Pathogens are microorganisms, such as bacteria, viruses, fungi, and parasites, that can cause disease in horses. These microorganisms interact with the equine immune system, often leading to a range of health issues that can affect individual horses or entire populations. Pathogens can be transmitted through various routes, including direct contact, vectors, or environmental exposure. Common equine pathogens include Streptococcus equi, Equine Herpesvirus, and Strongylus vulgaris. Understanding the interactions between equine hosts and pathogens is essential for disease prevention, management, and treatment. This page compiles peer-reviewed research studies and scholarly articles that explore the identification, transmission, and impact of pathogens on equine health.
Haque RU.A technique for identifying and characterizing staphylococcal hemolysins by first separating them electrophoretically in barbital-buffered agar gel (pH 8.4) at 5 ma/cm for 2 hr and then determining their hemolytic activities by exposing them to human, horse, rabbit, and sheep erythrocytes is described. The alpha-hemolysin produced by a White variant of the Wood 46 strain of Staphylococcus aureus migrated 18 mm towards the cathode, and it lysed horse, rabbit, and sheep erythrocytes, whereas a Clear variant of the Wood 46 strain of S. aureus produced a lysin which migrated similarly to the alpha...
BOYD WL, BOYD JW.Boyd, William L. (Ohio State University, Columbus) and Josephine W. Boyd. Viability of coliform bacteria in antarctic soil. J. Bacteriol. 85:1121-1123. 1963.-The distribution of coliform bacteria in soils of Ross Island and the nearby mainland was studied. None was found in almost all of the samples collected, including some from the Adelie penguin rookeries at Cape Royds and Cape Crozier and in soil at the McMurdo Base which had been recently contaminated by human sewage. Samples of pony manure left from previous expeditions were also negative, with one exception where Escherichia coli were p...
REBERS PA, HURWITZ E, HEIDELBERGER M.Rebers, Paul A. (Rutgers University, New Brunswick, N. J.), Esther Hurwitz, and Michael Heidelberger. Immunochemistry of pneumococcal types II, V, and VI. II. Inhibition tests in the type VI precipitating system. J. Bacteriol. 82:920-926. 1961.-As in other immune systems involving polysaccharides, rabbit antibodies but not those engendered in the horse were found sensitive to degradation of type VI pneumococcal (Pn) polysaccharide (SVI), and were readily inhibited by fragments of SVI. Large amounts, 30 to 111 mumoles, of most sugars gave up to 15% inhibition, while sugar and polyol phosphates ...
HETRICK FM, YANCEY FS, HANSEN PA, BYRNE RJ. Four horses inoculated with EEE virus remained asymptomatic following injection but did develop measurable HI and neutralizing antibodies as a result of infection. HI antibodies were detectable earlier than neutralizing antibodies but the levels tended to drop more rapidly. 2. Of 14 horses and ponies having significant levels of neutralizing antibody, 5 to 9 had measurable HI antibody depending on number of units of antigen employed in the test. 3. Sera from 3 clinical cases of EEE were positive on the HI test while only one of these animals had a significant neutralizing antibody level.
Strompfová V, Štempelová L, Bujňáková D, Karahutová L, Gondoľová D, Nagyová M, Siegfried L.In order to develop non-antibiotic therapies to treat dermatological diseases it is urgent to spread knowledge on composition and properties of skin bacteria in healthy animals. Since horses are popular companions of humans, it is necessary to know what risk skin bacteria pose to humans. Therefore the aim of this work was to analyse species composition of staphylococci isolated from skin swabs of 50 healthy horses using MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight) spectrometry and to characterize their virulence properties. Swabs were collected from five body areas (n...
Ketphan W, Sato M, Tsujimura K, Mizutani T, Takemae H.Equine rhinitis B virus (ERBV), a member of the Picornaviridae family, is associated with mild to moderate respiratory illness in horses, yet its genomic diversity remains incompletely characterized. In this study, we performed metagenomic analysis on a rectal swab sample from a diarrheic foal confirmed to be positive for rotavirus A. Unexpectedly, we identified a highly divergent ERBV strain with a 9,448-nucleotide genome encoding a 2,721-amino-acid polyprotein. Sequence analysis revealed only 62.5-63.1% identity in the polyprotein and 47.1-49.8% in the VP1 region compared to known ERBV serot...
