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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.
The bicolored white-toothed shrew Crocidura leucodon (HERMANN 1780) is an indigenous host of mammalian Borna disease virus. Borna disease (BD) is a sporadic neurologic disease of horses and sheep caused by mammalian Borna disease virus (BDV). Its unique epidemiological features include: limited occurrence in certain endemic regions of central Europe, yearly varying disease peaks, and a seasonal pattern with higher disease frequencies in spring and a disease nadir in autumn. It is most probably not directly transmitted between horses and sheep. All these features led to the assumption that an indigenous virus reservoir of BDV other than horses and sheep may exist. The search for such a reservoir had been unsuccessfu...
Anatomy of the vestibule of the omental bursa and epiploic foramen in the horse. Epiploic foramen entrapment (EFE) is a common cause of colic in horses and available anatomical descriptions of this foramen and the associated vestibule of the omental bursa tend to be inconsistent, contradictory and inaccurate. Objective: To describe the anatomy of the vestibule of the omental bursa and epiploic foramen. Methods: Dissection of 21 fresh equine cadavers shortly after euthanasia. Methods: The anatomy of the vestibule of the omental bursa, epiploic foramen and related structures in the cranial abdomen were examined in situ and after removal from the abdomen. Photographs were tak...
Genomic analysis establishes correlation between growth and laryngeal neuropathy in Thoroughbreds. Equine recurrent laryngeal neuropathy (RLN) is a bilateral mononeuropathy with an unknown pathogenesis that significantly affects performance in Thoroughbreds. A genetic contribution to the pathogenesis of RLN is suggested by the higher prevalence of the condition in offspring of RLN-affected than unaffected stallions. To better understand RLN pathogenesis and its genetic basis, we performed a genome-wide association (GWAS) of 282 RLN-affected and 268 control Thoroughbreds. Results: We found a significant association of RLN with the LCORL/NCAPG locus on ECA3 previously shown to affect body siz...
Comparison of prevalence factors in horses with and without seropositivity to Neospora hughesi and/or Sarcocystis neurona. Equine protozoal myeloencephalitis is a commonly diagnosed neurological disease of horses in North America and is caused by infection with Sarcocystis neurona or Neospora hughesi. The aim of this study was to compare prevalence factors among horses seropositive or seronegative to N. hughesi and/or S. neurona. A total of 3123 submissions were included in the study, with horses originating from 49 States. Thirty-eight animals from 21 States tested seropositive for N. hughesi only, 840 horses from 40 States were seropositive for S. neurona only, 25 horses from 14 States were seropositive for both...
Attempts to induce nocardioform placentitis (Crossiela equi) experimentally in mares. Nocardioform placentitis in horses is poorly understood, and the development of an experimental model would be of help in understanding the pathogenesis of the disease. Objective: To investigate whether (1) intrauterine inoculation of Crossiela equi during the periovulatory period or (2) i.v., oral or intranasopharyngeal inoculation of C. equi during midgestation would result in nocardioform placentitis, and (3) before and after mating endometrial swabs present evidence of nocardioform placentitis-associated organisms (C. equi or Amycolatopsis spp.). Methods: In Study I, mares (n = 20) rec...
Association of antibodies against Neospora caninum in mares with reproductive problems and presence of seropositive dogs as a risk factor. Sera from 112 mares from 5 horse-breeding farms was examined for the presence of antibodies to Neospora caninum and Toxoplasma gondii by an indirect fluorescent antibody test (IFAT), as well as from dogs and cattle present on these properties for the presence of antibodies to N. caninum. Among the 112 mares, 35 had a history of reproductive problems in the last breeding season and 77 had no reproductive problems. The rates of seroprevalence of N. caninum in mares with and without a history of reproductive problems were 25.71% and 6.49% and from T. gondii 2.85% and 1.29%, respectively. In dogs ...
Effects of age and macrophage lineage on intracellular survival and cytokine induction after infection with Rhodococcus equi. Rhodococcus equi, a facultative intracellular pathogen of macrophages, causes life-threatening pneumonia in foals and in people with underlying immune deficiencies. As a basis for this study, we hypothesized that macrophage lineage and age would affect intracellular survival of R. equi and cytokine induction after infection. Monocyte-derived and bronchoalveolar macrophages from 10 adult horses and from 10 foals (sampled at 1-3 days, 2 weeks, 1 month, 3 months, and 5 months of age) were infected ex vivo with virulent R. equi. Intracellular R. equi were quantified and mRNA expression of IL-1β, ...
Bovine calves as ideal bio-indicators for fluoridated drinking water and endemic osteo-dental fluorosis. Relative susceptibility to fluoride (F) toxicosis in the form of osteo-dental fluorosis was observed in an observational survey of 2,747 mature and 887 immature domestic animals of diverse species living in areas with naturally fluoridated (>1.5 ppm F) drinking water. These animals included buffaloes (Bubalus bubalis), cattle (Bos taurus), camels (Camelus dromedarius), donkeys (Equus asinus), horses (Equus caballus), goats (Capra hircus), and sheep (Ovis aries). Of these mature and immature animals, 899 (32.7 %) and 322 (36.3 %) showed evidence of dental fluorosis with varying grades, r...
