The inflammatory response in horses is a complex physiological process that occurs when the immune system reacts to harmful stimuli such as pathogens, damaged cells, or irritants. This response is characterized by the activation of various immune cells, the release of signaling molecules, and the production of inflammatory mediators. In horses, the inflammatory response involves both innate and adaptive immune mechanisms, which work together to eliminate the source of harm and initiate tissue repair. Key components of the equine inflammatory response include cytokines, chemokines, and leukocytes, which coordinate the body's defense and healing processes. This page gathers peer-reviewed research studies and scholarly articles that explore the mechanisms, regulation, and implications of the inflammatory response in equine health and disease.
Britton BA.Cervical and endometrial swabs were taken from 7 mares at various stages of the oestrous cycle. There was no consistent pattern of cell change throughout the cycle. The dominant cell in smears from normal mares was the columnar epithelial cell, especially in smears obtained during oestrus. A ciliated columnar epithelial cell was found much less frequently but appeared more often in smears before oestrus. Endometrial biopsies were also collected from 7 mares at intervals 2-3 weeks over an 8-month period from the beginning of spring to the end of autumn. There was no obvious change in the endome...
Adams SB, Fessler JF, Rebar AH.Cytologic examination of serial peritoneal fluid samples of nine experimental ponies was performed during a 72 hour period following laparotomy. Six of the ponies had jejunal infarction induced by occlusion of the corresponding vasculature. Cytologic examination was also performed on the peritoneal fluid of a series of horses with naturally occurring abdominal crises presented to the Large Animal Clinic. A rapid staining technique allowed evaluation of smears within 5 minutes of obtaining the fluid. Alterations in peritoneal fluid of the experimental and clinical cases reflected an acute infla...
Matthews AG.Three major antiprotease components in equine serum were identified and characterised. These were the acidic prealbumin Pr, the homologue of human alpha-1 antitrypsin and 2 protease binding proteins, the acidic prealbumin Xc and alpha-2 macroglobulin, both capable of inhibiting the proteolytic activity of trypsin, but with only limited inhibitory effect on its esterolytic activity. The possible role of these serum antiproteases in the onset of chronic obstructive pulmonary disease (COPD), analogous to the hereditary dysproteinaemia of alpha-1 antitrypsin in man, was investigated. There was no ...
Burrows GE.Repeated exposure of ponies in Escherichia coli endotoxin resulted in attenuation of the packed cell volume, beta-glucuronidase, capillary refill time and neutrophil responses usually accompanying endotoxin administration. An overall decrease in severity of clinical response including reduced mortality was also apparent in ponies with repeated endotoxin exposure. Modification of the febrile response was not observed in any of the experimental groups.
Timoney PJ, McArdle JF, O'Reilly PJ, Ward J.Contagious equine metritis 1977 was reproduced in pony mares using cultures of the Gram-negative coccobacillus aetiologically associated with the disease. Variability in clinical response was observed in the first of 2 experiments, with the presence of semen, either alone or in an extender, appearing to potentiate the pathogenicity of the challenge strain of the organism. The experimental disease was characterised by a variable degree of vaginal discharge and concomitant inflammatory changes involving the vervix and vagina. Although all of the affected mares recovered spontaneously, a high per...
Kramer JW, Nickels FA, Bell T.Examination of effusions from body cavities must include a search for neoplastic as well as inflammatory cells. Neoplastic cells found in the thorax are generally derived from adenocarcinomas or mesotheliomas. Mesotheliomas are relatively uncommon and the neoplastic cells found in effusions are difficult to differentiate from activated cells in inflammatory effusions. An ante-mortem diagnosis of mesothelioma was made in a mare on the basis of the large volume of fluid produced, the pleomorphic mesothelial cells, the polyp formation and the absence of PAS staining material after digestion of th...
Burka JF, Deline TR, Holroyde MC, Eyre P.Horses were sensitized to bovine plasma in Freund's complete adjuvant. Leukocytes, separated from venous blood, yielded histamine upon incubation with bovine plasma. Ioslated lung fragments incubated with bovine plasma liberated histamine and 5-HT, but not SRS-A. Pulmonary veins obtained from the same animals contracted to histamine, 5-HT and to antigen (Schultz-Dale reaction). Histamine and 5-HT probably contribute to immediate-type hypersensitivity in horses whereas the role of SRS-A is not proved.
