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.
Jackson CA, DE Lahunta A, Cummings JF, Divers TJ, Mohammed HO, Valentine BA, Hackett RP.The effectiveness of spinal accessory nerve branch biopsy evaluation as a means to confirm the diagnosis of equine motor neuron disease (EMND) was investigated. Sixteen horses with histories and clinical signs suggestive of EMND and 16 control horses with neither histories nor clinical signs of any neurological disorder, were subjects of the study. Biopsy samples of the ventral branch of the spinal accessory nerve were obtained either surgically, under general anaesthesia or post mortem immediately after euthanasia. Evaluation was done on the spinal cord of all horses to serve as the definitiv...
Hagedorn HW, Zuck S, Schulz R.The azaphenothiazine neuroleptic prothipendyl (Dominal) is suspected to be administered illegally at low doses to race-horses to improve their performance. Since for this species pharmacokinetic data of the drug are missing we studied its elimination from blood and urine in a standard-bred mare. At a low (subtherapeutic) dose (i.v., 0.24 mg/kg) the horse is described to be less excited while locomotor activity and attention remain unaffected. In contrast, sedation and ataxia are brought about at 1 mg/kg (therapeutic dose). Identification of prothipendyl given i.v. at subtherapeutic doses was a...
Patterson JS, Maes RK, Mullaney TP, Benson CL.An immunohistochemical (IHC) assay was developed for the detection of eastern equine encephalomyelitis (EEE) virus antigen in formalin-fixed, paraffin-embedded tissues. All cases of EEE diagnosed at the Michigan State University Animal Health Diagnostic Laboratory from 1991 through 1994 were evaluated. The diagnosis was based on histopathologic examination of the brain and confirmatory virus, isolation. Sections of cerebrum from 26 equids and 5 birds were assessed by IHC. Histologically normal brain tissues from 2 horses and 1 pheasant and brain tissues from 2 cases of equine neurologic diseas...
Each year, traumatic brain injury (TBI) is associated with 52,000 deaths and accounts for one third of all injury deaths in the United States; in addition approximately 80,000 persons who survive TBI incur some loss of function, residual disability, and increased medical-care needs because of these injuries. Major causes of TBI are motor-vehicle crashes, falls, assaults, and sports and recreational activities. During 1992-1993 in Oklahoma, horseback riding was the leading cause of sports-related TBI. To further characterize horseback-riding-associated TBIs, the Oklahoma State Department of Hea...
Fortier LA, Fubini SL, Flanders JA, Divers TJ.Two calves and two foals presented with episodic clinical signs of diffuse central nervous system disease. Portosystemic anomalies were tentatively diagnosed based on the history, clinical signs and increased serum concentrations of blood ammonia and total serum bile acids with normal concentrations of liver derived enzymes. one calf died before intraoperative contrast portography, whereas the other calf and both foals had marked clinical improvement after intensive medical therapy. Surgical correction was attempted in these three animals and was successful in one foal. A right paracostal celi...
Alape-Giron A, Stiles BG, Gutierrez JM.An ELISA based, non-radioactive acetylcholine receptor (AchR) binding assay was used to detect the alpha-neurotoxins present in Micrurus nigrocinctus nigrocinctus venom. Sera from horses hyperimmunized against M. nigrocinctus venom contain antibodies which inhibit the binding of M. n. nigrocinctus alpha-neurotoxins to AchR and reverse the binding of toxins already complexed with the receptor. This result supports the importance of using antivenom therapeutically in M. n. nigrocinctus envenomations even after the onset of neurological symptoms. M. nigrocinctus antivenoms cross-reacted in an ELI...
Yanai T, Masegi T, Ishikawa K, Sakai H, Iwasaki T, Moritomo Y, Goto N.Cerebral vascular mineralization was found in 12 (60%) of 20 3- to 10-year-old healthy horses collected at an abattoir. It was variable in degree and occurred mostly in the pallidal arteries showing two types of lesions; small globoid bodies along capillaries, and amorphous deposits in the wall of arterioles, small- or medium-sized arteries and veins. Both types were strongly positive for periodic acid-Schiff reaction, and weakly positive for von Kossa's and Berlin blue stains. Elemental analysis of the deposit revealed the presence of large amounts of aluminum, moderate amounts of phosphorus,...
