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Topic:Microbiology
Microbiology and horses explores the interactions between microorganisms and equine hosts, focusing on the role of bacteria, viruses, fungi, and other microbes in horse health and disease. This field examines the microbial flora present in various equine environments, including the gastrointestinal tract, skin, and respiratory system, and investigates how these microorganisms influence equine physiology and pathology. Research in this area includes studies on microbial infections that affect horses, the development of antimicrobial resistance, and the impact of probiotics and prebiotics on equine health. This page compiles peer-reviewed research studies and scholarly articles that investigate the diversity, dynamics, and implications of microbial communities in horses, as well as the strategies for managing microbial-related diseases.
Harnessing the Horse for Human Osteoarthritis: microRNA-181a-5p Antisense Oligonucleotides in Clinically Normal Equine Fetlock Joints Are Safe and Well Tolerated. Horses serve as a translational model for human osteoarthritis (OA) due to their comparable joint size, cartilage thickness, and incidence of naturally occurring disease. Overexpression of microRNA-181a-5p has been implicated in cartilage degradation in OA, and its inhibition using locked nucleic acid antisense oligonucleotides (LNA-miR-181a-5p ASOs) represents a potential therapeutic strategy. This study evaluated the safety of intraarticular (IA) LNA-miR-181a-5p ASO injection in clinically normal horse fetlock joints. Twelve horses were randomized to receive two IA injections, 28 days apart,...
In vitro anthelmintic activity of the monoterpene linalool, alone and combined with the nematophagous fungus Duddingtonia flagrans, in the control of gastrointestinal nematodes in horses. This study evaluated, in vitro, the anthelmintic activity of the monoterpene linalool, alone and in association with the fungus Duddingtonia flagrans, against gastrointestinal nematodes of horses. Nematodes from the superfamily Strongyloidea, obtained from naturally infected horses, were used. The ovicidal activity of linalool was evaluated using the Egg Hatch Test (EHT). The larvicidal activity was evaluated using the Larval Motility Inhibition Test (LMIT), in which infective larvae (L3) were assigned to experimental groups treated with linalool alone (0.15, 0.3, 0.6, 1.25, 2.5, 5, 10, 20, 40...
Fluorescent tagging for assessment of environmental cleaning in an equine hospital. Healthcare-associated infections increase morbidity, mortality, and treatment costs in both human and veterinary medicine, and environmental contamination can contribute to their occurrence. Monitoring of environmental cleaning is an important component of multimodal infection control strategies. Fluorescent tagging is a low-cost, practical approach that correlates with reduced environmental contamination in human and small animal hospitals. Its applicability in equine hospitals, where surface characteristics and contamination risks differ, has not yet been evaluated. Objective: To evaluate fl...
Quantitative assessment of specific bacterial taxa of the intestinal microbiota of healthy and diarrheic horses. Alterations in intestinal microbiota composition, as determined by DNA sequencing, are reported in horses with acute colitis compared with healthy horses. Objective: Changes in specific bacterial populations can detect overall intestinal disruption of the normal intestinal microbiota. Identify bacterial taxa that indicate intestinal dysbiosis or health in horses using quantitative PCR (qPCR). Methods: Thirty horses with undifferentiated colitis, 13 with colitis associated with Salmonella spp., 14 with antibiotic-associated diarrhea (AAD), 52 healthy horses from Canada and 48 from the United St...
Platelet-rich plasma exhibits antibacterial and anti-inflammatory effects in an in vitro donkey endometritis model. Infectious endometritis, mainly caused by Escherichia coli (E. coli) and Streptococcus equi subsp. zooepidemicus (SEZ), significantly impairs donkey reproductive performance. Platelet-rich plasma (PRP) shows promise as an anti-inflammatory and antibiotic alternative. Objective: To evaluate PRP's antimicrobial efficacy against key pathogens and assess its anti-inflammatory and tissue repair properties in an in vitro endometrial model. Methods: Non-randomised in vitro and explant experiments. Methods: In in vitro antibacterial assays, the inhibitory effects of PRP on the growth of E. coli and SE...
Characterisation of microbial metabolite profiles across the gastrointestinal tract of horses fed on pasture, hay or oat-supplemented rations. Dietary composition substantially influences the intensity and site of microbial metabolite production in the gastrointestinal tract. These metabolites have numerous beneficial effects on equine health, but may also be involved in the development of gastrointestinal disorders. It remains unclear whether different feeding strategies, including starch supplementation, can alter microbial metabolite profiles along the gastrointestinal tract. This study aimed to compare the metabolite profiles of the microbial communities in the gastrointestinal tract of horses fed on pasture 24 h/day (PST; n =...
