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.
Hampil B, Melnick JL.This paper summarizes the results of the second part of co-operative studies undertaken by the WHO International Reference Centre for Enteroviruses and a number of WHO Regional Virus Reference Centres, WHO Virus Collaborating Laboratories and other laboratories in a comprehensive testing programme of enterovirus equine antisera. The studies were designed to appraise the specificity of immune serum prepared in horses against 16 representative prototype enteroviruses (polioviruses 2 and 3, coxsackieviruses A7, B1, B2, B4, B5 and B6 and echoviruses 1, 2, 3, 5, 7, 9, 12 and 17). Tests for neutrali...
Ozawa Y, Bahrami S.Formalized African horse-sickness (AHS) type 9 virus cultivated in monkey kidney stable (MS) cell cultures was experimentally used for immunizing horses. Inactivated vaccines prepared either from viscerotropic or neurotropic type 9 AHS virus produced antibodies in vaccinated horses. Immunity developed in all horses vaccinated with various amounts of the vaccine, and protected them from infection, when challenged 5 weeks after vaccination.
Goebel WF, Staub AM.1. The immunization of horses with the colicinogenic bacillus E. coli K235 L + O(m) stimulates antibodies which precipitate and neutralize colicine K and neutralize the heterologous colicine I as well. 2. Unlike rabbits, horses evoke predpitating antibodies for the sialic acid-containing polysaccharide colominic acid.
INGRAM DG.A method is described for the quantitative measurement of the reactions between sensitized cells and horse complement and between alexinated cells and conglutinin. The method is laborious but its application has allowed the determination of the optimal times of the reactions at various temperatures. The results obtained in these experiments indicate that the alexinated configuration with which conglutinin and immuno-conglutinin react is not one of the recognized intermediates formed during the process of immune haemolysis.
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 ...
HETRICK FM, YANCEY FS, HANSEN PA, BYRNE RJ. Four horses inoculated with EEE virus remained asymptomatic following injection but did develop measurable HI and neutralizing antibodies as a result of infection. HI antibodies were detectable earlier than neutralizing antibodies but the levels tended to drop more rapidly. 2. Of 14 horses and ponies having significant levels of neutralizing antibody, 5 to 9 had measurable HI antibody depending on number of units of antigen employed in the test. 3. Sera from 3 clinical cases of EEE were positive on the HI test while only one of these animals had a significant neutralizing antibody level.
Yalavarthi G, Sabbinen H, Kosuri P, Amalaradjou M, Govoni K, Nadeau J.Strongyles are parasitic roundworms that cause significant gastrointestinal infections in equines, primarily through contact with infected soil. Worldwide, strongylosis affects nearly 90% of horse populations. Objective: The objectives of our study were to determine if there was a relationship between fecal egg count (FEC) and housing types on interleukin IL-4 and IL-13. Methods: Horses (N=25) were separated into two groups based on housing conditions: pasture (housed on pasture 24/7; PS, N=13) and semi-intensive (housed in stalls with turnout overnight; SI, N=12). Within each housing group, t...
Espinosa MA, Lack A, Kenney D, Arroyo LG.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 ...
Cooper BL, O'Donnell K, Hickman E, Bayless R, Sheats MK.To determine the impact of a commercially available docosahexaeonic acid (DHA) supplement (DHA, methylslfonylmethane, and mushroom blend) on equine alveolar macrophage metabolism and lipid and protein profiles in bronchoalveolar lavage (BAL) supernatant. Unassigned: This was a prospective, sequential, placebo-controlled study using 10 healthy adult horses. Bronchoalveolar lavage fluid was collected at baseline, following 45 days of oral placebo administration, and following 45 days of oral commercially available DHA supplement, with a 14-day washout. Whole blood was collected following placebo...