Doige CE.A midsagittal centrum cleft of T5-6, malformation and fusion of T3-7, intra- and extraspinal cyst, and myelodysplasia were found in a 3-month-old female Arabian foal that had experienced posterior ataxia since birth. Based on studies in other species, ecto-endodermal adhesions early in embryogenesis leading to formation of an enterogenous cyst is the most probable pathogenesis.
Carrigan MJ, Higgins RJ, Carlson GP, Naydan DK.A 17-year-old Arabian gelding with progressive neurologic signs had a velvety, reddish brain tumor protruding from the ventral midline caudal to the optic chiasma. Histologically, the tumor had a papillary formation with a single layer of elongate cells radially oriented around a central fibrovascular core. Intracytoplasmic globular inclusions were positive for glial fibrillary acidic protein and weakly positive for vimentin. Ultrastructurally, these inclusions were comprised of whorling intermediate filaments. Neoplastic cells also had cytoplasmic interdigitations and numerous zona adherens a...
van Essen GJ, Blom M, Fink Gremmels-Gehrmann J.To elaborate the diagnosis of rye-grass intoxication in a stallion demonstrating a neurotoxic syndrome characterized by ataxia and incoordination, a number of diagnostic tests were performed. Results of both, blood chemistry and haematology gave no indication for organ-specific or systemic lesions. Chemical analysis of the hay fed to the horse revealed the presence of the mycotoxin lolitrem B in concentrations consistent with those described in sheep and cattle with similar symptoms. Thus, it was concluded that the animals demonstrated the rye-grass-stagger(RGS)-syndrome.
Johnson PJ.Laboratory electrolyte and acid-base analyses are important for the characterization and assessment of the severity of disorders of fluid balance, and they enable the veterinarian to institute appropriate corrective therapeutic interventions. Abnormalities of electrolytes or acid-base rarely define the diagnosis, but certain diseases are characterized by predictable trends in these parameters. Important clinical situations in which assessment of electrolyte and acid-base status should be regarded as important to the equine practitioner include diarrhea, severe colic, peritonitis, pleuritis, dy...
Dame JB, MacKay RJ, Yowell CA, Cutler TJ, Marsh A, Greiner EC.Equine protozoal myeloencephalitis (EPM) is a neurologic disease of horses caused by Sarcocystis neurona. The horse is a dead-end host for S. neurona and the definitive and intermediate hosts have not previously been identified. We hypothesized that S. neurona is actually Sarcocystis falcatula, a parasite that cycles in nature between Virginia opossums (Didelphis virginiana) and any of a variety of avian intermediate hosts. We extracted DNA from S. falcatula sarcocysts in the muscle of a brown-headed cowbird (Molothrus ater) and from schizonts in a fixed specimen of lung from a Moluccan cockat...
Kortz GD, Madigan JE, Goetzman BW, Durando M.Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were determined in 8 clinically normal neonatal foals. After the foals oriented themselves and nursed the mares, they were sedated as necessary, and local anesthesia was provided for making the skin incisions. Using a technique similar to that used in human beings, an indwelling subdural catheter was placed to measure ICP. Carotid artery catheterization was used to measure arterial blood pressure. Cerebral perfusion pressure was calculated as the difference between mean arterial blood pressure and ICP. Intracranial pressure and ...
Heath SE, Peter AT, Janovitz EB, Selvakumar R, Sandusky GE.A 2-year-old Standardbred gelding was examined because of prolapse of the third eyelid; myoclonus of the muscles of the head, neck, and forelimbs; and persistent tail swishing. The horse had a high plasma sodium concentration but was not drinking water. The hypernatremia could not be corrected by means of IV administration of fluids, and the horse became worse and, 6 days later, died. At necropsy, a tumor was found to be compressing the neurohypophysis and the area in the brain in which the thirst centers are believed to be located. It is believed that hypernatremia in this horse was a result ...
