The nervous system in horses is a complex network responsible for transmitting signals between different parts of the body. It consists of the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which comprises nerves that extend throughout the body. The nervous system regulates various physiological processes, including movement, sensation, and the coordination of bodily functions. It plays a critical role in processing sensory information and initiating appropriate responses. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and clinical implications of the equine nervous system, including its role in behavior, response to stimuli, and neurological disorders.
Becker R, Haenssgen K, Precht C, Khoma OZ, Hlushchuk R, Koch C, Kaessmeyer S, de Preux M.Equine trigeminal-mediated headshaking is a painful neuropathic disorder comparable to trigeminal neuralgia in humans. The selective destruction of pain fibers within the trigeminal ganglion, called rhizotomy, is the surgical treatment of choice for idiopathic trigeminal neuralgia refractory to medical treatment in humans. The human trigeminal ganglion is enclosed by a dural recess called the Meckel's or trigeminal cave, in which the ganglion is surrounded by a cerebrospinal fluid (CSF)-filled subarachnoid space. During glycerol rhizotomy, glycerol is percutaneously injected in this CSF-filled...
Wolschrijn CF, Smit IH, Schouten J, Moller Te NCR.Facial expressions are important in pain recognition in horses, but current observation-based pain scales remain subjective. A promising technique to quantitatively measure subtle changes in expression patterns, including changes invisible to the human eye, is surface electromyography (sEMG). To achieve high-quality and reliable sEMG signals, unilateral placement of bipolar electrodes is required in relation to the motor endplates (MEP). We aimed to localize the nerve entry points (NEPs; where the nerve branch first pierced the muscle belly) and the direction of the terminal nerve endings to e...
Tan Yi Shean L, Milne EM, Shaw DJ, Maxwell S, Del-Pozo J.Lipofuscin is a complex mixture of highly oxidized, cross-linked macromolecules that accumulates in neurons with age and some neurodegenerative diseases. Equine dysautonomia (ED) is a polyneuropathy that mainly affects autonomic and enteric nervous systems, resulting in alimentary tract dysfunction. Our main aim was to determine whether neuronal lipofuscin increased with increasing duration of ED. We investigated the prevalence of lipofuscin in cranial cervical ganglia of horses with acute (AED), subacute (SED), and chronic ED (CED), young controls (of similar age to ED cases), and aged contro...
Izquierdo-Moreno J, de Paz MI, Manso-Díaz G, Villalba-Orero M, López-Sanromán J.An accurate evaluation of the degree of sedation is mandatory to adjust the dosage of sedative drugs. Objective: To determine the correlation between head height above the ground and ataxia degree in horses sedated with detomidine and the correlation existing between accelerometric variables and both parameters. Methods: Retrospective study. Methods: Twelve horses were given 0.01 mg/kg of detomidine hydrochloride iv. Measured accelerometric parameters, with one accelerometer positioned between both sacral tuberosities, included speed, stride frequency and length, regularity, dorsoventral, lo...
Flores JEM, Terrazas A, Lara Sagahon AV, Aleman M.Parasympathetic tone activity (PTA) in response to nociceptive stimulus in conscious non-sedated horses is unknown. Objective: Study PTA, heart rate (HR), and horse grimace scale (HGS) at rest and during mechanical nociceptive stimulation. Methods: Ninety healthy young adult horses (females, males): 30 each of Friesians, Quarter Horses, and Warmbloods. Methods: Prospective control study. The study consisted of habituation to equipment (Day 1), baseline recordings (Days 2 and 3), and nociceptive testing applying mild pressure to the metacarpus (Day 4). Parasympathetic tone, HR, and HGS were rec...
Tomberg C, Petagna M, de Selliers de Moranville LA.Spontaneous eye blinks are brief closures of both eyelids. The spontaneous eye blink rate (SEBR) exceeds physiological corneal needs and is modulated by emotions and cognitive states, including vigilance and attention, in humans. In several animal species, the SEBR is modulated by stress and antipredator vigilance, which may limit the loss of visual information due to spontaneous eye closing. Here, we investigated whether the SEBR is modulated by attention in the domestic horse (Equus caballus). Our data supported previous studies indicating a tonic SEBR specific to each individual. We also fo...
Crawford AE, Picken LK, Gabriel FD, Quade J, Gould S.Equestrian sports continue to gain popularity in the United States and are associated with a high injury rate, especially involving the central nervous system and thorax. Due to this high rate of injury and the potential for long-term consequences associated with participation, an understanding of the unique risks of this sport is needed. Unassigned: To describe severe injury in equestrian sports and review the role that protective gear plays in injury mitigation. Unassigned: The PubMed Database was searched using the search terms "equestrian" and "horse" combined with "spinal cord injury," "h...
