The immune system in horses is a complex network of cells, tissues, and organs that work together to protect the body from pathogens, such as bacteria, viruses, and parasites. This system includes both innate and adaptive immune responses, which function to identify and eliminate foreign invaders. The innate immune response provides an immediate, non-specific defense, while the adaptive immune response involves a more targeted and long-lasting protection through the production of antibodies. Key components of the equine immune system include white blood cells, such as lymphocytes and macrophages, as well as various signaling molecules like cytokines. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and regulation of the immune system in horses, with an emphasis on understanding its role in maintaining equine health and its response to diseases.
Mitchell G, Liu IK, Perryman LE, Stabenfeldt GH, Hughes JP.Immunoglobulin concentrations were compared in serum and in saline uterine washings from 10 normal mares and 7 subfertile mares with chronic endometrial pathology. Samples were collected in dioestrus and in oestrus. For each immunoglobulin class (IgA, IgG, IgG(T), IgM) the results were expressed as a percentage of total immunoglobulin present in uterine washings or serum. Comparison was also made between changes in immunoglobulin concentrations between dioestrous and oestrous uterine samples, and uterine immunoglobulin concentrations between groups of mares. There was significantly more IgA in...
Perryman LE, Magnuson NS.Significant contributions to understanding the role of lymphocyte subpopulations in the immune response and to the characterization of immunodeficiencies in children have been achieved through study of animal models of immunodeficiency. Additional contributions can be made in two important areas. One is through identification of relevant, naturally-occurring models of adenosine deaminase deficiency and purine nucleoside phosphorylase deficiency. The second, and potentially more important contribution, would be the identification of the metabolic basis for existing immune deficiencies. The nece...
Aref S.A study of the migration of fourth stage larvae of the parasite Strongylus vulgaris in the intestinal arteries of the horse is presented. It is established, that the larvae migrate along the arteries in almost straight lines. It is suggested that this is primarily due to their ability to sense the curvature of the vessel wall, and not, as might have been expected, because of an ability to sense the direction of blood flow. A larva will sometimes alter its direction of motion when encountering a small off-branching artery. This behaviour suggests, that the migration of S. vulgaris larvae can be...
Baskerville A.Related to its potential vulnerability the respiratory tract has a very complex and effective defence apparatus. The interaction between these defence mechanisms and certain characteristics of aetiological agents results in a pattern in which initial infections by these agents tend to occur at specific sites in the tract. Infections in which the primary portal of entry is in the upper respiratory tract include Bordetella bronchiseptica and Haemophilus spp in pigs; Pasteurella spp in cattle, sheep, pigs; Mycoplasma spp in cattle, sheep, pigs and poultry; equine herpesvirus 1 in horses; infectio...
Naylor JM, Kenyon SJ.Horses were deprived of food but not water for a period of five days. There was a progressive decrease in circulating lymphocyte count and compromised host deference. In vitro phagocytosis of yeast fell from a mean of 97 per cent in fed horses to 78 per cent in horses deprived of food for five days. The Arthus response to intradermal challenge with allergens fell to 57 per cent of fed values. These changes indicated that food deprivation increases the susceptibility to bacterial infections; persistent anorexia in chronic bacterial infections may limit the horse's ability to cast off infection....
Wells PW, McBeath DG, Eyre P, Hanna CJ.This article attempts to relate some of the more recently accepted concepts of immunology to an understanding of the mechanisms of immunity in the horse. The cellular mechanisms involved in the immune response are outlined, with an indication of their likely role in humoral and cell-mediated immunity. In describing the humoral immune response, the structure and function of the different equine immunoglobulins are reviewed. The significance of humoral and cell-mediated immune responses are considered in relation to actively and passively acquired immunity.
Mottironi VD, Perryman LE, Pollara B, Mickey MR, Swift R, McGrath P.Combined immunodeficiency disease (CID) is a genetic disorder of T and B lymphocyte production which results in a nonfunctional immune system. It is inherited as an autosomal recessive trait and has been reported in humans and in horses of the Arabian breed. Arabian horses known to have the CID gene and horses of unknown carrier status were tested using a microlymphocytotoxicity technique. Computer chi 2 analysis distinguished six serologically defined specificities. The study of unrelated horses and a limited number of families showed that the specificities behave as codominant alleles segreg...
