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Topic:Pathogenesis
Pathogenesis in horses refers to the biological mechanisms that lead to the development and progression of diseases within equine species. This process involves a complex interaction between the horse's immune system, genetic predispositions, environmental factors, and infectious agents such as bacteria, viruses, or parasites. Understanding pathogenesis is essential for identifying how diseases manifest and progress in horses, which can inform diagnostic and therapeutic strategies. Research in this area often focuses on specific diseases, examining factors such as pathogen entry, immune response, tissue damage, and recovery processes. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, contributing factors, and implications of pathogenesis in equine health.
Equine arteritis virus Nsp10 promotes MAVS proteasomal degradation via E3 ligases Smurf1/MARCH5. Equine arteritis virus (EAV) is a positive-sense, single-stranded RNA virus that belongs to the family , which also includes porcine reproductive and respiratory syndrome virus (PRRSV). EAV is the causative agent of equine viral arteritis (EVA), an economically important systemic, reproductive, and respiratory disease of equids. EAV infection triggers host innate immunity, yet the precise strategies employed by the virus to evade immune defenses and achieve productive infection are poorly characterized. In this study, it was observed that EAV infection can induce a cellular IFN response; howev...
Possible Effects of C-Reactive Protein in the Central Nervous System During Venezuelan Equine Encephalitis Virus Infection. Venezuelan equine encephalitis virus (VEEV) is an alphavirus vectored by mosquitos. It can cause disease in equines and humans characterised by a febrile illness that may progress into encephalitis. Replication of VEEV in the central nervous system induces activation of glial cells and neurons, compromising the blood-brain barrier (BBB) and inducing a state of neuroinflammation. This inflammation can lead to symptoms such as confusion, seizures, and coma, and sustained inflammation contributes to neurodegeneration. C-reactive protein (CRP) is a biomarker that has previously been associated wit...
Structural Features of the Equine Small Intestinal Mesenteric Attachment Predisposing to Rupture. Rupture of equine small intestine with formation of a pouch of ingesta within the mesentery has been reported in clinical colic cases. Multiple ex-vivo studies using anastomosed jejunum observed rupture into the mesentery, distant to the anastomosis. Both scenarios suggest the jejunum is predisposed to rupture at the mesenteric attachment. The aim of the study is to 1) document the location at which equine jejunal segments rupture when subjected to high intraluminal pressures, 2) identify predisposing anatomical features that may confer weakness at the point of rupture and 3) demonstrate jejun...
Insights from healthy mares reveal that mammalian uteri harbor a diverse virome. The Earth's estimated 10 virions, primarily phages, significantly impact microbial ecosystems. Despite their abundance, viromes remain relatively understudied-particularly in domestic animals. While recent studies have described a dynamic commensal microbiome in mammalian uteri, no research has yet characterized the commensal virome in a mammalian uterus. In this study, we report for the first time the presence of a sparse, but diverse native virome in the equine uterus. The resulting virome database consists of 513 non-redundant viral genomes (> 2 kb). Taxonomic annotations revealed the...
Genetic diversity of Toxoplasma gondii isolates from members of the families camelidae and equidae worldwide: a systematic review. Toxoplasma gondii is an apicomplexan parasite with a global distribution and significant public health and veterinary treatment implications. The present systematic review collates worldwide information on the genotypic diversity of T. gondii isolates infecting Camelidae (camels, alpacas, llamas, etc.) and Equidae (horses, donkeys, zebras, mules, etc.) and highlights their potential role as sentinels of environmental contamination and zoonotic spread. An exhaustive literature search of six electronic databases (PubMed, Web of Science, Scopus, ProQuest, Science Direct, and Google Scholar) from ...
