Aspergillus fumigatus antigen-reactive Th17 cells are enriched in bronchoalveolar lavage fluid in severe equine asthma.

Introduction: Equine asthma (EA) is a common disease of adult horses with chronic respiratory pathology and common neutrophilic airway inflammation. It presents with hyperreactivity to hay dust components such as molds, and underlying dysregulated T cell responses have been suggested. Thus far, T cells have been analysed in EA with conflicting results and the antigen reactivity of T cells has not been demonstrated. Serological and epidemiological data point to the relevance of Aspergillus fumigatus as an antigen source in EA. Here, we aimed to identify and characterise Aspergillus antigen-reactive T cells in EA. Methods: Cryopreserved bronchoalveolar lavage cells (BALC) and peripheral blood mononuclear cells (PBMC) from healthy horses (HE, n=9) and those with mild-moderate (MEA, n=3) or severe asthma (SEA, n=8) were stimulated in vitro with the recombinant A. fumigatus antigens Asp f 1, or Asp f 7 combined with Asp f 8, to assess antigen reactivity, and with phorbol-12-myristat-13-acetate and ionomycin (P/i) to assess overall T cell reactivity. Stimulated cells were analysed by flow cytometry for CD4, CD8, IL-17, IL-4, and IFN-γ. Cytokine expression in all lymphocytes, and in CD4+ or CD8+ T cells, was quantified and compared between the groups. In BAL fluid (BALF), soluble cytokines and chemokines were quantified by bead-based assays. Results: Antigen restimulation of BALC with Asp f 1 or Asp f 7/8 provoked higher frequencies of IL-17+ lymphocytes, CD4+IL-17+ Th17 cells, and CD4+IL-4+ Th2 cells in SEA than in HE, whereas MEA and HE were similar. Antigen stimulation of PBMC did not result in group differences. P/i stimulation of BALC resulted in increased IL-17+ lymphocyte and CD4+IL-17+ Th17 cell frequencies in MEA compared with HE but the limited number of horses with MEA must be considered. P/i-stimulated PBMC from MEA or SEA contained more IL-17+ lymphocytes compared with HE. Cytokines were hardly detected in BALF and similar between the groups but CCL2 and CCL5 concentrations were increased in BALF from SEA or MEA, respectively, compared with HE. Conclusion: Horses with SEA have increased Aspergillus antigen-reactive Th17 cells in their airways, emphasising local T cell responses to this mold, which were quantified in EA for the first time here.

Association between equine asthma and fungal elements in the tracheal wash: An environment-matched case-control study.

The presence of fungi in tracheal wash (TW) of horses was recently linked to mild-moderate equine asthma, indicating a possible causal role; however, increased numbers of fungi may also stem from asthma-related alteration of tracheal mucus clearance or from environmental exposure. Our objective was to elucidate the association between the presence of fungi in TW and asthma status while controlling for relevant confounders. We conducted a retrospective case-control study involving 73 horses, including 34 controls and 39 asthmatic cases. Each asthmatic horse was matched with a control from the same barn to account for the influence of environmental exposure. All horses underwent respiratory clinical scoring, endoscopy, TW, and bronchoalveolar lavage (BAL). The association between asthma status and presence of TW fungi was tested with multivariable logistic regression modelling, accounting for selected management factors, tracheal mucus accumulation, and selected TW and BAL cytological characteristics, including multinucleated giant cells (MGCs) in the TW. Given the variability in MGC definitions in the literature, particularly concerning their morphology and number of nuclei, we constructed two distinct models for each outcome (asthma status or presence of fungi in TW): one considering MGCs as cells with ≥ 3 nuclei, and another using a criterion of ≥ 10 nuclei. Horses with a tracheal mucus score ≥ 2 exhibited 3.6 to 4.3 higher odds of being asthmatic, depending on the MGC definition. None of the other variables examined were associated with either asthma status or TW fungi detection. Notably, the presence of fungal elements in the TW was not associated with equine asthma.

Prevalence and risk factors associated with nasal carriage of methicillin-resistant staphylococci in horses and their caregivers.

