The immune response in horses involves a complex network of cells, tissues, and molecules that work together to protect the animal from pathogens and other harmful agents. This process includes both innate and adaptive immune mechanisms. Innate immunity provides the first line of defense and involves components such as physical barriers, phagocytic cells, and the complement system. Adaptive immunity, on the other hand, is characterized by the activation of lymphocytes and the production of antibodies, which provide a targeted response to specific antigens. Key components of the equine immune system include T cells, B cells, and various cytokines that facilitate communication between immune cells. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of immune responses in equine health.
Todd EW.Antiproteinase sera were prepared by immunizing horses with filtrates from a selected strain of group A streptococcus. This strain, which produced high titred proteinase but no erythrogenic toxin, was selected from forty-two strains of group A streptococci which produced varying amounts of proteinase. A few strains belonging to groups B, C, and G were also tested; they were all proteinase-negative. Methods are described for titrating streptococcal proteinase in crude culture filtrates and for measuring the antiproteinase activity of serum. The antiproteinase titres of sera from immunized horse...
Olitsky PK, Harford CG.Young (12 to 15 day old) mice are approximately as susceptible to the virus of equine encephalomyelitis, Eastern or Western strain, when it is given intraperitoneally as are adult mice when the virus is injected intracerebrally. With this susceptibility by the intraperitoneal route as a basis, the injection of immune serum-virus mixtures intraperitoneally was found to result in protection in dilutions which give rise to infection after intracerebral inoculation. The difference of protective power by the two indicated routes was shown not to depend on the amount of inoculum nor on the age of th...
Inada R, Ido Y, Hoki R, Ito H, Wani H.Horses immunized with cultures of Spirochaeta icterohaemorrhagiae yield an immune serum having therapeutic properties. With rare exceptions the serum destroys completely the spirochetes contained in the circulating blood. The development of antibodies is promoted by the serum injections. The number of spirochetes in the organs is reduced by the treatment. Secondary manifestations due to the serum are slight and disappear promptly. The ultimate effects of the serum treatment on the symptoms and final outcome of the disease have still to be determined.
Smith T.The foregoing and earlier data taken together demonstrate that an active immunity lasting several years can be produced in guinea-pigs, by the injection of toxin-antitoxin mixtures which have no recognizable harmful effect either immediate or remote. They also show, what might have been anticipated, that under the same conditions mixtures which produce local lesions and which, therefore, contain an excess of toxin produce a much higher degree of immunity than the neutral mixtures, and that an excess of antitoxin reduces the possibility of producing an active immunity, and may extinguish it alt...
Although equine herpesvirus myeloencephalopathy (EHM) is a relatively uncommon manifestation of equine herpesvirus-1 (EHV-1) infection, it can cause devastating losses during outbreaks. Antemortem diagnosis of EHM relies mainly on the molecular detection of EHV-1 in nasal secretions and blood. Management of horses affected by EHM is aimed at supportive nursing and nutritional care, at reducing central nervous system inflammation and preventing thromboembolic sequelae. Horses exhibiting sudden and severe neurologic signs consistent with a diagnosis of EHM pose a definite risk to the surrounding...
Respiratory diseases are a major cause of morbidity and mortality in the horses of all ages including foals. There is limited understanding of the expression of immune molecules such as tetraspanins and surfactant proteins (SP) and the regulation of the immune responses in the lungs of the foals. Therefore, the expression of CD9, SP-A and SP-D in foal lungs was examined. Results: Lungs from one day old (n = 6) and 30 days old (n = 5) foals were examined for the expression of CD9, SP-A, and SP-D with immunohistology and Western blots. Western blot data showed significant increase in the...
Lam J, Eckert A, Rhiner T, Waldern N, Schwarz E, Birkmann K, Widmer D, Dietrich M, Kündig TM, Fettelschoss-Gabriel A.Insect bite hypersensitivity (IBH) is the most common allergic skin disease in horses, but existing clinical scoring systems lack extensive validation, limiting standardized disease monitoring and therapeutic evaluation. Objective: Develop and validate a standardized, sensitive, and reproducible clinical scoring system for IBH in horses. Methods: Forty-four privately-owned horses with clinically diagnosed IBH examined under field conditions in Switzerland. Methods: In this prospective field validation study, the equine IBH severity score (EqIS) integrates a lesion severity score and an area sc...
