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Topic:Nerves
The study of nerves in horses encompasses the structure, function, and disorders of the equine nervous system. This system is responsible for transmitting signals between different parts of the body and coordinating actions and sensory information. Key components include the central nervous system, consisting of the brain and spinal cord, and the peripheral nervous system, which includes nerves extending throughout the body. Research in this area investigates the role of nerves in equine behavior, movement, and response to stimuli, as well as conditions such as neuropathies and nerve injuries. This topic includes a collection of peer-reviewed research studies and scholarly articles that explore the anatomy, physiology, and clinical implications of the nervous system in horses.
[Nucleus motorius medialis in the lumbosacral segment of the spinal cord in horses]. The studies carried out on 2 spinal cords of horses showed that cells of the medial motor nucleus (nucleus motorius medialis) are present in all neuromers of the lumbar and sacral segment of the spinal cord. It lies in the medial part of grey matter of the ventral column, neighbouring laterally and ventrally with cells of the lateral motor nucleus, whereas dorsally with cells of the nucleus of the ventral commissural horn. Along the nucleus numerous constrictions and intervals are found, which are connected with various numbers of nerve cells in particular cross-sections.
[Diagnosis and therapy of guttural pouch diseases in horses]. Using a fibreoptic endoscope ("small gastroscope" with outside diameter of 9.3 mm) a simple and sparing inspection of the guttural pouch is performed. The flap-type tube cover is opened by means of medial leverage with a guidance probe shifted through the work duct of the endoscope. The same procedure is used in diagnostic specimen collection and therapeutical measures such as irrigations. Guttural pouch topography and pathological disorders are illustrated by endoscopic photography. The different diseases such as follicular hyperplasia, ascending pharyngeal catarrh, perforating abscesses of t...
Carotid and cerebral angiography in the horse. Carotid and cerebral angiography has been found to be a relatively simple technique to carry out in the horse. At most it involves a cutdown approach to the carotid artery, followed by catheterisation of the artery and selective catheterisation, if necessary, of one of its three branches. The technique can be carried out with standard equipment normally available within equine hospital facilities. The authors have employed angiography as a routine aid to diagnosis over the past nine years, without encountering any serious complications or adverse reactions. Carotid angiography has been especia...
Facial and vestibulocochlear nerve disease in six horses. In 6 horses, clinical signs of illness implicated a lesion involving the facial and vestibulocochlear nerves. One horse had signs of otitis externa. Five horses had radiographic changes primarily involving periosteal bony proliferation of the stylohyoid bone at its articulation with the temporal bone. Five horses improved with antibiotic therapy. Otitis media-interna was found at necropsy of one horse.
Sensory nerve conduction velocities in forelimb of ponies. Normal nerve conduction velocity values in 10 ponies were determined for sensory nerve fibers in the median and ulnar nerves. A percutaneous signal-averaging technique was developed and used. Medial and lateral palmar digital nerves on the abaxial surface of the proximal sesamoid bones were used as the sites for percutaneous stimulation, whereas recording sites included the medial and lateral palmar nerves just distal to the carpus and the median and ulnar nerves in the middle of the radius. Sensory nerve conduction velocities can be evaluated simply and clinically in the limbs of horses, usin...
The equine spleen: an electron microscopic analysis. The capacity of the equine spleen to store and rapidly release as much as half the circulating blood volume after adrenergic stimulation depends upon the size of the spleen, its muscular capsule, and the distinctive structure of its red pulp. The unit, or lobule, of red pulp is a cylinder of pulp spaces organized in a reticular meshwork, supplied by a peripheral ring of arterial capillaries, and drained by a central venule. Reticular cells, which make up the meshwork of the pulp, contain an extraordinarily large complement of microfilaments and intermediate filaments and are richly innervated ...
Distribution of internal carotid artery blood flow in the pony. This study determined whether blood flow through the internal carotid artery (ICA) could be used to sample total cerebral blood flow in the pony. To answer this question we considered both the anatomic arrangement of the ICA in cadavers and the relative distribution of ICA blood flow to cerebral and extracerebral tissue using radioactive microspheres. Acrylic corrosion casts of the ICA indicated that this vessel traveled directly to the base of the brain, contributing to the formation of the circle of Willis, and did not send any significant branches to other tissues. Two vessels (internal eth...
Electrophysiologic studies of the thoracic limb of the horse. The cutaneous innervation of the thoracic limb was investigated in 18 barbiturate-anesthetized horses, using electrophysiologic techniques. The cutaneous area (CA) innervated by each cutaneous nerve was delineated in at least 4 horses by stroking the hairs with a small watercolor brush while recording from the nerve. Mapping of adjacent CA revealed areas of considerable overlap. The part of a CA of a given nerve supplied only by that nerve is referred to as its autonomous zone (AZ). In contrast to the standard textbook illustrations cutaneous branches of the axillary, radial, musculocutaneous,...