Retrospective assessment of equine herpesvirus type 1 (EHV-1) genotype-associated clinical disease in Ontario. Equine herpesvirus type 1 (EHV-1) is an important viral pathogen in horses, associated with diverse clinical manifestations including fever, upper and lower respiratory disease, neurological signs, ocular disease, and abortion. Currently, EHV-1 variants (genotypes) are classified based on a single nucleotide polymorphism mutation of the open reading frame 30 (ORF30). Unassigned: The aim of this retrospective study was to evaluate the EHV-1 genotypes present in horses with various clinical presentations, including respiratory disease, abortion, and neurological disease, at a referral center in ...
CD8+ T-cells, CD86+ macrophages and TNF-α signalling pathways are correlated with fetlock osteoarthritis in racehorses. There is emerging evidence for the role of the immune system in osteoarthritis (OA) pathophysiology; however, little is known about how immune cells and the synovial transcriptome are altered in naturally occurring equine OA. Objective: To evaluate synovial fluid (SF) and synovial membrane (SM) immune cell populations and the SM transcriptome in racehorses with fetlock OA. Methods: Cross-sectional cadaver study. Methods: Fetlock joints from racehorses euthanised at NY racetracks were considered for inclusion. SF and SM were analysed by flow cytometry using T-cell (CD3, CD4, CD8) and macrophage...
Circulating microRNA profiles as diagnostic and prognostic biomarkers for acute and carrier Theileria equi infection. Equine piroplasmosis caused by Theileria equi exhibits a wide clinical spectrum ranging from acute disease to lifelong asymptomatic carriage, posing significant diagnostic and epidemiological challenges. In this cross-sectional case-control study, equines were classified as acutely infected, asymptomatic carriers, or uninfected controls based on clinical examination and quantitative PCR. Hematological and biochemical alterations were assessed, and plasma miRNA profiles were characterized using small RNA sequencing, followed by qRT-PCR validation of selected miRNAs. Cytokine gene expression in ...
Glanders: Past, Present and Future of a Neglected Zoonosis as a Threat in Veterinary and Human Health. Burkholderia mallei is the causative agent of glanders, a serious zoonotic disease of major concern for both animal and human health. This highly contagious and potentially fatal bacterium is always classified as a biothreat agent. In this review, we covered a comprehensive overview of glanders, including the biology of the pathogen, epidemiology, pathogenesis, diagnosis, control strategies and ongoing eradication programs in Eurasia. We also summarized human case reports, differential diagnosis, treatment and organism's antimicrobial properties. The section on vaccine development is among the...
Autochthonous Leishmaniosis in Dogs, Cats, Horses, and Wildlife in the United States of America. Leishmaniasis is endemic in 99 countries worldwide, including the United States of America (USA). Its causative pathogens, spp. have been detected in both humans and animals within the USA. Lately, we have comprehensively reviewed autochthonous leishmaniasis in humans in this region. Animals play a pivotal role in maintaining its endemicity in some endemic areas and regions, for example, dogs in Brazil and the Mediterranean. In this review, we thoroughly examine autochthonous leishmaniosis in dogs, cats, horses, and wildlife in the USA, and we synthesize integration across species, transmissi...
Multiple strategies, one mission: mesenchymal stromal cell-based mechanisms of action in osteoarthritis. Osteoarthritis (OA) is a cross-species, multifactorial joint disease characterized by the progressive degeneration of articular cartilage, morphological remodeling of the subchondral bone, and inflammatory and fibrotic changes of the joint capsule. These alterations arise from chronic, often subclinical, inflammatory processes and dysregulated cellular homeostasis, leading to profound shifts in the cellular and extracellular composition of the joint organ. Although the mechanisms driving persistent inflammation are only partially understood, their impact on all joint-associated tissues is well...
Molecular typing, biofilm characteristics and biofilm-targeted inhibition strategies of Streptococcus equi subsp. zooepidemicus isolated from donkey endometritis. Endometritis is a major cause of infertility in intensively farmed donkeys. Streptococcus equi subsp. zooepidemicus (SEZ) is a predominant pathogen that readily forms biofilms in equine endometritis, conferring resistance to conventional treatments. Objective: This study aimed to characterize the biofilm dynamics of SEZ isolates obtained from donkeys and to evaluate potential anti-biofilm strategies with different drug combinations. Methods: Uterine lavage samples were collected from 30 Dezhou Black donkeys with clinical endometritis. Bacterial cultures were performed on blood agar and MacConk...
