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Topic:Brain
The equine brain is a complex organ responsible for processing sensory information, regulating behavior, and controlling motor functions in horses. It plays a part in cognitive processes such as learning, memory, and decision-making. The equine brain is divided into several regions, each with distinct functions, including the cerebrum, cerebellum, and brainstem. Research in this area often focuses on understanding the neurological pathways and mechanisms that underlie equine behavior and performance. This topic encompasses studies that explore brain anatomy, neurophysiology, and the effects of various factors such as stress, training, and disease on brain function in horses. This page compiles peer-reviewed research studies and scholarly articles that investigate the structure, function, and health of the equine brain.
Brainstem auditory evoked responses in an equine patient population: part I–adult horses. Brainstem auditory evoked response has been an underused diagnostic modality in horses as evidenced by few reports on the subject. Objective: To describe BAER findings, common clinical signs, and causes of hearing loss in adult horses. Methods: Study group, 76 horses; control group, 8 horses. Methods: Retrospective. BAER records from the Clinical Neurophysiology Laboratory were reviewed from the years of 1982 to 2013. Peak latencies, amplitudes, and interpeak intervals were measured when visible. Horses were grouped under disease categories. Descriptive statistics and a posthoc Bonferroni test...
Straight from the horse’s mouth: neurological injury in equestrian sports. Equestrian sports can result in a variety of injuries to the nervous system due to many factors. We describe our series of 80 patients with injuries sustained during participation in equestrian sports. Results: All patients seen at the regional trauma center with injuries associated with equestrian sports between 2003 and 2011 were reviewed; 80 patients were identified. Fifty-four per cent were female and the average age was 37 years (2·2-79·3). The mean injury severity score (ISS) was 9·9 ± 0·7. Only two patients had documented helmet use. Glasgow coma score (GCS) was 15 in 93% of patien...
The brain of the horse: weight and cephalization quotients. The horse is a common domestic animal whose anatomy has been studied since the XVI century. However, a modern neuroanatomy of this species does not exist and most of the data utilized in textbooks and reviews derive from single specimens or relatively old literature. Here, we report information on the brain of Equus caballus obtained by sampling 131 horses, including brain weight (as a whole and subdivided into its constituents), encephalization quotient (EQ), and cerebellar quotient (CQ), and comparisons with what is known about other relevant species. The mean weight of the fresh brains in o...
Neurological trypanosomiasis in quinapyramine sulfate-treated horses–a breach of the blood-brain barrier? Trypanosoma evansi infection typically produces wasting disease, but it can also develop into a neurological or meningoencephalitis form in equids. Trypanosomiasis in horses was treated with quinapyramine sulfate, and all the 14 infected animals were recovered clinically. After clinical recovery, four animals developed a neurological form of the disease at various intervals. Two of these animals treated with diminazene aceturate recovered temporarily. Repeated attempts failed to find the parasite in the blood or the cerebrospinal fluid (CSF), but all of the animals were positive in enzyme-link...
The applicability of ambulatory electroencephalography (AEEG) in healthy horses and horses with abnormal behaviour or clinical signs of epilepsy. Short-duration electroencephalography (EEG) recordings in horses are helpful in diagnosing intracranial disorders. Potentially, long-duration ambulatory EEG (AEEG) recordings in horses will enhance the chance of detecting abnormal brain activity independent of the presence of an insult. Objective: The objective of this study was to test if AEEG recordings in unsedated horses can be acquired and benefit diagnosing abnormal brain activity. Methods: Recordings were taken from 8 adult control horses and 10 patients suspected of intracranial abnormalities. Self-adhesive electrodes and the 'Porti-5'...
Meningoencephalitis caused by Halicephalobus gingivalis in a thoroughbred gelding. A 6-year-old Thoroughbred gelding was euthanized after a 2-month period of abnormal neurological signs, such as circling left in his pen and hitting his head and body against the wall. After the horse was euthanized on the farm, a half of the brain and whole blood were submitted for diagnostic tests. Histopathological examination of the brain revealed granulomatous and eosinophilic meningoencephalitis with numerous intralesional nematodes, predominantly affecting the cerebrum. Multifocal malacic foci were scattered in the brain parenchyma. The intralesional parasites were identified as Halicep...
