, Hall RA, Kidd L, Bielefeldt-Ohmann H.This report summarises the findings from a case of naturally-occurring Murray Valley encephalitis in a 2-year-old filly presenting with acute onset of depression and weakness. Serum samples tested at the onset of clinical signs were negative for Hendra and Kunjin virus antibodies, but positive for Murray Valley encephalitis virus (MVEV) using IgM-capture ELISA (1 : 300 dilution). A virus neutralisation assay performed 4 weeks later confirmed a titre of 1 : 160. Sera collected in the weeks preceding neurological signs returned a negative titre for MVEV 2 weeks prior followed by a titre ...
Journée SL, Journée HL, Berends HI, Reed SM, de Bruijn CM, Delesalle CJG.Transcranial electrical (TES) and magnetic stimulation (TMS) are both used for assessment of the motor function of the spinal cord in horses. Muscular motor evoked potentials (mMEP) were compared intra-individually for both techniques in five healthy horses. mMEPs were measured twice at increasing stimulation intensity steps over the extensor carpi radialis (ECR), tibialis cranialis (TC), and caninus muscles. Significance was set at < 0.05. To support the hypothesis that both techniques induce extracranially elicited mMEPs, literature was also reviewed. Results: Both techniques show the pr...
El-Assaad I, Di Bari JA, Yasuda K, Divers TJ, Summers BA, de Lahunta A, Mohammed H.Equine motor neuron disease (EMND) is a neurodegenerative disorder of unknown etiology affecting horses worldwide. Trans-Active Response DNA Binding Protein of 43 kDa (TDP-43) has been reported in the central nervous system (CNS) of several neurodegenerative conditions in humans including Amyotrophic Lateral Sclerosis (ALS) and assumed to play role in the disease. We examined whether horses afflicted with EMND express the TDP-43 in CNS. Ten horses with EMND and 6 controls of different ages and breed we enrolled. Detection of presence of TDP-43 protein in the CNS was analyzed by immunohistoche...
Slocombe RF, Huntington PJ, Friend SC, Jeffcott LB, Luff AR, Finkelstein DK.Nine horses with clinical signs of Australian Stringhalt were killed and tissues collected for a detailed pathological study. Lesions were limited to peripheral nerves and muscles. The most severely affected nerves were the superficial and deep peroneal, distal tibial, plantar digital, volar and recurrent laryngeal nerve with changes characterised by a selective loss of large diameter myelinated fibres with various degrees of demyelination, fibrosis, Schwann cell proliferation and onion-bulb formation. A routine evaluation of the brain and spinal cord by light microscopy failed to reveal any c...
Roberts K, Hemmings AJ, McBride SD, Parker MO.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...
The Journal of parasitologyAugust 4, 2006
Volume 92, Issue 3 637-643 doi: 10.1645/0022-3395(2006)92[637:PAOPRC]2.0.CO;2
Furr M, McKenzie H, Saville WJ, Dubey JP, Reed SM, Davis W.The ability of ponazuril to prevent or limit clinical signs of equine protozoal myeloencephalitis (EPM) after infection with Sarcocystis neurona was evaluated. Eighteen horses were assigned to 1 of 3 groups: no treatment, 2.5 mg/kg ponazuril, or 5.0 mg/kg ponazuril. Horses were administered ponazuril, once per day, beginning 7 days before infection (study day 0) and continuing for 28 days postinfection. On day 0, horses were stressed by transport and challenged with 1 million S. neurona sporocysts per horse. Sequential neurologic examinations were performed, and serum and cerebrospinal fluid w...
Liu SJ, Wang Q, Tang HH, Bai JZ, Wang FY, Lv Z, Chen SZ, Liu JS, Hong Y, Zhang JW.Retrospective analysis. Methods: China Rehabilitation Research Center, Beijing, China. Objective: A retrospective study that documents the modalities and clarifies the heterogeneity among spinal cord injuries (SCIs) caused by trauma to the thoracolumbar vertebral junction. Methods: X-ray and MRI imaging, neurological records, and the urodynamics results of 190 patients were reviewed and used to categorize different SCI modalities. First, injuries were divided into complete and incomplete injuries using the International Standard for Neurological Classification of Spinal Cord Injury. Next, the ...
Uzal FA, Doxey DL, Robles CA, Woodman MP, Milne EM."Mal seco" is a disease of unknown aetiology affecting horses in Argentina. It is similar to grass sickness, a primary dysautonomia of horses in Europe. A histopathological study of the brain stem nuclei of three horses with "mal seco" was performed. Changes were found that consisted of chromatolysis, cytoplasmic vacuoles, eosinophilic sphaeroids, and pyknotic and eccentric nuclei. These changes were most severe at the oculomotor, vestibular and abducent nuclei. The results provide further evidence to suggest that "mal seco" and grass sickness may be the same disease.
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...
Peters M, Brandt K, Wohlsein P.An intracranial epidermoid cyst was diagnosed in a Haflinger gelding aged 12 years suffering from episodes of neurological disturbance, apathy and fever. The extracerebral cyst was located in the region of the tentorium cerebelli and measured 9 x 8 x 5 cm. It displaced the cerebral hemispheres anteriorly and compressed the cerebellum and brainstem underneath. Histologically, the cyst was lined by keratinizing, stratified squamous epithelium and contained keratin scales, debris, focal haemorrhages, and degenerating inflammatory cells. The epithelium was supported by a vascularized fibrous capsu...