Carakostas MC, Moore WE, Smith JE, Johnson D.The functional capacity of the marrow granulocyte reserve (MGR) in 4 adult horses was studied, using 51Cr-labeled leukocytes. The mean increase in the peripheral granulocyte count following injections of etiocholanolone (0.3 mg/kg) was 870 granulocytes/mm3, and the mean increase following prednisolone administration (200 mg) was 5,880 granulocytes/mm3. Etiocholanolone failed to mobilize the MGR and decreased the rate of granulocyte egress from the blood. Prednisolone rapidly mobilized the MGR and markedly decreased the granulocyte specific activity during the first 3 hours after injection.
Snyder DB, Myrup AC, Dutta SK.Pony foals, negative for detectable serum-neutralizing antibody to equine herpesvirus 1 by the standard tube-culture virus neutralization test, were experimentally infected with equine herpesvirus 1. Complement-requiring (CR) and non-complement-requiring (NCR) serum-neutralizing antibodies were evaluated in preinfection and postinfection sera by means of a complement-enhanced plaque reduction assay. Low levels of CR antibodies were found in the preinfection sera of only group II ponies. Upon infection, CR antibodies were detected by day 2 postinfection and reached peak titers between 7 and 14 ...
Barta O, Oyekan PP.Lymphocyte transformation test is a powerful tool in laboratory testing of immunologic competence of animals. The impaired function of the lymphocytes or presence of mitogenesis suppressing factors in the patient serum were detected by comparing lymphocyte transformation (expressed as thymidine incorporation) obtained in media containing either autologous, homologous, or fetal calf serum additions. Most valuable results were obtained by using at least two, preferably three, different phytomitogens: concanavalin A (Con A), pokeweed mitogen (PWM), and phytohemagglutinin (PHA) at optimal concentr...
Maxwell MH.A series of experiments is described in which attempts were made to produce an avian eosinophilia using various agents. Although none of the experiments was decisive, two demonstrated a slight rise in the eosinophil counts. In one experiment horse serum was injected into a group of fowls on alternate days for 42 days. No eosinophils were seen in any blood smears after this treatment. After a rest period of eight days the birds received further injections for 10 days. The mean eosinophil count rose to over 4 per cent with a range of 1 to 11 per cent. It is considered that this type of response ...
Siegel RC, Cathou RE.Complexes of IgM equine anti-dansyl antibodies and different dansyl substituted carriers were tested for their ability to fix complement (C). Only dansyl92-Ficoll and dansyl12-poly-L-lysine were found to be effective. Dansyl13-bovine serum albumin, dansyl127-keyhole limpet hemocyanin, and reduced and alkylated dansyl10-ribonuclease were all ineffective. Lack of C fixation by the dansyl-ribonuclease was not due to lack of antibody-antigen complex formation, since binding at the concentrations employed for C fixation was established. However, in contrast, polymerized dansyl-ribonuclease (polydis...
Al-Khalidi NW, Weisbrode SE, Dubey JP.Nine ponies were fed 100,000 infective Toxoplasma gondii oocysts and were given corticosteroid injections before and after feeding the T gondii oocysts. Titers to the Sabin-Feldman dye tests (1:2 to 1:16,384) developed within postinoculation days (PID) 7 to 21 and antibodies persisted to PID 133. Toxoplasma organisms were isolated from the tissues of 4 ponies (heart of 4, brain of 2, spinal cord of 3, diaphragm of 1, skeletal muscle of 1, liver of 1, kidneys of 1) killed between PID 36 and 63, but not from 5 ponies killed between PID 117 and 150. Seemingly, ponies are one of the more resistant...
Lew AM, Hosking CS, Studdert MJ.Tests for T- and B-cell quantitation and immune function were developed, and their application in the diagnosis of primary severe combined immunodeficiency disease (CID) in Arabian foals was investigated. Foals with CID had severe lymphopenia and had small or zero numbers of B cells, as shown by immunofluorescence of surface immunoglobulin (Ig), erythrocyte-antibody-complement rosetting, and staphylococcal protein A rosetting. Serum IgM was undetectable in four CID foals 25 to 71 days old. Demonstrable antibody responses were not elicited in CID foals by phage phi X-174, a potent antigen in no...