Horikawa T, Maekawa N, Okagawa T, Tiyamanee W, Ganbaatar O, Nakamura H, Ikehata M, Inoue M, Nakanishi T, Tachibana T, Kato Y, Yamamoto K, Suzuki Y....Horses develop spontaneous tumors, typically in old age. Although local tumor control can be achieved using conventional therapies, systemic therapies are required to treat recurrent and/or metastatic tumors. Immune checkpoint inhibitors, such as anti-PD-L1 antibodies, have been approved for the treatment of various tumor types in humans; however, little is known about the immunosuppressive roles of the PD-1/PD-L1 pathway in horses, and the therapeutic potential of these inhibitors remains to be elucidated. Previously, we reported that the rat monoclonal anti-PD-L1 antibody 6C11-3A11 cross-rea...
Malsa J, Chereau A, Guégnard F, Serreau D, Gesbert A, Reigner F, Chamoin L, Guillot J, Vernudachi A, Mach N, Fleurance G, Lacroix-Lamandé S....The emergence of anthelmintic-resistant parasite isolates necessitates alternative control strategies. The use of dietary additives with anti-parasitic or immunomodulatory activities has been proposed as a solution, but whether such additives can simultaneously exert dual bioactivities within this context has rarely been explored. Here, we evaluated whether selected terpenes could exert dual bioactivities (anti-parasitic and immunomodulatory) with a view to their use as food additives that can limit strongyle infections in horses. In vitro tests with cyathostomin larval development, larval mig...
Sancler-Silva YFR, Costa LML, Freitas MS, Teixeira CS, Albino MV, García HDM, Fiala-Rechsteiner SMDE, Schultz ÉB, da Fonseca LA, Catalán J.The limited fertility of jennies inseminated with frozen donkey semen remains a major challenge for donkey reproduction and conservation, contrasting with the more favorable outcomes observed in mares. Species-specific differences in post-breeding uterine inflammation have been proposed as a key factor underlying this disparity. This study compared the uterine inflammatory response and pregnancy outcomes of jennies and mares inseminated with frozen donkey semen. Twelve jennies and eleven mares were monitored over 48 and 44 estrous cycles, respectively. Artificial insemination (AI) was performe...
Tehrani AH, Toth K, Osinchuk N, Dufour A, Krawetz R, Sen A, Sparks H.Adult bone marrow-derived mesenchymal stromal cells (BM-MSCs) hold significant therapeutic potential in human and veterinary medicine. Traditionally, BM-MSC cultures use fetal bovine serum (FBS) to promote growth, but this practice introduces batch variability and xenogeneic contamination that complicate clinical translation. While serum-free medium (SFM) alternatives have been optimized for human MSCs, limited options have been explored for alternative or veterinary species. Here, we compared a chemically defined, customizable SFM formulation with conventional serum-containing medium (SCM) fo...
Junuzović M, Troillet A, Burk J.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...
Gago P, Cruz-Lopez F, Dorrego A, Rivera B, de Juan L, Lorente-Leal V.Equine viral arteritis (EVA) remains a relevant health and economic concern due to the ability of some infected stallions to establish long-term persistent infection with equine arteritis virus (EAV). Allelic variation in the CXCL16 gene has been identified as a determinant of susceptibility or resistance to the carrier state, positioning genotyping as a useful tool for risk-based reproductive and health management. Objective: To characterise the distribution of CXCL16 genotypes in export-bound horses from Spain and to assess the utility of CXCL16 genotyping for EVA prevention and control. Met...
Tanner K, Mays M, Nguyen TA, Lugo T.Multisystemic eosinophilic epitheliotropic disease (MEED) is a rare and severe equine disorder characterized by chronic eosinophilic inflammation, epithelial disruption, and multi-organ involvement, with an undefined genetic basis. We performed the high-depth (~40×) whole-genome sequencing of an affected horse and compared it to 40 control genomes. Over 6.3 million variants were identified, with moderate- and high-impact variants enriched in low-frequency categories, including rare and private variants absent from the controls. The affected horse was dominated by missense mutations, with rela...
