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.
Walton TE, Alvarez O, Buckwalter RM, Johnson KM.Ten horses (Equus caballus) were vaccinated with strain TC-83 Venezuelan equine encephalomyelitis (VEE) virus vaccine. Febrile responses and leukopenia due to a reduction of lymphocytes and neutrophils were observed in all animals. Viremias were demonstrable in eight horses, with a maximum of 10(3.5) median tissue culture infectious dose units per ml of serum in two horses. Clinical illness with depression and anorexia were observed in five horses. Neutralizing (N), hemagglutination-inhibiting, and complement-fixing antibodies to the vaccine virus were demonstrable by 5, 6.5, and 7 days, respe...
Eddy GA, Martin DH, Reeves WC, Johnson KM.A series of field studies using strain TC-83 attenuated Venezuelan equine encephalomyelitis vaccine in horses was made to determine the rate of seroconversions, the postvaccination viremia, and the possibility of adverse reactions to the vaccine. The rate of seroconversions varied from 50% in one study to 91 and 100% in two others. The highest level of viremia measured was 7 x 10(3) to 8 x 10(3) plaqueforming units per ml. No adverse reactions to the vaccine were observed in any horses, including 42 pregnant mares and their resulting foals.
Gruber J.Purified and concentrated Venezuelan equine encephalitis (VEE) virus derived from tissue cultures, rendered noninfectious by ionizing radiation with retention of in vitro serological activity, also retained a high level of immunogenicity. In mice, fluid vaccines afforded excellent protection against lethal challenge with homologous Trinidad strain VEE virus. A direct relationship was observed between concentration of vaccine or number of injections and survival. One intraperitoneal inoculation of undiluted vaccine protected essentially all mice challenged 21 days later with 100,000 mouse intra...
James K, Pullar DM, Morton JB, Dalton RG, Nolan B, Woodruff MF.Methods are described for the intravenous administration of equine antilymphocytic globulin (ALG) to renal transplant recipients. The development of circulating antibodies to the equine IgG has been investigated using primary and secondary immunological procedures. The need for primary immunoassay procedures to assess both the immune response and induction of tolerance to equine IgG in ALG treated patients is extensively discussed.
Schmidt NJ, Melnick JL, Wenner HA, Ho HH, Burkhardt MA.Immune horse sera to 42 enterovirus immunotypes were pooled according to the Lim Benyesh-Melnick and the "intersecting serum" schemes. Each serum was diluted in the pools to contain 50 antibody units. After it was established that the pools correctly neutralized prototype virus strains, they were evaluated in tests against 273 enterovirus field strains representing most of the viral types included in the pools. With test virus doses of 10-100 TCD(50), most of the poliovirus and coxsackievirus field strains were correctly identified in both schemes, but a number of the echoviruses were neutrali...
Rouse BT, Ditchfield WJ.The antibody response in serum and nasal secretions of groups of ponies vaccinated or infected with Myxovirus influenzae A-equi 2 was examined. Following infection by aerosol with live virus, a weak antibody response was recorded in both serum and secretions. Antibody levels were undetectable in secretions at 31 days after infection. After primary intramuscular vaccination with killed virus, using sodium alginate as an adjuvant, antibody was detected only in the serum. However, following revaccination, a pronounced antibody response was demonstrated in both serum and secretions. Antibody was s...
Müller F, Segerling M.Complement activity in the serum of eight species has been studied in two ways: by immobilization of sensitized with human or rabbit antibody and by haemolysis of sheep red cells sensitized with rabbit antibody. Serum of the pig, monkey and man was actively haemolytic but contained a heatlabile factor that immobilized unsensitized in the presence of guinea-pig complement and precluded the detection of immune immobilizing activity. Sera of other species, although without action on unsensitized treponemes, even with added guinea-pig complement, differed in their relative haemolytic and immobil...