Stigson H, Klingegård M.Equestrian sports, also referred to as equestrianism, is practiced all over the world and a popular leisure activity in Sweden. Equestrianism is the country's second-largest youth sport, and previous studies indicate that accidents are common in equestrianism. However, few previous studies have examined acute equestrian injuries leading to permanent medical impairment (PMI). Methods: By using nationwide insurance data comprising all injured equestrians registered in the Swedish Equestrian Federation, the aim was to analyse characteristics of equestrian accidents and particularly injuries leadi...
Knych HK, Steinmetz SJ, Traynham ML, McKemie DS, Kass PH.Morphine is an effective analgesic in horses, however, IV administration at therapeutic doses has been shown to produce dose-dependent neuroexcitation and unwanted gastrointestinal effects. The analgesic effects of morphine have, at least in part, been attributed to the morphine-6-glucuronide (M6G) metabolite. Oral administration to horses results in comparable M6G concentrations to that achieved following IV administration of a therapeutic dose without the adverse effects. The anti-nociceptive effects have not yet been reported. In the current study the thermal anti-nociceptive effects of sin...
Martínez-Aranzales JR, Córdoba-Agudelo M, Pérez-Jaramillo JE.Crib-biting is a stereotyped oral behavior with poorly understood etiology and pathophysiology. The relationship between the gut microbiome and brain function has been described in behavioral disorders such as schizophrenia, depression and anxiety in humans. In horses, studies of behavioral problems and the microbiome are very limited. This study aimed to characterize the fecal microbiome and the predicted functional profile of horses with and without aerophagia. Fecal samples were collected from 12 Colombian Creole Horses of both sexes, divided into two groups: group 1, composed of six horses...
Zimmermann B, Castro ANC, Lendez PA, Carrica Illia M, Carrica Illia MP, Teyseyre AR, Toloza JM, Ghezzi MD, Mota-Rojas D.An emotion is defined as the affective response to a stimulus that leads to specific bodily changes, enabling individuals to react to positive or negative environmental conditions. In the absence of speech, emotions in animals are primarily studied by observing expressive components, such as facial expressions. This review aims to analyze the available literature on the influence of environmental stimuli on measurable behaviors in horses, describing the anatomical components involved in perception at the central nervous system level and the efferent pathways that trigger facial muscle contract...
Studies on short- and long-term memory and their decline with aging in horses are still limited. This research aimed to assess the learning and short- and long-term memory abilities of adult and senior horses. A total of 21 adult horses (5-15 years) and 23 senior horses (16 years and older) were subjected to a behavioral test (Target Touch Test), which was repeated three times each for the initial test (T1) and again after 10 days (T10). Statistical analysis revealed no significant differences between adult and senior horses in the three tests conducted at T1. However, a significant difference...
Ryu SH, Lee KE, Forbes E, An SJ, Kim JG, Lee H, Kim BS.Equine behavioral traits are important criteria to assess the suitability of retired Thoroughbred racehorses for equestrian sports. Objective: This study aims to develop a practical procedure to assess retired Thoroughbreds for their suitability for equestrian sports or leisure purposes and to assess if horses identified as having reactive temperaments in response to a standardized startle test, will have improved test results following a period of transition training. Methods: Behavioral reactivity data and cardiac autonomic responses to a startle test (comprising of a plastic bag applied to ...
Broman A, Rawlinson JE, Bass L, Boscan P, Rao S.The use of proper sedative and regional anesthetic protocols is essential when performing equine dental surgical procedures under standing sedation. The efficacy of the rostral inferior alveolar nerve block via the mental foramen has not been previously studied. Aims of this study included determining the efficacy of the block, investigating whether any region (labial mucosa, alveolar mucosa, or teeth) was more reliably anesthetized, and if differences in efficacy existed between bilateral and unilateral blocks. In this blinded trial, 10 horses each were randomly assigned to receive a left uni...
Witt P, Stas EKL, Hardeman LC, van Proosdij ER, Weerts EAWS, Lloyd-Edwards RA, Veraa S, Kranenburg LC, van den Boom R.A sixteen-year-old Friesian mare was admitted to the university clinic with the following clinical signs: anorexia, weight loss, fever, bilateral nasal discharge, unilateral facial paralysis and a non-healing corneal lesion. Endoscopic examination of the upper airways showed thickening of the proximal portion of the right stylohyoid bone. Computed tomography imaging showed pneumocephalus due to grade 3 unilateral temporohyoid osteoarthropathy (THO) with fracture of the petrous temporal bone. The horse did not improve following medical treatment. Surgical intervention was declined by the owner ...