Targowski SP.All chronically diarrheal horses given (orally) 2 series of treatments with normal horse serum recovered in 2 to 4 weeks. However, mild diarrhea sometimes persisted several months in the group of horses with severe diarrhea. Weight gains were approximately 35% in horses with severe diarrhea and approximately 10% in horses with mild diarrhea. Serum specimens from 12 diarrheal and 20 normal horses were examined for immunoglobulins by single radial immunodiffusion technique. Concentration of immunoglobulin A in serum of diarrheal horses was approximately 50% lower than that in serum of normal hor...
Hatziolos BC, Sass B, Albert TF, Stevenson MC.Recurrent epistaxis and locomotor and visual disturbances leading to blindness in a 7-year-old gelding appeared to have resulted from a spreading fungal granuloma of the guttural pouch. The inflammatory area extended to the intracranial segment of the right optic nerve and to the region adjacent to the optic chiasma. Microscopically, changes indicative of multiple foci of ischemic infarction were noticed in the retina, optic nerves, optic chiasma, and optic lobe. The profusely growing fungal elements in the guttural granuloma had the morphologic characteristics of an Aspergillus sp.
Targowski SP.Serum specimens from 12 sick and 20 normal horses were examined for levels of different classes of immunoglobulin (Ig) by a single radial immunodiffusion. The level of IgA in the sera of sick horses was about 50% lower than in the sera of normal horses. By contrast, the level of serum IgG was higher in sick than in normal horses. Phytohemagglutinin (PHA) responsiveness of blood lymphocytes showed transient suppression during the stage of severe diarrhea. The regaining of PHA responsiveness of lymphocytes was observed simultaneously with the recovery process. However, the responsiveness of lymp...
Duncan JL, Pirie HM.The clinical signs, pathology and clinical pathology associated with single experimental infections of Strongylus vulgaris in worm-free pony foals are described. The major clinical signs which became apparent in the infected foals during the first three weeks were pyrexia, anorexia, dullness and abdominal pain. Within the first two weeks of infection lesions were confined to the intestine and terminal branches of the intestinal arteries and consisted of mucosal, submucosal and serosal haemorrhage together with arteritis of submucosal and serosal arteries and also a marked inflammatory reaction...
Williams MR.Rats were injected intradermally with rabbit anti-ovalbumin serum and 3 hours later were challenged intravenously with ovalbumin and Evans Blue dye. Inflammatory lesions were produced within 20 minutes and their size was markedly dose-dependent. Attempts were made to interfere with this passive cutaneous anaphylaxis (PCA) by admixture of normal IgG with the rabbit anti-ovalbumin to measure the relative tissue binding affinities of IgG from various species. It was found that normal IgG from any of the species tested had an enhancing effect on PCA in rats. These immunoglobulins serially arranged...
Lindholm A, Johansson HE, Kjaersgaard P.LINDHOLM, A., H.-E. JOHANSSON & P. KJÆRSGAARD: Acute rhabdomyolysis (“tying-up”) in standardbred horses. A morphological and biochemical study. Acta vet. scand. 1974, 15, 325–339. — Morphological, biochemical and histochemical changes were studied in muscle needle biopsy specimens (gluteus medius) from 59 standardbred trotters with acute clinical symptoms of the “tying-up” disease. All horses had increased levels of serum enzymes SGOT and SCPK. The biopsy specimens were taken at various intervals after onset of clinical symptoms (1–4 hrs., 18–24 hrs. and 2–20 days). Ry light...
King LS.The behavior of a fixed strain of Eastern equine encephalomyelitis virus was studied in guinea pigs after intraocular inoculation. Such inoculation concerns the central and not the peripheral nervous system. The susceptibility to intraocular injection lies midway between the highly virulent intracerebral and the quite avirulent peripheral routes. The virus must act for 10 to 13 hours in order to induce a fatal infection. Removal of the inoculated eyeball before this interval almost always prevents fatality although it may allow immunity to develop. The virus, at suitable intervals after inject...
