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Topic:Disease Etiology
Disease etiology in horses refers to the study of the causes and development of diseases within equine populations. It encompasses various factors, including genetic predisposition, environmental influences, infectious agents, and nutritional imbalances, that contribute to the onset and progression of diseases in horses. Understanding disease etiology is essential for identifying risk factors and implementing preventative measures in equine health management. This topic includes research on pathogen-host interactions, the impact of management practices on disease incidence, and the role of genetic and environmental factors in disease susceptibility. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, contributing factors, and implications of disease etiology in horses.
Full-Genome Sequence of a Neuroinvasive West Nile Virus Lineage 2 Strain from a Fatal Horse Infection in South Africa. We report here the complete genome sequence of a lineage 2 West Nile virus (WNV) strain that resulted in fatal neurological disease in a horse in South Africa. Several recent reports exist of neurological disease associated with lineage 2 WNV in humans and horses in South Africa and Europe; however, there are a lack of sequencing data from recent fatal cases in Southern Africa, where these strains likely originate. A better understanding of the genetic composition of highly neuroinvasive lineage 2 strains may facilitate the identification of putative genetic factors associated with increased v...
Preliminary study of tissue concentrations of penicillin after local administration into the guttural pouches in four healthy horses. Treatment of subclinical carriers of Streptococcus equi subsp. equi with a gelatine-penicillin formulation deposited in the guttural pouch has been empirically proposed, but data on local tissue penicillin concentrations after treatment are lacking. Methods: We analysed tissue levels of penicillin after administration into the guttural pouches of four healthy horses. Two horses received local treatment with gelatine-penicillin and two horses received local treatment with an intramammary formulation of penicillin. Tissues were harvested for analysis either 12 or 24 h later. Conclusions: Resul...
Endocrine Disease in Aged Horses. Aging horses may be at particular risk of endocrine disease. Two major equine endocrinopathies, pituitary pars intermedia dysfunction and equine metabolic syndrome, are commonly encountered in an aging population and may present with several recognizable signs, including laminitis. Investigation, treatment, and management of these diseases are discussed. Additionally, aging may be associated with development of rarer endocrinopathic problems, often associated with neoplasia, including diabetes mellitus and other confounders of glucose homeostasis, as well as thyroid, parathyroid, and adrenal d...
Risk Factors for Equine Gastric Glandular Disease: A Case-Control Study in a Finnish Referral Hospital Population. Equine gastric glandular disease (EGGD) is a term used to classify erosive and ulcerative diseases of the glandular mucosa of the equine stomach. Epidemiologic studies of risk factors for EGGD have not been reported. Objective: To determine risk factors for EGGD. Methods: Cases (n = 83) had endoscopic evidence of EGGD; controls (n = 34) included healthy horses and horses with equine squamous gastric disease (ESGD) without EGGD. Methods: Retrospective case-control study. The data were analyzed by multivariable logistic regression modeling. Analysis was performed on the full dataset. An addi...
Evidence for marsh mallow (Malva parviflora) toxicosis causing myocardial disease and myopathy in four horses. Investigation of toxicosis caused by Malva parviflora was required after 4 horses from the same farm developed severe muscle fasciculations, tachycardia, sweating and periods of recumbency leading to death or euthanasia after ingesting the plant. Objective: To describe historical, clinical, clinicopathological and pathological findings of 4 horses with suspected M. parviflora toxicosis. The role of cyclopropene fatty acids (found in M. parviflora) and mechanism for toxicosis are proposed. Methods: Case series. Methods: Historical, physical examination, clinicopathological and pathological find...
Prevalence, survival analysis and multimorbidity of chronic diseases in the general veterinarian-attended horse population of the UK. The average age of the global human population is increasing, leading to increased interest in the effects of chronic disease and multimorbidity on health resources and patient welfare. It has been posited that the average age of the general veterinarian-attended horse population of the UK is also increasing, and therefore it could be assumed that chronic diseases and multimorbidity would pose an increasing risk here also. However, evidence for this trend in ageing is very limited, and the current prevalence of many chronic diseases, and of multimorbidity, is unknown. Using text mining of firs...
Finite-Element Analysis of Bone Stresses on Primary Impact in a Large-Animal Model: The Distal End of the Equine Third Metacarpal. To assess whether the transient stresses of foot impact with the ground are similar to those found during midstance loading and if the location of high stress correlate with the sites most commonly associated with mechanically induced osteoarthritis (OA). We compared impact stresses in subchondral bone between two subject-specific, three-dimensional, finite-element models of the equine metacarpophalangeal (MCP) joint-one with advanced OA and one healthy, and with similar published data on the stresses that occur at midstance. Methods: Two right MCP joints (third metacarpal and proximal phalanx...
