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.
Equine laryngeal hemiplegia. Part II. An electron microscopic study of peripheral nerves. The recurrent laryngeal nerves were examined by electron microscopy in five control, four subclinical and four clinical laryngeal hemiplegic horses. In addition, the peroneal nerve was examined in two horses in the latter group. The distally distributed loss of large myelinated fibres in the left recurrent laryngeal nerve seen by light microscopy was confirmed. In addition, active axonal pathology was found to be more evident than indicated by light microscopic investigations. The onion bulb formations observed indicated the repetitive nature of the damaging influence to nerve fibres. Although...
Episodic muscle tremors in a quarter horse: resemblance to hyperkalemic periodic paralysis. A three year old Quarter Horse stallion was presented with a one year history of episodes of generalized muscle tremors and stiffness, and spasm of the muscles of facial expression, lasting 10-15 minutes. Between attacks, the horse was either normal or had a localized muscle tremor in the flank region. Episodes appeared unrelated to exercise. The major abnormal findings included 1) a rise in plasma potassium from a resting level of 4.4 to 7.9 mmol/L during an attack and 2) electromyographic findings of generalized increased insertion activity and myotonic discharges. The horse was treated with...
Stringhalt in horses: a distal axonopathy. A detailed investigation of the neuropathology of a horse affected with stringhalt was performed. Qualitative and quantitative light and electron microscopy, and single teased fibre preparations of peripheral nerve demonstrated predominantly axonal degeneration, the stage of which was appropriate for the duration of clinical signs. There was selective involvement of large myelinated nerve fibres. A proximal to distal increase in the severity of pathological changes was present in the peripheral nerves. The long left recurrent laryngeal nerve was the most severely affected, followed in order by...
Equine protozoal myeloencephalitis in a pony. 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.
Familial congenital occipitoatlantoaxial malformation (OAAM) in the Arabian horse. Familial occipitalization of the atlas with atlantalization of the axis was defined as a single congenital disease in Arabian horses following a clinical, radiologic, and morphologic study of 16 horses with congenital malformations of the occiput, atlas, and axis, and from a study of three reported cases. The constant morphologic features were interpreted as congenital atlantooccipital fusion, hypoplasia of the atlas and dens, malformation of the axis, and modification of the atlantoaxial joint. Atlantoaxial subluxation was also a frequent finding. The clinical syndromes shown by these horses ...
Vertebral body osteomyelitis in the horse. Over a 4-year period, vertebral body abscess was diagnosed in 5 young cattle. The laboratory findings in most of these cases did not suggest a diagnosis of vertebral body abscess. The most important basis for diagnosis of this condition was a thorough neurologic examination. In 4 cases, necropsy revealed abscesses in the lungs or thoracic cavity as well, suggesting that a history of pneumonia preceding paresis may favor the diagnosis of vertebral body abscess.
Hindlimb hyperesthesia associated with rabies in two horses. Rabies was diagnosed in 2 adult Quarter Horses with hindlimb hyperesthesia and progressive weakness. Microscopic examination of the cord and brain of the first horse revealed nonsuppurative meningomyelitis and ganglioneuritis in the cord extending cranially to the 6th cervical segment. Fluorescent antibody test results of both horses were positive for rabies in hindlimb peripheral nerve specimens, but negative in sections of the upper lip. Salivary gland, cerebrum, cerebellum, hippocampus, musculocutaneous nerve, cornea, and optic nerve specimens were tested for rabies by fluorescent antibody ...
Four cases of traumatic optic nerve blindness in the horse. Traumatic optic nerve atrophy is characterised clinically by a unilateral or bilateral sudden onset of blindness. Dilated, fixed pupils and a lack of a menace reflex are the only abnormalities noted soon after the trauma. Within three to four weeks the optic disc becomes paler and the retinal vasculature is markedly decreased. The pathological lesion is a rupture of the nerve axons from stretching forces produced by the posterior movement of the brain against the fixed canalicular portion of the optic nerves. Medical therapy has not been successful.
Postanesthetic hemorrhagic myelopathy in a horse. Acute hemorrhagic myelopathy developed in the sixth cervical to the eighth thoracic spinal cord segments of a 1-year-old Quarter Horse colt that was castrated under general anesthesia while in dorsal recumbency. Clinical signs were consistent with severe transverse myelopathy caudal to the brachial enlargement and cranial to the lumbosacral enlargement of the spinal cord. Histologic examination of the spinal cord revealed hemorrhage in the gray matter, with multiple blood-filled clefts in otherwise normal neuropil. Hemodynamic changes in the spinal cord associated with anesthesia and dorsal re...
[Structure and topography of the nucleus proprius cornus dorsalis of the spinal cord of horses]. The studies performed on spinal cords of two horses revealed that cells of the nucleus of the own dorsal horn are present in all segments of lumbo-sacral part of the spinal cord. The nucleus is composed of two parts: basal and marginal. Basal part is composed of large and medium size cells situated in 2/3 of the lower part of the grey substance of the dorsal horn. The marginal part of the described nucleus is composed of elongated and spindle shaped cells situated along the dorsal margine of the grey substance of the dorsal horn. Continuity of the nucleus in lumbo-sacral part of the spinal cor...