Bozzola C, Sala G, Stancari G, Ferrucci F, Zucca E.Exercise-Induced Pulmonary Hemorrhage (EIPH) results from alveolar capillary stress failure after strenuous exercise, leading to bleeding and pulmonary inflammation. Bronchoalveolar lavage fluid (BALF) cytology is considered the gold standard for the assessment of airway inflammation; however, it is often considered more invasive compared to tracheal wash (TW). It has been demonstrated that TW is a reliable diagnostic tool that may substitute BALF to diagnose and grade the severity of EIPH in racehorses; however, no information about airway inflammation in EIPH-affected horses has been reporte...
Chaimbeul SF, Rodrigues NNP, Thurston DD, Scoggin KE, Janes J, Jacobs CA, MacLeod JN, Stone AV, Menarim BC.Synovitis resolution is critical for joint homeostasis and prevents the progression of osteoarthritis (OA). Treatments like NSAIDs and intra-articular corticosteroids relieve symptoms by blocking pro-inflammatory mediators, but also impair the production of pro-resolving mediators, contributing to the likelihood of chronic synovitis. PPARγ signaling is an essential mechanism of synovitis resolution, which is decreased in OA tissues. To evaluate the potential of PPARγ agonists to promote pro-resolving pathways, equine macrophages cultured in autologous, normal, or inflamed synovial fluid ( = ...
Duderstadt S, Distl O.Dülmen wild horses are kept in a fenced wooden and marsh area around Dülmen in Westphalia, Germany, since 1856. Previous analyses supported early genetic divergence from other domesticated horse populations and the Przewalski horse. Therefore, the objective of this study was to evaluate genetic diversity using high-density genomic data. Methods: We collected 337 one-year-old male Dülmen wild horses, captured at 12 annual auctions, for genotyping on the Illumina GGP Equine Plus Beadchip. All analyses were performed for 63,123 autosomal SNPs. Results: On average, each horse had 27.96 ROH with...
Edwards VL, Reed R, Perlini M, Moorman VJ.To determine the analgesic effects of detomidine and morphine administered by cervical epidural catheter (CEC) on a model of thoracic limb pain. Methods: Prospective, randomized, blinded crossover study. Methods: Five adult horses. Methods: Cervical epidural catheters were placed under ultrasound guidance, followed by induction of lipopolysaccharide (LPS)-mediated carpal synovitis. Horses received either saline or detomidine/morphine (DM; 10 μg/kg, 0.1 mg/kg, respectively) via CEC 4 h after synovitis. After a 7 day washout, synovitis was induced in the contralateral carpus, and the alternate ...
Pınar O, Çelik Doğan C, Aktaran Bala D, Kumaş C, Mete A.Riding clubs face significant financial losses due to upper respiratory infections caused by Beta-hemolytic (β-hemolytic) streptococci, leading to strangles and related diseases that negatively impact the health and performance of horses. Our objective was to determine the relationship between these inflammatory cells, the presence of β-hemolytic streptococcal species, and the clinical symptoms exhibited by the horses. This study investigated the presence of β-hemolytic streptococcus in 133 tracheal lavage samples from horses exhibiting various clinical respiratory symptoms and quantified t...
Friend MM, McGaffigan EM, Hall SM, Staniar WB, Smarsh DN.Early detection of inflammation using a common test could be a valuable tool for preserving horse health. Objective: This observational study aimed to identify variation in complete blood count (CBC) parameters and inflammatory indices with inflammation, and to develop reference intervals (RIs) from horses with known inflammatory states, hypothesizing that RIs developed from horses with normal acute phase protein concentrations would improve the ability to predict inflammation. Methods: Concentrations of serum amyloid A (SAA) and haptoglobin from clinically healthy horses and horses under vete...