Itoh K, Kikumura N, Maeda T, Hirata S, Ringhofer M.Despite the long history of the horse-human bond, our understanding of the brain and mind of horses remains limited due to the lack of methods to investigate their brain functions. This study introduces a novel methodology for completely non-invasive, multi-channel recording of electroencephalography (EEG) and evoked potentials in awake horses to examine equine auditory cortical processing. The new approach utilizes specially designed brush-shaped active electrodes that facilitate stable signal acquisition through the hair coat by penetrating electrode pins and integrated pre-amplifiers. A 12-...
McGivney CL, McGivney BA, Farries G, Gough KF, Han H, Holtby AR, MacHugh DE, Katz LM, Hill EW.Equine recurrent laryngeal neuropathy (RLN) is an economically important upper respiratory tract (URT) disease with a genetic contribution to risk, but genetic variants independent of height have not been identified for Thoroughbreds. The method of clinical assessment for RLN is critical to accurately phenotype groups for genetic studies. Objective: To identify genetic risk loci for RLN in Thoroughbreds in a genome-wide association study (GWAS) following high-resolution phenotyping. Methods: Case-control. Methods: Thoroughbred horses were characterised as RLN cases and controls using resting a...
Pusterla N, Lawton K, Barnum S, Ross K, Purcell K.The objective of this study was to describe an outbreak of equine herpesvirus-1 myeloencephalopathy (EHM) in a population of aged equids. The outbreak was linked to the introduction of five healthy non-resident horses 15 days prior to the first case of acute recumbency. This fulminant EHM outbreak was predisposed by the grouping of the 33 unvaccinated animals in two large pens with shared water and feed troughs. Fourteen horses (42.4%) developed neurological deficits within the first week of the outbreak. Four additional equids developed fever and respiratory signs (EHV-1 infection), while fif...
Finno CJ, Rogers SL, Donnelly CG, Affolter VK, Woolard K, Miller AD, Bellone RR, Petersen JL.Equine spinal neurodegenerative conditions are frequently encountered in sport and racing horses and may be career-ending diagnoses. To further define the spatial transcriptomic landscape of equine dorsal root ganglia (DRG) in healthy adult horses, we investigated gene expression differences in distinct DRG regions using the GeoMx Digital Spatial Profiling from NanoString. Four human cell markers demonstrated high fidelity for equine cells; microtubule-associated protein 2 (MAP2), myelin basic protein (MBP), allograft inflammatory 104 factor 1/ionized calcium-binding adaptor molecule 1 (IBA1/A...
Sanigavatee K, Poochipakorn C, Huangsaksri O, Vichitkraivin S, Pakdeelikhit S, Chotiyothin W, Wongkosoljit S, Wonghanchao T, Chanda M.Older horses often show reduced autonomic responses, affecting their well-being. While regular exercise can help maintain autonomic function, the impact of structured exercise on geriatric horses is not well understood. A study involving 27 geriatric horses examined their autonomic modulation over 12 weeks under different activity levels. Horses were divided into three groups: (1) sedentary (SEL), (2) those participating in unstructured activities (RAT), and (3) those following a structured exercise regimen (SER). Results showed that the minimum and average heart rates decreased in the structu...
Bercovitz GR, Sullivan SN, Reed RA, Ryan CA, Diehl KA.To evaluate the effect of intravenous mannitol and hypertonic saline (HS) on intraocular pressure (IOP) and biometry parameters of horses with elevated intracranial pressure (ICP). Methods: Seven horses with normal ophthalmic exams were anesthetized and placed in lateral recumbency. A subarachnoid transducer was placed, and the head was lowered until ICP measured 40 mmHg +/- 2 mmHg. Five intravenous boluses of mannitol 20% (0.4 g/kg) or HS 7.2% (1 mL/kg) were administered, each 15 min apart. A 2-day washout period ensued, and the procedure was repeated with the other hyperosmotic age...
Domańska-Kruppa N, Stefanik E, Wierzbicka M, Kleinpeter A.Cervical spine injuries that impact young horses and foals can result in mild to severe neurological signs or even result in sudden death. There are only a few reports on conservative treatment options for this condition in the scientific literature. If the condition is left untreated, it can lead to the development of degenerative joint disease, resulting in chronic neurological symptoms and discomfort. We present the case of a two-day-old Arabian foal that showed signs of ataxia following a neck injury, being the result of cervical spine subluxation. Radiological examination revealed a dislo...
Haussler KK, le Jeune SS, MacKechnie-Guire R, Latif SN, Clayton HM.The defining characteristic of laterality is the dominance of one side of the brain controlling specific functions of paired organs or on one side of the body. Structural and functional asymmetries are ubiquitous in horses and range from anatomical features (e.g., the length of long bones) to the gathering of sensory information (e.g., which eye is used to observe unfamiliar scenes) and motor functions (e.g., left-right differences in locomotion). There is a common tendency to assign observed structural or functional asymmetries to lateralization, which often involves more than a simple left-r...
