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.
Klebe EA, Holcombe SJ, Rosenstein D, Boruta D, Bartner LR, Tessier C.Dysfunction of the glossopharyngeal nerve has been implicated as a cause of dysphagia in horses. However, recent studies have indicated that this is not the case. Objective: To determine whether bilateral glossopharyngeal nerve anaesthesia would cause dysphagia in horses or result in measurable alterations in the timing, function, or sequence of swallowing. Methods: Swallowing was evaluated in 6 normal horses with and without bilateral glossopharyngeal nerve anaesthesia. Swallowing dynamics were assessed subjectively and objectively based on time from prehension of food until swallowing, numbe...
Bolt DM, Burba DJ, Hubert JD, Strain GM, Hosgood GL, Henk WG, Cho DY.To determine functional and morphologic changes in palmar digital nerves after nonfocused extracorporeal shock wave (ESW) treatment in horses. Methods: 6 horses. Methods: The medial and lateral palmar digital nerves of the left forelimb were treated with nonfocused ESWs. The medial palmar digital nerve of the right forelimb served as a nontreated control nerve. At 3, 7, and 35 days after treatment, respectively, 2 horses each were anesthetized and nerves were surgically exposed. Sensory nerve conduction velocities (SNCVs) of treated and control nerves were recorded, after which palmar digital ...
McBride SD, Hemmings A.Stress-induced changes in mesoaccumbens dopamine neurophysiology have been associated with the development of stereotypic behaviour in in-bred strains of laboratory rodents. This experiment evaluated whether similar changes are associated with environmentally-induced stereotypic behaviour in a higher-vertebrate species, the horse. D1- and D2-like dopamine receptor densities (B(max)) and dissociation constants (K(d)) were measured in control (n=9) and stereotypy (n=9) horses in the nucleus accumbens, caudate nucleus, putamen, substantia nigra and ventral tegmentum brain regions. Results reveale...
Prieto D, Arcos LR, Martínez P, Benedito S, García-Sacristán A, Hernández M.The distribution of neuropeptide Y (NPY)-immunorective nerves and the receptors involved in the effects of NPY upon electrical field stimulation (EFS)- and noradrenaline (NA)-elicited contractions were investigated in horse penile small arteries. NPY-immunoreactive nerves were widely distributed in the erectile tissues with a particularly high density around penile intracavernous small arteries. In small arteries isolated from the proximal part of the corpora cavernosa, NPY (30 nM) produced a variable modest enhancement of the contractions elicited by both EFS and NA. At the same concentration...
McCann JL, Dixon PM, Mayhew IG.Disorders of the equine sphenopalatine sinus, including empyema and neoplasia, have been reported to cause damage to cranial nerves II and V. However, the clinical anatomy of these sinuses is not well described in horses. Objective: To examine the anatomy of the sphenopalatine sinuses in a range of equidae and, in particular, to examine the relationship of these sinuses to adjacent major nerves and vessels. Methods: The anatomy of the sphenoidal and palatine paranasal sinuses was examined in 16 equidae, primarily using transverse skull sections. Relevant structures were documented and photogra...
Watanabe T, Hosaka Y, Yamamoto E, Ueda H, Tangkawattana P, Takehana K.The Golgi tendon organ (GTO) is an encapsulated fusiform mechanoreceptor siding in the musculo-tendinous junction of many animal species. Inhibitory function of afferent nerve fibers distributed from nearby motor units, the organ responds to active tension exerted onto the muscle. The morphological features of the equine GTO have not yet been elucidated. Additionally, there is some controversy regarding to the existence of the GTO in the equine superficial digital flexor tendon (SDFT). Therefore, immunohistochemistry and immunoelectron microscopy using alcian blue (pH 2.5) staining and the sil...
Wilkie DA, Gilger BC.Glaucoma is a diverse group of vision-impairing disorders that have as a common bond an elevation of intraocular pressure(IOP) to a level incompatible with the health of the eye. Glaucoma can be congenital, primary, or secondary. Congenital equine glaucoma is associated with developmental abnormalities of the iridocorneal angle or, in many cases, with the more severe anterior segment dysgenesis.
