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.
Bykovsky AF, Yershov FI, Zhdanov VM.Morphogenesis of Venezuelan equine encephalomyelitis virus was studied by means of electron microscopy. Virus-specific structures (factories, viroplasts) were found at early stages of infection; these structures were composed of fibrillar and cylindrical formations, aggregates of ribosomes, and viral nucleoids. The latter emerged from fibrillar and cylindrical structures. Aggregates of viral nucleoids were found in the cytoplasm and occasionally in the nuclei of virus-infected cells. Viral envelopes and mature virions were formed on the cell membranes and on the membranes of intracellular vacu...
Rubarth S, Krook L.Following a description of the histopathology of so-called mucoid degeneration of the nasal conchae in the horse, the authors conclude that the morphologic nature of the disease is osteodystrophia fibrosa. The lesions are believed to be expressions of nutritional secondary hyperparathyroidism.
RANDALL CC, WALKER BM.Randall, Charles C. (University of Mississippi School of Medicine, Jackson) and Barbara M. Walker. Degradation of deoxyribonucleic acid and alteration of nucleic acid metabolism in suspension cultures of L-M cells infected with equine abortion virus. J. Bacteriol. 86:138-146. 1963.-Metabolic alterations in log-phase suspension cultures infected with equine abortion virus (EAV) were determined in L-M cells simultaneously labeled or prelabeled with H(3)- or C(14)-thymidine. Although infection produced an early stimulation of the uptake of labeled thymidine (TdR) into the acid-soluble fraction of...
REBERS PA, HURWITZ E, HEIDELBERGER M.Rebers, Paul A. (Rutgers University, New Brunswick, N. J.), Esther Hurwitz, and Michael Heidelberger. Immunochemistry of pneumococcal types II, V, and VI. II. Inhibition tests in the type VI precipitating system. J. Bacteriol. 82:920-926. 1961.-As in other immune systems involving polysaccharides, rabbit antibodies but not those engendered in the horse were found sensitive to degradation of type VI pneumococcal (Pn) polysaccharide (SVI), and were readily inhibited by fragments of SVI. Large amounts, 30 to 111 mumoles, of most sugars gave up to 15% inhibition, while sugar and polyol phosphates ...
Gamage C, Holl W, Parreño V, Thieulent CJ, Balasuriya UBR, Vissani MA, Barrandeguy ME, Carossino M.Group A rotavirus (RVA) infections are a leading cause of neonatal diarrhoea in foals. Neonatal mice could serve as a useful tool to study the pathogenesis of equine RVA (ERVA) as well as a preclinical model for assessment of vaccine efficacy. This study aimed to comparatively evaluate the clinical, virological and pathological features of ERVA G3P[12] and G14P[12] infection in neonatal mice and compare them with porcine OSU G5P[7] and bovine UK G6P[5] RVA reference strains. Neonatal mice orally inoculated with equine, bovine and porcine RVA developed short-lived diarrhoea at variable rates, G...
Bauquier J, Takahashi C, Rosales C, Pitt J.There is limited published information on Malva parviflora toxicosis in horses. Four previously reported cases all resulted in death or euthanasia. The aim of this cluster investigation was to describe historical, clinical and clinicopathological findings of four ponies with suspected M. parviflora toxicosis and compare these to previously reported cases. Historical, clinical and clinicopathological findings were collated. Ponies were grazing pasture of approximately >90% M. parviflora. Pony 1 died rapidly without veterinary examination. Pony 2 was examined for prolonged recumbency attribut...
de Souza Lima E, de Oliveira Filho RB, Malta KC, Pires IC, Rosa DS, Chideroli RT, Aburjaile FF, de Jesus Sousa T, Ramos RTJ, Góes-Neto A....Corynebacterium pseudotuberculosis is a bacterium that causes significant economic damage to farmers, mainly in the semiarid region of Northeastern Brazil. In this context, only biovar ovis has been reported, and it is widespread in small ruminants. However, this report describes the first equine case in Brazil attributable to a biovar equi. Clinically, it is the causative agent of ulcerative lymphangitis, mastitis, necrotic and ulcerative dermatitis. A Quarter Horse from the semiarid Northeast presented ulcerative lymphangitis. Culture, nitrate reduction test, MALDI-TOF, and whole-genome sequ...
Fennouh C, Mokrani D, Dahmani H, Salhi O, Ouchetati I, Nabi M, Aouina K, Chettih I, Ouchene N, Khelifi Touhami NA.Fasciolosis, a parasitic disease of ruminants, poses significant economic and animal-health challenges in Algeria. This study aimed to assess spatial, temporal, and species-specific patterns of fasciolosis prevalence across diverse agro-climatic zones and to estimate associated economic losses. Between 2013 and 2023, eight wilayas El-Tarf, Skikda, Jijel (Region I), Blida, Mila (Region II), and M'Sila, Medea, Laghouat (Region III) were surveyed. Systematic postmortem inspections of 1,569,392 animals (349,176 cattle; 982,669 sheep; 235,639 goats; 1,882 camels; 26 horses) were performed by qualif...