Manguin E, Dickson RP, Jamon J, Dubuc V, Leclère M.The use of inhaled corticosteroids (ICs) could influence the respiratory microbiota. In animals with asthma it is, however, difficult to separate the immunomodulatory effects of ICs from their indirect effects via improvement of ventilation. Our objective was to determine if ICs alter the pulmonary microbiota independently from their effects on lung function, using a blinded, controlled trial in an experimental model of asthma exacerbation in horses. We treated horses with severe asthma with either bronchodilators alone, or in combination with ICs. Twelve horses in exacerbation received long-a...
Wilson I, Kiger K, Reynolds S, Justice M, Kapadia C, Coleman SJ, Crook RA, Fedorka CE.Pulsed electromagnetic field (PEMF) therapy is commonly used in equine sports medicine for its proposed anti-inflammatory effects; however, limited controlled studies have evaluated its physiologic effects in horses. Objective: The objective of this study was to investigate the effects of PEMF therapy on flexion-induced lameness and circulating cytokines in horses with radiographic evidence of distal tarsal osteoarthritis. Methods: Six mares were enrolled in a repeated-measures crossover design in which each horse served as its own control. Horses were evaluated at baseline (sham PEMF) and at ...
Cho GJ, Jeon J, Eun JK, Almazbek I.The purpose of this study was to evaluate the clinical applicability of a multiplex serum specific Immunoglobulin E (sIgE) test kit 'ANITIA Equine IgE' for identifying the causes of allergic diseases in horses raised in Korea, and to determine the major sensitization antigen profiles in the domestic horse population. Serum or plasma samples were collected from a total of 140 horses, classified by management system (Group A, n=108) and purpose (Group B, n=32). IgE concentrations for 120 environmental and dietary allergens were measured using a multiplex line-blot assay based on an indirect immu...
de Bruijn E, Pas ML, Castelain D, Dufourni A, Paulussen E, Pardon B.Single measurements of serum amyloid A (SAA) concentration at hospital admission has limited sensitivity for predicting sepsis and death. Objective: To determine whether differences in SAA during the first 2 days of hospitalization could predict sepsis and death in critically ill foals. Methods: One hundred twenty-seven critically ill neonatal foals, <14 days of age. Methods: Prospective cohort study. SAA was measured at hospital admission and on day 2 of hospitalization using a validated point-of-care test. Logistic regression was conducted to evaluate the predictive value of individual S...
Pinto EM, Hurtado LH, Cuervo MM, da Silva CB.Failure of passive transfer (FPT) is a major contributor to morbidity and mortality in neonatal foals worldwide. Adequate ingestion and intestinal absorption of colostral immunoglobulin G (IgG) during the first hours of life are essential to ensure protection against early-life infections, such as diarrhoea and pneumonia, frequently with fatal outcome. This review summarizes current knowledge on the physiology of passive immunization, risk factors for inadequate IgG absorption, diagnostic methods, therapeutic strategies, and evidence-based preventive measures. Recent research highlights the im...
Olbrich K, Venner M, Wagner B.Vaccination recommendations for foals against Clostridium tetani vary. Available studies assessing foal immune responses, maternal antibody interference, or individual variation often used small foal numbers. Objective: To quantify antibody responses after tetanus vaccination in foals and explore associations with passively transferred tetanus antibodies. Methods: Longitudinal cohort study. Methods: Sixty-two Warmblood foals from a single stud farm were followed from birth to 360 days of age. Foals received tetanus vaccinations at day 180 (d180) and d220 of life. Serum samples were collected...
Jagannathan V, Leeb T, Gerber V, Sage SE. Bulk RNA sequencing (RNA-seq) averages signals across heterogeneous cell populations. Computational deconvolution methods aim to infer cell type composition and cell type-specific gene expression from bulk data, but their performance in equine samples has not been evaluated. In this study, we assessed the ability of computational deconvolution to recover cellular composition and differential expression signals in bronchoalveolar lavage fluid (BALF) from horses with severe equine asthma (SEA) and controls (CTL). Cryopreserved BALF samples from six SEA and five CTL horses previously analyzed b...
Mulcahy G, Byrne O, Walshe N.Cyathostomins (also known as small strongyles or small redworms) are ubiquitous parasites of equids. They are found in a wide range of climatic regions, and inhabit the large intestine of their hosts. While infections are often sub-clinical, clinical consequences ranging from chronic to acute, and most notably, acute larval cyathostominosis, can occur in specific circumstances. Control of cyathostomin infection is complicated by widespread drug resistance. This Chapter provides a broad review of cyathostomin biology and host-parasite relationships, and also highlights significant knowledge gap...