Treatment of idiopathic headshaking in horses with pulsed high-dose dexamethasone. Treatment of idiopathic headshaking in horses is complicated by an incomplete understanding of underlying pathophysiology and partially effective treatments. If an inflammatory etiology exists, corticosteroids could be beneficial. Objective: An anti-inflammatory dose of dexamethasone reduces the signs of idiopathic headshaking in a field setting. Methods: Convenience sample of 20 adult horses with idiopathic headshaking syndrome. Cases were recruited from the general population and diagnosed by attending veterinarians. Methods: Prospective, blinded clinical trial. Pulsed dosing was with oral d...
Diagnostic value of tissue monensin concentrations in horses following toxicosis. Two separate incidents of monensin exposure in horses resulting in toxicosis provided insight into the diagnostic value and interpretive criteria of various biological samples. In case 1, 25 horses broke into a shed and ingested feed that was supplemented with 800 g/ton (880 µg/g) of monensin. Within 48 hr, 1 horse had died, 2 developed cardiac arrhythmias, lethargy, and recumbency, and another was euthanized due to severe deterioration. Minimal histologic lesions were noted in the horse that died peracutely, while another showed characteristic lesions of acute cardiomyocyte degeneration and ...
Unraveling the equine lymphocyte proteome: differential septin 7 expression associates with immune cells in equine recurrent uveitis. Equine recurrent uveitis is a spontaneous, lymphocyte-driven autoimmune disease. It affects horses worldwide and presents with painful remitting-relapsing inflammatory attacks of inner eye structures eventually leading to blindness. Since lymphocytes are the key players in equine recurrent uveitis, we were interested in potential changes of their protein repertoire which may be involved in disease pathogenesis. To create a reference for differential proteome analysis, we first unraveled the equine lymphocyte proteome by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis ...
Expression and regulation of facilitative glucose transporters in equine insulin-sensitive tissue: from physiology to pathology. Glucose uptake is the rate-limiting step in glucose utilization in mammalians and is tightly regulated by a family of specialized proteins, called the facilitated glucose transporters (GLUTs/SLC2). GLUT4, the major isoform in insulin-responsive tissue, translocates from an intracellular pool to the cell surface and as such determines insulin-stimulated glucose uptake. However, despite intensive research over 50 years, the insulin-dependent and -independent pathways that mediate GLUT4 translocation are not fully elucidated in any species. Insulin resistance (IR) is one of the hallmarks of equin...
Gammaherpesviruses and pulmonary fibrosis: evidence from humans, horses, and rodents. Progressive lung fibrosis in humans, typified by idiopathic pulmonary fibrosis (IPF), is a serious cause of morbidity and mortality in people. Similar diseases have been described in dogs, cats, and horses. The cause and pathogenesis of such diseases in all species is poorly understood. There is growing evidence in human medicine that IPF is a manifestation of abnormal wound repair in response to epithelial injury. Because viruses can contribute to epithelial injury, there is increasing interest in a possible role of viruses, particularly gammaherpesviruses, in the pathogenesis of pulmonary fi...
A genome-wide association study demonstrates significant genetic variation for fracture risk in Thoroughbred racehorses. Thoroughbred racehorses are subject to non-traumatic distal limb bone fractures that occur during racing and exercise. Susceptibility to fracture may be due to underlying disturbances in bone metabolism which have a genetic cause. Fracture risk has been shown to be heritable in several species but this study is the first genetic analysis of fracture risk in the horse. Results: Fracture cases (n = 269) were horses that sustained catastrophic distal limb fractures while racing on UK racecourses, necessitating euthanasia. Control horses (n = 253) were over 4 years of age, were racing during the s...
Landscape features and reservoir occurrence affecting the risk for equine infection with Borna disease virus. Borna disease (BD) is a severe endemic and fatal disorder caused by the neurotropic Borna disease virus (BDV) which mainly occurs in horses and sheep. Borna disease virus belongs to the order Mononegavirales, which includes many reservoir-bound viruses with high zoonotic and pathogenic properties including the filoviruses and lyssaviruses. Clinically manifest BD occurs in endemic areas of Germany, Switzerland, Liechtenstein, and Austria. A seasonal accumulation of cases in spring and summer, incidences that vary from year to year, and the recent detection of BDV in bicolored shrews (Crocidura ...
Does intraoperative low arterial partial pressure of oxygen increase the risk of surgical site infection following emergency exploratory laparotomy in horses? Decreased tissue oxygenation is a critical factor in the development of wound infection as neutrophil mediated oxidative killing is an essential mechanism against surgical pathogens. The objective of this prospective case series was to assess the impact of intraoperative arterial partial pressure of oxygen (PaO2) on surgical site infection (SSI) in horses undergoing emergency exploratory laparotomy for acute gastrointestinal disease. The anaesthetic and antibiotic protocol was standardised. Demographic data, surgical potential risk factors and PaO2, obtained 1h after induction of anaesthesia w...