Rames DS, Miller DK, Barthel R, Craig TM, Dziezyc J, Helman RG, Mealey R.Ocular contents from a horse with a 4-week history of severe unilateral uveitis were submitted for histopathologic examination. A severe unilateral granulomatous chorioretinitis with intralesional Halicephalobus deletrix was diagnosed. The horse developed progressive neurologic signs several days following the surgery to remove ocular contents and implant a prosthesis and was subsequently euthanatized. A severe multifocal granulomatous encephalitis with intralesional H. deletrix, localized primarily to the optic chiasm, thalamus, and brain stem, was diagnosed from tissues acquired at necropsy....
Fletcher J, Davies PT, Lewis T, Campbell MJ.Jockeys accept bony fractures and soft tissue injuries as occupational hazards. An average National Hunt jockey falls once in ten races with an injury rate of 4.25%. Head injury is a common cause of morbidity and the benefit of helmets is well recognized. Neck injuries are also common and usually musculoskeletal. Although rare, trauma to the neck arteries may go unnoticed yet have catastrophic consequences. Internal tears can allow arterial blood to dissect the layers of the arterial wall and obstruct the lumen. Severe obstruction may lead to cerebral ischaemia and infarction. An appreciation ...
Cheeke PR.Plant toxins are the chemical defenses of plants against herbivory. Grasses have relatively few intrinsic toxins, relying more on growth habit to survive defoliation and endophytic fungal toxins as chemical defenses. Forage grasses that contain intrinsic toxins include Phalaris spp. (tryptamine and carboline alkaloids), sorghums (cyanogenic glycosides), and tropical grasses containing oxalates and saponins. Toxic effects of these grasses include neurological damage (Phalaris staggers), hypoxia (sudangrass), saponin-induced photosensitization (Brachiaria and Panicum spp.), and bone demineraliza...
Miller SM, Short CE, Ekström PM.We compared the anesthetic combination of detomidine, ketamine, and halothane in control horses not undergoing apparently painful procedures with that in horses during arthroscopic surgery. The effectiveness of this regimen in suppressing neurologic response to surgery was, thus, evaluated. In this study, significant differences were not observed in electroencephalographic total amplitude, spectral edge, or beta-to-delta frequency ratio between surgically treated and nonsurgically treated (control) horses. On the basis of its attenuation of encephalographic responses, we conclude that detomidi...
Chaffin MK, Honnas CM, Crabill MR, Schneiter HL, Brumbaugh GW, Briner RP.A 4-month-old male Quarter Horse was referred for evaluation of urinary incontinence. Physical examination revealed clinical signs consistent with cauda equina syndrome. Radiography revealed diskospondylitis of S2 through S4. Infected bone was surgically curretted, and drainage was established for an associated paravertebral abscess. Rhodococcus equi was isolated from specimens of bone and from fluid samples obtained from the paravertebral abscess. Bethanechol was administered to stimulate urination. Erythromycin and rifampin were administered for 120 days. The foal's neurologic dysfunction re...
Gosztonyi G, Ludwig H.Natural BD is a nonpurulent acute/subacute encephalitis of horses and sheep with a propensity to involve the olfactory and limbic systems, and the brain stem. The inflammation is concentrated primarily in the gray matter, but subcortical white matter may also be affected. Experimental BD can be produced in a series of animals from birds to primates. The neuropathology after experimental infection is similar to that in natural disease but the inflammatory changes are more diffuse. In the rat and mouse, a persistent/tolerant infection can also be induced, in which inflammatory changes are conspi...