Albornoz A, Morales B, Fernandez VB, Henriquez C, Quiroga J, Alarcón P, Moran G, Burgos RA.Equine asthma is a chronic respiratory disease characterised by neutrophilic inflammation, airway hyperresponsiveness, and impaired pulmonary function. Obesity, increasingly prevalent among domestic horses, has been identified as a potential risk factor for exacerbating inflammatory conditions. This study aimed to explore whether obesity modifies neutrophil metabolism and inflammatory responses in horses affected by asthma. Six asthmatic horses in clinical remission were categorised into two groups: obese and non-obese, based on body condition score. Serum levels of interleukin-1β (IL-1β) an...
Golen GS, Erganiş O, Balevi A. is an important bacterial pathogen and causes severe chronic granulomatous pneumonia in foals below 6 months of age. It has also become an opportunistic and emerging pathogen in immunocompromised humans. Vaccination is the most cost-effective strategy for controlling and preventing this infection. Although several potential virulence genes and candidate immunogens have been identified over the years, no effective vaccine is currently available to prevent disease in horses. Recently, bacterial vector vaccines have been shown to be promising for In this study, the gene of was cloned into P...
Duaso J, Perez-Ecija A, Navarro A, Martínez E, De Las Heras A, Mendoza FJ.Equine piroplasmosis (EP), caused by and , is a worldwide tick-borne disease with severe economic, commercial, and sanitary implications for equids. Although diagnosis is based on direct (blood smear or PCR) or indirect (serology) methods, these techniques are expensive, laborious, and false-negative and false-positive results can be yielded. Biochemistry blood profiles are routinely performed in horses. Biochemical parameters and ratios could be a reliable complementary diagnostic tool to assist clinicians in EP diagnosis, mainly in endemic areas, or for discarding similar disorders (piro-li...
Mohamed E, Van Cleemput J, Şahin B, Van den Broeck W, Boyen F, Nauwynck H.The equine respiratory and reproductive tract microbiomes are complex and subject to constant fluctuations. Among the microbial inhabitants, subsp. (SEZ) is recognized as the dominant bacterium. It is an opportunistic pathogen that may occasionally lead to various types of infections. A key virulence factor of SEZ is the streptolysin S (SLS) toxin, which is responsible for the characteristic β-hemolysis on blood agar and tissue damage. Viruses and bacteria may interact and aggravate lesions and disease. This study aimed to evaluate the impact of an SLS-containing supernatant from SEZ on the...
Tesena P, Vinijkumthorn R, Kingkaw A, Yanyongsirikarn P, Phasuk K, Ploypetch S, Phaonakrop N, Roytrakul S, Vongsangnak W, Prapaiwan N.Equine melanocytic neoplasm (EMN) is a skin tumor commonly observed in grey horses. Limited research has yet to investigate proteomic profiles of EMN, particularly in the early stages and their expression patterns. This study, therefore, aimed to identify signature proteins from tissue biopsies to distinguish early EMN, severe EMN, and normal groups. Results: Using proteomic analysis of 19 tissue samples (normal: n = 6, early EMN: n = 7, severe EMN: n = 6) through LC-MS/MS, 12,310 proteins were identified. Differentially expressed proteins (DEPs) and functional interaction analysi...
Ryu SH, Forbes E, Kim BS, Park KT.Five previously healthy horses in Korea, including a 19-year-old mixed-breed gelding, a 16-year-old mixed-breed mare, a 13-year-old Thoroughbred gelding, a 12-year-old Belgian warmblood mare, and a 12-year-old Andalusian mare, developed subcutaneous abscesses in the left neck after receiving intramuscular vaccination without prior skin disinfection. The vaccination used was Equivac® 2 in1, containing toxoid and cell-free extract. Within one week, the horses developed localised swelling and/or abscessation at the injection site. One case involved a ruptured abscess, while the others presente...
Kang H, Lee GKC, Bienzle D, Hammermüller J, Arroyo LG, Lillie BN, Beeler-Marfisi J.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...
Hodgson E, Romano TR, Stewart A, Bond S, Wise J.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...
Brandt S.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...
Dillmann JB, Dos Santos TS, Dos Santos RC, Monteiro SG.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...
Magdesian KG.Alloimmune disorders occur in foals when pregnant mares produce antibodies against antigens on the foal's cells or tissues, and concentrate them within colostrum. Once foals nurse and absorb colostral antibodies, they can develop hematologic or cutaneous manifestations that can occur individually or in combination. These include neonatal isoerythrolysis, a hemolytic anemia directed against factors on the foal's erythrocytes, alloimmune thrombocytopenia when the antibodies are directed against platelet antigens, alloimmune neutropenia when they are directed against neutrophil antigens, and a co...