Schumacher J, Livesey L, DeGraves FJ, Schumacher J, Schramme MC, Hathcock J, Taintor J, Gomez J.Anaesthesia of the palmar digital nerves is claimed to attenuate lameness in some horses that are lame because of pain in the proximal interphalangeal (PIP) joint. Objective: To determine the response of horses with pain in the PIP joint to anaesthesia of the palmar digital nerves. Methods: Horses were video recorded trotting before and after induction of pain in the PIP joint and 10 mins after anaesthesia of the palmar digital nerves. The palmar digital nerves were anaesthetised 3 times at different sites, and the video recorded gaits were scored subjectively. Results: The median lameness sco...
Velde K, Ross MW, Orsini JA, Parente EJ, Foley B, Richardson DW, Miselis RR.To study the fascicular anatomy of peripheral nerves, three different groups of retrograde axonal tracers were evaluated: fluorophores, horseradish peroxidase conjugated to subunit B of cholera toxin (CT-HRP), and adeno-associated virus (AAV). The hindlimb nerves in rats served as a model to identify the most efficient tracer in regard to labeling axons within peripheral nerves. The rat's tibial and common peroneal nerves were injected with the different tracers and the sciatic nerve was subsequently examined for evidence of labeled axons. The CT-HRP clearly provided the best results in this r...
Tessier C, Holcombe SJ, Derksen FJ, Berney C, Boruta D.Nasopharyngeal collapse has been observed in horses as a potential cause of exercise intolerance and upper respiratory noise. No treatment is currently available and affected horses are often retired from performance. Objective: To determine the effect of bilateral glossopharyngeal nerve block and stylopharyngeus muscle dysfunction on nasopharyngeal function and airway pressures in exercising horses. Methods: Endoscopic examinations were performed on horses at rest and while running on a treadmill at speeds corresponding to HRmax50, HRmax75 and HRmax, with upper airway pressures measured with ...
MacKay RJ.Brain injury after impact to the head is due to both immediate mechanical effects and delayed responses of neural tissues. In horses, traumatic brain injury occurs in three main settings: (1) poll impact in horses that flip over backwards; (2) frontal/parietal impact in horses that run into a fixed object, and (3) injury to the vestibular apparatus secondary to temporohyoid osteoarthropathy. Distinct forebrain, vestibular, midbrain, hindbrain, or multifocal syndromes may be encountered in horses with traumatic brain injury. The most important components of treatment are those consistent with p...
Recio P, Prieto D, Martínez MP, García P, Rivera L, Benedito S, Martínez AC, Sacristán AG, Orensanz LM, Hernández M.Our aim was to study the presence of noradrenergic nerves and to characterize the alpha-adrenergic receptors involved in the contractions to electrical field stimulation and to alpha-adrenergic agonists of the horse penile deep dorsal vein. Noradrenergic fibres were visualized by immunohistochemistry using an antibody against dopamine-beta-hydroxylase (DBH). For functional studies, the responses of the venous rings to electrical field stimulation and to alpha-adrenergic agonists (noradrenaline, phenylephrine and BHT 920) were studied in the absence and the presence of noradrenergic transmissio...
Verdegaal EJ, Kroeze EJ, Dik KJ, van Oijen LA, Sloet van Oldruitenborgh-Oosterbaan MM.A 9-year-old Dutch Warmblood mare was presented with a history of abnormal behaviour and acute facial nerve paralysis on the left side. Clinical examination revealed a slight head tilt and a corneal ulcer of the left eye. The base of the left ear was warm and painful. Endoscopic examination of the left guttural pouch showed thickening of the proximal part of the stylohyoid bone. Computer tomography revealed a left-sided prominent bony enlargement of the middle and proximal part of the stylohyoid bone and the tympanic bulla, fusion of the temporrhoid joint, and osseous proliferation of the pars...
Yadernuk LM.A 13-year-old broodmare was referred for weight loss and left facial nerve paralysis. Bilateral temporohyoid osteoarthropathy was diagnosed based on proliferation of the temporohyoid joints and stylohyoid bones on radiographs and guttural pouch endoscopy. The left side was more severely affected. Treatment resulted in little or no improvement.
Margalit E, Sadda SR.A variety of disease processes can affect the retina and/or the optic nerve, including vascular or ischemic disease, inflammatory or infectious disease, and degenerative disease. These disease processes may selectively damage certain parts of the retina or optic nerve, and the specific areas that are damaged may have implications for the design of potential therapeutic visual prosthetic devices. Outer retinal diseases include age-related macular degeneration, pathologic myopia, and retinitis pigmentosa. Although the retinal photoreceptors may be lost, the inner retina is relatively well-preser...