Roy DN, Peyton DH, Spencer PS.Horses grazing for prolonged periods on yellow star thistle (YST), a plant which grows wild in western parts of the United States, develop an extrapyramidal disorder known as nigropallidal encephalomalacia (NPE). Attempts have been made to identify, isolate, and characterize the toxins responsible for the disease in animals. Using the organotypic tissue culture system on mouse cortical explants as a specific assay method for neurotoxicological evaluation, it has been possible to isolate and characterize two potent neuroexcitotoxic compounds, aspartic and glutamic acids, the former being the ma...
de la Rúa-Doménech R, Mohammed HO, Cummings JF, Divers TJ, de Lahunta A, Valentine B, Summers BA, Jackson CA.We have conducted an ambidirectional study to estimate the incidence of equine motor neuron disease (EMND) in the northeastern US. The clinical and pathological features of EMND are similar to those described in human motor neuron disease. We have also collected data on all EMND cases reported in the US and described the geographic distribution of the disease. To identify factors associated with the risk of EMND, the authors assembled 163 control horses from the population in which cases were identified. The significance of association between the hypothesized factors and the risk of EMND was ...
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...
Elliott CR, McCowan CI.Nigropallidal encephalomalacia was diagnosed in two horses in northern Victoria that had a history of long-term pasture access to a dense growth of Rhaponticum repens. The region in which the affected horses lived had received well above average rainfall for several months preceding the poisoning. Affected horses had sudden onset of subcutaneous oedema of the head, impaired prehension and mastication, dullness, lethargy and repeated chewing-like jaw movements. Diagnosis was confirmed at necropsy, with characteristic malacic lesions in the substantia nigra and globus pallidus of the brain. This...
Ellison S, Witonsky S.Sarcocystis neurona is the principal etiologic agent of equine protozoal myeloencephalitis (EPM). An immunodominant protein of S. neurona, SnSAG-1, is expressed by the majority of S. neurona merozoites isolated from spinal tissues of horses diagnosed with EPM and may be a candidate for diagnostic tests and prophylaxis for EPM. Five horses were vaccinated with adjuvanted recombinant SnSAG1 (rSnSAG1) and 5 control (sham vaccinated) horses were vaccinated with adjuvant only. Serum was evaluated pre- and post-vaccination, prior to challenge, for antibodies against rSnSAG1 and inhibitory effects on...
Watrous BJ.Head tilt in the horse is commonly a sign of either central or peripheral vestibular disease. The confirmation of vestibular disease is based on physical findings, including results of cranial-nerve function evaluation and observation of stance, posture, and gait. Further localization is made by ancillary tests such as cerebral spinal fluid analysis, electrodiagnostic testing, and radiography. The normal anatomy and physiology of the vestibular system, the abnormal clinical signs demonstrated during physical examination, and the various etiologies are discussed.
Roy DN, Peyton DH, Spencer PS.Horses grazing for prolonged periods on yellow star thistle (YST), a plant which grows wild in western parts of the United States, develop an extrapyramidal disorder known as nigropallidal encephalomalacia (NPE). Attempts have been made to identify, isolate, and characterize the toxins responsible for the disease in animals. Using the organotypic tissue culture system on mouse cortical explants as a specific assay method for neurotoxicological evaluation, it has been possible to isolate and characterize two potent neuroexcitotoxic compounds, aspartic and glutamic acids, the former being the ma...
KIVALO E, TALANTI S.A good deal of hypothetical evidence has been presented for the view that the antidiuretic and oxytocic hormones are not produced in the posterior lobe of the hypophysis. These hormones appear to originate from a neurosecretory process in the neurosecretory nerve cells of the supraoptic and paraventricular nuclei in the hypothalamus and to migrate within the nerve fibers of the supraoptico-hypophysial tract and into the neurohypophysis (Hild, 1951, 1954 a, b and Hild & Zetler, 1951, 1952, 1953 a, b). Here they are stored and if necessary released. Neurosecretory neurons are described in many s...