Gao W, Liu M, Nurdaly K, Caidan D, Sun Y, Duan J, Zhao J, Gong X, Zhou J, Zhang Y, Chen Q.Equine bacterial abortion presents substantial economic and One Health challenges; however, comprehensive epidemiological data from China are limited. This study sought to ascertain the overall prevalence of key pathogens-namely, spp., , , and spp.-in equine populations in northwestern China. In this study, we aimed to further elucidate the characteristics of co-infections, profile antimicrobial resistance genes, and identify associated risk factors. Conducted as a cross-sectional analysis across four provinces, we collected 508 blood samples and 24 abortion tissue samples from 15 farms. Pat...
Souza LL, Lima AS, Martins AS, Silva TA, Borsanelli AC, Dutra IS, Pupin RC, Gomes DC, Lemos RA.An outbreak of botulism occurred in March 2024 among horses at a Quarter Horse stud farm in Central-West Brazil. After ingesting baleage, 22 of 26 (85%) horses housed in stables and fed baleage became ill. The affected horses had dysphagia, muscular weakness, fasciculations, and progressive recumbency; 13 of 22 (59%) died within a few days. The diagnosis of type C botulism was established based on clinical and epidemiologic findings and confirmed by mouse bioassays, which indicated botulinum toxin type C in liver samples and intestinal contents. Furthermore, PCR testing identified toxigenic i...
Rinnovati R, Meistro F, Ralletti MV, D'Angelo P, Spadari A, Zingariello E, Pollera C, Stancampiano L.In horses, surgical site infections (SSIs) are multifactorial complications influenced by patient-related, procedural, and environmental factors. While perioperative contamination has been extensively studied in the operating theater, the anesthetic induction and recovery environment has received limited attention. The aim of this study was to characterize bacterial contamination within an equine anesthetic induction and recovery stall and to evaluate its spatial and temporal distribution. Environmental samples were collected from four predefined locations within the stall at three time points...
Veit M, Matczuk AK.Equine arteritis virus (EAV) is a positive-stranded RNA virus of the Arteriviridae family. Its GP5/M dimer, the principal component of the viral envelope, mediates virus budding and serves as a key target for neutralizing antibodies. Using AlphaFold3, we predicted the 3D structure of the EAV GP5/M dimer and compared it to its homolog in porcine reproductive and respiratory syndrome virus (PRRSV). Both complexes share a conserved architecture comprising a short ectodomain, three helical transmembrane regions, and a β-sheet-rich endodomain. EAV GP5 features a longer ectodomain with four α-heli...
Rudeekiatthamrong A, Nguyen GT, Kamyingkird K. infection (Surra) remains a major constraint to equine health and productivity in Thailand. The only available trypanocidal drug, diminazene aceturate (DA), has limited efficacy, poor blood-brain barrier penetration, and toxicity in horses. This study aimed to investigate the inhibitory effects of commonly used equine antibiotics, gentamicin (GMC), ceftiofur (CTF), and trimethoprim-sulfamethoxazole (TS), against (Thai strain isolated from dairy cattle number 953; TEDC 953) to identify potential therapeutic alternatives or adjuncts for equine trypanosomosis. Unassigned: An growth inhibition...
Li Z, Yu T, Ge L, Lv S, Fu Q, Shi H.Equine herpesvirus type 1 (EHV-1) is a major veterinary pathogen causing significant economic losses in the livestock industry. Despite its impact, effective vaccines and targeted antiviral strategies remain limited, largely due to an incomplete understanding of host factors regulating viral replication and pathogenesis. Unassigned: To systematically identify host genes essential for EHV-1 infection, we established a BHK-21 cell line stably expressing Cas9 and performed a genome-wide CRISPR/Cas9 knockout screen using a pooled lentiviral single-guide RNA library. Significantly enriched candidat...
Uprety T, Shaffer CL, Loynachan A, Janes J, Cassone L, Kennedy L, Bryant U, Ruby R, Swan M, Sponseller BT, Adam E, Lubbers B, Erol E.Salmonellosis is a highly contagious, zoonotic disease affecting both animal and human health. Early characterization of emerging Salmonella serotypes and associated antimicrobial resistance patterns are essential for outbreak controls in animals and humans. Between 2018 and 2025, 245 Salmonella enterica subsp. enterica were isolated from both ante-mortem and post-mortem equine cases. The predominant Salmonella serotypes were Typhimurium (83), Newport (28), 1,4,[5],12:i:- (26), Saintpaul (25), Hartford (15), and Mbandaka (12). S. Saintpaul, previously rare in horses, was detected in 21 cases i...