Zarucco L, Swanstrom MD, Driessen B, Hawkins D, Hubbard M, Steffey EP, Stover SM.To develop and test an experimental model for in vivo short-term recording of peak isometric forces of the digital flexor muscles in the forelimb of adult horses. Methods: In vivo experimental study. Methods: Four healthy, anesthetized, adult Thoroughbred horses (3 to 7 years old; 527 +/- 87 kg) Methods: In dorsal recumbency, ulnar and median nerves were exposed and instrumented with insulated bipolar cuff stimulation electrodes for later connection to an electrical stimulator. In left lateral recumbency, a biplanar fixator was applied to the right humerus and a custom-made, rigid, aluminum fr...
Hellyer PW, Bai L, Supon J, Quail C, Wagner AE, Mama KR, Magnusson KR.To test the hypothesis that the distribution, density, and subtype of opioid and alpha (alpha)-2 adrenergic receptors within the central nervous system (CNS) are significantly different between horse and dog. Methods: Prospective experimental study. Methods: Three dogs (3 years of age) and three horses (2-5 years of age). Animals were opioid- and alpha-2 agonist-free at the time of euthanasia. Methods: Brain tissue was obtained at 126 days post-surgery from dogs and 72 days post-surgery from horses. The brains were removed, sectioned coronally into 1-cm slabs, frozen in methylbutane, which was...
Alexander K, Dobson H.A study of the ultrasonographic appearance and size of the sciatic, tibial, peroneal, suprascapular, radial, median, and ulnar nerves and a comparison with the anatomic size and location of these nerves in the normal adult horse is reported. Cadavers and live horses were studied. Landmarks for localization and techniques for nerve identification are described. The depth and diameter of each nerve at various locations and the success rate in imaging each nerve are reported. Statistically significant correlations were found between anatomically and ultrasonographically measured nerve depths and ...
Seino KK, Foreman JH, Greene SA, Goetz TE, Benson GJ.Capsaicin is a local substance P depleter with dramatic analgesic effects. We tested the hypothesis that the topical application of capsaicin ointment over the palmar digital nerves would attenuate the clinical effects of a reversible model of equine foot lameness. Seven healthy adult horses shod unilaterally with adjustable heart bar shoes were studied in a crossover design for 2 weeks. Grade 5.0/5.0 lameness (nonweight bearing) was induced by tightening the adjustable heart bar shoe. One hour later, capsaicin ointment was applied over the medial and lateral palmar digital nerves 3 cm proxima...
López-Sanromán J, Cruz J, Santos M, Mazzini R, Tabanera A, Tendillo FJ.The objective of this study was to determine the effects of the alkalinization on the local analgesic efficacy of 1% ketamine in the abaxial sesamoid nerve block in horses. Thirty-six mature healthy horses were randomly assigned to four groups for the following treatments; an abaxial sesamoid block with 5 mL of saline solution (control saline); an abaxial sesamoid block with 5 mL of a solution containing 1% ketamine (KETs 1%); an abaxial sesamoid block with 5 mL of a solution containing saline solution and 0.5 mEq of sodium bicarbonate (control bicarbonate); and an abaxial sesamoid block with ...
Spadavecchia C, Arendt-Nielsen L, Andersen OK, Spadavecchia L, Doherr M, Schatzmann U.To compare nociceptive withdrawal reflexes (NWRs) evoked from the distal aspect of the left forelimb and hind limb in conscious standing horses and to investigate NWR recruitment for graded electrical stimulation intensities. Methods: 20 adult horses. Methods: Surface electromyographic (EMG) activity evoked by transcutaneous electrical stimulation of the digital palmar (or plantar) nerve was recorded from the common digital extensor and cranial tibial muscles. Stimuli consisted of 25-millisecond train-of-5 constant current pulses. Current intensity was gradually increased until NWR threshold i...
Fulton IC, Stick JA, Derksen FJ.Left laryngeal hemiplegia is a frustrating condition for the equine athlete and equine veterinarian. Treatment for the past 30 years has centered on the prosthetic laryngoplasty ("tie-back") with or without ventriculectomy. Laryngeal reinnervation has been used successfully in people and has been shown experimentally to benefit affected horses. This article reviews equine laryngeal reinnervation using the nerve muscle pedicle graft and describes the surgical technique, its complications, and the follow-up in 146 cases treated over the past 10 years. Also discussed is ongoing research into stim...