Equine herpesvirus type 1 (EHV-1) induced abortions and paralysis in a Lipizzaner stud: a contribution to the classification of equine herpesviruses. Out of 30 cases of abortion and perinatal deaths in a Lipizzaner stud in Austria 10 mares died after having shown central nervous system disturbances, ataxias and paralysis. The etiological agent of this "abortion storm" was equine herpesvirus type 1 (EHV-1). The restriction enzyme pattern of the DNA from 5 isolates recovered from fetuses has been analyzed and compared with the known reference strains of EHV-1, -2, -4 and an Austrian vaccine strain. The DNA restriction profiles of the Lipizzaner isolates as well as of the vaccine strain could be identified as being typical of abortigenic strai...
[Frontal sinusitis in a horse with a neurological complication]. The case of a horse affected with frontal sinusitis, in which neurological complications occurred following trepanation, is reported. The previous history of the animal as well as the clinical, radiological and pathological findings are discussed.
Paralysis and lipofuscin-like pigmentation of farm stock caused by the plant, Trachyandra laxa var. laxa. A paralytic condition of farm stock in South West Africa, characterized by prominent neuronal and some mild extraneuronal pigmentation, is described. The distribution of the pigment, which was mainly located in the larger neurones of the brain and spinal cord, is given. Experimental evidence, obtained by feeding the plant, is presented that the condition is caused by Trachyandra laxa var. laxa. The histochemical features of the pigment proved to be compatible with a lipofuscin.
A surgical approach to treatment of suprascapular nerve injury in the horse. Suprascapular nerve decompression has proven to be a useful treatment for refractory neuropraxia in horses. The surgical procedure used to effect that decompression is described. The surgery can be undertaken when conservative treatment has failed, but the sooner the surgery is done, the more likely the muscle mass is to be cosmetically satisfactory.
Powassan viral encephalitis: a review and experimental studies in the horse and rabbit. Powassan virus strain M794, a member of the Flavivirus genus known to infect man and animals in Canada, was inoculated intracerebrally into rabbits and horses. No clinical signs were observed in rabbits, but widespread encephalitis resulted, characterized by lymphoid perivascular cuffing, lymphocytic meningitis, and lymphocytic choroiditis. In horses, eight days after inoculation, prominent neurological signs occurred and lesions were those of non-suppurative encephalomyelitis, neuronal necrosis, and focal parenchymal necrosis. The virus could not be reisolated from the rabbit or horse brains....
Degenerative optic neuropathy in a horse. The research article discusses a case of blindness in a horse due to degeneration of the optic nerves and tracts and explores potential causes for the condition. Case Presentation and […]
Antibodies against equine herpesvirus 1 in the cerebrospinal fluid in the horse. Neutralizing antibodies against equine herpesvirus 1 were measured in serum and cerebrospinal fluid of 16 horses and ponies from a closed herd both before and after vaccination with modified live equine herpesvirus 1. These titers were also measured in 22 neurologically normal and 15 neurologically abnormal horses at a teaching hospital. Animals from the closed herd had prevaccination serum titers up to 1:8 and postvaccination serum titers up to 1:128. Horses from the teaching hospital had serum titers up to 1:64. Cerebrospinal fluid titers were not detected in the vaccinated horses or the neu...
Occipitoatlantoaxial malformation in two non-Arabian horses. 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...
Bilateral laryngeal paralysis in the horse. Four two-year-old Thoroughbreds suffered an acute gastrointestinal illness shortly after dosing with mineral oil which was thought to have been contaminated with an organophosphate compound. Three weeks later all four were noted to be dyspnoeic and endoscopic examination showed that they had developed bilateral laryngeal paralysis. Two of the horses died during severe bouts of dyspnoea six and eight months later and the third was killed shortly thereafter. Examination of the left and right recurrent laryngeal nerves from these horses showed a severe loss of myelinated fibres distally, especial...
Neurologic diseases. The responses of apparently healthy newborn foals to neurologic testing differ significantly from those of adult horses. These responses and the diagnostic techniques pertinent to neurologic problems are reviewed as a basis for evaluation of the compromised neonatal foal. The more frequently encountered neurologic diseases are discussed in a problem-oriented format. These clinical problems include behavioral abnormalities, convulsions, changes in consciousness, blindness, ataxia without loss of strength, ataxia with weakness and paralysis, and the floppy foal.
Ataxia and weakness associated with fourth ventricle vascular anomalies in two horses. Two adult horses with progressive neurologic signs were examined clinically and at necropsy. Both horses had signs of progressive ataxia and weakness, clinically diagnosed as spinal cord in origin. Differential diagnoses for cervical spinal ataxia in horses included cervical vertebral malformation, equine degenerative myeloencephalopathy, equine herpes-virus-I myeloencephalopathy, and equine protozoal myeloencephalopathy. Necropsy findings in both horses were similar and consisted of a large hematoma in the fourth ventricle, with upward compression of the cerebellum and downward compression of...
Vertebral fracture, extensor hypertonia of thoracic limbs, and paralysis of pelvic limbs (Schiff-Sherrington syndrome) in an Arabian foal. An Arabian foal, which was recumbent for 4 days, had signs of extensor rigidity of the thoracic limbs and hypotonic paralysis of the pelvic limbs. Survey radiography revealed a lesion at T15, with radiographic impression of a compression fracture or a hemivertebra. Postmortem examination revealed a fracture at T15. Clinical and pathologic findings in this case were compatible with the Schiff-Sherrington syndrome, which is characterized by thoracic limb extensor hypertonia associated with paraplegia from acute thoracolumbar trauma.