Antimicrobial resistance is a global threat, and pet-associated strains may pose a risk to human health. Equine veterinarians are at high risk of carrying methicillin-resistant staphylococci (MRS), but specific risk factors remain elusive, and few data are available for other personnel involved in the horse industry. The prevalence, characteristics, and risk factors for nasal carriage of MRS in horses and their caregivers were studied in northwestern Italy. Nasal swabs from 110 asymptomatic horses housed at 21 barns and 34 human caregivers were collected. Data on barns, horses, and personnel were acquired through questionnaires. The samples were incubated in selective media, and the bacterial isolates were identified by mass spectrometry. Risk factors were investigated by Poisson regression. MRS were isolated from 33 horses (30%), 11 humans (32.4%) and 3 environmental samples (14.2%). Most isolates were multidrug resistant (MDRS). The prevalence of MRS and MDRS was greater in racehorses and their personnel than in pleasurable and jumping/dressing horses. MRS carriage in caregivers was associated with an increased prevalence of MRS carriage in horses. The frequency of antimicrobial treatments administered in the barn during the last 12 months was a risk factor for MRS carriage in horses [prevalence ratio (PR) 3.97, 95% CI 1.11, 14.13] and caregivers (PR 2.00, 95% CI 1.05, 3.82), whereas a good ventilation index of the horse tabling environment was a protective factor (PR 0.43, 95% CI 0.20, 0.92). Our data reveal relevant interactions occurring between bacterial communities of horses and humans that share the same environment, suggesting that One Health surveillance programs should be implemented.

Prevalence, risk factors, and characterisation of extended-spectrum ß-lactamase -producing Enterobacterales (ESBL-E) in horses entering an equine hospital and description of longitudinal excretion.

BACKGROUND: Extended-spectrum ß-lactamase -producing Enterobacterales (ESBL-E) are important zoonotic pathogens that can cause serious clinical infections, also in horses. Preventing the spread of ESBL-E, especially in the equine hospital environment, is key to reducing the number of difficult-to-treat infections. Estimating the local prevalence of ESBL-E in horses is crucial to establish targeted infection control programs at equine hospitals. We conducted a prevalence and risk factor study in equine patients on admission to an equine teaching hospital in Finland through a rectal ESBL-E screening specimen of the horse and a questionnaire. RESULTS: The prevalence of ESBL-E in admitted horses was 3% (5/161, 95% CI 1-7%); none of the tested factors remained statistically significant in multivariate analysis, although antimicrobial treatment within three months was borderline significant (p = 0.052). Extended-spectrum ß-lactamase -producing Klebsiella pneumoniae ST6179:CTX-M-15 was detected in three horses using whole-genome sequencing, which in combination with patient records suggested nosocomial transmission. Escherichia coli isolates were ST1250:CTX-M-1 (n = 1), ST1079:CTX-M-1 (n = 1), and ST1245:CTX-M-14 (n = 1). Multiple virulence genes were detected in the ESBL-E isolates. In the ESBL-E positive horses enrolled in a one-year follow-up study, ESBL-E were unlikely to be isolated in rectal screening specimens after the initial positive specimen. CONCLUSIONS: The prevalence of ESBL-E in horses visiting a veterinary teaching hospital in Finland is low, indicating an overall low prevalence estimate in the country's equine population. No statistically significant risk factors were identified, likely due to the low number of cases. The duration of ESBL-E carriage is likely to be very short in horses.

Significance of Anaplasma phagocytophilum, Babesia caballi, and Theileria equi as etiologic agents in horses with clinical manifestations from the metropolitan area of Rio De Janeiro, Brazil.

Equine Piroplasmosis (EP) and Equine Granulocytic Anaplasmosis (EGA) are diseases that affect horses, transmitted by ixodid ticks, causing a nonspecific febrile syndrome. Equine Piroplasmosis is endemic in Brazil, and most horses are in enzootic stability. Serological and molecular studies carried out on horses in Brazil have shown the presence of Anaplasma phagocytophilum, however, the clinical relevance of this infection has not yet been established. The present study aims to evaluate the importance of Babesia caballi, Theileria equi, and A. phagocytophilum as etiological agents in horses with clinical manifestations suggestive of these diseases in the metropolitan mesoregion of Rio de Janeiro. A total of 45 animals with clinical signs were submitted to DNA extraction followed by qPCR test. Anaplasma phagocytophilum, Neorickettsia risticii and Theileria haneyi were not found in any of the horses with clinical signs, however 62.2% were infected with at least one agent of EP. Theileria equi was the most frequent etiologic agent (35.5%), followed by coinfection (15.5%) and B. caballi (11.2%). These results suggest that A. phagocytophilum has minor clinical importance in the region, while EP is frequently found in symptomatic horses, representing an important differential diagnosis in suspected cases.

Effects of fecal microbiota transplantation on clinical outcomes and fecal microbiota of foals with diarrhea.