Mining the brain metabolome to understand behavioural disruptions induced in mouse fed Hypochoeris radicata (L.), a neurotoxic plant for horse. Mining the brain metabolome to understand behavioural disruptions induced in mouse fed Hypochoeris radicata (L.), a neurotoxic plant for horse. C57BL/6J mice orally exposed to 9% H. radicata (HR) are metabolically competent laboratory animals which can be used as model of Australian stringhalt, a neurological horse disease induced by HR ingestion. So, the present study was conducted to assess the brain metabolome and the behavioural performances of mice fed with a 9%-HR-based diet for 21 days. By the end of the period of exposure, mice were investigated for motor activity and coordination, anx...
Phenotypic characteristics of hydrocephalus in stillborn Friesian foals. Hydrocephalus is uncommon in horses. However, in recent years, it has become clear that the prevalence of hydrocephalus is greater in Friesian horses than in other breeds probably due to their limited gene pool. Before identification of candidate genes that predispose to the development of hydrocephalus in Friesian horses can be pursued, an in-depth, phenotypic, pathological description of the condition in Friesians would be of great benefit. Our study aimed to characterize the morphology of hydrocephalus in Friesian horses, to support further investigation of the genetic background of this co...
On the repair of oxidative damage to apoferritin: a model study with the flavonoids quercetin and rutin in aerated and deaerated solutions. Ferritin (Ft) impairment through (•)O2(-), H2O2, and (•)OH production occurs in the cases of ketoses, diabetes mellitus, acute intermittent porphyria and tyrosinemia. In addition to (•)Trp and TyrO(•) radical production, ferrous iron liberation and Ft synthesis stimulation, site-specific oxidation reactions are induced leading to toxic iron accumulation in organs with high Ft content, for example, liver and brain. To elucidate the potential pathways to Ft recovery, repair of oxidative damage to horse spleen apoferritin (apoFt) and Ft by quercetin (QH) or rutin (RH) was studied in the p...
Unilateral cerebellar hypoplasia and mesencephalic malformation in a Hanoverian foal. Neurological cases, especially in foals, are rare in the daily practical work. The most common causes are traumata and infectious diseases of the central nervous system (CNS). This case report provides further insights into the wide spectrum of possible neuropathological lesions by detailing a complex malformation with unilateral neurological signs that occurred later post natum. Thus, clinicians should also be aware of malformations in case of respective neurological patients. A Hanoverian foal was presented with progressive ataxia. General and blood examination revealed no further alteration...
Age-related changes in the central nervous system in selected domestic mammals and primates. Aging is a process which operates at many levels of physiological, genetic and molecular organization and leads inevitably to death. Brain macroscopic changes by MRI investigation during aging were observed in humans and dogs but chimpanzees did not display significant changes. This suggestion led to the statement that brain aging is different in various species. Although human brain changes, e.g. β-amyloid storage, neurofibrillary tangle formation, lipofuscin, are relatively well known, we are still looking for a suitable animal model to study the mechanisms of aging and neurodegenerative di...
Diagnosis and isolation of Toxoplasma gondii in horses from Brazilian slaughterhouses. This study aimed to investigate anti-Toxoplasma gondii antibodies and to isolate the parasite from the brains of horses processed at slaughterhouses in Brazil. We collected brain and blood samples from 398 horses of various ages, from six Brazilian states. Serum samples were evaluated by indirect fluorescent antibody test (IFAT cut-off titre ≥ 1:64), and brains were submitted to mouse bioassay. Among the 398 horses, positivity for T. gondii was identified in 46 (11.6%) by IFAT and in 14 (3.5%) by mouse bioassay. In 12 of those 14 bioassays, mice were positive only by IFAT (cut-off titre ≥ ...
A review on epilepsy in the horse and the potential of Ambulatory EEG as a diagnostic tool. Epilepsy in the horse is diagnosed based on clinical signs, but diagnosing can be difficult if a grand mal is not present. The future prospects of the horse and potentially the safety of the owner depend on an accurate diagnosis. This review presents information on epilepsy and focuses on the diagnostic potential of (Ambulatory) electroencephalography ((A) EEG). An epileptic seizure is a brain disorder, which expresses itself as a recurrent episode of involuntary abnormal behaviour. The aetiology can originate from inside or outside the brain or is idiopathic. Besides those categories, seizure...