Nolte LC, Rosiak M, Baechlein C, Baumgärtner W, Allnoch L.Idiopathic systemic granulomatous disease (ISGD), also known as equine sarcoidosis is an uncommon disease of horses, manifesting in exfoliative dermatitis and granulomatous inflammation in various organs. The current report presents a case of a 15-year-old Hanoverian mare with a 4-month history of weight loss, recurrent fever, skin lesions, and movement disorders. Pathological examination revealed granulomatous and necrotizing inflammation in the skin, regional lymph nodes, and cerebellum. Based on histological, immunohistochemical, and microbiological findings, the diagnosis of ISGD was made....
Fordyce PS, Edington N, Bridges GC, Wright JA, Edwards GB.In 27 potential neuropathies an enzyme-linked immunosorbent assay, using P2 preparations from either bovine or equine myelin, detected all cases of cauda equina neuritis in which there was caudal involvement. The test was of limited value in differentiating neuropathies involving only cranial or other peripheral nerves.
de la Rúa-Doménech R, Mohammed HO, Cummings JF, Divers TJ, de Lahunta A, Valentine B, Summers BA, Jackson CA.We have conducted an ambidirectional study to estimate the incidence of equine motor neuron disease (EMND) in the northeastern US. The clinical and pathological features of EMND are similar to those described in human motor neuron disease. We have also collected data on all EMND cases reported in the US and described the geographic distribution of the disease. To identify factors associated with the risk of EMND, the authors assembled 163 control horses from the population in which cases were identified. The significance of association between the hypothesized factors and the risk of EMND was ...
Gaughan EM, Gift LJ, DeBowes RM, Frank RK, Veatch JK.An 8-year-old Quarter Horse mare was examined for chronic nasal discharge and obstruction of both nasal passages. A solid mass lesion was identified in the maxillary sinuses, soft palate, nasal and pharyngeal cavities. Palliative surgery was used to debulk the lesion and facilitate nasal airflow. Squamous cell carcinoma was diagnosed from surgical biopsies. Approximately 7-8 weeks after surgery, the mare was observed to be acutely blind. Ophthalmologic examination revealed central origin blindness and active retinitis. The squamous cell carcinoma had reobstructed the nasal passages. Pressure b...
Cudmore LA, Groenendyk JC, Hodge P, Church S.This case report describes neurological signs associated with a pyogranulomatous lesion within the sacral vertebral canal of a horse. The clinical findings included urinary overflow incontinence and reduced anal, perianal and tail tone. The horse failed to respond to medical management and a guarded prognosis for return to athletic performance initiated the decision for euthanasia.
Civello ANE, Dunkel B, Summers BA, Martineau HM.A neurofibroma of granular cell subtype is described in a 7-year-old horse. The horse had a 3-month history of ataxia affecting the forelimbs and hindlimbs, suggesting a C1-C6 neuroanatomical localization. Post-mortem examination revealed an intradural mass arising from the right sixth cervical spinal nerve and compressing the spinal cord. Histologically, the mass was composed largely of wavy spindle cells (a mixture of Schwann cells, perineurial cells and fibroblasts) intimately associated with ropy collagen fibres. Approximately 25% of the spindle cells were swollen and contained densely-pac...
Cahill JI, Goulden BE.Evidence for a central nervous system component of the distal axonopathy associated with equine laryngeal hemiplegia was found in this survey of 33 horses (control, 15; subclinical, 8; clinical, 10). Significantly higher numbers of axonal spheroids were present in sections of the lateral cuneate nuclei in layngeal hemiplegic horses than in those unaffected by the disease.
Elitsur E, Marsh AE, Reed SM, Dubey JP, Oglesbee MJ, Murphy JE, Saville WJ.Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 x 10(6) S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days ...
Rossano MG, Kaneene JB, Schott HC, Sheline KD, Mansfield LS.Equine protozoal myeloencephalitis (EPM) is a neurological disease of equids that is caused by infection of the central nervous system with Sarcocystis neurona. Veterinarians diagnose EPM by performing a neurological examination and by ordering Western blot tests for antibodies to S. neurona in the blood and/or cerebrospinal fluid (CSF). The negative predictive value of the Western blot test is generally accepted to be high for both serum and CSF. If the agreement between serum and CSF test results is strong, serum tests could be used to substitute for CSF tests in some cases. The purpose of t...