Qin S, Kulabieke T, Mizhamuhan D, Zhang M, Jin M, Abula G, Pi M, Wang H, Zhang Y, Guo Q.Equine theileriosis, caused by the protozoan parasite , represents a significant economic threat to the equine industry. In Xinjiang, China, an endemic area for this disease, systematic research on the genetic diversity of has been notably lacking. The aim of this study was to obtain molecular epidemiological data pertaining to the parasite in selected regions of Xinjiang, China, and analyze the genetic characteristics (including rRNA, , and genes) and genotype distribution patterns of isolates from these regions, providing a scientific basis for developing targeted prevention and control s...
Dorrego A, Olvera-Maneu S, Jose-Cunilleras E, Gago P, Raez A, Rivera B, Oporto A, Gonzalez S, Cruz-Lopez F.The forest fly ) is an obligate haematophagous dipteran insect (order Diptera) that primarily infests horses and may contribute to the circulation of vector-borne pathogens. This study aimed to investigate the presence of , s.l., , and , important vector-borne pathogens of equids, in forest flies collected from horses in endemic areas of Spain. A total of 170 forest flies were collected from 39 equids across four geographical regions in Spain (Segovia, Madrid, Toledo, and Menorca) and blood samples were collected from 27 of these horses. All flies were morphologically and molecularly identifi...
Konstantinović N, Gotić J, Baban M, Csik G, Listeš E, Gagović E, Jurković Žilić D, Arežina I, Šubara G, Čulina FE, Delić N, Višal D....Hemotropic mycoplasmas (hemoplasmas) are uncultivable, cell wall-less bacteria that parasitizeon the surface of red blood cells of mammals, potentially causing anemia and other systemic signs. While widely distributed among domestic and wild animals, their occurrence in equids remains poorly understood, and no species has been identified as host-specific to horses or donkeys. This study presents the first systematic survey of hemoplasmas in equids from southeastern Europe and only the second molecularly confirmed case in horses in Europe. A total of 843 equids (817 horses and 26 donkeys) from ...
Stolle LM, Oltmanns H, Meißner J, Heun F, Schieder AK, Wolff HT, Ohnesorge B, Busse C.To determine the in vitro antimicrobial activity of specific antiseptics against common equine ocular surface pathogens. Methods: Staphylococcus aureus (S. aureus) (n = 12), Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) (n = 9), Enterobacter hormaechei (E. hormaechei) (n = 6), and Bacillus cereus (B. cereus) (n = 5) were collected from corneal samples of horses with ulcerative keratitis. Reference strains were included. Minimum bactericidal concentrations (MBC) of polyhexanide, povidone-iodine, and hypochlorous acid were tested using the microdilution method. ...
Petry S, Tapprest J, Maillard K, Barbut F, Duquesne F, Kozak S, Foucher N, Bernez-Romand M, Bridoux L, Poquet I. an anaerobic, spore-forming enteropathogen, is less studied in animals than in humans despite its importance in One Health. We evaluated occurrence, diversity, circulation, and virulence in French Equidae ( = 100) after their necropsy in northwestern France, from 2019 to 2021. We systematically recovered all cecal contents and any watery intestinal contents. We isolated strains, determined their toxin gene profile by PCR, and established their PCR-ribotype according to the WEBRIBO database. We also performed free toxin detection. Twenty-seven Equidae were positive for and 20 had a toxigeni...
Hoerdemann M, Sahoo DK, Allbaugh RA, Kubai MA.To assess if an inexpensive, commercially available ultraviolet C (UV-C) light device with a peak emission of 275 nm can inhibit equine keratomycosis-associated pathogens located at different corneal depths in an ex vivo model. Methods: A controlled, randomized experimental design. Aspergillus fumigatus and Fusarium solani isolates were inoculated in fresh bovine corneoscleral transplants, superficially or at 450 μm of stromal depth for the ulcerative keratomycosis or stromal abscess model, respectively. After a minimum of 18 h of incubation, treatment groups received 15 s of UV-C li...
Barber C, McGlennon A, Whitlock F, Grewar J, Spalding S, Newton R, Dewé T.Charlotte Barber, Abigail McGlennon, Fleur Whitlock, John Grewar, Sophie Spalding, Richard Newton and Tamsin Dewé introduce a new government-funded initiative to strengthen the surveillance of antimicrobial resistance in the equine sector.