Lateralized suckling in domestic horses (Equus caballus). Brain lateralization enables preferential processing of certain stimuli and more effective utilization of these stimuli in either the left or the right cerebral hemisphere. Horses show both motor and sensory lateralization patterns. Our aim was to determine whether a lateralized response could be detected in foals during the naturally side-biased behaviour, suckling. The foals' preferred suckling side could be the effect of either visual or motor lateralization. In the case of a visual lateralized response, foals are expected to suck more often from the mother's right side, so potential danger...
Time-of-flight magnetic resonance angiography (TOF-MRA) of the normal equine head. 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...
Mycotic encephalitis, sinus osteomyelitis, and guttural pouch mycosis in a 3-year-old Arabian colt. Mycotic encephalitis caused severe ataxia and other neurologic deficits in a horse. The finding of a single, large focus of cerebral malacia, with histopathologic evidence of fungal elements, suggested infection was a result of direct transfer from the frontal sinuses, rather than hematogenous spread from the guttural pouch. Une encéphalite mycotique a causé une ataxie grave et d’autres déficits neurologiques chez un cheval. La découverte d’un grand foyer unique de malacie cérébrale avec une preuve histopathologique d’éléments fongiques a suggéré que l’infection était un tr...
Allopregnanolone infusion induced neurobehavioural alterations in a neonatal foal: is this a clue to the pathogenesis of neonatal maladjustment syndrome? Increased plasma progestagen concentrations have been reported in foals with neonatal maladjustment syndrome (NMS). These steroids may cross the blood-brain barrier and have dampening effects in the central nervous system. Objective: To evaluate if the infusion of a progesterone derivative (allopregnanolone) in a healthy neonatal foal would induce clinical signs compatible with NMS. Methods: A healthy neonatal foal from a healthy mare with a normal gestation (length, no complications), birth and placenta was infused with allopregnanolone to observe its neurobehavioural effects. Heparinised blo...
Poisoning by Indigofera lespedezioides in horses. Poisoning by Indigofera lespedezioides is reported in horses in the state of Roraima, northern Brazil. The main clinical signs are anorexia, sleepiness, unsteady gait, severe ataxia, weakness, stumbling, and progressive weight loss. To induce the disease experimentally, a 7-year-old horse was introduced in a small paddock invaded by the plant. The first nervous signs were observed 44 days from the start of grazing. The animal was euthanized on day 59. No significant gross lesions were observed upon necropsies of the experimental horse as well as one spontaneously affected horse. Upon histologi...
Vascular mineralization in the brain of horses. Vascular mineralization (siderocalcinosis) in the brain of horses has been usually assumed to be an incidental age-related finding with no clinic significance. In the present study, eight 15-32-year-old horses of different breeds with cerebral siderocalcinosis were studied. Four of these horses had acute and severe central nervous system clinical signs of unknown etiology, 2 horses had neurological signs of known cause, and 2 horses did not have neurological signs. Gross examination of the brains in 4 animals revealed symmetrical foci of malacia in the cerebellar white matter. Histologically, ...
Nigropallidal encephalomalacia in horses grazing Rhaponticum repens (creeping knapweed). 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...
Diagnostic sensitivity and specificity of in situ hybridization and immunohistochemistry for Eastern equine encephalitis virus and West Nile virus in formalin-fixed, paraffin-embedded brain tissue of horses. Immunohistochemistry (IHC) and in situ hybridization (ISH) can be used either to detect or to differentiate between Eastern equine encephalitis virus (EEEV) and West Nile virus (WNV) within formalin-fixed, paraffin-embedded (FFPE) brain tissue of horses. To compare the diagnostic sensitivity and specificity of ISH and IHC, FFPE brain tissue from 20 EEEV-positive horses and 16 WNV-positive horses were tested with both EEEV and WNV oligoprobes and EEEV- and WNV-specific antibodies. Reverse transcription polymerase chain reaction (RT-PCR) for detection of EEEV and WNV was used as the gold standar...
Confirmed case of encephalitis caused by Murray Valley encephalitis virus infection in a horse. A 5-year-old Australian stock horse in Monto, Queensland, Australia, developed neurological signs and was euthanized after a 6-day course of illness. Histological examination of the brain and spinal cord revealed moderate to severe subacute, nonsuppurative encephalomyelitis. Sections of spinal cord stained positively in immunohistochemistry with a flavivirus-specific monoclonal antibody. Reverse transcription polymerase chain reaction assay targeting the envelope gene of flavivirus yielded positive results from brain, spinal cord, cerebrospinal fluid, and facial nerve. A flavivirus was isolate...