Jonsdottir S, Stefansdottir SB, Mirkovitch J, Ziegler A, Torsteinsdottir S, Marti E.Insect bite hypersensitivity (IBH) is an IgE-mediated dermatitis in horses caused by bites of spp. The allergens are salivary gland proteins from these insects, and nine major allergens from have been identified and expressed in . However, proteins expressed in procaryotic systems have limitations in cellular assays, particularly in functional assays assessing the allergen-induced release of mediators , such as sulphidoleukotrienes (sLT) from basophils. The aims of the study were to produce functional allergens in insect cells, to assess their allergenicity using a sLT release assay, and to...
Perkins GA, Wagner B, Rollins A, Sfraga H, Pearson E, Cercone M.To apply equine herpesvirus type 1 (EHV-1) antibody testing in nasal swabs and serum in nonclinical horses during a naturally occurring outbreak of (EHV-1). Previous experimental EHV-1 challenge studies showed stable serum anti-EHV-1 antibody concentrations paired with rapidly increasing nasal mucosal antibodies (mucAbs) prevent EHV-1 infection, viral shedding, and cell-associated viremia. From this, we hypothesized that EHV-1 antibody testing can confirm exposure in non-clinical horses during an outbreak. Unassigned: 2 horses with neurological signs from 1 farm were admitted to an equine hosp...
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...
Hildebrandt D, Venner M, Hart KA, Berghaus L.Early and specific diagnosis of bronchopneumonia in foals is important to prevent severe disease. In human medicine, C-reactive protein (CRP) and interleukin-6 (IL-6) are important diagnostic and prognostic biomarkers in neonatal pneumonia in other species. Evaluation of these markers in foals with naturally occurring respiratory diseases is lacking. Objective: To determine if CRP and IL-6 were useful predictors of respiratory disease in foals from birth to weaning. Methods: Prospective cohort study. Methods: Periodic blood samples from 200 initially healthy foals were collected from birth to ...
Roncaglia-Pereira VA, Dumard CH, Monteiro-Machado M, Melo PA, Fonseca J, Meirelles L, Cunha-Ribeiro L, Souza P, da Silva JL, Castilho L....In this study, we aim to report the persistent presence of anti-SARS-CoV-2 immunoglobulins in pre-immunized mare offspring. Three mares from Vital Brazil Institute were pre-immunized with recombinant SARS-CoV-2 spike protein and became pregnant during this period. After parturition, the mares' serum and colostrum/milk and foal serum were collected over 6 weeks. Our results have shown high and persistent presence of IgG and neutralizing antibodies over the weeks not only in the mares' serum, as expected, but in mares' colostrum/milk and foal serum as well-what were very surprising. This peculia...
Khaliji E, Marycz K, Horna M, Morgan JM, Galuppo LD, Vapniarsky N, Cassano JM.To evaluate IA autologous platelet-derived mitochondrial preparation versus vehicle control in a bilateral lipopolysaccharide (LPS)-induced model of equine synovitis. Unassigned: 2 ng of LPS was injected into bilateral intercarpal joints of 6 horses over 3 months. Autologous mitochondria, isolated with a commercial kit, were injected into one joint, while the contralateral joint received a vehicle control, a within-subject controlled experimental design. Mitochondrial organelle appearance was visualized on transmission electron microscopy. Outcome measures included synovial fluid and whole-blo...
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...
Jafari H, Abebe BK, Cong L, Ahmed Z, Zhaofei W, Sun M, Muhatai G, Chuzhao L, Dang R.The domestication and selective breeding of horses have profoundly influenced the emergence of adaptive traits and stress resistance mechanisms, shaping modern equine populations. This comprehensive review examines the genomic foundations of these traits, emphasizing recent advancements in high-throughput sequencing technologies and bioinformatics. These tools have elucidated the genetic underpinnings of key characteristics such as endurance, speed, metabolic efficiency, and disease resistance. Importantly, the review identifies and connects gene variants associated with thermoregulation, immu...