Salinas-Varas C, Espinosa G, Muñoz-Caro T, Conejeros I, Gärtner U, Fey K, Arnhold S, Taubert A, Hermosilla C.Neutrophil extracellular trap (NET) are thin and long web-like structures composed of DNA and antimicrobial proteins released by activated polymorphonuclear neutrophils (PMN) as part of the innate immune response. Adipose-derived stem cells (ADSCs) represent an accessible, abundant and minimal invasive source of mesenchymal stem cells (MSCs), with high regenerative potential, immunomodulatory and anti-inflammatory properties. Although recognized immunomodulatory properties of ADSCs, their interaction with PMN and their role on NET formation remains poorly characterized. The present study aimed...
Saberinia A, Ozmaei S, Anoushepour A.Conjunctivitis is an inflammation of the conjunctiva caused by infectious or non-infectious factors. Infectious conjunctivitis comes in two forms: viral and bacterial. Bacterial conjunctivitis is commonly caused by organisms such as Staphylococcus and Streptococcus, with the severity of the disease influenced by the specific bacterial species involved. Because both viral and bacterial conjunctivitis are highly contagious, preventive measures are essential to reduce transmission-especially to the unaffected eye. Objective: To evaluate the tear film osmolality in horses with bacterial conjunctiv...
Mitlyng N, Hobbs KJ, Cooper BL, Sheats MK.Lipopolysaccharide (LPS) is frequently used in equine research to model clinical endotoxemia; however, there is no standardized protocol for inducing cytokine production in equine whole blood. To address this knowledge gap, the goal of this study was to compare the cytokine responses elicited by three different LPS stimulation protocols. Whole blood was collected from six healthy horses (aged 5-30 years; mixed breeds and genders) from the North Carolina State University teaching herd (IACUC #23-412). Sixty milliliters of heparinized blood were aseptically drawn and divided into 15 mL aliquots....
Cooper BL, Hobbs KJ, Bayless R, Stinson-Miller A, Gruber E, Hepworth-Warren K, Lavoie JP, Sheats MK.Severe equine asthma (sEA) is characterized by increased lower airway neutrophils that contribute to dysregulated inflammation through the release of cytokines, reactive oxygen species and neutrophil extracellular traps (NETs). NETs are composed of cell-free DNA (cfDNA) intercalated with enzymatic proteins and are known to be increased in the lower airway of asthmatic horses. The objectives of this study were two-fold: 1. Determine if cfDNA can be accurately measured in equine bronchoalveolar lavage fluid (BALF) and tracheal wash (TW) with a Qubit 4 fluorometer. 2. Determine whether Qubit-meas...
Meeremans M, Devriendt B, Bairiot S, Van Poucke M, Peelman L, Demeyere K, Meyer E, Van Vlierberghe S, De Schauwer C.Macrophages play key roles in tissue homeostasis and regeneration-associated inflammation. Unlike humans, a reliable protocol to obtain and polarise equine monocyte-derived macrophages is lacking. In this study the polarisation of equine macrophages, derived from CD172a peripheral blood monocytes is described. After differentiation, IFN-γ/LPS or IL-4 were used to induce pro- and anti-inflammatory phenotypes, respectively. Evaluation criteria included morphology, mRNA (RT-qPCR) and protein expression (flow cytometry, immunofluorescence), nitric oxide and arginase production, cytokine secretion...
Zamith Cunha R, Gobbo F, Morini M, Salamanca G, Zanoni A, Bernardini C, Gramenzi A, Chiocchetti R.Evidence suggests that the endocannabinoid system (ECS) is crucial for regulating inflammation, cell proliferation and pain. The ECS is composed of cannabinoid receptors such as type 1 (CBR1), type 2 (CBR2) and GPR55, endocannabinoids and enzymes. Proteins of ECS have previously been localized in the epidermal cells of the horse hooves. Given the physio-pathological role and cellular distribution of the ECS across species, the authors hypothesized that cannabinoid receptors are expressed within the inflammatory cells, fibroblasts and endothelial cells of the equine hoof laminae, going beyond t...