Immunohistochemical analysis of cartilage-derived retinoic acid-sensitive protein (CD-RAP)/melanoma inhibitory activity (MIA) in murine, canine, bovine and equine cerebrospinal tissues. Cartilage-derived retinoic acid-sensitive protein (CD-RAP)/melanoma inhibitory activity (MIA), which appears abundantly in hypertrophic cartilage at the stage of endochondral ossification, is also detected in cerebrospinal fluid (CSF) following spinal cord injury. In this study, the localization of the CD-RAP/MIA molecule in normal tissues of the spine and brain obtained from mice, rats, dogs, cattle and horses was examined using immunohistochemistry with a specific antibody. The positive signals of CD-RAP/MIA were found at nerve cells in the spinal cords of all species and were especially str...
Advanced imaging of the nervous system in the horse. Neuroimaging underwent a dramatic revolution during the past few decades due to the development of new technologies that produce exquisite images of patient morphology and function, new technologies that store and distribute information more efficiently, and research that has improved understanding of pathogenesis and effective clinical use of new imaging methods. Advanced equine neuroimaging is a specialized field with unique challenges associated with patient size, availability of equipment, using equipment designed for humans, small sample size for various diseases, and issues associated wi...
Neonatal encephalopathy in foals. Neonatal encephalopathy is a common central nervous system disorder of neonatal foals and human infants, resulting in clinical signs such as lethargy, inappropriate behavior, seizures, and other neurologic deficits. Although neonatal encephalopathy is frequently seen in equine practice, a paucity of veterinary clinical and basic science research data is available. Therefore, the pathophysiologic mechanisms of this disorder in equids, such as energy deprivation, excess excitatory amino acids, and free radical injury, have been extrapolated from human medicine. Equine veterinarians have used var...
Early use of Xeomin neurotoxin for local anti-spasticity therapy for pes equines after acquired brain injury (ABI). The acute management of spasticity following ABI is challenging. Contractures can occur during the acute phases of illness. The joints most affected are the shoulders and the ankles. Methods: A case study of a 48-year-old female patient who received local chemoneurolytic anti-spasticity therapy following a severe subarachnoid haemorrhage for pes equines deformity is presented to illustrate the role of focal neurotoxin therapy. Methods: The increasing spasticity in her legs was observed and could not be effectively treated with oral anti-spasticity agents or intensive physiotherapy. As spastici...
Molecular characterization of alternative transcripts of the horse BMAL1 gene. The horse BMAL1 gene encodes the brain and muscle Arnt-like protein 1, which is a key regulator of circadian rhythmic systems in most organs and cells. The first exon of the horse-specific BMAL1 gene is produced by an exonization event of LINE3 (CR1) and SINE (MIR) was detected by bioinformatic analysis. Alternative variants generated by cassette exon event in various horse tissues were also detected by RT-PCR amplification and sequencing. The cDNA sequences of the horse transcripts (BMAL1a, BMAL1b) contain additional 21 bp and 71 bp fragments relative to horse BMAL1. Quantitative real-time RT...
Computed tomographic findings in the pituitary gland and brain of horses with pituitary pars intermedia dysfunction. Pituitary pars intermedia dysfunction (PPID) is the most common endocrinologic disorder of aged horses. Objective: Pituitary glands of PPID-affected horses are larger than those of aged horses without signs of PPID, and the size difference can be detected using computed tomography (CT) imaging. Methods: Eight horses with clinical signs of PPID and supportive endocrinologic test results and 3 aged control (PPID-negative) horses. Methods: Computed tomography examination of the brain and pituitary gland was performed twice in 10 of the 11 horses, approximately 6 months apart. Six PPID-affected ho...
Preliminary investigation of somatosensory evoked potentials in equine headshaking. The aim of this study was to develop a technique for recording electrical activity of the equine cerebral cortex following application of a noxious electrical stimulus to the maxillary branch of the trigeminal nerve in order to investigate trigeminal nerve neurophysiology in control and headshaking horses. Triphasic somatosensory evoked potentials (SEPs) were recorded using subcutaneous needle electrodes in four control and four headshaking horses under general anaesthesia. Dural electroencephalography electrodes were used to record SEPs in one further control and one further headshaking horse...