Perryman LE, McGuire TC.Between January 1973 and September 1979, 2,092 horses and ponies were evaluated for immunologic disorders. A total of 418 abnormalities were detected in 416 (20%) of the animals tested. Disorders encountered were failure or partial failure of colostral immunoglobulin transfer from mare to foal (228 cases), combined immunodeficiency (159 cases), selective immunoglobulin M deficiency (19 cases), agammaglobulinemia (3 cases), transient hypogammaglobulinemia (2 cases), and lymphosarcoma (7 cases). Four conclusions were drawn from the study. (1) Immunologic abnormalities occur commonly in horses an...
Magnuson NS, Perryman LE, Grant B, Estergreen VL.Plasma corticosteroid concentrations of seven Arabian foals with combined immunodeficiency (CID) and five non-CID Arabian foals were measured. Plasma corticosteroid concentrations were quantitated throughout gestation for ten mares heterozygous for the CID trait and pregnant with CID foals, as well as for 20 mares heterozygous for the CID trait and pregnant with non-CID foals. Five nonpregnant mares heterozygous for the CID trait also were tested during the same period. Concentrations of plasma corticosteroids in foals with CID (34.4 +/- 5.2 ng/ml) were not different from those of non-CID foal...
Scott DW, Wolfe MJ, Smith CA, Lewis RM.In a review of non-viral bullous skin diseases of domestic animals and a 4-year study of cases presented to the New York State College of Veterinary Medicine, we found 15 diseases: pemphigus vulgaris, pemphigus vegetans, pemphigus foliaceus, pemphigus erythematosus, bullous pemphigoid, systemic lupus erythematosus, dermatitis herpetiformis, toxic epidermal necrolysis, drug eruption, epidermolysis bullosa, epidermolysis bullosa simplex, familial acantholysis, bovine congenital porphyria, impetigo and subcorneal pustular dermatosis. The 15 diseases were placed in five categories: autoimmune, imm...
Shaw FD, Morton H.The developing embryo/fetus bears antigens which are foreign to the mother and it could be expected that immune rejection of the conceptus would occur. One of the reasons why the fetus is not rejected is because a depression of the maternal immune response takes place during pregnancy. Serum from pregnant animals of several species has been shown to contain a factor, early pregnancy factor (EPF), which is immunosuppressive. EPF has been detected as early as six hours after mating and its detection could aid diagnosis of early pregnancy in all species.
Fernandez C, Möller G.After a primary immune response to the alpha 1-6 epitope of dextran B512, dextran high responder strains exhibit a specific inability to produce IgM and IgG antibodies against this epitope, although they gave an expected secondary response to horse erythrocytes. Spleen cells from dextran-primed and-suppressed mice responded well to dextran after transfer to lethally irradiated previously untreated mice, indicating that tolerance or exhaustive proliferation of dextran reactive B cells is not responsible. Thymus-dependent dextran-protein conjugates also induced specific suppression. Suppression ...
Horenstein AL, Glait HM, Koss A.A monoclonal anti-equine infectious anemia virus (anti-EIAV) antibody (1B15) has been generated by fusion of X63 Ag 8.653 myeloma cells and spleen cells from mice hypersensitized with viral antigen p29. Ouchterlony double-diffusion analysis indicated that antibody 1B15 is of the IgG class. The specificity of the immune reaction for p29 was confirmed by cross-over immunoelectrophoresis and disc-gel electrophoresis. MAb 1B15 was used to devise a solid-phase 'capture' RIA for EIAV-p29 antigen. The antigen, bound by 1B15 adsorbed onto wells of flexible microtitre plates, was detected using a rabbi...
Jongbloets AM, Sloet van Oldruitenborgh-Oosterbaan MM, Meeus PJ, Back W.Equine canker is a chronic, hyperplastic, exudative pododermatitis affecting one or more feet. Although many causes and treatments have been suggested, the cause of the disease is still unknown and most probably multifactorial. Local treatments include radical surgical debridement of the diseased hoof tissue and application of caustic substances, antibiotics, and pressure bandaging. Nevertheless, the number of recurrences is high (45%). This article presents a 3-year-old New Forest pony-cross mare in which all horny structures (frogs, coronets, spurs, chestnuts) of all feet were affected. Bact...
Péterfy F, Varró R, Fatrai Z, Barna I, Kiss I.Horse immune sera do not give satisfactory results in immunochemical techniques based on electrophoresis of antigens through antibody-containing agarose gel. As the majority of precipitating horse antibodies belongs to the beta globulins, they migrate in the gel during electrophoresis. After enzymatic treatment the pepsin fragments work well in all electroimmunodiffusion methods.