Albrecht M, Perez J, Wong D, Browne N, Burns T, Stevens ME, Dembek K.Hypothalamic-pituitary-adrenal gland axis (HPAA) dysfunction impairs survival and can be diagnosed with an arginine vasopressin (AVP) stimulation test. Objective: Adrenocorticotropic hormone (ACTH) and cortisol response to an AVP stimulation test will be attenuated in hospitalized foals compared to healthy foals and associated with severity of disease. Methods: Fifteen healthy and 45 hospitalized foals: 19 septic, 26 sick non-septic (SNS). Methods: A prospective, observational case-control design was utilized to assess HPAA function and compare corticotropin-releasing hormone, ACTH, and cortis...
Siwińska N, Żak-Bochenek A, Trodd H, Czekaj Z, Kumiega E, Niedźwiedź A, Hewetson M.Equine gastric ulcer syndrome (EGUS) is commonly treated with proton pump inhibitors such as omeprazole, administered orally or by injection. In humans, omeprazole has been associated with acute interstitial nephritis (AIN) and acute kidney injury (AKI), potentially linked to oxidative stress, and urinary interleukins may serve as early non-invasive markers. However, this association has not been established in horses. Objective: To evaluate the effects of oral and injectable omeprazole on basic urinary parameters and selected interleukin levels, with particular emphasis on the potential risk ...
Musoles-Cuenca B, de la Cuesta-Torrado M, Álvarez AV, Vitale V, Lorenzo-Bermejo T, Ballester B, Rubio-Guerri C, Álvarez L, Maiques E.Equine herpesvirus type 1 (EHV-1) outbreaks associated with international equestrian events have demonstrated the capacity of this virus for rapid transboundary dissemination. However, detailed longitudinal data integrating viral shedding across multiple biological matrices within the same animals during naturally occurring outbreaks remain limited. In this study, ten horses hospitalized during a naturally occurring EHV-1 outbreak linked to an international jumping competition were monitored for 10-12 days, from which 306 nasal, ocular, urine and faecal samples were obtained and analysed by qu...
Baillou A, Botos M, Oberhaensli S, Cvitas I, Jonsdottir S, Ziegler A, Brito F, Summerfield A, Marti E, Talker SC.Detailed classification of equine dendritic cells (DC) is necessary to address various research questions, such as the role of DC subsets in immune-mediated diseases of horses. Unassigned: We applied single-cell RNA sequencing (scRNA-seq) on DC enriched from the blood of two horses. Unassigned: All main DC subsets were detected by key gene expression, including conventional DC type 1 (cDC1; ) and type 2 (cDC2; , ), as well as plasmacytoid DC (pDC; ). In addition, we detected a small cluster of hematopoietic progenitors, as well as transitional DC (tDC; , ) and putative DC type 3 (DC3; , ). Our...
Cequier A, Romero A, Bernad E, Serrano B, Vitoria A, Fuente S, Fernández I, Zaragoza P, Vázquez FJ, Barrachina L, Rodellar C.Mesenchymal stem/stromal cells (MSCs) hold great potential for treating various conditions, but their effectiveness and safety in allogeneic therapies can be affected by the recipient's immune response, among other factors. Allogeneic MSC administration has been associated with immune recognition in different species, including horses. These animals are both veterinary patients and translational models, offering valuable insights into how allogeneic MSCs interact with the immune system in vivo. Factors such as inflammation, chondrogenic differentiation, and major histocompatibility complex (MH...
Chen K, Du C, Duan Y, Guo K, Liu D, Wang F, Wang X, Wen Y.Macrophage phenotypic adaptation critically regulates inflammatory balance during infection; however, progress in equine immunology has been limited by a lack of specific tools for standardized identification. To address this gap, we established a reliable, antibody-based detection method for characterizing equine macrophage M1-like and M2-like marker profiles. After initially validating canonical marker genes via qPCR, we developed specific monoclonal antibodies targeting the differentially expressed surface proteins CD80 (M1-like) and CD163 (M2-like). These novel antibodies enabled the creat...
Słyszewska M, Guerreiro M, Sadowska A, Jaworska J, Ferreira-Dias G, Szóstek-Mioduchowska A.Tissue fibrosis is described as the excessive accumulation of extracellular matrix (ECM) components. This process is associated with inflammation, and the interaction between fibroblasts and immune cells plays a key role, driving the progression of fibrosis. Results of recent study suggest that interleukin (IL)-12 may play a role in the processes associated with the development of fibrosis. This proinflammatory cytokine is synthesized and released by macrophages, dendritic cells, and B cells. Objective: The objective of this study was to determine: (i) the expression of IL-12 and its receptor ...