Friedlund AM, Bracamonte JL, Koziy RV, Epp T, Thomas KL.To evaluate if high-volume lavage results in a negative bacterial culture of egress fluid, regardless of pathogen in an experimental model of equine septic arthritis. Methods: Experimental study. Methods: A total of 11 horses in three groups (lipopolysaccharide [LPS] Group 1, n = 4; Escherichia coli [E. coli] Group 2, n = 4; Staphylococcus aureus [S. aureus] Group 3, n = 3). Methods: A middle carpal joint of each horse was injected with LPS (synovitis Group 1), E. coli (septic arthritis Group 2) or S. aureus (septic arthritis Group 3). Arthroscopic lavage of the middle carpal joint...
Deniz Ö, Erol HS, van den Hoven R, Onmaz AC, Aragona F, Fazio F.Weaning represents a major developmental milestone for foals, especially when 4- to 7-month-old foals are abruptly separated from their dams. Studies have shown that the post-weaning period is associated with physiological and psychological stress, which may affect immune function. The present study aimed to describe and analyze the pattern of blood inflammatory biomarkers related to the innate immune system. A gradual foal-dam separation procedure was chosen, which included post-weaning social buffering by a familiar adult horse. Twelve Thoroughbred foals (six fillies, six colts) aged 4-6 mon...
Underberg BA, Van der Vekens E, Drews B, Kaessmeyer S.Equine laminitis is a complex and potentially fatal disease characterized by severe vascular and inflammatory alterations within the equine foot. This study aimed to develop immunohistochemistry (IHC) protocols for the detection of cyclooxygenase-2 (COX-2) and von Willebrand factor (vWF) in equine feet with and without laminitis, post-mortem perfused with paraffin oil. Unassigned: A total of 12 equine forelimbs from 8 horses were utilized in this study, divided into two study cohorts: one with laminitis and the other as a non-laminitis control. To develop the IHC protocols thoroughly, the tiss...
Rodrigues MF, Neves AP, Ferreira R, Pessoa GA, Araujo DN, de Souza GV.Melatonin has demonstrated beneficial effects in regulating inflammatory processes in various tissues, but its role in mare uterine physiology remains unclear. Objective: To investigate the effects of melatonin on the gene expression of cytokines (IL-1β, IL-6, IL-8, IL-10, and TNF-α) in equine uterine explants cultured for 6, 12, or 24 hours. Methods: The study was divided into two experiments. Part 1 aimed to evaluate the cytotoxicity of melatonin at concentrations of 0, 0.5, 1, 2, 4, and 8 mM on endometrial cells. Part 2 aimed to determine the expression of inflammatory cytokines in uterin...
Mojsym W, Kowalik S, Chałabis-Mazurek A, Janczarek I, Kędzierski W.Some correlations between serum Cu, Zn and Se and cytokines have been reported in humans. Especially, the Cu:Zn ratio corresponded with inflammation. To date, relationships between microelements and proinflammatory proteins are poorly understood in horses. The aim of the study was to evaluate whether Cu, Zn and Se may influence turnover of IL-6, IL-8 and tissue factor (TF) in breeding and working horses. Blood samples obtained from 66 horses were analysed. There were 37 pregnant broodmares of different breeds, 13 barren broodmares and 16 race Thoroughbred horses. Serum Cu, Zn and Se concentrat...
Wei L, Wei J, Liu X, Chen W, Wang C, Khan MZ, Zhang Z.Donkeys () remain nutritionally understudied despite their critical roles in agriculture across developing regions, with current feeding practices inappropriately extrapolating horse standards without accounting for species-specific digestive physiology. No comprehensive synthesis has integrated how dietary modifications systematically alter gut microbial communities to drive measurable health outcomes in donkeys, preventing development of evidence-based feeding strategies. This review critically synthesizes current evidence on donkey nutritional requirements and gut microbiota dynamics to est...
Del Prete C, Gaspari G, Kosior MA, Merlo B, Iacono E, Longobardi C, Martino NA, Dell'Aquila ME, Damiano S, Cocchia N, Gasparrini B, Lange-Consiglio A.Over the years, regenerative therapies have emerged as promising alternatives for persistent breeding-induced endometritis. In vitro studies testing the effects of these therapies on equine endometrial cells are still scarce. This study aimed to evaluate in vitro the effect of Wharton's jelly (WJ) mesenchymal stromal/stem cell (MSCs)-derived conditioned medium (WJ-CM) and platelet-rich plasma (PRP) on equine endometrial cells, with or without lipopolysaccharide (LPS)-induced inflammation. The WJ-CM was obtained after 24 h of starvation in Ringer's lactate of WJ-MSCs and PRP was prepared using...