Mucosal T cell activation pathways are upregulated by equine herpesvirus type 1 infection. Equine herpesvirus type 1 (EHV-1) is a high morbidity and mortality virus that impacts horse populations worldwide. As a respiratory virus, it enters through the upper respiratory tract (URT), where mucosal immunity plays a crucial role in preventing severe disease. In this study, flow cytometry was used to characterize the nasal leukocyte population during EHV-1 infection, and RNA sequencing of nasal secretions was employed to assess transcriptional markers of the mucosal immune response. Horses with distinct immune statuses were compared at four stages: pre-infection, early (day 1 and 3 post...
The transition from winter to spring has an impact on the airway metabolome profile of asthmatic horses. Equine asthma is a chronic, non-infectious inflammatory disease of the lower airways in horses, classified as mild to moderate (MEA) or severe (SEA). Its pathogenesis is not fully understood and is influenced by environmental and seasonal factors. In this cross-sectional study, seasonal effects on the bronchoalveolar lavage fluid (BALF) metabolome were investigated in asthmatic and non-asthmatic horses. The metabolome of 230 BALF samples from horses across different seasons, classified as cytologically unremarkable (CUA), MEA, or SEA, was analyzed using proton nuclear magnetic resonance spectr...
Histological properties of the distal sesamoidean impar ligament in racing Thoroughbreds and Quarter horses. The distal sesamoidean impar ligament (DSIL) is a key component of the equine podotrochlear apparatus, yet its role in conditions such as caudal heel pain and navicular syndrome remains poorly understood. The objective of this study was to characterize the histological properties of the DSIL and evaluate how it is influenced by breed and age. Eighty-four cadaveric forelimb DSIL samples were collected from young, athletic Quarter horses (QHs), Thoroughbreds (TBs), and older, retired Quarter horses. Samples were stained and assessed for vessel size and count, number of nerve fascicles, and the r...
Nucleolar proteins nucleolin and nucleophosmin 1 differentially relocalize during equid alphaherpesvirus 1 (EHV1) infection. We investigated equine nucleolar proteins nucleophosmin 1 (NPM1) and nucleolin (NCL) during EHV1 infection to develop understanding of EHV1-nucleolar interactions. Equine NPM1 primarily localized throughout nucleoli whereas NCL accumulated in a peri-nucleolar ring and localized throughout the nucleoplasm. EHV1 did not notably affect NPM1 or NCL protein levels but did alter their subnuclear localization. NPM1 accumulated in EHV1 replication compartments and remained nucleolus-associated until very late infection stages, characterized by a kidney bean-shaped nucleus and round cell morphology. NC...
Septic Endophthalmitis Following Suprachoroidal Cyclosporine Implant Placement in Two Horses With Equine Recurrent Uveitis. This article presents the clinical and histopathological findings from two horses that developed severe postoperative complications following suprachoroidal procedures routinely employed in the management of equine recurrent uveitis (ERU). Case 1 was a 5-year-old warmblood stallion that initially received a unilateral suprachoroidal triamcinolone injection, followed later by bilateral suprachoroidal cyclosporine implant (CSI) placement. At 9 weeks postoperatively, the right eye (which had undergone both procedures) developed secondary glaucoma necessitating enucleation. Case 2 was a 14-year-ol...