Yoshida S, Takeyama A, Maeda Y, Nambo Y.Maternal cells and antibodies are present in equine colostrum, but their relationship with immune cells in foals after colostrum ingestion remains unclear. This study longitudinally analyzed immune cells in the peripheral blood of neonatal foals at short intervals and investigated their relationship with colostral immune cells. Eleven clinically healthy draft mares and their foals were examined. Foal blood was collected before colostrum intake (0 hr) and at 2-3, 6, 12, 36-48 hr, and 3 and 7 days after ingestion. Mare blood and milk (0, 36-48 hr; 0 hr milk defined as colostrum) were also collec...
da Costa Kamura B, de Oliveira Ferreira LV, Chimenes ND, de Oliveira JPM, Rodriguez-Sanchez DN, de Carvalho M, Amorim RM.Peripheral nerve injuries (PNI) often lead to long-term functional impairment. Mesenchymal stem cells (MSCs) and cannabidiol (CBD) have shown anti-inflammatory and neuroprotective effects in vitro, which may be relevant for PNI research. The aim of this study was to evaluate CBD-rich cannabis extract’s potential to induce anti-inflammatory and neurotrophic gene expression in equine adipose tissue-derived MSCs (EqAT-MSCs) in an inflammatory in vitro environment. The morphology and metabolic activity of EqAT-MSCs (n = 4) were assessed after CBD-rich extract priming at concentrations of 3, ...
Khan FA, Caissie MD, Wagner B, Scholtz EL, Chenier TS.Persistent breeding-induced endometritis (PBIE) is a major cause of infertility in mares. Recent research has shown that PBIE-affected mares treated with intrauterine N-acetyl cysteine (NAC) 12 hours before breeding showed no improvement in clinical signs at 12- and 60-hours post-breeding. Objective: The present study was designed to examine the effects of NAC treatment on the uterine inflammatory cytokine and chemokine profiles in PBIE-affected mares. Methods: Using a randomized, blinded, cross-over design, mares susceptible to PBIE (n=9) were allocated to Control and Treatment cycles with at...
Armonaitė A, Olivier M, Kerzienė S, Picandet V.The treatment for failure of transfer of passive immunity (FTPI) in foals with hyperimmune plasma has substantial variability of efficacy. Objective: The aims of the study were to assess the safety and efficacy of plasma transfusion and to investigate factors that may predict transfusion results, thereby allowing estimation of plasma volume requirements prior to transfusion. Methods: A retrospective review was conducted of foals admitted to an equine hospital that received a plasma transfusion for FTPI. Results: The study included 110 foals and 150 hyperimmune plasma transfusions. The median i...
Barbazanges P, Richard EA, Debonnaire C, Le Digarcher G, Lemonnier LC, Toquet MP, Couroucé A.Guttural pouch (GP) disorders are clinically important in horses, yet the relationship between endoscopic findings and GP cytology remains poorly defined. Objective: To establish reference cytological values for GP lavage fluid in horses and to investigate associations between inflammatory cytology and endoscopic findings. Methods: Asymptomatic racing horses sampled in the field and horses referred for investigation of respiratory disorders. Methods: Prospective cross-sectional study. Horses underwent clinical examination, upper airway endoscopy, and bilateral transendoscopic GP lavage. A GP i...
Lauková A, Focková V, Micenková L, Gancarčíková S, Plachá I, Grešáková Ľ, Kováčik A, Halo M, Gálik B, Pogány Simonová M.Antimicrobial proteinaceous postbiotic substances (PS) and/or bacteriocins can beneficially influence animal health, as previously shown with enterocins from non-autochthonous enterococcal strains. Therefore, the effectiveness of PS 412, produced by our beneficial autochthonous strain EF 412, was assessed in horses. In the pilot experiment, PS 412 was administered to 12 horses of various ages and breeds for 21 days via a small feed ball. Sampling was performed on days 0/1, 21, and 42 (after a 3-week cessation of PS 412). The horses served as their own controls. Although the number of horses w...