Case Report : Streptococcus equi subspecies zooepidemicus bacteriemia and spondylodiscitis following direct contact with a horse. Streptococcus equi subspecies zooepidemicus is a zoonotic pathogen that commonly colonizes the respiratory tract and oral cavity of horses. Human infections are rare and most frequently present as bacteremia, meningitis, or pneumonia. Methods: We report the case of an 88-year-old patient who developed Streptococcus equi subspecies zooepidemicus spondylodiscitis after direct and exclusive contact with a live horse. Clinical, microbiological, and radiological findings were reviewed. Results: Blood cultures identified Streptococcus equi subspecies zooepidemicus. Magnetic resonance imaging confirm...
Bacterial isolates and antimicrobial susceptibility patterns in tracheal wash samples from horses with equine asthma in Poland. Equine asthma (EA) is a chronic inflammatory lower-airway disease. Bacterial growth from tracheal wash (TW) may occur in samples from horses with EA, but may represent colonisation rather than active infection. This study described cultivable bacterial isolates recovered from TW samples from horses with EA in Poland and assessed their antimicrobial susceptibility patterns and association with month/season of sampling and airway neutrophil percentage. Unassigned: In total, 165 adult horses diagnosed with EA according to American College of Veterinary Internal Medicine-based criteria underwent e...
Application of digital pathology to assess the effect of hormone treatment on placental histomorphometry in mares with induced ascending placentitis. This study aimed to evaluate the effects of hormonal treatments with altrenogest (ALT) and estradiol cypionate (ECP) on placental histomorphometry in mares with experimentally induced ascending placentitis, using digital pathology as a quantitative tool. Thirty pregnancies from 27 Criollo-type mares were assigned to six groups: healthy controls (n = 5); basic treatment (n = 5), treated with trimethoprim-sulfamethoxazole (TSM), and flunixin meglumine (FM); ALT group (n = 5) + basic treatment; ECP group (n = 5) + basic treatment; ALT + ECP group (n = 5) in addition to basic treat...
Alterations in the gut resistomes of endangered wild equids associated with anthropogenic activities: Insights for One Health surveillance. Antibiotic resistance genes (ARGs) are emerging environmental contaminants, but how human-associated management practices are associated with mobile resistomes in endangered wildlife remains poorly resolved. Here, we used fecal metagenomics to compare Przewalski's horses, Mongolian khulans, and domestic horses from Xinjiang, China, including Przewalski's horses from a protected area and a captive-breeding setting under human management. Across 47 fecal metagenomes, we identified 380 ARG subtypes, 23 metal resistance gene (MRG) types, and 26 mobile genetic element (MGE) subtypes. Przewalski's h...
Multitechnique Physicochemical Characterization of Horse Hoof Trimmings as Sustainable and Untapped Keratin Source. In the keratin-rich biomass scenario, horse hoof trimmings play a marginal role due to the limited volume and the scarce background on material features, despite added values such as cruelty-free, localized and routine production and traceability. This work presents a multitechnique characterization of horse hooves, including physicochemical, structural, thermal, and compositional analysis, providing a solid background knowledge of material features, mandatory for upcycling strategy definition. FT-IR, Raman spectroscopy, X-ray powder diffraction, SEM-EDX, thermogravimetric analysis, and elemen...
Characterization of the Healthy Ocular Mycobiome of Purebred Lusitano Horses Using Oxford Nanopore Long-Read Sequencing. The ocular surface represents a unique microbial ecosystem continuously exposed to environmental microorganisms; however, the fungal component of the healthy equine ocular microbiome remains poorly characterized. This study aimed to characterize the ocular surface mycobiome of 12 clinically healthy Purebred Lusitano horses from three geographical regions in Portugal kept in two housing systems using Oxford Nanopore long-read sequencing and conventional fungal culture. Sequencing revealed a highly diverse fungal community with marked inter-individual variability. The most abundant genera were ,...
Limited evidence for exposure of horses in the United Kingdom to influenza D virus. Since it was first detected in 2011, antibodies to influenza D virus (IDV) have been found in several species, although cattle are the major host. In cattle, IDV is typically associated with mild respiratory signs, but it is clinically significant as a component of bovine respiratory disease complex. Although antibodies to IDV have been detected in equids, no association of IDV with naturally occurring respiratory disease in horses has yet been demonstrated. Objective: The aim of this study was to determine whether IDV may be a causal agent of equine respiratory disease in the UK. Methods: Nas...
Effects of steaming and storage on microbial quality and nutrient losses of hay. Steaming reduces microbial content of hay but the effect of steaming on nutrient quality and the effects of storage after steaming on microbial content are incompletely known. Objective: It was hypothesized that steamed hay can be stored for up to 24 h without an increase in microbial content and that steaming of hay favors the increase in measurable Maillard reaction products. Methods: Spoiled hay was steamed and then stored in hay nets, buckets or the hay steamer itself under summer and winter climate conditions. Microbial content was assessed by bacterial and fungal culture before and after...