Carotenuto SE, Broussard G, Fox GA, Hayes WK.To assess the efficacy of a new equine F[ab'] antivenom (US Department of Agriculture code 6101.05) in removing serum venom and lowering the snakebite severity score (SSS) in animals suffering from naturally occurring viperid envenomation. Methods: Retrospective study, April 2020 to October 2021. Methods: Veterinary hospitals across four North American regions. Methods: Twenty-two dogs, one cat, and one horse. Methods: All patients received the new antivenom intravenously and were assessed for clinical response. Most dogs required one vial for clinical control of signs. Results: Among the dogs...
Cooper CJ, Arroyo LG, Hammermueller JD, Botts MM, Pearl DL, Wootton SK, Lillie BN.Equine herpesvirus-1 (EHV-1) is ubiquitous in the horse population, but prevalence estimates have ranged from 3 to 88% depending on the population and method of sampling. No prevalence studies have been carried out in Ontario, Canada. The objective of this study was to measure the prevalence of EHV-1 shedding in healthy broodmares in Ontario. A total of 381 mares from 42 farms in Ontario were sampled, including pregnant and barren broodmares. Samples were collected from the nose, vagina, and blood of each mare up to 6 times from December 2016 through October 2017 using a cross-sectional study ...
In horses, heat exposure modulates the hypothalamic-pituitary-adrenal axis, autonomic nervous system, and hypothalamic-pituitary-thyroid axis to maintain body temperature and prevent excessive heat accumulation. However, during strenuous exercise under hot and humid conditions, heat production may exceed dissipation, leading to heat stress, anhidrosis, heat stroke, or brain damage. Unassigned: Incremental field standardized exercise tests (fSETs) provide a reliable approach to assess training and fitness levels. Six Arabian horses from Italia Endurance Stable and Academy were monitored during ...
Young KAS, Schnabel LV, Gilger BC.Equine ocular disease is common and often challenging to treat using traditional methods. This has led to the development of new therapies. Like human medicine, veterinary medicine is adopting cellular and gene therapy as innovative approaches. Equine ocular disease is a particularly promising area for these techniques. Notably, immune-mediated diseases (such as immune-mediated keratitis and equine recurrent uveitis), ulcerative keratitis, and infectious ocular diseases are of interest. Several ocular gene therapy products are approved for use in humans, and more are currently being researched...
Korac L, St George L, MacNicol J, McCrae P, Jung L, Golestani N, Karrow N, Cánovas A, Pearson W.Low-dose intra-articular injection of recombinant equine interleukin-1β (reIL-1β) may offer a useful model for studying early onset or subclinical joint inflammation in horses. This pilot study aimed to determine the lowest intra-articular dose of reIL-1β required to produce biochemical evidence of synovitis, and to correlate synovitis biomarkers with functional, upper-body asymmetry parameters. Saline (control) and 50, and 75 ng reIL-1β were injected into the left or right intercarpal joint of three ( = 3) horses in a three-way crossover design. Synovial fluid was collected by aseptic art...
Böckmann S, Trzebiatowski L, Georgiev P, Büttner K, Wehrend A.Immunoglobulins ingested via colostrum must remain intact to be absorbed by the neonate. Equine colostrum contains antitrypsin activity, which likely protects these proteins from proteolysis in the gastrointestinal tract. Objective: To quantify antitrypsin activity in equine colostrum and milk, describe its temporal changes during the first five days after parturition, compare actitvity between left and right mammary glands, evaluate differences between nulliparous and pluriparous mares, and examine associations with immunoglobulin G (IgG) concentrations and mare age. Methods: This retrospecti...
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...
Golestani NG, Paton MP, Ross BR, Wildish AW, Duarte MSD, Williams CAW, Pearson WP.Horses experience rapid physiological, inflammatory, and oxidative responses during exercise. Spirulina, a nutrient-dense microalga with antioxidant and anti-inflammatory properties, may help modulate these responses and support recovery. Objective: This study evaluated the effects of 30-day dietary Spirulina supplementation on physiological, inflammatory, and oxidative stress responses to moderate-intensity exercise in sedentary horses. We hypothesized that 30-day Spirulina supplementation would modulate hematologic and inflammatory responses and support recovery from moderate-intensity exerc...