The threat of midge-borne equine disease: investigation of Culicoides species on UK equine premises. There are concerns that outbreaks of exotic or novel vector-borne viral diseases will increasingly occur within northern Europe and the UK in the future. African horse sickness (AHS) is a viral disease of equids that is transmitted by Culicoides and is associated with up to 95 per cent mortality. AHS has never occurred in the UK; however, it has been suggested that appropriate Culicoides species and climatic conditions are present in northern Europe to support an outbreak. No data are currently available regarding the Culicoides species present on UK equine properties. This study demonstrates ...
Alterations in sclerostin protein in lesions of equine osteochondrosis. Osteochondrosis (OC) is a common and clinically important joint disease that occurs in many species, including humans, pigs, chickens and horses. It has been described as a focal failure of endochondral ossification (EO), but no cellular/molecular mechanisms are fully described that explain the cause of this condition. Recently a Wnt signalling inhibitor, sclerostin, has been described in osteoarthritic cartilage, where it has been proposed to protect damaged cartilage from degradation. Cartilage degradation is a key event in EO, thus, abnormalities of sclerostin in growth cartilage could, pot...
Characterization of a mucoid clone of Streptococcus zooepidemicus from an epizootic of equine respiratory disease in New Caledonia. Streptococcus equi subspecies zooepidemicus (Sz) is a tonsillar and mucosal commensal of healthy horses with the potential to cause opportunistic infections of the distal respiratory tract stressed by virus infection, transportation, training or high temperature. The invasive clone varies from horse to horse with little evidence of lateral transmission in the group. Tonsillar isolates are non-mucoid although primary isolates from opportunist lower respiratory tract infections may initially be mucoid. In this study, a novel stably mucoid Sz (SzNC) from a clonal epizootic of respiratory disease ...
Neospora spp. antibodies in horses from two geographical regions of the state of Santa Catarina, Brazil. The aims of this study were to determine occurrences of Neospora spp. IgG antibodies in horses from two geographical regions of the state of Santa Catarina, southern Brazil, and identify risk factors for infection. Analyses were performed on 615 samples using the immunofluorescent antibody test (IFAT ≥ 1:50). Out of the 615 samples, 25 (4.1%) were positive for Neospora spp. The titers for Neospora spp. were distributed as follows: 1:50 (13), 1:100 (eight), 1:200 (three) and 1:400 (one). Out of the 311 samples taken in the mountain region, eight were positive (2.6%). Among the samples from th...
Genome-wide detection of copy number variations among diverse horse breeds by array CGH. Recent studies have found that copy number variations (CNVs) are widespread in human and animal genomes. CNVs are a significant source of genetic variation, and have been shown to be associated with phenotypic diversity. However, the effect of CNVs on genetic variation in horses is not well understood. In the present study, CNVs in 6 different breeds of mare horses, Mongolia horse, Abaga horse, Hequ horse and Kazakh horse (all plateau breeds) and Debao pony and Thoroughbred, were determined using aCGH. In total, seven hundred CNVs were identified ranging in size from 6.1 Kb to 0.57 Mb across a...
Epidemiology and Genetic Characterization of H3N8 Equine Influenza Virus Responsible for Clinical Disease in Algeria in 2011. An outbreak of equine influenza (EI) was reported in Algeria between May and July, 2011. The outbreak started in Tiaret, in west province of Algeria, and spread to the other parts of the country affecting almost 900 horses in many provinces. The population studied was composed of 325 horses from different groups of age. Clinical sign expression was age dependent. Indeed, a morbidity rate of 14.9% was observed in horses under 15 months old and a rate of 4.95% in horses over 8 years old. Interestingly, the morbidity rate raised sharply to reach 100% in horses aged between 18 months and 7 yea...
Recent advances in understanding the pathogenesis of Lawsonia intracellularis infections. Proliferative enteropathy is an infectious disease caused by an obligate intracellular bacterium, Lawsonia intracellularis, and characterized by thickening of the intestinal epithelium due to enterocyte proliferation. The disease is endemic in swine herds and has been occasionally reported in various other species. Furthermore, outbreaks among foals began to be reported on breeding farms worldwide within the past 5 years. Cell proliferation is directly associated with bacterial infection and replication in the intestinal epithelium. As a result, mild to severe diarrhea is the major clinical si...
Genetic risk factors for insidious equine recurrent uveitis in Appaloosa horses. Appaloosa horses are predisposed to equine recurrent uveitis (ERU), an immune-mediated disease characterized by recurring inflammation of the uveal tract in the eye, which is the leading cause of blindness in horses. Nine genetic markers from the ECA1 region responsible for the spotted coat color of Appaloosa horses, and 13 microsatellites spanning the equine major histocompatibility complex (ELA) on ECA20, were evaluated for association with ERU in a group of 53 Appaloosa ERU cases and 43 healthy Appaloosa controls. Three markers were significantly associated (corrected P-value <0.05): a SNP ...