Geng A, Wang X, Li L, Cowie S, Bai D, Dugarjaviin M, Zhang X.The scientific evidence regarding the use of plant-derived extracts to alleviate exercise-induced muscle damage in horses remains limited. Mulberry leaf flavonoids (MLFs) are the primary bioactive constituents of a traditional medicinal plant and are potent antioxidants. The aim of this study was to investigate the protective effects of MLFs against exercise-induced muscle damage. In this study, twelve Mongolian horses were used in a 3 × 3 Latin square design to investigate the protective effects of MLFs. Our results showed that high-intensity exercise negatively impacted the immune status, m...
Eertink LG, Jacob O, Adam EN, Page AE, Wang D, Li F.Despite a monovalent G3P[12] ('G3') vaccine being available for horses, equine rotavirus A (ERVA) is still the predominant infectious pathogen causing diarrhea in foals in the United States of America (U.S.). Previous research has shown that maternal neutralizing antibody (NAb) titers are too high and will interfere with the vaccination of foals at 30 and 45 days of age. We aimed to determine if it is possible to increase NAb titers in foals through vaccination before they are vulnerable to ERVA infection. We immunized two foals with the commercially available vaccine (G3) at solely three mont...
Magalhães VLP, Pinho FA, Souza FN, Santos KR, Santos AS, Hlavac N, Libera AMPD, Massoco CO, Barrouin-Melo SM.There are diverse uses for equine peripheral blood mononuclear cells (PBMC) in research. Studies have shown that PBMC isolation protocols can affect immune parameters of diagnostic and research assays. We aimed to assess the impact of equine blood handling techniques on cell yield, viability, and proliferation under mitogen stimulation. Whole blood (WB) samples were collected from eight healthy adult horses into heparinized tubes for PBMC isolation by comparing method 1 (M1) where freshly collected WB was layered directly over a density gradient medium for centrifugation, followed by PBMC harv...
Ren H, Chen K, Zhou B, Zhang W, Wang XF, Wang X.Type I interferons (IFNs) play a pivotal role in antiviral defence by inducing interferon-stimulated genes (ISGs) that target multiple stages of viral replication. Equine infectious anemia virus (EIAV) is an ancient lentivirus that establishes long-term asymptomatic infections in equids, suggesting its exceptional immune evasion capabilities. However, the mechanisms by which EIAV modulates IFN responses remain unclear. Here, we demonstrate that EIAV infection attenuates ISG expression at the post-transcriptional level. The viral Rev protein plays a central role by interacting with the stress g...
Pinto JEL, Gervásio JHB, Ng JC, Gomes-Silva A, de Matos Guedes HL, Cunha L, Castilho LR, da Silva JL, Franco GR, Navas C, Felicori LF.The humoral immune response relies on a diverse antibody repertoire, which is expanded through processes such as somatic hypermutation, class-switch recombination and gene conversion. These processes are primarily mediated by activation-induced cytidine deaminase (AID). Gene conversion generates diversity in immunoglobulin heavy and light chains (IGHVs) in species such as chickens and rabbits, though it has not been widely studied. Since 80% of the equine IGHV repertoire originates from only three functional gene segments, we examined gene conversion events in horses to assess their role in an...
Attia MM, Mohamed HI.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 ...
Valero-Cedeño N, Durán A, Mosquera JA.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...
Brown KA, Max LNF, Struble SE, Linardi RL, Ortved KF.Determine the acute effects of xylazine and detomidine on concentrations of selected growth factors, cytokines, and α2-macroglobulin (A2M) in platelet-rich plasma (PRP) and autologous protein solution (APS) and the long-term effects of these sedatives on serum A2M. We hypothesized that sedative administration would decrease concentrations of all bioactive proteins in PRP and APS acutely and A2M in serum for 6 days following sedative administration. Unassigned: 6 horses were randomized to receive IV xylazine (200 mg) or detomidine (10 mg). Blood was collected before and 5 minutes after sedativ...