Glanders and the risk for its introduction through the international movement of horses. Glanders is the contagious zoonotic disease caused by infection with Burkholderia mallei. It affects primarily horses, donkeys and mules. The disease was eradicated from large areas of the Western world in the early 20th century, but, over the last 10-20 years, has emerged and re-emerged in areas in which it was previously unknown or had been eradicated. Although glanders was previously thought to manifest in only acute or chronic presentations, it now appears that B. mallei can produce latent infections similar to those caused by Burkholderia pseudomallei. These latent infections may or may...
African horse sickness: The potential for an outbreak in disease-free regions and current disease control and elimination techniques. African horse sickness (AHS) is an arboviral disease of equids transmitted by Culicoides biting midges. The virus is endemic in parts of sub-Saharan Africa and official AHS disease-free status can be obtained from the World Organization for Animal Health on fulfilment of a number of criteria. AHS is associated with case fatality rates of up to 95%, making an outbreak among naïve horses both a welfare and economic disaster. The worldwide distributions of similar vector-borne diseases (particularly bluetongue disease of ruminants) are changing rapidly, probably due to a combination of globalisa...
Identification of copy number variations in three Chinese horse breeds using 70K single nucleotide polymorphism BeadChip array. Copy number variation (CNV), an essential form of genetic variation, has been increasingly recognized as one promising genetic marker in the analysis of animal genomes. Here, we used the Equine 70K single nucleotide polymorphism genotyping array for the genome-wide detection of CNVs in 96 horses from three diverse Chinese breeds: Debao pony (DB), Mongolian horse (MG) and Yili horse (YL). A total of 287 CNVs were determined and merged into 122 CNV regions (CNVRs) ranging from 199 bp to 2344 kb in size and distributed in a heterogeneous manner on chromosomes. These CNVRs were integrated with s...
Citrobacter freundii induced endocarditis in a yearling colt. Endocarditis is a rare pathology in horses and the clinical signs can be misleading. We describe the clinical, echocardiographic, and pathological features of Citrobacter freundii induced bacterial endocarditis in a horse. This bacterium has never been reported before as an agent of vegetative endocarditis in the horse. L’endocardite est une pathologie rare chez les chevaux et les signes cliniques peuvent être trompeurs. Nous décrivons les caractéristiques cliniques, échographiques et pathologiques d’une endocardite bactérienne induite par chez un cheval. Cette bactérie n’a jamai...
Clinical behavior of intraocular teratoid medulloepithelioma in two-related Quarter Horses. The objective of this paper is to describe clinical behavior, histopathologic features, and immunohistochemical staining of two-related horses with intraocular teratoid medulloepithelioma. Two-related Quarter Horses with similar intraocular masses presented to the UF-CVM Comparative Ophthalmology Service for evaluation and treatment. The first horse, a 3-year-old gelding, had glaucoma and a cyst-like mass in the anterior chamber. Enucleation was performed. Histopathology revealed a teratoid medulloepithelioma. The tumor was considered to be completely excised. Fifteen months later, the gelding...
Candidate gene analysis of osteochondrosis in Spanish Purebred horses. Equine osteochondrosis (OC) is a frequent developmental orthopaedic disease with high economic impact on the equine industry and may lead to premature retirement of the animal as a result of chronic pain and lameness. The genetic background of OC includes different genes affecting several locations; however, these genetic associations have been tested in only one or few populations, lacking the validation in others. The aim of this study was to identify the genetic determinants of OC in the Spanish Purebred horse breed. For that purpose, we used a candidate gene approach to study the associati...
Prevalence of netF-positive Clostridium perfringens in foals in southwestern Ontario. NetF-producing Clostridium perfringens have recently been identified as a cause of necrotizing enteritis in neonatal foals, but little is known about its prevalence in clinically normal foals. Foals (n = 88) ranging in age from < 1 wk to 2 to 4 mo (median age 2 to 4 wk) on 8 horse-breeding farms in Ontario were examined on 1 or 2 occasions for the presence of C. perfringens. Of the foals that tested positive, 5 isolates (n = 675) were examined for the netF and enterotoxin (cpe) genes. Colonization by C. perfringens was most marked in foals < 1 wk of age [4.85 ± 2.70 log10 colony-forming...