Martens JG, Stephens KA, Kerchner LJ, Heck FC, Martens RJ.Plasma fibronectin concentrations were measured in clinically healthy mares and their neonatal foals, using a modified human fibronectin competitive enzyme-linked immunosorbent assay. Ranges of plasma fibronectin were established in clinically healthy horses, and the assay was reliable and reproducible. Plasma fibronectin concentrations were similar in mares and foals, both before and after colostrum ingestion.
Frymus T, Degórski A, Kowalski B, Crisman M.
Summary:
Serum lysozyme (LZM) activity and nitroblue tetrazolium (NBT) reduction capacity of circulating phagocytes were determined by the lysoplate technique and the microquantitative method, respectively. As blood donors 47 clinically normal Arabian foals ranging in age from 6 hours to 22 days and their 40 dams were used.
A significantly (p < 0.05) lower serum LZM activity was found in foals older than 24 hours, compared with the mares (40.84 U/ml ± 15.32 and 48,96 U/ml ± 17.9, respectively), but the LZM/phagocyte ratio was similar in foals and mares.
Circulating phagocytes from...
Seeger K, Thurow H, Haede W, Knapp E.A simple enzyme immunoassay (EIA) for the measurement of progesterone is described. Antibody against 11-OH-hemisuccinate-BSA is bound to polystyrene tubes. 11-OH-hemisuccinyl-beta-D-galactosidase is used as enzyme-coupled antigen and methylumbelliferyl-beta-D-galactoside as substrate. Concentrations down to 0.156 ng/ml plasm or amounts of 93 pg/tube are detectable. Probit analysis gave a linear relationship between log concentration and percentage of binding. A comparison of EIA and radioimmunoassay gave a correlation coefficient of 0.81. The assay is sufficiently sensitive to estimate progest...
Takafuji VA, Howard RD, Ward DL, Sharova LV, Crisman MV.The effect of recombinant equine IL-1beta (EqIL-1beta) on steady-state mRNA levels of equine articular chondrocytes in high-density monolayer culture was investigated using a customized cDNA array analysis. Total RNA samples isolated from chondrocytes cultured in media alone or with the addition of 1 ng/ml EqIL-1beta for 1-, 3-, and 6-h durations of exposure were reverse transcribed, radiolabeled, and hybridized to a customized 380-target cDNA array. Means of duplicate log base 2 transformed hybridization signals were normalized to equine glyceraldehyde 3-phosphate dehydrogenase (GAPDH) mean s...
Giguère S, Prescott JF.The remarkable ability of the horse and other animals to prevent infection by most bacterial pathogens encountered is the result of a complex set of distinct but overlapping defense mechanisms. This article summarizes the current state of knowledge on innate and adaptive immunity to bacterial pathogens and reviews various ways in which some bacteria have evolved in order to evade components of the host response.
Nunez R, Gomes-Keller MA, Schwarzwald C, Feige K.RATIONALE: Thrombocytopenia is a platelet associated process that occurs in human and animals as result of i) decreased production; ii) increased utilization; iii) increased destruction coupled to the presence of antibodies, within a process know as immune-mediated thrombocytopenia (IMT); or iv) platelet sequestration. Thus, the differentiation of the origin of IMT and the development of reliable diagnostic approaches and methodologies are important in the clarification of IMT pathogenesis. Therefore, there is a growing need in the field for easy to perform assays for assessing platelet morpho...
McClure JJ.Although relatively little is known about autoimmunity and autoimmune mechanisms specifically in horses, the similarities between clinical syndromes with identifiable effector mechanisms in horses and other species suggest that comparable mechanisms may be applicable. Our understanding of equine autoimmunity undoubtedly will benefit from the extensive study of autoimmunity in other species.
Minamijima Y, Niwa H, Uchida E, Yamamoto K.In the past decade, mass spectrometry has become an important technology for protein identification. Recent developments in mass spectrometry allow a large number of identifications in samples; therefore, mass-spectrometry-based techniques have been applied to the discovery of biomarkers. Here, we conducted a proteomic study to compare the proteomes in sera between healthy Thoroughbreds and Thoroughbreds with respiratory disease associated with transport (RDT). We found that four proteins, apolipoprotein F, lipopolysaccharide binding protein, lysozyme and protein S100-A8, were upregulated, whi...