Bartenschlager F, Kuropka B, Schmitz P, Dumke F, Landmann K, Gruber AD, Weise C, Schnabel CL, Gehlen H, Mundhenk L.Mucus hypersecretion and accumulation are hallmark features of equine asthma (EA), a meaningful respiratory disorder in horses occurring in mild to moderate (MEA) and severe (SEA) forms. Changes of the proteomic composition of airway mucus in EA are poorly understood. Using label-free quantitative liquid chromatography-mass spectrometry, we analyzed airway mucus from SEA (n = 10), MEA (n = 6), and healthy (n = 8) horses. We identified and quantified 2,275 proteins including gel-forming mucins MUC5AC and MUC5B and membrane-bound mucins MUC1 and MUC4. Compared with healthy controls, ...
Scoggin KE, Rakha SI, Abdellatif AM, Adlan F, Helmy YA, Ruby R, Ball B, Boakari Y, Ali HE.Ascending placentitis is a significant cause of equine pregnancy loss, yet the upstream inflammatory triggers are poorly defined. Recently, we identified S100A8/S100A9 (S100A8/A9) alarmins as potential upstream regulators in a chronic equine placentitis model. The current study aimed to determine whether this upregulation is sustained in the acute model and in clinical cases, and to elucidate the expression of their downstream inflammatory mediators. Using an experimental model, we quantified mRNA expression in acute ( = 5) and chronic ( = 6) placentitis induced by ssp. . We found mRNA expre...
Toddy T, Ledbetter EC, Knickelbein KE.To describe the demographics and treatment outcomes of horses definitively diagnosed with epithelial or stromal immune-mediated keratitis (IMMK) by use of in vivo confocal microscopy (IVCM) and/or histopathology. Unassigned: Medical records of horses presented to the Cornell University Equine Hospital definitively diagnosed with epithelial or stromal IMMK with IVCM and/or histopathology between 2020 and 2024 were reviewed. Patient signalment, affected eye(s), diagnostics, treatments, and outcomes were assessed. Unassigned: 22 horses met the inclusion criteria. The mean age was 16.9 years (SD, ...
Samuels AN, Collins N, Albrecht M, Cuming R, Reed S, Gomez D, Toribio R.To evaluate associations between the neutrophil-to-lymphocyte ratio (NLR), nonsurvival, illness severity, and infectious etiologies. Unassigned: This was a retrospective multicenter study that included 100 healthy horses and 444 horses presenting with acute diarrhea to 5 equine referral hospitals. Inclusion criteria were diarrhea duration < 48 hours, complete hemograms, and outcome data. Illness severity was assessed using systemic inflammatory response syndrome. The results of pathogen testing for Salmonella spp, equine coronavirus, Clostridium spp, and Neorickettsia risticii/findlayensis ...
von der Höden FJ, Stefansdottir SB, Torsteinsdottir S, Svansson V, Björnsson JM, Wagner B, Mahmuti D, Marti E, Jonsdottir S.Insect bite hypersensitivity (IBH) is a seasonal, IgE-mediated allergic dermatitis of horses caused by salivary gland proteins of biting midges ( spp.). Current management relies on relief of clinical signs and on physical protection. In a previous pilot study, healthy horses were fed transgenic barley expressing a allergen via a special spiral bit, which successfully induced allergen-specific antibody responses. Building on this concept, the present study aimed to evaluate a more practical feeding approach, delivering transgenic barley expressing the major allergen Cul o 2p in a feed-compat...
Ivester K, Couetil L, Arora D, Wilkes R, Thimmapuram J.Fungal exposure is strongly implicated in the pathogenesis of asthma in horses, but the importance of specific fungi is unknown. Geographic variation in equine asthmatic endotypes is suspected and might be related to different fungal exposures due to different climatological and geographical conditions. This study had two objectives: evaluate the effect of the ecoregion upon BALF inflammatory cells and fungal community composition in horses with asthma and evaluate the effect of BALF fungal community composition upon the likelihood of neutrophilic, mastocytic and eosinophilic inflammation in t...