Concha D, Azocar-Aedo L, Ricardo T, Rodriguez A, Ramirez R, Paffetti MG.Leptospirosis is a bacterial zoonotic disease with clinical consequences and potential sequelae in horses. Objective: To estimate the pooled global seroprevalence of anti-Leptospira antibodies in horses, detected with the Microscopic Agglutination Test, the frequency by serogroups and serovars, the geographical distribution of studies and the main reported clinical signs and organic manifestations through a systematic review and meta-analysis. Methods: A bibliographic search was conducted for cross-sectional epidemiologic studies published between 2015 and 2025. The risk of bias was determined...
Chow L, Contino E, Seabaugh K, Goodrich L, McIlwraith CW, Impastato R, Singer J, Das S, Dow S, Pezzanite LM.To determine differential gene expression in synovial tissues following injection of IA 2.5% polyacrylamide hydrogel (2.5% iPAAG), a biocompatible nondegradable synthetic polymer, to treat osteoarthritis (OA). Unassigned: Osteoarthritis was induced in 1 middle carpal joint of 16, 2- to 5-year-old horses (7 mares and 9 geldings) via surgical osteochondral fragment creation in combination with exercise on a high-speed treadmill; the contralateral limb underwent a sham operation. Horses were exercised 5 days per week, beginning on day 16 postoperatively. The osteochondral fragment joint was injec...
De Heus P, Maute J, Huber N, Tichy A, Palme R, Steinmann E, Volz A, Cavalleri J-V, Trachsel DS.Stress is an umbrella term indicating increased allostatic load with the potential to reach a pathological state of the organism. In this context, cortisol concentration and neutrophil granulocytes-to-lymphocyte ratio (NEU: LYM) are expected to increase. On the functional pathway, stress reduces the oxidative burst capacity of neutrophils and therefore, the leucocyte coping capacity (LCC) quantifying this oxygen radical generation of neutrophils. Therefore, we hypothesized that in ponies subjected to repetitive handling, LCC will decrease and will be negatively correlated with cortisol concent...
Bindi F, Cingottini D, de Marchi L, Sala G, Vitale V, Sgorbini M.Oxidative stress both contributes to and results from sepsis pathophysiology, but its role in ill foals remains poorly characterized. Objective: Ill foals will exhibit decreased antioxidant defense activity and increased oxidative products compared with healthy foals, and these changes will be associated with higher sepsis scores, lower survival scores, and non-survival. Methods: Twenty-six foals < 14 days old: 16 hospitalized foals (11 sick non-septic, 5 septic; median age, 1.5 days; range 1-13) and 10 healthy Standardbred foals (2 days old). Nine of 16 ill foals survived to discharge...
Długopolska D, Siwińska N, Noszczyk-Nowak A, Niedźwiedź A, Żak-Bochenek A.Equine Asthma (EA) is a common, lower airway disease. Yet current diagnostic standards rely on bronchoalveolar lavage fluid (BALF) cytology, which is moderately invasive and not always feasible in field conditions. This review aimed to synthesize current evidence on candidate biomarkers of EA, with a primary focus on blood-based matrices and BALF, while also including data on biomarkers measured in tracheal wash (TW), saliva and exhaled breath condensate (EBC), where available. Searches were performed in PubMed, Scopus and Google Scholar, and original studies in horses with mild-to-moderate or...
Wierzbicka M, Samsel A, Siemieniuch-Tartanus M.Equine asthma is a chronic inflammatory disease of the lower respiratory tract, primarily associated with inhalation of organic dust, microbial particles and environmental aeroantigens. Although the inflammatory and immunological mechanisms underlying equine asthma have been extensively investigated, the potential contribution of neuroimmune pathways remains poorly understood. In humans and rodent models, asthma is increasingly recognised as a disorder involving complex bidirectional interactions between the nervous and immune systems. Sensory nerve activation, neuropeptide release, autonomic ...