Interaction of Trypanosoma evansi with the plasminogen-plasmin system. Trypanosoma evansi is a widely-distributed haemoflagellated parasite of veterinary importance that infects a variety of mammals including horses, mules, camels, buffalos, cattle and deer. It is the causal agent of a trypanosomiasis known as Surra which produces epidemics of great economic importance in Africa, Asia and South America. The main pathology includes an enlarged spleen with hypertrophy of lymphoid follicles, congested lungs, neuronal degeneration and meningoencephalitis, where migration of the parasites from the blood to the tissues is essential. Most cells, including pathogenic cel...
Factors associated with equine aural plaque in Brazil. Aural plaques can be found on the inner surfaces of one or both ears of horses. Despite their low malignancy, these lesions can sometimes cause discomfort and sensitivity in horses, and a loss in commercial value due to their aesthetic effect. There has been a study describing the epidemiological features and the clinical prevalence of equine aural plaques in Brazil. Objective: To determine the clinical prevalence and selected associated factors of aural plaques. Methods: In the study, 891 horses were assessed for aural plaques. The sample group had a median age of 5 years and comprised both s...
Gingival Toll-like receptor and cytokine messenger RNA levels in equine periodontitis and oral health. Equine periodontitis is a common and painful condition. However, the disease often goes unnoticed by owners and is thus a major welfare concern. The aetiopathogenesis of the condition remains poorly understood and has been investigated in few studies. The innate immune system is known to play an important role in human periodontitis, but its role in equine periodontitis has not been examined. Objective: To quantify the messenger (m)RNA levels of Toll-like receptors (TLRs) and cytokines in gingival tissue from orally healthy horses and those affected by periodontitis. Methods: Observational stu...
Clinical course of sarcoids in 61 Franches-Montagnes horses over a 5-7 year period. The progression of equine sarcoids (ES) is notoriously unpredictable. Making a choice for the appropriate treatment is challenging when dealing with milder manifestations of ES. Objective: The aim of this study was to investigate the clinical course of ES in young horses. Methods: A cohort of 61 ES-affected three-year-old Franches-Montagnes horses and a breed-, age- and geographically matched control group of 75 ES-free peers were examined twice over a period of 5-7 years. Owners and caretakers were queried, using a standardized questionnaire. Results: More than half of the 38/61 (62%) horses...
Pythiosis in the Nasal Cavity of Horses. Two cases of nasal pythiosis are reported in horses from the semi-arid region of northeastern Brazil. From January 1986 to December 2015, the Laboratory of Animal Pathology, Federal University of Campina Grande received 830 equine samples, 156 (18.79%) of which were diagnosed with pythiosis. Of these, two horses (1.28%), a male and a female adult cross-breed, had lesions in the nasal cavity. Both horses had access to water reservoirs. Clinically, they had swelling in the rhinofacial region and a serosanguineous nasal discharge. Macroscopically, in case 1, the lesion affected the nasal vestibul...
Large Deletions at the SHOX Locus in the Pseudoautosomal Region Are Associated with Skeletal Atavism in Shetland Ponies. Skeletal atavism in Shetland ponies is a heritable disorder characterized by abnormal growth of the ulna and fibula that extend the carpal and tarsal joints, respectively. This causes abnormal skeletal structure and impaired movements, and affected foals are usually killed. In order to identify the causal mutation we subjected six confirmed Swedish cases and a DNA pool consisting of 21 control individuals to whole genome resequencing. We screened for polymorphisms where the cases and the control pool were fixed for opposite alleles and observed this signature for only 25 SNPs, most of which we...
Quantitative analysis of the probability of introducing equine encephalosis virus (EEV) into The Netherlands. Equine encephalosis is a midge-borne viral disease of equines caused by equine encephalosis virus (EEV, Orbivirus, Reoviridae), and closely related to African horse sickness virus (AHSV). EEV and AHSV share common vectors and show similar transmission patterns. Until now EEV has caused outbreaks in Africa and Israel. This study aimed to provide insight in the probability of an EEV outbreak in The Netherlands caused by infected vectors or hosts, the contribution of potential source areas (risk regions) to this probability, and the effectiveness of preventive measures (sanitary regimes). A stoch...
Twenty years of Hendra virus: laboratory submission trends and risk factors for infection in horses. Hendra virus (HeV) was first described in 1994 in an outbreak of acute and highly lethal disease in horses and humans in Australia. Equine cases continue to be diagnosed periodically, yet the predisposing factors for infection remain unclear. We undertook an analysis of equine submissions tested for HeV by the Queensland government veterinary reference laboratory over a 20-year period to identify and investigate any patterns. We found a marked increase in testing from July 2008, primarily reflecting a broadening of the HeV clinical case definition. Peaks in submissions for testing, and visitat...