Gut Microbiota as a Molecular Regulator of Mineral Homeostasis in Horses: Mechanisms and Future Perspectives. Mineral homeostasis in horses is traditionally attributed to the coordinated regulation of the intestine, kidneys, skeleton, and endocrine system. Emerging evidence suggests the gut microbiota also shapes this process by modifying the intestinal environment where mineral absorption occurs. Despite the growing interest in host-microbiota interactions, the mechanisms linking the equine gut microbiota to mineral metabolism remain poorly understood and have not been comprehensively synthesized. This review integrates current knowledge of equine gastrointestinal physiology, gut microbial ecology, a...
Exhaled breath condensate in horses: a first microbiological insight. Exhaled breath condensate (EBC) is a non-invasive method for obtaining samples reflecting the airway lining fluid; however, its microbiological composition remains poorly characterized. Objective: To perform an exploratory microbiological comparison of EBC in clinically healthy horses maintained under different environmental conditions. Methods: An observational study included 30 mares equally distributed into two groups: horses housed in stalls (Racetrack group) and horses maintained under pasture conditions (Farm group). EBC samples were collected using a validated device developed by the re...
Identification and phylogenetic analysis of Mannheimia haemolytica isolated from nasal samples of horses. The Mannheimia genus, which is part of the upper respiratory tract microbiota, harbours species that have the potential to cause progressive infections, such as haemorrhagic septicaemia and enzootic pneumonia, when the host immune system is suppressed. Among these species, Mannheimia haemolytica is considered the most pathogenic, and horses can be a host for this agent. This study aimed to investigate the occurrence of Mannheimia haemolytica in horses with and without respiratory clinical signs and to assess the potential pathogenic significance of isolates recovered from animals through serot...
Bacterial Pneumonia in Horses: Insights from a 10-Year European Single-Centre Retrospective Study. Bacterial pneumonia in horses typically occurs secondary to predisposing factors that compromise defence mechanisms. This 10-year retrospective study evaluated bacterial pneumonia in 81 horses treated at the equine clinic of Freie Universität Berlin from January 2015 to December 2024. Horses infected with primary pathogens such as or ssp. were not included in the study. The most common predisposing events were aspiration, mainly following oesophageal obstruction (37.0%), post-anaesthetic disease (27.2%), primary respiratory signs (24.7%), and other conditions (11.1%). Horses with aspiratio...
Multiple Probiotic Lactic Acid Bacteria with Marked Cholesterol-Lowering Effects Were Discovered in Equine Colostrum. Xinjiang ranks among the key domestication origins of horses. Local nomadic ethnic groups have a long-standing tradition of consuming equine dairy products, which endows mare-derived dairy matrices with abundant, distinctive and scarce probiotic resources. Equine colostrum is rich in immunoglobulins and growth factors; nevertheless, its pharmacological activities and micro-ecological composition remain poorly characterized. This study aimed to isolate and screen native strains with cholesterol-lowering potential from Xinjiang equine colostrum and conduct a preliminary investigation into their ...
Serum physiology, fecal microbiota, and metabolome signatures associated with perinatal stage transitions in Mongolian mares. Lactation is a critical reproductive trait that influences offspring survival and livestock productivity in equine production. Characterizing physiological transitions during the perinatal period can improve our understanding of how mares adapt to late gestation, parturition, and early lactation. However, in horses-a typical monogastric herbivore with unique digestive characteristics-the associations between gut microbiota and perinatal physiological adaptation, as well as related stage-associated microbial and metabolic features, remain largely uncharacterized. Unassigned: In this study, para...
Correction: Epidemiological study of strongyle infections in equines in Egypt: prevalence and risk factors. [This corrects the article DOI: 10.3389/fvets.2026.1901312.].
Development and Evaluation of an Indirect ELISA for Strangles Based on an Untagged EQ8-SclF Fusion Protein. Strangles, caused by subsp. (), is a highly contagious respiratory disease that causes substantial economic losses to the horse industry worldwide. Serological diagnosis currently relies mainly on the imported IDvet dual-antigen sandwich ELISA kit, which shows good diagnostic performance but is expensive and lacks a domestic alternative in China, thereby limiting its routine use in primary veterinary settings. The aim of this study was to develop a domestic indirect ELISA based on novel antigen targets and an untagged antigen purification strategy. Using comparative bioinformatics analyses, ...