Kolb DS, Klein C.Congenital hydrocephalus has been reported for a number of horse breeds, and for Friesian horses this condition has been associated with a nonsense mutation of B3GALNT2. We report the first case of congenital hydrocephalus associated with the said mutation in a Belgian draft horse. Genetic testing and consideration of the testing results in breeding programs are warranted. Hydrocéphalie congénitale chez un cheval de trait Belge associée à une mutation non-sens de B3GALNT2. L’hydrocéphalie congénitale a été signalée pour plusieurs races de chevaux et, pour les chevaux Frisons, cette ...
Favro G, Habib H, Gennity I, Puschner B, Hales EN, Finno CJ, Moeller BC.Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a hereditary, deteriorating central nervous disease in horses. Currently, the only way to confirm eNAD/EDM is through a postmortem histological evaluation of the central nervous system. Vitamin E, specifically the isoform alpha-tocopherol (α-TP), is known to protect eNAD/EDM susceptible horses from developing the clinical phenotype. While vitamin E is an essential nutrient in the diet of horses, there are no diagnostic tests able to quantitate vitamin E and its metabolites in urine. An ultra-performance liquid chromat...
Anor S, Espadaler JM, Monreal L, Pumarola M.To reassess reference values for the components of the electrically induced blink reflex, document reference values for facial motor nerve conduction velocity, and demonstrate usefulness of the blink reflex as a diagnostic tool in peripheral facial and trigeminal nerve dysfunction in horses. Methods: 10 healthy adult horses (8 males, 2 females) without neurologic abnormalities. Methods: Blink reflex tests were performed by electrical stimulation of the supraorbital nerve and facial (auriculopalpebral) nerve. Reflex and direct muscle-evoked potentials of the orbicularis oculi muscles were recor...
Kelly DF, Watson WJ.An aged Connemara mare had a neurological illness lasting 3 weeks and characterised by episodes of dullness, head-pressing, staggering gait and hyperexcitability. The signs recurred at intervals of 3 to 4 days, with intervening periods of apparent normality. Post-mortem examination revealed an epidermoid cyst on the dorsal surface of the occipital lobe of the left cerebral hemisphere. The cyst was lined by stratified squamous epithelium and contained desquamated keratinised material and blood. The lesion is considered to be a congenital malformation which enlarges and produces space-occupying ...
Edington N, Wright JA, Patel JR, Edwards GB, Griffiths L.Equine adenovirus 1 was recovered after four to six passages from two out of three cases of cauda equina neuritis (CEN) using kidney monolayers. Similar treatment of lumbo-sacral spinal cord from six normal horses did not yield adenovirus. All three cases of CEN had antibodies to the neuritogenic myelin protein P2 while immunofluorescence demonstrated that autologous IgG bound to the myelin of affected nerves. Adenovirus was not detected in neural tissue by immunofluorescence.
Bunton TE.Developmental defects are rarely reported in the horse. Severe craniofacial and central nervous system defects in an equine foetus are described and their possible causation and pathogenesis are suggested.
Wijnberg ID, Graubner C, Auriemma E, van de Belt AJ, Gerber V.Reference values for quantitative electromyography (QEMG) in neck muscles of Royal Dutch Sport horses are lacking. Objective: Determine normative data on quantitative motor unit action potential (QMUP) analysis of serratus ventralis cervicis (SV) and brachiocephalicus (BC) muscle. Methods: Seven adult normal horses (mean age 9.5 standard deviation [SD] ± 2.3 years, mean height 1.64 SD ± 4.5 cm, and mean rectal temperature 37.6 SD ± 0.3°C). Methods: An observational study on QMUP analysis in 6 segments of each muscle was performed with commercial electromyography equipment. Measurements wer...