Mitochondrial function is altered in horse atypical myopathy. Equine atypical myopathy in Europe is a fatal rhabdomyolysis syndrome that results from the ingestion of hypoglycin A contained in seeds and seedlings of Acer pseudoplatanus (sycamore maple). Acylcarnitine concentrations in serum and muscle OXPHOS capacity were determined in 15 atypical myopathy cases. All but one acylcarnitine were out of reference range and mitochondrial respiratory capacity was severely decreased up to 49% as compared to 10 healthy controls. The hallmark of atypical myopathy thus consists of a severe alteration in the energy metabolism including a severe impairment in muscl...
Equine antibody response to larval Parascaris equorum excretory-secretory products. Parascaris equorum is an intestinal nematode of foals and young horses that can produce mild to severe pathology. Current diagnosis is limited to detection of patent infections, when parasite eggs are identified during fecal examinations. This study examined the use of larval P. equorum excretory-secretory (ES) products in a western blot test for diagnosis of prepatent equine P. equorum infection. Sera from adult mares negative for patent P. equorum infections, foals prior to consuming colostrum, and P. equorum infected foals were used as controls in this study. Study samples included sera fro...
[Detection of leptospira by culture of vitreous humor and detection of antibodies against leptospira in vitreous humor and serum of 225 horses with equine recurrent uveitis]. In the ongoing discussion regarding the aetiopathogenesis of equine recurrent uveitis (ERU) it was the aim of the present study to elucidate the relationship of leptospira infection and ERU. In a population of 225 horses leptospira were examined in vitreous humor by culture and leptospira antibody were detected in vitreous humor and serum samples. Preoperative serum samples were collected from 221/225 ERU patients of different age, gender and breed. Undiluted vitreous humor was aseptically taken from 198/225 patients that underwent pars plana vitrectomy at the beginning of surgery and from 27/...
Major Histocompatibility Complex I and II Expression and Lymphocytic Subtypes in Muscle of Horses with Immune-Mediated Myositis. Major histocompatibility complex (MHC) I and II expression is not normally detected on sarcolemma, but is detected with lymphocytic infiltrates in immune-mediated myositis (IMM) of humans and dogs and in dysferlin-deficient muscular dystrophy. Objective: To determine if sarcolemmal MHC is expressed in active IMM in horses, if MHC expression is associated with lymphocytic subtype, and if dysferlin is expressed in IMM. Methods: Twenty-one IMM horses of Quarter Horse-related breeds, 3 healthy and 6 disease controls (3 pasture myopathy, 3 amylase-resistant polysaccharide storage myopathy [PSSM]). ...
Nociceptive and sympathetic innervations in the abaxial part of the cranial horn of the equine medial meniscus: an immunohistochemical approach. In athletic horses, diseases leading to lameness are of great importance due to the loss of performance and the resultant economic concerns. Although stifle lesions are frequent in the hindlimb, due to the large size and complexity of the joint, and although meniscal tears have been identified as the most common soft tissue injuries in this joint, little is known about the mechanism that causes the painful sensation and thus the lameness. The aim of our study was to highlight any peripheral fibres involved in meniscal nociception in five macroscopically sound cranial horns of the equine medial...
Equine herpesvirus type 1 modulates inflammatory host immune response genes in equine endothelial cells. Equine herpesvirus myeloencephalopathy (EHM), a disease caused by equine herpesvirus type 1 (EHV-1), is characterized by severe inflammation, thrombosis, and hypoxia in central nervous system (CNS) endothelial cells, which can result in a spectrum of clinical signs including urinary incontinence, ataxia, and paralysis. Strains of EHV-1 that contain a single point mutation within the viral DNA polymerase (nucleotide A2254>G2254: amino acid N752→D752) are isolated from EHM afflicted horses at higher frequencies than EHV-1 strains that do not harbor this mutation. Due to the correlation between...
Immunological and pathological investigations in equine experimental uveitis. The pathogenic mechanism of equine recurrent uveitis (ERU) is still poorly defined and many variations between experimental animal models and spontaneous disease exist. Objective: The aim of our study was to investigate if Th17 cell-mediated response plays role in the pathogenesis of the used experimental model in horses and to reveal its pathological findings. Methods: Experimental uveitis was induced in 6 healthy horses. The concentrations of retinal autoantigen CRALBP and IL-17 were measured using ELISA in aqueous humor and vitreous body of the 12 inflamed eyes as well as in 12 control non-...