Migration of a spiruroid nematode through the brain of a horse. A pregnant 10-year-old Paint mare was examined because of an acute neurologic disturbance. Physical examination revealed signs consistent with extensive, asymmetric brain stem disease. The hemogram, serum chemical panel, and results of lumbosacral spinal fluid analysis were within normal limits. A primary diagnosis of equine protozoal myeloencephalitis was considered, and the mare was placed on treatment with trimethoprim-sulfadiazine. After 5 weeks of steady improvement, an acute exacerbation of neurologic signs necessitated euthanasia of the mare. At necropsy, large, malacic tracts were foun...
Brain abscess in three horses. Three horses with brain abscesses had different clinical manifestations: 1 had a protracted clinical course whereas 2 had a short clinical course. Clinical signs in 2 horses (1 acute case, 1 chronic case) included unilateral loss of vision, head tilt, circling, abnormal mental status, and ataxia. The 3rd horse had bilateral loss of vision, altered mental status, and apparent deafness. Results of cerebrospinal fluid analysis were inconsistent. The horse with the protracted clinical course had paradoxic central vestibular disease.
Innervation of the equine intrinsic laryngeal muscles. The nerve supply to the intrinsic laryngeal muscles of the horse was studied by gross dissection and by electromyography which was carried out before, during and after section of various intralaryngeal nerve branches. The anatomical relationships and passage of the laryngeal nerves throughout the larynx were defined. Unlike the dog and man there was no evidence of the passage of motor nerve fibres from one side of the larynx to the other.
[Gangliosides of neural and extraneural tissues of various species of mammals]. The ganglioside patterns of the forebrain, cerebellum and brain stem from horse, donkey, mule and goat have been determined by thin-layer chromatography. GM1, GD1a, GD1b and GT1b are the four major brain gangliosides. N-acetylneuraminic acid as the predominant sialic acid (congruent to 97%) and traces of N-glycolyneuraminic acid were found. The four above mentioned major gangliosides were also found in the forebrain, cerebellum and brain stem of adult rats. This pattern is not modified in rats under stress situation (at 4 degrees C for 3 months). In other extraneural organs from rats such as l...
Further observations on the innervation of the proximal sesamoidean ligament of the horse and ox. A vegetative innervation is described for the first time in this district. On the contrary, the finding of Pacini and pacini-like corpuscles, of Golgi Mazzoni's receptors, of muscle spindles and Golgi's tendon-organs testifies the existence of a sensitive innervation in this anatomical territory. According to Karamanlidis free nervous endings are not present. All the above recorded receptors show the typical structure and can be found isolated, grouped to constitute flower-sprays, organized to form opposito-polar corpuscles or associated to originate pecilomorphic fibers. These two last findin...
Proximal equine radial and median motor nerve conduction velocity. Radial and median motor nerve conduction velocities were determined on 10 clinically healthy 1- to 11-year-old ponies. These velocities were obtained by stimulation at the brachial plexus directly through a surgical incision and later in the ambulatory pony via implanted Formvar-coated wire electrodes. Percutaneous stimulation was used at the cubital region in both anesthetized and ambulatory ponies. The values for radial motor nerve fibers ranged from 96.4 to 100 m/s. These were 15.3% faster than previously reported distal values. Median motor nerve fiber values ranged from 86.8 to 90.2 m/s, ...
Laryngeal paralysis in Arabian foals associated with oral haloxon administration. Bilateral laryngeal paralysis is described in 5 Arabian and part-Arabian foals aged between 23 and 35 days. Tracheotomies resulted in complete relief of dyspnoea. Two cases showed recovery of abductor function of the right arytenoid cartilage after 3 weeks and one of these cases later recovered left abductor function. Four of the foals were autopsied at various times from one week to 6 months after the onset of respiratory obstruction. Histology of the recurrent laryngeal nerves showed active Wallerian degeneration and loss of nerve fibres in many fascicles in cases affected for one to 2 weeks...
GnRH localization in the equine brain and infundibulum: an immunohistochemical study. Immunohistochemical localization of the decapeptide gonadotropin releasing hormone (GnRH) in neural structures in the pony brain and infundibulum (INF) was conducted at the light-microscopic level. This procedure utilized an antiserum generated against GnRH conjugated to bovine serum albumin. In the rostral INF, GnRH was distributed mainly in the external layer, with greatest concentrations adjacent to the long capillary loops of the hypophyseal portal system. The intermediate portion of the INF contained the hormone throughout the external layer, especially in the dorsolateral regions just ve...