Deniz Ö, Ekinci G, Çitil M, Onmaz AC, Derelli FM, Timur MC, Altınbay K, Mete A, Yeğen E, Hoven RVD, Fazio F, Aragona F.Equine herpesvirus type 1 (EHV-1) is a major cause of reproductive loss in mares. This cross-sectional field study evaluated serum concentrations of interleukin-2 (IL-2), interleukin-10 (IL-10), interferon-alpha (IFN-α), and interferon-gamma (IFN-γ), together with the IL-10/IL-2 and IFN-γ/IL-10 ratios, in 26 vaccinated pregnant Thoroughbred mares. The analytical cohort comprised healthy, EHV-1 PCR-negative mares (HM, n = 10), EHV-1 PCR-positive mares sampled within 4 h after fetal expulsion at approximately the sixth month of gestation (AM, n = 9), and EHV-1 PCR-positive pregnant mares with...
Biondi V, Gambadauro P, Bruno F, Palmieri V, Licata P, Sicuso DA, Passantino A, Pugliese M.Equine piroplasmosis, caused by the intraerythrocytic protozoan , is a globally distributed tick-borne disease characterized by persistent infection and variable clinical manifestations. Although oxidative stress has been implicated in the pathogenesis of several hemoprotozoan diseases, information regarding redox imbalance and its relationship with inflammatory responses in horses naturally infected with remains limited. This study aimed to evaluate oxidative stress, antioxidant status, inflammatory cytokines, and clinicopathological alterations in horses naturally infected with . Thirty-fiv...
Dörner C, Lagos N, Oyaneder L, González C, Ramírez-Toloza G, Menarim BC.Chronic synovial inflammation is a hallmark of osteoarthritis progression and is tightly regulated by synovial macrophages. Recently, voltage-gated sodium channels (NaV) have emerged as potent modulators of macrophage-driven inflammation, positioning them as novel therapeutic targets. Among selective NaV channel blockers, neosaxitoxin exerts remarkable anesthetic and immunomodulatory effects; however, its effects on joint inflammation upon intra-articular delivery remain unexplored. Using an equine model of bilateral carpal osteoarthritis, this study evaluated the immunomodulatory and tissue-p...
Ferlini Agne G, Barratt DT, May BE, Hutchinson MR, Holmes J, Steel C, Simon O, Evans SG, Somogyi AA, Sykes BW, Franklin S.Equine gastric ulcer syndrome (EGUS) is highly prevalent in horses. Despite its presumed painful nature, evaluation of objective biomarkers associated with EGUS presence and severity remains limited. The objective of this study was to investigate the potential of interleukin-1 beta (IL-1β) release by peripheral blood mononuclear cells (PBMCs) following ex vivo stimulation of toll-like receptors 2 and 4 (TLR2 and TLR4) as a potential biomarker for EGUS status, with gastric lesions used as a proxy for presumed EGUS-associated pain. Venous blood was collected from 77 horses, PBMCs were isolated ...
Zhang B, Agdour H, Riihimäki M, Hansen S, Raine A.Circulating cell-free RNA (cfRNA) has emerged as a promising minimally invasive biomarker capable of capturing transcripts originating from multiple tissues and cell types, but its utility in chronic inflammatory airway diseases remains poorly understood. Equine asthma (EA), a naturally occurring respiratory disease that shares key clinical and immunopathological features with human asthma, provides a valuable comparative model for evaluating plasma cfRNA in this context. We performed transcriptomic profiling of plasma cfRNA from horses with EA and healthy controls and compared these findings ...
Fedorka CE, Funes JA, Razquin P, Roussel DA, Denison G, Burden CA, Hatzel JN, Sones JL, McCue PM.Persistent breeding-induced endometritis (PBIE) is characterized by a prolonged and dysregulated uterine inflammatory response following breeding. Although inflammatory cytokines are central to the post-breeding immune response, their assessment in the equine uterus has historically relied largely on gene expression analyses. Multiplex immunoassays provide an opportunity to simultaneously quantify multiple cytokine proteins within uterine secretions; however, the application of equine-specific multiplex immunoassays utilizing the Luminex platform to low-volume uterine lavage (LVL) fluid remain...
Ząbek T, Szmatoła T, Witarski W, Ropka-Molik K.Cellular senescence is a biological state of a cell that triggers inflammation and gradually contributes to pathological conditions. Unlike programmed cell death, prolonged inhibition of cell division induces a metabolic state in senescent cells, in which they release pro-inflammatory factors that drive inflammation affecting the tissue microenvironment. Along with prolonged excessive mechanical stress, low-grade inflammation raised by senescent chondrocytes may contribute to articular cartilage defects, which are prevalent in ageing populations. Moreover, the use of chemotherapeutics used to ...
Zhou B, Chen K, Liang H, Qi T, Guo X, Wen Y-J, Du C, Wang X.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...