Santos R, Hunyadi L, Sundman E, Morales Luna L, Hyde SC, Cain M, Migl K, Ancira J, Tipton C, Rosa F.Severe equine asthma (SEA) is a chronic inflammation of airways affecting ~14-20% of adult horses in the Northern Hemisphere. SEA is characterized by a mixed phenotype of T helper cell responses with marked neutrophilia in the bronchoalveolar lavage fluid (BALF) of affected horses. Human studies have demonstrated the impact of gut microbiota in many diseases, including asthma susceptibility and severity. However, the potential role of the gut-lung axis in the development and persistence of SEA remains to be determined. This study aimed to identify key bacterial, archaeal, and fungal microbiota...
van den Brom-Spierenburg AJ, Siegers EW, Westermann CM, Vernooij JCM, Sloet van Oldruitenborgh-Oosterbaan MM, Theelen MJP.In hospitalized foals, limited data are available on the utility of sequential measurement of SAA concentrations and the value of these data in a clinical setting. Objective: To determine serum amyloid A (SAA) concentrations in ill neonatal foals at multiple timepoints during hospitalization, and to evaluate a potential association with systemic inflammatory response syndrome (SIRS) status, blood culture (BC) result, and survival. Methods: Hospitalized ill foals (n = 90, ≤ 14 days). Methods: In this retrospective study, foals were classified based on SIRS criteria: "SIRS" or "NonSIRS," ...
Dörsam K, Nischang V, Büttner K, Fey K, Werz O, Jordan PM.Equine asthma (EA) is a chronic inflammatory disease of the lower respiratory tract in horses, which is mainly triggered by dusty hay. EA is becoming increasingly acknowledged as a valuable animal model for studying human asthma. Research on the pathogenesis of EA has primarily focused on the associated cells and cytokines involved. However, the role of inflammation-related lipid mediators (LM) in the development and progression of equine asthma remains elusive. LMs are categorized into pro-inflammatory arachidonic acid (AA)-derived leukotrienes (LTs) and prostaglandins (PGs), as well as infla...
Arroyo LG, Borges AS, Baird JD, Perry BD, Rikihisa Y, Greiman SE.Equine neorickettsiosis (EN) is an infectious, non-contagious systemic disease of horses caused by the closely related obligatory intracellular bacterial species Neorickettsia risticii and N. findlayensis. Clinical cases are considered endemic in multiple regions across the United States and Canada, as well as in parts of South America, including Uruguay and Brazil. Neorickettsia spp. are obligate endosymbionts of digenean trematodes, which have complex life cycles involving a molluscan first intermediate host, a wide range of invertebrate or vertebrate second intermediate hosts, and a vertebr...
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...
Cottone A, Seiter K, Thomas B, Schank N, Wulf M, Miller L, Anderson S, Munkhsaikhan U, Verma A, Abidi AH, Kassan M.Colic remains one of the most frequent and costly causes of equine morbidity and mortality, with significant welfare and economic implications. Disturbances in the gut microbiome are increasingly recognized as an important contributing factor. In recent years, prebiotics, non-digestible substrates that promote beneficial microbes, have emerged as promising microbiome-targeted strategies. () has gained attention for its unique ability to degrade mucin, maintain epithelial integrity, and exert potent anti-inflammatory effects. Although its benefits are well established in humans and rodent mode...
Rakowska A, Biazik A, Sobuś M, Cywińska A.The article aimed to review the current literature analysing the complexity of an exercise-induced acute phase response in athletic horses undergoing intense training and endurance competitions. Since the endurance discipline demands physical fitness, exceptional health and excellent adaptation to an increasing workload, diagnostic methods of assessing the factors mentioned above are highly required. Athletic horses in endurance training undergo numerous metabolic but also immune adaptations, including changes in pro-inflammatory and anti-inflammatory cytokine levels. The inflammatory reaction...
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...