Brainstem auditory evoked response in the diagnosis of inner ear injury in the horse. Brainstem auditory evoked response (BAER) testing was done to evaluate inner ear/VIIIth cranial nerve (CN8) function in the horse. The BAER test consisted of stimulating the auditory system with clicks and recording far-field responses of the brainstem auditory components via cutaneous electrodes and a signal averaging system. The normal response was shown to be a series of waves occurring within the first 10 msec after the stimulus click. Functional loss of the auditory receptor organ (cochlea) or CN8 results in loss of the entire response on the side of the injury. Because of the anatomic re...
Recovery of peripheral chemoreceptor function after denervation in ponies. Resting ventilation (PaCO2) and ventilatory responses to acute hypoxia and to intravenous NaCN were assessed over a 4-yr period following cutting of the carotid sinus nerves and stripping the adventitia of the aortic arch. The data indicated essentially complete loss of peripheral chemoreceptor function immediately after surgery and hypoventilation during normoxia (delta PaCO2 = +8.7 Torr). There was a time-dependent, partial recovery of peripheral chemoreceptor function between 2 and 22 mo after surgery. Approximately 10% of the ventilatory response to iv NaCN returned, and 30-40% of the norm...
Effects of denervation of the digit of the horse. A study was conducted in an effort to explain why digital necrosis sometimes follows neurectomy in the horse. Six horses were subjected to unilateral section of the medial and lateral palmar nerves. Arteriography was done on each digit prior to surgery. Terminally, arteriography was repeated. Sections of bone, nerve, artery, skin, coronary band, and deep flexor tendon were examined histologically. Changes in arterial pattern and bone quality were noted. During the study, 2 of the horses had clinical signs of digital necrosis. The composite findings suggested trauma or infection, or both, of th...
Cryoneurectomy in the horse. Cryoneurectomy was performed experimentally on 10 digital plantar nerves of normal horses. All nerves were frozen to -30 C, using a double freeze-thaw cycle. Nerves were harvested at 10 days and at 4, 12, 16, and 24 weeks and were examined histologically for evidence of regeneration. The terminal portion of the transected nerves treated with cryosurgery did not have any signs of regeneration or neuroma formation at these periods. Cryoneurectomy was performed on 101 nerves of 32 horses with diseases requiring neurectomy. Twenty-seven of these nerves had been subjected to previous neurectomy, an...
Pathological observations on an outbreak of paralysis in broodmares. A description is given of the pathological changes present in 8 mares which died or were euthanased in the course of an outbreak of paralysis on a Thoroughbred studfarm. In all cases the principal changes were in the central nervous system (CNS) and consisted of a severe and widespread vaculitis in the brain, cord, sheaths of nerves, capsules of ganglia and occasionally elsewhere in the body. Associated with the damage to vessel walls there was haemorrhage and exudation of plasma into the perivascular tissues. Involvement of neurones was minimal and no neuronophagia was present. Six cases had ...
Clinical approach to determine the contribution of the palmar and palmar metacarpal nerves to the innervation of the equine fetlock joint. To determine the sensory nerve supply of the metacarpophalangeal joint, lameness was induced in eight horses by injecting the joint with a glycerin suspension of glass micropheres. When the medial and lateral palmar nerves were anesthetized in 4 horses, there was noticeable improvement in the gait, but each horse remained lame. When the medial and lateral palmar metacarpal nerves were also anesthetized, 3 of the 4 horses became sound. To confirm the results of local anesthesia, neurectomies were performed on a second group of four horses. The lameness was alleviated only upon resection of both...
Basilar skull fractures in three horses. Of three horses with basilar skull fractures, two died within 48 hours. The remaining horse was euthanatized because of a locomotion deficit. Clinical signs included epistaxis followed by ataxia. In each case, the basi-occipital bone and ventral portion of the calvarium were involved in the fracture. Diagnosis was based on clinical signs or radiographic appearance of guttural pouches, or both.
Bilateral ventral accessory neurectomy in windsucking horses. Bilateral neurectomy of the ventral branch of the spinal accessory nerve was performed in an attempt to control windsuckling. There was no permanent improvement in the eight cases described.
[Structure and topography of nucleus dorsalis in the spinal cord of horses]. The material for the study was taken from 2 spinal cords of sexually mature horses. Preparations obtained from this material were stained according to Nissl and with the use of cresyl violet. The nucleus dorsalis of the horse extends from the 8th cervical neuromere to the 3rd lumbar neuromere of the spinal cord. The cells which form this nucleus lie in the grey matter of the spinal cord, dorsolaterally of the central canal. The nucleus dorsalis is made out of large and medium-size round and oval cells. The characteristic feature of the structure and configuration of this nucleus in the horse i...