Machado RZ, André MR, Pereira JG, Oliveira MDSC, Ribeiro LSDS, Toledo CZP, Gonçalves LR.Equine Piroplasmosis (EP) is a tick-borne disease caused by the protozoan parasites Babesia caballi, Theileria equi, and Theileria haneyi, characterized by intravascular hemolysis and associated systemic illness. Although T. equi and B. caballi have been widely reported in some regions of Brazil, data from other states are limited. Additionally, despite reports of T. equi genotype C, currently recognized as T. haneyi, has been identified in Brazil, there are no investigations using T. haneyi-specific molecular tools. This study assessed the presence of these three agents in horses from Baixada...
Roy CN, Wiechmann CE, Dev A, Walther BK, Musser JM, Olsen RJ, Beres SB, Axell-House DB. subsp. (SESZ) are zoonotic group C streptococci primarily acquired from contact with horses and other animals, such as llamas. They are unusual causes of infection in humans and rarely cause infective endocarditis. Unassigned: A 58-year-old woman presented with fever, malaise, and polyarthritis. Clinical evaluation diagnosed native tricuspid valve SESZ endocarditis. The SESZ isolate was genetically closely related to a clone causing an outbreak of post-streptococcal glomerulonephritis linked to the consumption of unpasteurized cheese in Brazil. The patient had no exposure to unpasteurized ch...
Beshir A, Kemal J, Abraha B, Tola EH.Wounds on the skin are a common health issue affecting working equines. This study aimed to evaluate the in-vitro antibacterial properties of crude methanolic extracts from selected medicinal plants against pathogens isolated from equine skin wounds in Merti district. Agar well and disc diffusion tests were used to determine the mean zone of inhibition, while broth dilution methods were used to determine the minimum inhibitory concentrations and minimum bactericidal concentrations (MBCs), further confirming the potent antibacterial effects of the selected medicinal plant extracts. One way anal...
Godoi APDS, Sobral GG, da Silva Vieira JC, Carneiro GF, Conceição FR, da Silva ER, Mendonça M.Equine rhodococcosis is caused by Rhodococcus equi, an intracellular coccobacillus whose main virulence factor is a plasmid that harbors genes encoding proteins from the Vap family, with the vapA gene being the most important in equine isolates. Furthermore, other factors observed in R. equi strains, such as antimicrobial resistance and biofilm production, may represent significant challenges in the treatment of affected animals. The objective of this study was to characterize four isolates of R. equi from foals in the state of Pernambuco, Brazil. All isolates were identified as R. equi throug...
Pettersson J, Levanov L, Tervo S, Hautala K, Aaltonen K, Utriainen M, Kareinen L, Gadd T, Sironen T, Vapalahti O, Kinnunen PM.Parapoxviruses (PPV) cause skin and mucous membrane signs to several animal species and humans worldwide. Equine parapoxvirus (EqPPV) was first detected in a sick horse in Finland in 2013. It is potentially zoonotic, and a similar virus has been detected in humans in the USA. In winter 2021–2022, EqPPV caused a large-scale pastern dermatitis epidemic in racehorses all over Finland. Field reports suggest that similar epidemics of unverified cause have also occurred in 2015 and 2019. The aim of this study was to develop a serological test and study the immune response, seroprevalence, and hist...
Liu J, Huang X, Wang Y, Wang Y, Luo R, Lu X, Cao K, Xing J, Tu Y, Zheng W.Antibiotic resistance genes (ARGs) are emerging contaminants threatening public health, yet their transmission risk via mare milk products remains understudied. Using metagenomics, we analyzed lactic acid bacteria (LAB)-inoculated fermented, naturally fermented, raw, and pasteurized mare milk to investigate the effect of LAB inoculation on the distribution and transmission pathways of ARGs in mare milk. The results showed that naturally fermented, raw, and pasteurized mare milk had the highest number of pathogens, relative abundance of ARGs, and relative abundance of mobile genetic elements (M...
He L, Khine NO, Song J, Loubière C, Butaye P.Strangles, caused by the host-adapted subsp. (. ), imposes significant welfare and economic losses on the equine industry worldwide. Understanding its genomic features, virulence-associated genes (VAGs), antimicrobial resistance (AMR) and mobile genetic elements (MGEs) is essential for disease control and vaccine development. This study aimed to characterize the accessory genome composition, geographic distribution of VAGs and MGEs, and AMR profiles of . by a large-scale genomic analysis of global publicly available . sequences. All publicly available . sequences in the Sequence Read Arch...