Molecular characterization of Anaplasmataceae in Turkmen horses (Akhal-Teke breed) and ticks in racetracks, Iran. Due to the abundance of ticks on open grassy surfaces, racetracks may represent ideal scenarios for tick-borne pathogens. Therefore, in 2024/2025 Turkmen horses (Akhal-Teke breed) and ticks collected by dragging in paddocks of Iran were screened for Anaplasmataceae using Sanger sequencing on 16S rRNA, TRP36 and dsb genes. Amongst 200 horses, 11 (5.5%) tested positive without signs/symptoms, being 8 (4%) for Ehrlichia canis and 3 (1.5%) for Anaplasma ovis; no difference in prevalence was found by gender and age (p>0.05). All ticks were identified as Hyalomma asiaticum and Haemaphysalis sulca...
Theileria haneyi: An Emerging Equids Hemoparasite with Milder Virulence but Major Diagnostic and Therapeutic Implications. , a recently discovered tick-borne hemoparasite infecting equids globally, has significant implications for equine health. Although it is closely related to (sharing 23% genomic divergence), it establishes an asymptomatic carrier state in persistently infected horses, creating a silent transmission reservoir. Its discovery and unique genetics justify its classification as a new taxon. A critical diagnostic challenge is that the lack of the gene in prevents its detection by the standard cELISA, emphasizing the need for species-specific tools. Although species-specific PCR assays, including ...
Spontaneous regression of equine sarcoids is an exceptional event. Sarcoids are benign, yet locally aggressive skin tumours that commonly affect horses and other equid species. The lesions are induced by bovine papillomavirus types 1, 2, and probably 13 in conjunction with other factors including trauma and a genetic predisposition. Although sarcoids have a substantial impact on the health and welfare of affected equids, information on the immune response to bovine papillomavirus infection and resulting sarcoids is limited. However, there is evidence that sarcoid disease is associated with an impaired immune response to bovine papillomavirus infection. This o...
Computational modelling of the equine arteritis virus GP5/M Dimer: Implications for immune evasion and virulence. Equine arteritis virus (EAV) is a positive-stranded RNA virus of the Arteriviridae family. Its GP5/M dimer, the principal component of the viral envelope, mediates virus budding and serves as a key target for neutralizing antibodies. Using AlphaFold3, we predicted the 3D structure of the EAV GP5/M dimer and compared it to its homolog in porcine reproductive and respiratory syndrome virus (PRRSV). Both complexes share a conserved architecture comprising a short ectodomain, three helical transmembrane regions, and a β-sheet-rich endodomain. EAV GP5 features a longer ectodomain with four α-heli...
Evaluation of multiple methods for the diagnosis of equine Hemomycoplasmosis in Misan, Iraq. Hemomycoplasmosis caused by Hemotropic mycoplasmas, or Hemoplasma, which were previously classified as Eperythrozoon spp., are uncultivable parasites that infect the cell wall of erythrocytes in many susceptible mammals, including cattle, buffalo, goats, sheep, horses, cats, dogs, and even camels, and can be transmitted to humans. Unassigned: The purpose of the present work is to display and evaluate the different diagnostic criteria for detecting the most precise method for diagnosing Hemomycoplasma in horses. Unassigned: Different diagnostic methods were used to diagnose equine Hemomycoplasm...
Prolonged wireless measurement of intragastric pH in foals. The pathogenesis of gastric ulceration is not well understood in foals, and its relationship with gastric acidity requires further investigation. A wireless capsule, designed for intraesophageal pH monitoring in humans, was adapted to measure intragastric pH in adult horses. Objective: To (1) determine the feasibility of wireless intragastric pH measurement in foals; (2) determine capsule attachment duration; and (3) describe the intragastric pH profiles recorded. Methods: Eight healthy foals aged 24-98 days. Methods: Prospective interventional study. Capsules were attached to the glandular g...
Association between ultraviolet-related TP53 mutations and immune microenvironment in equine ocular squamous cell carcinoma. This study investigates the molecular and immune characteristics of equine ocular squamous cell carcinoma (eoSCC). Immunohistochemistry (IHC) and next-generation sequencing (NGS) were used to detect protein expression and TP53 mutations, respectively. T lymphocytes (CD3+), regulatory T cells (FoxP3+), B lymphocytes (CD20+), and macrophages (IBA-1+) were quantified. A total of 29 cases of eoSCC were evaluated, consisting of 3/29 carcinomas in situ (CISs) and 26/29 squamous cell carcinomas (SCCs). p53 positivity by IHC was detected in 19/29 cases while by NGS, 21 TP53 mutations were found in 13/...