Dubey JP, Miller S.A 10-year-old pony died 5 days after the onset of a nervous disorder. Necropsy revealed a yellowish area of discoloration (1.5 by 1 cm) in the medulla oblongata. Microscopically, necrosis and nonsuppurative myeloencephalitis were found in the medulla oblongata. Immature and mature meronts (25 by 10 microns) were seen in neural tissue and in capillaries of the brain stem. Organisms were similar structurally to those seen in equine protozoal myeloencephalitis of horses.
Roest HI, de Bruijn CM, Picavet MT, Prins B, Parmentier D, de Zwart GM, Dijkstra YE, van Zijderveld FG.Symptoms, diagnosis and therapy of equine botulism are discussed by the presentation of two detailed reports of horses with neurological symptoms and the results of laboratory investigations over the period 2003-2008 in the Netherlands. In addition a brief summary of the available literature is presented. Prevailing symptoms of botulism in horses include paralysis of the tongue, salvation, dysphagia and paresis and paralysis of the skeletal muscles, as well as signs of colic. Symptoms and prognosis vary with the amount of botulinum neurotoxin (BoNT) involved. For early clinical diagnosis of bo...
Schott HC, Major MD, Grant BD, Bayly WM.Spinal cord compression by melanomas at C7-T1 is described in 2 horses. Despite similar location of the lesions, the onset of neurologic signs and clinical progression varied. Both horses were gray, but few cutaneous melanomas were found. Internal dissemination, however, was extensive in both horses. Antemortem diagnosis was made in one horse, and surgical decompression of the spinal cord was performed. Neoplasms of the vertebral canal and spinal cord are uncommon in horses. Melanoma in the spinal canal should be included in the differential diagnosis of neurologic disease, especially in matur...
Wheeler SJ.Single teased fibre studies were made on samples of the lateral palmar nerve from 16 horses of mixed age and size which had no evidence of neuromuscular disease. Significant proportions of abnormal fibres indicative of axonal degeneration/regeneration and demyelination/remyelination were identified. Measurements of internodal length and fibre diameter were made. Internodal length was shown to be related to fibre diameter, changes in this relationship being mainly influenced by the incidence of abnormal fibres rather than by the age of the horse. Information about the incidence of abnormal fibr...
Mirra A, Klopfenstein Bregger MD, Levionnois OL.A 15-year-old Selle Francais gelding was presented to the equine referral hospital for treatment of a left guttural pouch mycosis previously diagnosed. After induction, the horse was shortly hoisted by all four feet, moved on a padded surgical table, and positioned in right lateral recumbency. In order to reduce the risk of bleeding during surgical manipulation of the carotid and maxillary arteries, a mean arterial pressure between 60 and 70 mmHg was targeted. After surgery, the horse was moved in a padded recovery box keeping the same lateral recumbency. Four unsuccessful attempts were perf...
Carrigan MJ, Higgins RJ, Carlson GP, Naydan DK.A 17-year-old Arabian gelding with progressive neurologic signs had a velvety, reddish brain tumor protruding from the ventral midline caudal to the optic chiasma. Histologically, the tumor had a papillary formation with a single layer of elongate cells radially oriented around a central fibrovascular core. Intracytoplasmic globular inclusions were positive for glial fibrillary acidic protein and weakly positive for vimentin. Ultrastructurally, these inclusions were comprised of whorling intermediate filaments. Neoplastic cells also had cytoplasmic interdigitations and numerous zona adherens a...
Sasaki N, Imamura Y, Sekiya A, Itoh M, Furuoka H.In this study, fasciculation of the limbs and tongue was observed in four horses kept by a riding club. Neurogenic muscle atrophy was also observed in biopsy of pathological tissues. In addition, in two cases that subjected to autopsy, Bunina-like bodies of inclusion in the cell bodies of neurons in the spinal cord ventral horn were confirmed, leading to a diagnosis of equine motor neuron disease (EMND). Serum vitamin E concentrations varied between 0.3 and 0.4µg/ml, which is significantly lower than the levels in normal horses. Although lack of vitamin E is speculated to be a contributory fa...