Narouei M, Rahimi H, Kafshdouzan K.Infections caused by and , as zoonotic diseases, pose a serious threat to the health of humans and animals. To date, there is limited information regarding these diseases in horses. This study aimed to evaluate the prevalence of and in the serum of racehorses in Iran (Golestan province). 350 blood samples were collected from racehorses in four regions of Golestan province, and demographic data (sex, age, and sampling location) were recorded. The collected serum samples were examined by PCR to identify the genomes of and . The results showed that 3.4 % (P < 0.05, 95 % CI: 1.97 % - 5.9 %) of...
Harel B, Sévin C, Le Hello S, Moreau P, Giard JC, Petry S, Gravey F.Enterobacteriaceae are opportunistic pathogens responsible for local or systemic infections in both human and veterinary medicine. To monitor circulating strains in stud farms in Normandy (France), we investigated a collection of Enterobacteriaceae isolated from necropsied equids performed in the region between 1997 and 2020. These strains were initially identified using MALDI-TOF; however, as this method failed to identify some isolates, whole genome sequencing followed by rMLST analysis was subsequently performed. Different genera were identified: Enterobacter spp., Huaxiibacter spp., Lellio...
Mota RA, Silito IS, Martins MP, Oliveira PRF, Melo RPB, Vieira da Silva V, Jorge FR, Martins TF, Labruna MB.Tick-borne diseases are among the most widespread vector-borne infections, including zoonoses caused by bacterial and protozoal microorganisms. This study consisted of a serosurvey for Rickettsia spp. in 270 horses from 11 farms in the coastal region of Pernambuco, Brazil. Through the indirect immunofluorescence assay (IFA) based on antigens of five Rickettsia species, 164 (60.7%) horses were seroreactive to Rickettsia spp., with seroreactivity among farms ranging from 10 to 100%. Through molecular analysis, all 270 horse blood DNA samples tested negative by PCR assays targeting Anaplasmatacea...
Werle J, Nunes GT, Machado CS, Silva CBD, Vogel FSF, Vargas APC, Cargnelutti JF.The genus Corynebacterium encompasses versatile bacteria that act as natural microbiota or pathogens, causing infections in humans and animals, including equine reproductive disorders. Corynebacterium uterequi (C. uterequi) is a potential pathogen in mares, associated with reproductive disorders including endometritis, embryonic loss, and infertility, raising concerns for equine reproductive health. This study aimed to characterize C. uterequi isolates from mares in southern Brazil and deepen the understanding of this species. Phenotypic, molecular, and phylogenetic analyses were performed on ...
Snedden K, Frye E, Conklin R, Aprea M, Rishniw M, Lejeune M, Goodrich E.To analyze the results and metadata of canine, feline, and equine respiratory PCR panel assays performed at the New York State Animal Health Diagnostic Center and inform veterinary diagnostic sample submission. Unassigned: This retrospective study reviewed laboratory data from routine sample submissions to the Animal Health Diagnostic Center for canine, feline, and equine respiratory PCR panels from January 1 through December 31, 2023. Associations were compared between variables using χ2 tests of independence or Fisher exact tests. Unassigned: A total of 1,902 canine, feline, and equine resp...
Nakajima K, Kasuya K, Senba H, Tagami K, Kinoshita Y, Niwa H.Strangles is a globally widespread, commonly diagnosed and important infectious disease of equids caused by Streptococcus equi subsp. equi. We performed whole genome sequencing of 19 S. equi isolates collected from imported horses at the Japanese border. Of these isolates, 15 isolates were obtained from clinical cases and 4 were from subclinical cases. The 19 isolates were grouped into 3 Bayesian analysis of population structure (BAPS) groups by the core genome single nucleotide polymorphism analysis corresponding to exporting country, SeM typing, or exporter of the horses. The 19 isolates pos...
Hu B, Gao S, Zhang H, Li Q, Li G, Zhang S, Xing Y, Huang Y, Han S, Tian Y, Zhang W, He H.Rhodococcus equi (R. equi) is a Gram-positive zoonotic pathogen that frequently leads to illness and death in young horses (foals). This study presents the complete genome sequence of R. equi strain BJ13, which was isolated from a thoroughbred racehorse breeding farm in Beijing, China. Results: The BJ13 genome has a length of 5.30 Mb and consists of a complete chromosome and a plasmid measuring 5.22 Mb and 0.08 Mb, respectively. We predicted 4,929 coding gene open reading frames, along with 52 tRNAs and 12 rRNAs. Through analysis of mobile genetic elements, we identified 6 gene islands and ...