López-Sanromán FJ, Cruz JM, Santos M, Mazzini RA, Tabanera A, Tendillo FJ.To evaluate the local analgesic effect of ketamine in a palmar digital nerve block at the base of the proximal sesamoid (abaxial sesamoid block) in horses. Methods: 36 mature healthy Andalusian horses. Methods: Horses were randomly assigned to 4 groups of 9 horses each and received an abaxial sesamoid block in a randomly chosen forelimb with 1 of the following: saline (0.9% NaCl) solution, 1% ketamine solution, 2% ketamine solution, or 3% ketamine solution. To determine analgesia, the radiant heat lamp-hoof withdrawal model was used as a noxious thermal stimulus. Before each nerve block, basel...
Chou CC, Vickroy TW.To determine the presence of adenosine receptor subtypes A1 and A2a in equine forebrain tissues and to characterize the interactions of caffeine and its metabolites with adenosine receptors in the CNS of horses. Methods: Brain tissue specimens obtained during necropsy from 5 adult male research horses. Methods: Membrane-enriched homogenates from cerebral cortex and striatum were evaluated by radioligand binding assays with the A1-selective ligand [3H]DPCPX and the A2a-selective ligand [3H]ZM241385. Functional responses to adenosine receptor agonists and antagonists were determined by a nucleot...
Prince D, Corcoran BM, Mayhew IG.Equine grass sickness is a dysautonomia characterised by widespread destruction of autonomic ganglia, resulting in the clinical signs of dysphagia, constipation, profuse sweating, tachycardia, rhinitis sicca and high mortality rate. Rhinitis sicca is a common finding in horses with the chronic form and we have postulated that alterations in autonomic innervation of the nasal mucosa might underlie this clinical presentation. Objective: In this study, the expression and distribution of nerve fibres immunoreactive for calcitonin gene-related peptide (CGRP), substance P (SP), the general neuronal ...
Wijnberg ID, van der Kolk JH, Franssen H, Breukink HJ.To determine whether electromyographic abnormalities are evident in skeletal muscles in horses with induced hypocalcemia and hypomagnesemia. Methods: 7 healthy adult Dutch Warmblood horses. Methods: Electromyographic examination was performed in the lateral vastus, triceps, and subclavian muscles before and after IV infusion of EDTA. An initial dose (mean +/- SD, 564+/-48 ml) of a 10% solution of sodium EDTA was administered IV during a period of 21+/-73 minutes to establish a blood concentration of ionized calcium of approximately 0.5 mmol/L. Average rate of EDTA infusion to maintain ionized ...
Rozovsky I, Hoving S, Anderson CP, O'Callaghan J, Finch CE.Premarin, which contains several equine estrogens, as well as estradiol (E2) as a minor component, is widely used for replacement therapy of estrogen deficits, but little is known of its direct actions on brain cells. In mixed glial cultures, apolipoprotein E (apoE) and glial fibrillary acidic protein (GFAP) are induced by estrogens. GFAP induction showed an inverted-U shape E2 dose response, with a maximum induction at 1 pM, whereas apoE mRNA induction was greatest at 100 pM. GFAP and ApoE mRNAs were induced by equine estrogens in the following order: E2=equilin>estrone>17 alpha-dihydro...
Delacalle J, Burba DJ, Tetens J, Moore RM.To report an neodymium:yttrium-aluminum garnet (Nd:YAG) laser-assisted modified Forssell's surgical technique and outcome for treatment of cribbing (crib-biting) in horses. Methods: Retrospective clinical study. Methods: Ten adult horses with stereotypic cribbing behavior. Methods: Data were obtained from medical records and telephone conversations with owners, trainers, and veterinarians. Surgical technique involved an approximately 34-cm ventral median skin incision starting rostral to the larynx and extending caudally. A 10-cm section of the ventral branch of the spinal accessory nerve was ...
Wijnberg ID, Franssen H, van der Kolk JH, Breukink HJ.To evaluate the application of analysis of motor unit action potentials (MUAP) in horses and to obtain values of MUAP for the subclavian muscle of horses. Methods: 10 healthy adult Dutch Warmblood horses. Methods: Electromyographic examination of the subclavian muscle in conscious nonsedated horses was performed to evaluate insertional activity, spontaneous activity, MUAP variables, and recruitment patterns. Muscle and body temperatures were measured at the beginning and end of the procedure. Amplitude, duration, number of phases, and number of changes in direction (ie, turns) for all represen...