Sanada Y, Noda H, Nagahata H.The blastogenic response of lymphocytes from 16 newborn foals naturally infected with Rhodococcus equi was investigated, in order to evaluate the relationship between R. equi infection and depressed host response. Naturally infected foals showed evidence of R. equi infection at 5-6 weeks of age, as determined by clinical, haematological, bacteriological and serological methods. The blastogenic response of lymphocytes against phytohaemagglutinin was significantly depressed (stimulation index < 1.80; P < 0.01, P < 0.05) in R. equi-infected foals at 5-6 weeks of age compared with those o...
Hurtig MB, Livesey MA.Two horses were examined because of chronic lameness, which followed arthroscopy in one case, and tendon sheath lavage in a second case. Clinical investigations linked both cases to the use of irrigating fluids containing preservatives. The clinical signs were reproduced in a Shetland pony by injection and lavage of the carpal joints with the same fluid. Lameness was slow in onset and accompanied by profound periarticular fibrosis. Postmortem examination confirmed the presence of a severe, erosive, noninfectious arthritis that may have an immune-mediated component. Clinicians should read produ...
Roberts MC, Kelly WR.A four-year-old thoroughbred was presented with clinical manifestations of purpura haemorrhagica. Evidence of renal involvement consistent with glomerulopathy and nephrotic syndrome, characterised by heavy proteinuria and azotaemia, became apparent and may have been exacerbated by diuretic therapy. Autopsy revealed membrano- and mesangial proliferative glomerulonephritis and chronic pleuritis. Circulating immune complexes may have been responsible for the renal diseases and the purpura.
Scheel J, Duswald KH, Ring J, Seifert J, Scholz S, Brendel W.Eight mongrel dogs received a standard daily i.v. infusion of 20 mg/kg b.w. deaggregated horse-anti-dog-lymphocyte-globulin (ALG) and additional prednisolone (1 mg/kg b.w. daily i.v.) over a maximum period of 82 days following pretreatment with deaggregated normal horse IgG. No sensitization against horse protein was observed during therapy of afterwards as proved by lack of humoral antibodies against horse antigens, maintained lymphopenia, good compatibility, longterm prolongation of xenogeneic skin graft survival (85.6+/-20.6 days, n=8' untreated controls 12.5+/-1.3 days, n=4) and longterm s...
Mackenzie CD.The basic components of the immune system, and the defence mechanisms in the gastrointestinal tract, are briefly reviewed. Histological studies in 84 equine foetuses showed that lymphoid cells begin populating the thymic primordium at 11-12 weeks, the mesenteric lymph nodes at 13 weeks, the spleen at 25 weeks and the intestinal lamina propria at 13-14 weeks' gestation. Lymphocytes were seen in the intestinal epithelium very early in gestation. Histological signs of response to antigenic stimulation were seen in five foetuses, indicating that the horse is likely to be capable of mounting an imm...
Watson ED.Incubation of equine neutrophils with povidone-iodine solutions of greater than or equal to 0.2 per cent resulted in total inhibition of migration under agarose. This was caused by the cytotoxic effects of the solutions as shown by pyknosis and cell lysis. Lower concentrations of povidone-iodine, however, did not adversely affect neutrophil viability or locomotion.
Shaw FD, Morton H.The developing embryo/fetus bears antigens which are foreign to the mother and it could be expected that immune rejection of the conceptus would occur. One of the reasons why the fetus is not rejected is because a depression of the maternal immune response takes place during pregnancy. Serum from pregnant animals of several species has been shown to contain a factor, early pregnancy factor (EPF), which is immunosuppressive. EPF has been detected as early as six hours after mating and its detection could aid diagnosis of early pregnancy in all species.
Leid RW.The investigation of the mast cell-basophil products has progressed from studies directed solely at implicating histamine or serotonin in allergic diseases to molecular definitions of pathways to target cell activation and mediator release. In addition, within the last several years the detection and molecular characterization of the many other mediators of immediate hypersensitivity have begun. This area should continue to prove a fruitful arena in the future. Identification of the physiologic importance of these mediators in the heaves syndrome or other potential equine allergic syndromes ma...
Stellmann C, Petermann HG.After vaccination of chickens, rabbits, foals and horses, HI and SN antibody dose response curves were compared for A/Equi 1/Prague and A/Equi 2/Paris strains.
The two curves are parallel for a given strain and the relationship of HI and SN titres is constant, whatever the animal species.
The distribution of HI and SN titres varies for the two strains.