Martano M, Montagnaro S, Power K, Cuccaro B, Cutarelli A, Maiolino P, Restucci B.This study investigated the presence of δ bovine papillomaviruses (BPV-1, BPV-2, BPV-13, BPV-14) in equine skin lesions from Southern Italy, focusing on equine sarcoids and their histopathological correlations. 63 equine skin samples were analysed using PCR and sequencing for BPV detection, and their histopathological features were assessed. BPV DNA was detected in 69.84% of the samples, with BPV-1 and BPV-2 being the most prevalent genotype, followed by BPV-13, while BPV-14 was not detected. BPV DNA was also found in non-sarcoid tumours and non-neoplastic conditions. Histopathological analys...
Neira-Egea P, Alamar Malvoisin C, de la Cuesta-Torrado M, Bautista-Erler C, Vitale V, Jolly S, Cesarini C. spp. are ubiquitous yeasts that are part of most mammals' microbiota and can become opportunistic pathogens under predisposing conditions. Interestingly, recent studies in human medicine report an increased abundance of spp. in association with inflammatory bowel disease (IBD). Gastrointestinal candidiasis has been primarily reported in neonatal foals, but not in adult horses. The aim of this study is to describe the morphological, histopathological, and microbiological features of gastric lesions associated with infiltration in five horses referred to two tertiary hospitals for different r...
Parashar R, Singla LD, Kaur P, Sharma SK.Relative association of haemato-biochemical findings with oxidative stress markers was evaluated between natural patent and latent infection of in horses to divulge the role of these parameters in the pathogenesis of illness due to non-availablity in literature. Blood samples were collected from 429 equines of 16 districts of the Punjab and samples positive by conventional microscopy (patent Group I; oll = 13), by polymerase chain reaction (PCR) (latent group II; = 38) and healthy control (group III, = 64) were compared for haematological-biochemical index and stress parameters....
Muderspach ND, Daucke R, Nielsen MW, Scoggin KE, Fedorka CE, Miller LMJ, May MG, Troedsson MHT, Ferreira-Dias G, Agerholm JS, Schoof EM....Endometrial fibrosis leads to subfertility when periglandular fibrosis impairs endometrial gland function. Identifying distinct protein expressions in mares suffering from this condition is essential for understanding the pathogenesis and developing treatments to delay fibrotic progression. To gain a better understanding of protein dynamics underlying this condition, Data-Independent Acquisition Mass Spectrometry was utilized to comprehensively characterize and compare the equine endometrial and plasma proteome from mares with different severities of endometrial fibrosis. Mares in diestrus wer...
Mazur SE, Toribio RE.Complications in critically ill equine patients are often related to the underlying disease process but can also be a consequence of diagnostic and therapeutic interventions. Complications can be specific to the affected organ or body system; however, in critically ill patients, they frequently affect the vasculature, acid-base, electrolyte, and fluid balance, energy homeostasis, and coagulation, with systemic consequences. Infrequent monitoring, late detection, failure to adapt therapies, hematologic and biochemical abnormalities, coagulopathies, and systemic inflammation can all contribute t...
Seeger MG, de Vargas APC, Vogel FSF, Cargnelutti JF.Streptococcus equi subsp. equi (S. equi) is the etiological agent of strangles, a contagious equine disease characterized by lymph node abscess and respiratory complications. To clarify the epidemiology and virulence factors of isolates, this study demonstrated phenotypic and genotypic differences between S. equi obtained from nasal secretions and lymph node aspirates of clinical strangles cases. Additionally, circulating alleles were differentiated through sequencing of the 5' end of the seM gene. A total of 23 clinical isolates collected from horses with strangles over the past decade were a...
Meiseberg LK, Mergani A, Delarocque J, Imker R, Köhn D, Wanes D, Bonilla MC, Veldhuizen EJA, von Köckritz-Blickwede M, Ohnesorge B, de Buhr N.Equine asthma (EA) is the most prevalent chronic lung disease in horses. Neutrophils are the main effector cells in severe EA. Neutrophil extracellular traps (NETs) have been described as contributors to severity in human asthma and chronic obstructive pulmonary disease. Thus, we aimed to investigate if NET-related factors in equine neutrophils, blood and bronchoalveolar lavage fluid (BALF) allow us to differentiate EA severities and to identify NET-related mechanistic insights in EA. We quantified NETs and NET-related factors in the blood and BALF of eight healthy horses and 18 horses with di...