Manso-Díaz G, García-Real MI, Casteleyn C, San-Román F, Taeymans O.Noncontrast magnetic resonance angiography (MRA) is widely used in human and small animal medicine. However, this technique has not yet been described in the horse, and compared to other angiographic techniques MRA could be more cost efficient and potentially safer. Objective: The aim of this study was to provide a comprehensive anatomical reference of the normal equine head vasculature using a noncontrast MRA technique, on both low- and high-field MRI. Methods: Five healthy adult horses were examined, 4 with a low-field magnet (0.23T) and the remaining one with a high-field magnet (1.5T). The...
Cruz-Sanabria JA, Gaschen L, Bragulla HH, Mitchell M, Leise BS.To develop an ultrasound-guided cervical perineural injection technique for horses and to evaluate and compare the distribution of contrast agent among perineural, intra-articular and periarticular injections. Methods: Prospective, experimental cadaveric study. Methods: A total of 14 equine cadaveric necks. Methods: Bilateral ultrasound-guided perineural injection technique for the caudal cervical spinal nerve roots (CSNRs 5-7) was developed. Paramagnetic or iodinated contrast was injected and the distribution of contrast was evaluated using magnetic resonance (MR) or computed tomography (CT) ...
Sonea IM, Bowker RM, Robinson NE, Broadstone RV.Immunohistochemical methods were used to determine the distribution of pulmonary nerves containing either an enzymatic marker of adrenergic nerves, dopamine beta hydroxylase, or the putative neurotransmitter neuropeptide Y in 7 equids with healthy lungs. Nerves immunoreactive for these substances were found on airway smooth muscle in nearly all the samples of healthy equine lung examined. These nerves were generally more numerous in the larger airways but could be detected even in noncartilaginous bronchioles. Pulmonary and bronchial vessels also contained numerous immunoreactive nerves. On th...
Seabaugh KA, Selberg KT, Valdés-Martínez A, Rao S, Baxter GM.To investigate tissue diffusion of anesthetic agent following administration of low palmar nerve blocks (LPBs) in horses. Methods: Randomized clinical trial. Methods: 12 adult horses. Methods: In 9 horses, mepivacaine hydrochloride-iohexol (50:50 dilution) injections were administered bilaterally (2 or 4 mL/site) to affect the medial and lateral palmar and palmar metacarpal nerves (4 sites). Lateral radiographic views of both metacarpal regions were obtained before and at 5, 15, 30, 60, 90, and 120 minutes after block administration; proximal and distal extents of contrast medium (and presumab...
Johnson JP, Peckham RK, Rowan C, Wolfe A, O'Leary JM.Blinded techniques to desensitize the inferior alveolar nerve (IAN) include intraoral, angled, and vertical extraoral approaches with reported success rates of 100%, 73%, and 59%, respectively. It has not been determined whether an ultrasound-guided extraoral approach is feasible. Further, the fascicular nature of the inferior alveolar and lingual nerves of the horse has not been described. The objectives of this study were to describe a low-volume ultrasound-guided vertical extraoral inferior alveolar nerve block technique and to describe the fascicular nature of these nerves. An ultrasound-g...
Faramarzi B, Lantz L, Lee D, Khamas W.The digital cushion (DC) plays a role in absorbing and dampening forces applied to the foot and therefore supports internal structures such as navicular bone; yet, its architecture is not well-known. The goal of this study was to characterize the microanatomical structure of the DC in horses with clinically sound hooves. Both forefeet from the cadavers of 12 adult Quarter horses were cut and sectioned and samples of the following 4 regions of the DC were obtained: axial proximal (AxProx), axial distal (AxDis), abaxial lateral (AbxLat), and abaxial medial (AbxMed). The samples were processed an...
Virgin JE, Holcombe SJ, Caron JP, Cheetham J, Kurtz KA, Roessner HA, Ducharme NG, Hauptman JG, Nelson NC.Pharyngeal dysphagia is a debilitating, sometimes fatal condition in horses, with multiple aetiologies. The pathophysiology is complex and not fully understood. Treatment is largely supportive. Laryngeal advancement surgery may diminish symptoms of dysphagia and improve swallowing in affected horses. Objective: 1) to induce reversible moderate and marked pharyngeal dysphagia by regional anaesthesia of branches of the glossopharyngeal (IX), vagus (X) and hypoglossal (XII) nerves; 2) to characterise the dysphagia produced by each model; and 3) to determine whether laryngeal advancement surgery i...