This variation, which is independent of animal species, may be related to the number of sites necessary for the antigenic-antibody response in vitro.
It is suggested that the testing of equine influenza vaccine be carried out in the ...
CRAWFORD M.This disease has a very long history, with the earliest written description by Vegetius in the fourth century A.D. It has many names, such as periodic ophthalmia, recurrent ophthalmia, iridocyclitis, uveitis, moon-blindness, etc. Periodic ophthalmia is perhaps the name more generally used, but I prefer to use recurrent iridocyclitis because (a) there is no definite fixed period between the recurrent attacks and (b) because the essential lesion is iridocyclitis.
Journal of biochemistryNovember 1, 1963
Volume 54 388-397 doi: 10.1093/oxfordjournals.jbchem.a127804
JOHKE T.This research article investigates the differences in acid-soluble nucleotides in the milk of various species including cows, goats, mares, and humans through different stages of lactation, and compares the nucleotide […]
Berger J, Valdez S, Puschner B, Leutenegger CM, Gardner IA, Madigan JE.Highly reactive horses may pose risks to humans involved in equestrian activities. Among the factors that may affect horses' reactivity to external stimuli are pesticides used for fly control in equine facilities. The organophosphorus (OP) insecticide tetrachlorvinphos (TCVP) is used as a feed-through larvicide to prevent completion of the fly larval life cycle in horse manure. TCVP exerts its effect by inhibiting the enzyme cholinesterase (ChE) leading to the accumulation of the neurotransmitter acetylcholine (AChE) in synapses of the central and peripheral nervous systems. The aim of the pre...
Georgadze IA, Nozadze ZM.The hyperimmunization of horses with large doses of tetanus toxoid is accompanied by an increase in the levels of both specific antitoxic antibodies and autoantibodies to the tissue antigens of the liver, the spleen, the heart. The reverse relationship between the level of autoantibodies and the titer of antitoxin has been established. The authors suggest that the synthesis of autoantibodies is stimulated by the presence of antigen-antibody immune complexes in the circulating blood, as well as by the action of exo- and endopolyclonal stimulators.
Woolcock JB.An atypical variety of Streptococcus equi is described. It was shown to be deficient in capsular material, to be very virulent for mice and to possess a cell-wall protein similar to the M-like protein of classical Str equi. Antiserum prepared against classical Str equi effectively opsonised the atypical strains, and induced the formation of long chains by these atypical strains. It is possible that this variant of Str equi can be used to overcome many of the current problems associated with the manufacture and use of strangles vaccines.
Hannant D.This study investigates severe equine asthma (sEA), a significant health risk in horses similar to human asthma, identifying latex found in riding arenas and racetracks as a potential risk factor. […]
Knickelbein KE, Lassaline ME.Immune-mediated ocular inflammation is a common clinical diagnosis reached for horses with keratitis and uveitis. This diagnosis is made as a diagnosis of exclusion following a thorough effort to rule out an underlying cause for the inflammation, most importantly infectious and neoplastic disease. Practically, response to ophthalmic and systemic anti-inflammatory or immunomodulatory medications is used to support a diagnosis of immune-mediated ocular inflammation; however, such medications are often contraindicated in the face of infection or neoplasia. This article will summarize our current ...
Marsella R.Autoimmune dermatopathies are not common in horses. These autoimmune diseases can be idiopathic or triggered by an antigen such as drugs, vaccines, or neoplasia. The most common one is pemphigus foliaceus, which manifests as a pustular, crusting eruption. Other more common pustular diseases should be ruled out before considering pemphigus. Vasculitis is relatively common in horses and can be triggered by a variety of antigenic stimulations. Systemic lupus and true idiopathic autoimmune vasculitis are very rare in horses. Every effort should be made to reach a final diagnosis, as the prognosis ...
Ghaeli T, Karimi B, Kojouri GA, Dehkordi RR, Ahadi AM.One of the initial responses of the host's innate immunity of newborns against pathogens is the use of oxidative enzymes. This study aimed to evaluate changes in serum xanthine oxidoreductase (XOR) activity, the leukocyte myeloperoxidase (MPO) and XOR genes expression, and some biochemical parameters in healthy Darehshuri newborn foals up to 60 days of life. Blood samples were collected from 16 foals at 1, 7, 15, 30, and 60 days and used for detecting XOR activity, biochemical parameters, and also gene expression by real-time RT-PCR. High activity of XOR was observed at birth, explained by phy...