Kingsley NB, Sandmeyer L, Dwyer A, Langefeld CD, McMullen RJ, McCue M, Lassaline M, Bellone RR.Equine recurrent uveitis (ERU), an inflammatory eye disease, is the leading cause of blindness among horses. Insidious uveitis, a form of ERU, is especially pervasive within the Appaloosa breed and is highly heritable (h = 0.68-1.0). To date only one risk locus, leopard complex (LP), has been identified, and it explained 0.16-0.33 of the heritability estimate, suggesting that insidious uveitis is a complex genetic disease within the Appaloosa horse breed with multiple unknown predisposing loci. Results: A genome-wide association study (GWAS) using relatedness, LP genotype, sex, and age as ...
Partusch L, Rutland CS, Martens A, Du Cheyne C, De Spiegelaere W, Michler JK.Exuberant granulation tissue (EGT) is a second intention wound healing disorder. It commonly occurs in the distal limb of horses. EGT causes significant increase in the duration and cost of treatment, potentially leading to the decision not to pursue treatment and euthanize the patient. The underlying pathomechanisms of this fibroproliferative disorder remain unclear, particularly in terms of collagen composition and the association between myofibroblasts and blood vessels. This study investigated the collagen composition in naturally occurring EGT following trimming in 19 horses (EGT group). ...
Rimayanti R, Khairullah AR, Mustofa I, Utomo B, Lestari TD, Utama S, Akintunde AO, Mulyati S, Hernawati T, Dawood AQ, Riady G, Khan IU, Rasad SD.... is a protozoan parasite that causes the sexually transmitted disease known as "dourine" in horses. This chronic illness is directly spread from one animal to another during mating. Doflein proposed the name in 1901. Despite being distributed worldwide, the broad use of artificial insemination technology over the past three decades has resulted in only a few cases being documented. The condition is typically fatal and is characterized by gradual emaciation, nervous system involvement, and edematous lesions of the genitals. The incubation period between exposure and the onset of clinical sympt...
McLachlan AD, Woolford L.Chlamydia psittaci was detected by real-time PCR in the lung, liver and kidney of an equine foetus that had aborted in South Australia in August 2023. The corresponding microscopic lesions included lymphocytic and histiocytic chorionitis, necrosis of placental villi associated with bacteria in the cytoplasm of trophoblastic epithelial cells, and multiple microgranulomas in the liver. Equine chlamydial abortion had not been diagnosed previously in South Australia. Eight days after examining the foetus and placenta, the veterinary pathologist developed fever and subsequently was admitted to hosp...
Haugaard SL, Nissen SD, Schneider MJ, Birk JB, Carstensen H, Hopster-Iversen C, Altıntaş A, Barrès R, Kjøbsted R, Wojtaszewski JFP, Herum KM....High recurrence rates after atrial fibrillation (AF) treatment may be driven by myocardial changes induced by the arrhythmia itself. Understanding the molecular mechanisms behind these changes is crucial for developing targeted therapies and improving outcomes. Objective: To characterise the cardiac transcriptome of healthy horses and explore transcriptional changes associated with persistent AF (naturally occurring and tachypacing-induced). Methods: Case-control study. Methods: RNA-sequencing was performed on atrial and ventricular tissue samples collected from six horses with naturally occur...
Haywood LMB, Clark A, Hause B, Sheahan B.Many cases of equine enterocolitis are suspected to be infectious in nature, but no pathogen is identified in many cases. Objective: Perform next-generation sequencing on faeces collected from cases of equine enterocolitis for the presence of novel viruses and determine if an identified novel virus is associated with cases of equine enterocolitis. Methods: Retrospective cohort study. Methods: Next generation sequencing was performed targeting viral genomes from n = 13 pooled faecal samples (n = 5 horses/pool) with enterocolitis. Subsequent qPCR was performed targeting the highly conser...
Saberinia A, Ozmaei S, Anoushepour A.Conjunctivitis is an inflammation of the conjunctiva caused by infectious or non-infectious factors. Infectious conjunctivitis comes in two forms: viral and bacterial. Bacterial conjunctivitis is commonly caused by organisms such as Staphylococcus and Streptococcus, with the severity of the disease influenced by the specific bacterial species involved. Because both viral and bacterial conjunctivitis are highly contagious, preventive measures are essential to reduce transmission-especially to the unaffected eye. Objective: To evaluate the tear film osmolality in horses with bacterial conjunctiv...
Khan MZ, Ji Y, Fan X, Liu Y, Liu W, Wang C.Equine herpesvirus (EHV) infections represent a significant global veterinary and economic challenge affecting both horses and donkeys across all inhabited continents. This narrative review comprehensively examines the nine distinct EHV species (EHV-1 through EHV-9), their taxonomic classification within Alphaherpesvirinae and Gammaherpesvirinae subfamilies, and their diverse host tropism patterns. The complex molecular pathogenesis involves sophisticated viral glycoproteins (gK, gB, gC, gH, gM, gL, gG, gD, gI, gE) that orchestrate cellular invasion, immune evasion, and intercellular transmiss...