Valberg SJ.Clinical signs that are easily referred to spinal muscle pathology include atrophy of epaxial muscles, focal swelling and palpable tenderness, as well as enlarged muscles with increased tone. Less easily recognized signs include rigidity of the spine, shortened stride, hindlimb lameness, and indicators of poor performance. Muscle biopsy is one option in evaluating sore backs and is best used when physical examination and imaging procedures do not reveal a likely diagnosis or when conventional treatments are unsuccessful. Rhabdomyolysis of spinal muscles may be due to nutritional myodegeneratio...
Johnson JP, Vinardell T, David F.Ultrasound-guided injections can be used for a wide variety of conditions in the horse, including both diagnostic and therapeutic applications. Benefits of ultrasound guidance include more accurate deposition of injectate compared with blind approaches. Improved identification of vital structures, including nerves and blood vessels, allows their avoidance and thus reduces procedure-associated complications. Validation of such ultrasound-guided techniques has shown that they can be easily learnt by inexperienced veterinarians, assuming a proper knowledge of the sonographic anatomy. In many case...
Roßgardt J, Heilen LB, Büttner K, Dern-Wieloch J, Vogelsberg J, Staszyk C.In the crown pulp of brachydont teeth, a cell-free and a cell-rich zone are established beneath the odontoblastic layer, indicating a mature status. For the equine dental pulp, there are no descriptions which allow for a comparative analysis with regard to functional requirements in terms of lifelong secondary dentin production to compensate for occlusal wear. For histomorphological and immunohistological investigations, ten incisors and ten check teeth were used from seven adult horses and five foals. In the periphery of the equine dental pulp, a constant predentin and odontoblastic cell laye...
Sheldon SA, Aleman M, Costa LRR, Santoyo AC, Weich KM, Howey Q, Madigan JE.Trigeminal-mediated headshaking results from a low threshold for firing of the trigeminal nerve. A seasonal component has been implicated in onset of clinical signs, which occur during the spring and summer months. Geldings are overrepresented in the affected population and hormonal differences as compared to a healthy control population of geldings might contribute to headshaking. Objective: To assess concentrations of luteinizing hormone (LH) over an 8-hour period in gelded healthy controls and horses affected with headshaking. Our hypothesis was that geldings with seasonal headshaking would...
Milner PI, Dimmock O, Barnes K.Neurovascular variation may be relevant when performing surgical techniques to the proximal plantar metatarsal region. Objective: To document variations in the neurovascular anatomy of the proximal plantar metatarsal region and study the relationship of the neurovascular components to each other and other structures located in this area. Methods: Descriptive anatomical study. Methods: Paired cadaver hind limbs from 15 horses were dissected from the distal tibia to the metatarsophalangeal joint. Deep branch of the lateral plantar nerve (DBLPN) length, location of its origin from the lateral pla...
López-Sanromán FJ, Cruz JM, Santos M, Mazzini RA, Tabanera A, Tendillo FJ.To evaluate the local analgesic effect of ketamine in a palmar digital nerve block at the base of the proximal sesamoid (abaxial sesamoid block) in horses. Methods: 36 mature healthy Andalusian horses. Methods: Horses were randomly assigned to 4 groups of 9 horses each and received an abaxial sesamoid block in a randomly chosen forelimb with 1 of the following: saline (0.9% NaCl) solution, 1% ketamine solution, 2% ketamine solution, or 3% ketamine solution. To determine analgesia, the radiant heat lamp-hoof withdrawal model was used as a noxious thermal stimulus. Before each nerve block, basel...
Wood AD, Sinovich M, Prutton JSW, Parker RA.To evaluate the accuracy of ultrasonographic guidance for injection near the ventral rami of the cervical spinal nerves (VRCSN). Methods: Ex vivo study. Methods: Ten cadavers (n = 40 injections). Methods: Left and right VRCSN at C4/5 and C5/6 were infiltrated at the intervertebral foramen (IVF) under ultrasonographic guidance. A vertically orientated 3.5-MHz curvilinear probe was used to identify the craniocaudal midpoint of the articular process joint (APJ). The probe was moved ventrally until the IVF was identified. An 18-gauge 15-cm-long spinal needle was aimed immediately below the ventral...