Evidence-based interpretation of uterine cultures in mares: Linking bacterial growth patterns to endometrial inflammation. We evaluated uterine bacterial growth patterns and their association with endometrial inflammation (EI) in equine samples collected using uterine swabs (US) or low-volume uterine lavage (UL). A database including 1,545 US and 2,066 UL with cytological and bacteriological results was retrospectively analysed. Endometrial inflammation was defined as ≥2 polymorphonuclear cells per high-power field, and bacterial culture was considered positive when aerobic growth occurred within 48 h, with the number of bacterial isolates per sample recorded (0, 1, 2, or ≥3). Data were analysed using generali...
Effect of sample storage on pH-value in equine faeces. Measurements of pH-value in equine faeces are often performed in studies on nutrition and health in horses, but a standard protocol for it is lacking despite the knowledge that different sample handling may affect the pH-value. Sample handling prior to pH-measurement is often determined by practical settings and has been reported to vary in published studies within the area. The purpose of the current study was therefore to investigate the influence of different combinations of storage time and temperature on the pH-value in equine faecal samples in comparison to immediate pH-measurement at de...
Isolation of Moraxella spp. strains in horses. Two species of Moraxella were isolated from swabs obtained from two symptomatic horses suffering from conjunctivitis and rhinitis. The isolates were identified via MALDI-TOF as Moraxella osloensis and Moraxella equi respectively, with a good genus identification and a probable species identification score. The first one was also confirmed by BLAST sequence analysis with a high homology (99%). Antimicrobial susceptibility testing obtained by minimum inhibitory concentration method showed that the two isolates were sensitive to all the tested molecules. The therapeutic protocols applied had an e...
Microbiological, Molecular Diagnosis and Antimicrobial Resistance of Bordetella bronchiseptica in the Equine Reproductive Tract in Brazil. The genus Bordetella comprises 16 species of aerobic Gram-negative bacteria, with the most notable being B. pertussis, B. parapertussis and B. bronchiseptica. The latter stands out for its ability to infect various hosts, causing both respiratory and reproductive issues, such as endometritis and infertility in mares. These infections impair reproductive efficiency and facilitate the spread of the pathogen among susceptible animals. Objective: The present study aimed to report the isolation and molecular diagnosis of B. bronchiseptica associated with endometritis and infertility in mares in Bra...
Challenges for interpreting results of antimicrobial susceptibility testing for treating infections of foals with Rhodococcus equi. Rhodococcus equi is a facultative intracellular pathogen and a major cause of pneumonia in foals worldwide. The standard treatment for affected foals is a combination of a macrolide with rifampicin. The widespread use of this combination has led to the emergence of multidrug-resistant (MDR) strains of R. equi. Consequently, antimicrobial susceptibility testing is essential for guiding treatment of rhodococcal pneumonia. Unfortunately, clinical breakpoints for macrolides and other antimicrobials against R. equi for foals are lacking, thereby complicating clinical interpretation of in vitro resu...
Guttural pouch tympany or empyema in 38 ٍStraight Egyptian Arabian foals: clinical presentation, diagnostic features and outcome. As a breed, Straight Egyptian Arabian horses are susceptible to many disorders that mostly affect the head, such as guttural pouch (GP) tympany and empyema. This retrospective study evaluated the findings of clinical examination, ultrasonography, endoscopy, laboratory analyses and outcome of treatment of 38 Straight Egyptian Arabian foals with GP tympany and empyema. Methods: Data from medical records of foals diagnosed with GP tympany or empyema over a 2-year period (2024-2025) were reviewed. Foals with verified GP tympany or empyema who had complete medical records and had not previously rec...
From Diet to Disease: The Role of the Gut Microbiome and Microbial Metabolites in Horses. The equine gastrointestinal microbiome plays an essential role in digestion, energy metabolism, immune regulation, and maintenance of intestinal homeostasis. Increasing evidence suggests that microbial-derived metabolites provide a functional link between diet, the microbiome, and host physiology. This narrative review summarizes current knowledge on how dietary factors, including structural carbohydrates, non-structural carbohydrates, protein, and lipids, influence microbial function and metabolite production in horses. Relevant publications available up to June 2026 were identified through s...
Correlation between microbial communities, metabolites, and bioactivities in fermented mare’s milk revealed by metagenomics and metabolomics. Koumiss exhibits various functional properties, including antioxidant, hypoglycemic, and antihypertensive effects; however, natural fermentation is characterized by an uncontrollable microbial community structure, significant fluctuations in product quality, and a lack of specialized fermentation agents. The mechanisms underlying the links between microbial communities, functional metabolites, and bioactivity in natural and inoculated fermentation systems remain unclear. Therefore, this study employed bioactivity assays, metagenomics, and non-targeted metabolomics to systematically analyze dif...