Jehle MC, Reinthaler B, Patan-Zugaj B, Schwendenwein I, Licka TF.To evaluate an ex vivo model of synovitis induced by IA lipopolysaccharide (LPS) and IL-1β in isolated, perfused equine forelimbs. Unassigned: Forelimbs and blood were collected from 12 clinically unremarkable horses following slaughter at a licensed abattoir. In 8 limbs, 2 of 3 phalangeal joints were injected with LPS (0.5 to 5 ng, 4 limbs) or IL-1β (100 ng, 4 limbs) diluted in 1 mL of distilled water. All limbs were perfused with autologous perfusate for 8 hours. Synovial fluid cytology and synovium sample histology scores for synovitis (0 = no changes and 3 = marked changes) were assessed...
DiSilvestro AN, Wesolowski LT, Williams BD, Warren LK, Athrey G, White-Springer SH.Energy-dense feeds commonly provided to equine athletes may be high in starch, which alter gastrointestinal microbiota and could promote systemic inflammation. Objective: To test the hypothesis that exercise-induced inflammation would be greater in horses receiving a starch- versus fiber-based concentrate. Methods: Quarter Horses (mean±SD 16±1mo; 337±30kg) received either a fiber-based control (CON; 7 fillies, 8 geldings) or an isocaloric, isonitrogenous starch concentrate (STARCH; 8 fillies, 7 geldings) for 24d. Fecal metagenomics were evaluated on d0 and 21. Blood inflammatory mediators w...
Demchenko G, Berdikulov M, Sansyzbay A, Abdreshov S, Koibasova L, Khusainov D, Lessova Z.Understanding the distribution of antibodies in the bloodstream is critical for advancing diagnostic and therapeutic approaches in veterinary medicine and comparative immunology. While most studies have focused on plasma antibodies, the presence and role of membrane-bound immunoglobulins remain underexplored, particularly in equine species such as the Jabe horse. Unassigned: This study aimed to analyze the amount of antibodies in the plasma and blood cells of Jabe horses for their potential future use. Unassigned: Blood samples were collected from Jabe horses and separated into plasma and cell...
Borashid N, Hakami B, Alyousef Z, Ballan H, Alsalman M, Alwabari A, Shawaf T.Sandy enteropathy is more common in horses living in sandy environments, such as those in Saudi Arabia. Sand accumulation in the intestines can be eliminated and prevented by administering psyllium husk. Unassigned: This study focuses on the combination of psyllium and aloe vera extract, known for its protective and anti-inflammatory properties. Unassigned: Fourteen Arabian horses with naturally acquired sand accumulation were randomly assigned to two groups: the psyllium group (PG, = 7) and the psyllium and aloe vera group (PAG, = 7), both of which were treated daily for 7 days. Efficacy wa...
Pfeifle RL, Hart KA, Berghaus LJ, Coleman MC.Equine asthma is a chronic inflammatory airway disease with limited safe long-term treatments. Alpha-2-macroglobulin (A2M), a natural anti-inflammatory protease inhibitor, may provide a novel non-steroidal therapeutic option for horses with lower respiratory tract inflammation. Objective: To characterize the impact of nebulization with alpha-2-macroglobulin (A2M) on clinical signs, bronchoalveolar lavage cytology, and local and systemic cytokine response in horses with lower respiratory tract inflammation. Methods: Thirteen university-owned horses with lower airway inflammation were randomized...
Rodgers EE, Yates DT, Parrish BL, Luck LM.Housing horses in stalls restricts natural roaming behaviors, which in turn increases stress and stereotypic behaviors. Daily turnout for voluntary exercise is common for stress mitigation, but there is no consensus for optimal duration of turnout sessions. Objective: We sought to understand how minimal and moderate-duration daily turnout affects behavioral and physiological stress indicators. Methods: In a Latin-square design, adult Quarter horses (N=11) were allowed 0, 15, or 60 minutes/day of solitary turnout for 12-day periods. In-stall behaviors and 24-hour time budgets were assessed on d...