Guo X, Aoyama M, Sugita S.Three optic nerves (L1, R2, R3) 12-18 mm behind the eyeball of the horse (Thoroughbred) were investigated quantitatively under light and electron microscopes. Thin sections at the thickness of 0.35 microm were cut, stained by toluidine blue and observed under the light microscope. The areas of the optic nerve and the axon bundles were 20.03 +/- 1.04 and 16.59 +/- 0.79 mm2 (mean +/- SD, n=3), respectively. The axon numbers for optic nerve L1, R2 and R3, estimated from light micrographs, were about 481 x 10(3), 543 x 10(3), and 494 x 10(3), respectively. Axons of optic nerve L1 were also counted...
Yachida Y, Kashiwagi M, Mikami T, Tsuchihashi K, Daino T, Akino T, Gasa S.A novel galactosylalkylglycerol modified with a long-chain cyclic acetal at the sugar moiety, 3-O-(4'6'-plasmalogalactosyl) 1-O-alkylglycerol, was isolated from equine brain. The presence of cyclic acetal linkage, its linked position, and the length of the acetal chain of the natural plasmalo lipid were determined by proton NMR spectroscopy and fast-atom bombardment;-mass spectrometry, as well as gas chromatography;-mass spectrometry and gas;-liquid chromatography. To identify the isomeric stereostructure of the natural product, the plasmalo derivative was chemically synthesized from 3-O-galac...
José Antonio G, Jim S, Ramés SJ, Rohrbach BW, Alejandro Rodríguez M, Laura Romero R, Robert D.To examine changes occurring in normal pelvic suspensory ligaments (SLs) of horses after denervating these ligaments and to investigate the effect chronic inflammation might have on these changes. Methods: 10 horses. Methods: The SL of 1 randomly selected pelvic limb of each of 5 horses was injected with collagenase to induce desmitis, and 42 days later, the proximal aspect of both pelvic SLs were denervated. The SLs were harvested 120 days after being denervated, and the morphological and histological characteristics of each collagenase-injected, denervated SL were compared with those of the ...
Pickles K.Horses with trigeminal mediated headshaking (TMHS) have a decreased activation threshold of the trigeminal nerve and clinical signs are suspected to be a manifestation of trigeminal neuralgia. Electrical nerve stimulation (ENS) is used for management of neuralgia in humans and appears to work via gate control theory. Use of an equine specific percutaneous ENS program in over 130 TMHS horses has resulted in approximately 50% success return to previous work. Electroacupuncture may also be useful in the management TMHS. Optimization of ENS procedures for TMHS is likely to require a greater unders...
Lopez-Navarro G, Trigo-Tavera FJ, Rodriguez-Monterde A, Gutierrez-Ospina G, Arechavaleta-Velasco M, Schumacher J, Schumacher J.Proximal suspensory desmitis (PSD) is a common cause of lameness in the pelvic limb, but could also affect the thoracic limb of competing and non-competing horses. Most horses diagnosed with PSD in a thoracic limb respond to rest followed by controlled exercise, but in a small percentage of affected horses, lameness persists. In one study, four horses chronically lame because of PSD in a thoracic limb became sound after neurectomy of the deep branch of the lateral palmar nerve (DBLPaN), which innervates the proximal aspect of the suspensory ligament (SL; Guasco et al., 2013). Whether neurectom...
Arrighi S, Domeneghini C.An immunohistochemical study was carried out on specimens of testis, excurrent duct including the male accessory glands and urethra in its various tracts in the horse and the donkey, in order to localize nine regulatory peptides. Immunoreactivities were tested by means of Labelled Strept Avidin-Biotin (LSAB) method. The study has shown that Equine male genitalia are supplied by many peptide immunoreactive nerves containing NPY-, VIP-, leu- and met-Enkephalin-, Substance P-, CGRP- and Bombesin/GRP-like peptides, each of them having a characteristic distribution pattern. These neurotransmitters ...
McCann JL, Dixon PM, Mayhew IG.Disorders of the equine sphenopalatine sinus, including empyema and neoplasia, have been reported to cause damage to cranial nerves II and V. However, the clinical anatomy of these sinuses is not well described in horses. Objective: To examine the anatomy of the sphenopalatine sinuses in a range of equidae and, in particular, to examine the relationship of these sinuses to adjacent major nerves and vessels. Methods: The anatomy of the sphenoidal and palatine paranasal sinuses was examined in 16 equidae, primarily using transverse skull sections. Relevant structures were documented and photogra...