Adjunctive use of Maggot Debridement Therapy in the treatment of equine cutaneous pythiosis: A case report. Equine cutaneous pythiosis, caused by Pythium insidiosum, is a severe disease in tropical and subtropical regions, often leading to progressive granulomatous lesions with poor response to conventional therapies. Standard treatment includes surgical excision and immunotherapy, but recurrence is common, particularly in distal limb lesions. Maggot Debridement Therapy (MDT) with disinfected Lucilia cuprina larvae provides selective debridement, microbial control, and stimulation of granulation, representing a potential adjunctive option. This report describes the successful use of MDT combined wit...
Beyond the host: Unveiling the independent microbiome of equine gastrointestinal nematodes. Gastrointestinal nematode infections significantly impact equine health and welfare, with rising anthelmintic resistance demanding alternative control strategies. Emerging evidence suggests that parasitic nematodes harbour distinct microbiomes, potentially influencing host-parasite dynamics and parasite survival. This study aimed to characterize and compare the microbiomes of equine gastrointestinal nematodes and their hosts, focusing on differences in composition, diversity, and core microbiota structure across different intestinal sites, nematode subfamilies, and sexes. Faecal and nematode s...
RNA-seq evaluation of equine alveolar macrophages and monocyte-derived macrophages exposed to an inflammatory stimulus (short communication). Macrophage populations in the lung, including resident alveolar macrophages (AMs) and recruited monocyte-derived macrophages (MDMs), recognize the inhaled particulates in barn dust that cause severe equine asthma and orchestrate an immune response though the cytokines they produce. Despite their importance, the specific contributions of these macrophage subsets to lower airway inflammation remain poorly understood. This exploratory in vitro study investigated the likely contributions of AMs and MDMs from healthy horses to the early inflammatory response using RNA-seq. If biologically importan...
Occurrence of tick-borne pathogens in questing ticks, ticks from riding horses, and red deer blood in Western Pomerania, Poland. Ixodes ricinus is a widespread vector of numerous microorganisms pathogenic to humans and animals in Europe. The risk of exposure to tick-borne pathogens (TBPs) has increased in recent years due to climate change, the conversion of natural green areas to recreational areas, and growing human and animal populations, including pets. Using molecular methods, the prevalence, diversity, and co-occurrence of selected tick-borne microorganisms were assessed in questing I. ricinus collected from recreational areas (n = 409), in ticks feeding on horses (n = 135), and in blood samples from red d...
Genome-wide CRISPR/Cas9 screening identifies host factors critical for antiviral defense against equine herpesvirus type 1. Equine herpesvirus type 1 (EHV-1) is a major veterinary pathogen causing significant economic losses in the livestock industry. Despite its impact, effective vaccines and targeted antiviral strategies remain limited, largely due to an incomplete understanding of host factors regulating viral replication and pathogenesis. Unassigned: To systematically identify host genes essential for EHV-1 infection, we established a BHK-21 cell line stably expressing Cas9 and performed a genome-wide CRISPR/Cas9 knockout screen using a pooled lentiviral single-guide RNA library. Significantly enriched candidat...
Clostridioides difficile infection in animals: a literature review. Clostridioides difficile affects humans, and several other animal species, such as horses, pigs, gerbils, guinea pigs, hamsters, and rabbits. This microorganism has also been isolated from the gastrointestinal tract of healthy individuals of a wide variety of animal species in which its association with disease is not known. Traditionally, in most domestic animal species, C. difficile-infection disease (CDI) was antibiotic-associated, although in the past few years more cases in which no antibiotic association was known have been described. In addition, no antibiotic association has been descr...