Primo ALM, Assis DM, Santos VGS, de Melo LRB, da Nóbrega LD, Medeiros Dantas AF, Maciel TA.Cerebellar abiotrophy is a neurodegenerative disease that affects the Purkinje cells of the cerebellum, resulting in premature neuronal death. In horses, its occurrence has been reported mainly in the Arabian breed as a congenital mutation inherited in an autosomal recessive manner. The objective of this study was to describe the case of cerebellar abiotrophy in a Quarter Horse foal. An 8-day-old foal was treated after presenting signs of ataxia, hypermetria, difficulty maintaining a standing position, and decreased menace response. The foal was hospitalized for 26 days, received treatment wit...
de Oliveira Ferreira LV, Maia L, de Andrade DGA, da Costa Kamura B, de Carvalho M, Amorim RM.Cell-based therapy has emerged as a promising strategy for treating peripheral nervous system (PNS) injuries across different species. However, there is a scarcity in the literature regarding the transplantation of mesenchymal stem cells (MSCs) for treating PNS injuries in horses. This report aims to describe the therapeutic potential of equine MSC transplantation in two horses with chronic traumatic facial nerve paralysis. Both horses presented with lip ptosis and right deviation of the nostril and upper lip, being clinically diagnosed with left facial nerve paralysis. Due to the refractorine...
Holz N, Suárez J, Hetzel U, Rampazzo A, Stoppini R.A 15-year-old Swiss Warmblood gelding was presented to the ophthalmology service of Zurich University due to severe visual impairment. Ophthalmic and neurologic examinations were performed, raising suspicion of post-retinal blindness. Standing contrast computed tomography (CT) of the head revealed a partially calcified, soft tissue attenuating mass in the sphenopalatine sinus with concurrent compression of the optic nerves and chiasm. Differential diagnosis included neoplasia and granulomatous disease. The horse was euthanized, and the head was subsequently examined by magnetic resonance imagi...
Yamaga T, Tagami M, Takeyama A, Kato F, Suzuki T, Tagami M, Tsuzuki N.Computed tomography (CT) offers high-resolution, three-dimensional imaging, making it particularly valuable for assessing complex structures, such as the head, especially when conventional radiography and endoscopy are insufficient for a definitive diagnosis. Herein, we present two cases of equine cranial disorders resulting from congenital malformations. In case 1, which had a dentigerous cyst, CT images confirmed the location of the ectopic tooth within the skull and a detailed fistula tube. In case 2, which had temporohyoid osteoarthropathy, CT examination revealed that the stylohyoid bone ...
Mota-Rojas D, Whittaker AL, Coria-Avila GA, Martínez-Burnes J, Mora-Medina P, Domínguez-Oliva A, Hernández-Avalos I, Olmos-Hernández A....The growing interest in managing and recognizing pain in animals has led to the search for more sensitive methods to evaluate it, especially because some species conceal any visible changes associated with pain or are not easily assessed. Research has shown that an animal's facial expression changes when exposed to painful stimuli. Thus, developing several pain scales (grimace scales) in species such as horses, cattle, pigs, sheep, donkeys, rabbits, rats, mice, and cats has helped to improve the study of pain in veterinary medicine. The possibility of using facial expression as an indicator of...
Rankins EM, Faremi BE, Hartmann K, Quinn A, Posada-Quintero HF, McKeever KH, Malinowski K.Heart rate variability (HRV) can be measured as an indicator of autonomic nervous system (ANS) balance and thus, stress and affective arousal. Mixed results have been reported in the limited literature addressing the effects of equine-assisted services (EAS) on HRV in the human and horse participants. The aims of the present study were to determine the effects of ground-based adaptive horsemanship (AH) lessons on veterans' and horses' HRV during weekly lessons as well as veterans' resting HRV outside of lessons. Veterans with post-traumatic stress disorder (PTSD) were randomly assigned to 8 w...
Mota-Rojas D, Whittaker AL, Bienboire-Frosini C, Buenhombre J, Mora-Medina P, Domínguez-Oliva A, Martínez-Burnes J, Hernández-Avalos I....Recognizing that nonhuman animals are sentient beings has increased interest in studying their emotional state. Similar to humans, research has shown that some nonhuman mammals can modify facial expressions by contraction/relaxation of facial muscles according to their affective state. From a neurophysiological perspective, emotions are processed in several brain structures, mainly from the limbic system, such as the hypothalamus, hypophysis, hippocampus, prefrontal cortex, and amygdala. The converged pathways between the amygdala, the motor cortex, and its projections to the facial nerve cont...