Birckhead EM, Raidal SL, Das S, Raidal SR.Sepsis is a main cause of death in neonatal foals. While the syndrome is not completely understood, sepsis is a dysregulated inflammatory response of the host to infection. It can be difficult to diagnose because of varying and non-specific clinical signs and imperfect diagnostic tests. Increased circulating nucleosome levels have been detected in humans and animals with sepsis, but this has not been documented in foals. Nucleosomes are released extracellularly during neutrophil extracellular trap formation, as well as from damaged and dead cells. We analysed plasma samples from clinically hea...
Peralta AG, Raeisimakiani P, Hayashi K, Mahal LK, Reesink HL.Post-traumatic osteoarthritis (PTOA) is a common sequela to joint injury in both humans and companion animal species such as horses and dogs. Despite the increasing prevalence of osteoarthritis (OA) in humans, investigation of glycosylation changes associated with OA remains in its infancy. Recent advances, such as lectin microarray analysis, now enable detailed glycan profiling in complex biofluids such as synovial fluid. Using lectin microarray technology, this study characterized glycosylation patterns in synovial fluid samples from healthy and OA-affected joints in horses, dogs, and humans...
Domańska D, Witkowska-Piłaszewicz O, Trela M, Pawłowski K, Pawliński B, Domino M.Mastitis is an emerging health concern in lactating mares, particularly given the growing commercial interest in mare's milk. This study evaluated the diagnostic potential of acute phase proteins (APPs), specifically serum amyloid A (SAA), milk amyloid A (MAA), and haptoglobin (Hp), measured in blood and milk as indicators of clinical and subclinical mastitis. Twenty-four Thoroughbred mares were prospectively monitored during lactation and weaning. Plasma and milk samples were collected and analyzed using commercial ELISA kits. Plasma SAA concentrations were significantly higher in mares with ...
Sugimoto K, Nakamura J, Deng D, Hirano E.Indoxyl sulfate (IS) is a dietary metabolite of tryptophan that is produced in the liver. It is a uremic toxin that facilitates the progression of chronic kidney disease (CKD). We previously observed that equine placental extract (ePE) inhibited IS synthesis in an inhibition assay using the liver S9 fraction. Unassigned: This study was designed to investigate the effects of ePE on adenine-induced renal failure in mice at the histological and molecular levels to understand the mechanism of action of ePE. Unassigned: We assessed this effect through biochemical and histological analyses using a...
Baumgarten CM, Delph Miller KM, Davis EG, Beard LA, Blevins CA, Wottowa M, Hill M, Larson RL.To measure the effect of routine vaccination on serum amyloid A (SAA) concentration in apparently healthy horses. We hypothesized that routine vaccination would increase SAA in healthy horses. Methods: 21 apparently healthy client-owned horses and 15 Kansas State University College of Veterinary Medicine-owned horses. Methods: In experiment 1 (n = 8 horses), a blinded, randomized, prospective, crossover study was performed. Horses were either vaccinated (rabies, tetanus, West Nile, Eastern and Western equine encephalomyelitis, equine herpesvirus-1/-4, influenza) or administered saline, and SAA...
Nowicka B, Torres A, Polkowska I, Jackow-Nowicka J, Przewozny M, Jackow-Malinowska J.Chronic tendon and ligament diseases are commonly encountered in both athletic humans and animals, especially horses. Distal limb diseases, including suspensory ligament (SL) pathology due to anatomical, histological, and biomechanical properties, can be considered a model for tendon and ligament pathologies in humans. The appropriate selection of therapy is often crucial in optimising the healing process. One decisive factor influencing the possibility of returning to pre-disease training levels appears to be the utilisation of physical activity, including controlled movement, during the reha...