Gaynor JS, Hubbell JA.Local and regional anesthetic techniques are useful tools for the equine practitioner. These techniques allow surgery to be performed without the risk and cost of general anesthesia. There are, however, risks associated with the local and regional techniques. Neurotoxicity, although rare, may occur when 200 mL or more of a local anesthetic are infiltrated in a short period of time to a 450-kg horse. More likely, horses may become ataxic after nerve blockade in the limbs. This ataxia may lead to self trauma because the horse may not know where the limbs are actually being placed. Although local...
Bengtsdotter EA, Ekman S, Andersen PH.Inguinal pain, unexplained hind limb lameness, back pain or behavioural problems in geldings could be attributable to painful neuromas that develop as a consequence of crushing and severing the testicular nerves during castration. The presence of neuroma in this anatomical location has never been reported, hence the knowledge of possible clinical relevance is limited. The aim of this study was to histologically investigate the testicular nerves at the castration site in geldings for the presence of neuromas. Proximal spermatic cord remnants were collected from 20 geldings admitted to routine p...
Cahill JI, Goulden BE, Jolly RD.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...
Kitchell RL, Stromberg MW, Davis LH.Quantitative studies were made of cells in the dorsal motor nucleus of the vagus nerve in the horse, dog, cat, pig, sheep, goat, and calf. This nucleus was larger in ruminants than in nonruminants. Some cells in all parts of the nucleus supplied visceral structures in the head, cervical, thoracic, and abdominal regions; however, a definite topographic localization did exist within the nucleus. Eighty percent of the cells which supplied the abdominal viscera were in the rostral and rostral-middle regions. The cells which supplied the thoracic viscera were distributed almost equally within the r...
Harding PG, Smith RL, Barakzai SZ.To compare two approaches to performing the inferior alveolar nerve block in the horse and to evaluate the consistency of described topographical landmarks. Methods: Experimental cadaver model. Methods: Eleven cadaver heads were positioned to mimic a standing sedated horse and the position of the mandibular foramen approximated. The vertical approach to the approximate location of the mandibular foramen was undertaken and red dye was deposited. The angled approach was then undertaken and blue ink was used to identify it. The heads were then dissected to determine the location of the dye. Place...
Fu Z, Shi J.BACKGROUND The differences between the peripheral and central branches of the dorsal root ganglion (DRG) have not been fully elucidated. This study aimed to explore the expression of tubulin post-translational modifications (acetylation and deacetylation) between damaged peripheral and central branches of DRG neurons. MATERIAL AND METHODS Fifty Sprague-Dawley rats were randomly assigned to five groups with 10 rats in each group. These five groups consisted of spinal nerve ligation (SNL) at 24 hour and 48 hour, and cauda equina compression (CEC) at 24 hour and 48 hour, and a sham group. SNL inj...
Palmieri G, Panu R, Asole A, Farina V, Sanna L, Gabbi C.The most developed and organized lamina running trough the biceps brachii muscle belly forms a well-marked tendinous intersection connecting the proximal tendon with the distal one. Moreover, the lacertus fibrosus arises from this lamina close to the distal tendon and blends with the fascia of the forearm and joins the extensor carpi radialis muscle. The nerve supply for the biceps tendinous intersection arises from the intramuscular rami of the musculo-cutaneous nerve, whereas the lacertus fibrosus is provided with some cutaneous rami of the same nerve. The biceps brachii tendinous intersecti...
Archer RM, Knight CG, Bishop WJ.Six horses from several geographical locations in New Zealand presented with signs of guttural pouch mycosis. All horses had experienced epistaxis within 14 days of presentation. Results: In five horses with epistaxis, a diagnosis of guttural pouch mycosis was made on endoscopic observation of fungal plaques in the affected guttural pouches. One of these cases died before surgery was attempted. The remaining four cases underwent ligation and balloon catheter occlusion of the internal carotid artery of the affected pouch. Three of these horses survived and were reported to be healthy 1 year aft...
Duncan ID, Schneider RK, Hammang JP.The suprascapular nerve from 14 horses, which had no clinical evidence of spinatus muscle atrophy, were obtained to determine whether the nerve was sub-clinically compressed at the scapular edge. The nerves were divided into three portions, proximal and distal to the scapular edge and as it reflected around it. In nine horses there was evidence of a chronic neuropathy which varied in severity and which was most severe at the site of reflection, where the nerve appeared constricted by a tendinous band. At this site the predominant change was that of chronic demyelination and remyelination, with...