BACKGROUND: Diarrhea in foals can be associated with disruption of the intestinal microbiota (dysbiosis). Effective management of intestinal dysbiosis in foals has not been demonstrated. HYPOTHESIS/OBJECTIVES: Fecal microbiota transplantation (FMT) in foals with diarrhea influences the intestinal microbiota and improves clinical and clinicopathological outcomes. ANIMALS: Twenty-five foals <6 months of age with diarrhea and systemic inflammatory response syndrome at 3 veterinary hospitals. METHODS: A prospective randomized placebo-controlled cohort study. Foals in the FMT group (n = 19) or control group (n = 9) received FMT or electrolyte solution once daily for 3 days. Fecal samples were obtained on Day 0 (D0), D1, D2, D3, and D7. Within group and between group data analyses were performed for clinical, clinicopathological, and microbiota variables. RESULTS: Treatment had no effect on survival (FMT 79%; control 100%, P = .3) or resolution of diarrhea (FMT 68%; control 55%, P = .4). On D3, the white blood cell count of the FMT group was lower than the control group (D3 FMT group median 6.4 g/L [5-8.3 g/L]; D3 control group median 14.3 g/L [6.7-18.9 g/L] P = .04). Heart rate reduced over time in the FMT group (D0 median 80 bpm [60-150 bpm]; D2 median 70 bpm [52-110 bpm] [P = .005]; and D3 median 64, [54-102 bpm] [P < .001]). Phylum Verrucomicrobiota, genus Akkermansia, and family Prevotellaceae were enriched in the FMT group on D1 (linear discriminate analysis > 4). CONCLUSIONS AND CLINICAL IMPORTANCE: In foals with diarrhea, FMT appears safe and can be associated with some clinical and microbiota changes suggestive of beneficial effect.

Methicillin-resistant Staphylococcus aureus outbreak in a Dutch equine referral clinic.

In 2020 and 2022, nine cases of surgical site infections with a methicillin-resistant Staphylococcus aureus (MRSA) were diagnosed in horses in an equine referral clinic. Sixteen isolates (horses, n=9; environment, n=3; and staff members, n=4) were analysed retrospectively using Nanopore whole-genome sequencing to investigate the relatedness of two suspected MRSA outbreaks (2020 and 2022). The MRSA isolates belonged to ST398 and ST612. ST398 genomes from 2020 and 2022 formed three phylogenetic clusters. The first ST398 cluster from 2020 consisted of isolates from five horses and one staff member, and we suspected within clinic transmission. The second cluster of ST398 isolates from 2022 originated from two horses and two staff members but showed higher single nucleotide polymorphism (SNP) distances. One ST398 isolate from an individual staff member was not related to the other two clusters. The ST612 isolates were isolated in 2022 from two horses and three environmental samples and showed very low SNP distances (<7 SNPs), indicating the transmission of MRSA ST612 in this clinic in 2022. Molecular characterization revealed an abundant set of virulence genes and plasmids in the ST612 isolates in comparison to ST398 isolates. Phenotypic antimicrobial susceptibility showed that differences between the two sequence types were consistent with the genetic characteristics. MRSA ST612 has not been reported in Europe before, but it is a dominant clone in African hospitals and has been described in horses and people working with horses in Australia, indicating the importance of surveillance.

Equine uterine sanitizer: in vitro inhibition of endometritis-causing microorganisms and its stability to dilute antibiotics.

Endometritis is the leading cause of mare subfertility. Most mares respond to standard therapy, but alternative therapies have been developed for mares failing to respond. This study aimed to investigate a commercially available, yet unassessed, product labeled as a uterine sanitizer to determine the in vitro antimicrobial activity against microorganisms associated with endometritis and its in vitro stability to dilute antibiotics. In experiment 1, the microdilution broth technique and antimicrobial effects were assessed against Escherichia sp, Staphylococcus sp., Klebsiella sp., Pseudomonas sp., and Candida sp. Percentage inhibition was calculated by comparing the optical density. The minimum inhibitory concentration (MIC) 100% was determined using the resazurin dye technique. MIC 50% and 90% were determined using a dose-response non-linear regression. In experiment 2, the uterine sanitizer was used to dilute commonly used antibiotics achieving a final volume of 90 mL at 5°C, 21°C, and 37°C. The pH was measured at 0, 1, 3, 6, and 24 h after dilution. The uterine sanitizer had inhibitory properties against all microorganisms; Escherichia sp. being the most susceptible, and Pseudomonas sp. the most resistant. The uterine sanitizer had an acidic pH=4; however, when combined with the antibiotics, the pH of the antibiotic remained unchanged with the different temperatures and did not precipitate. In conclusion, the uterine sanitizer showed antimicrobial effects against endometritis-causing microorganisms. The dilution of antibiotics in the uterine sanitizer was stable and this association could potentiate the antimicrobial effects. Uterine sanitizer's safety and clinical efficacy in vivo remain to be tested.

Acute leptospirosis in horses: A retrospective study of 11 cases (2015-2023).

BACKGROUND: Reports of leptospirosis in horses are limited. OBJECTIVES: To describe the clinical and diagnostic findings of acute systemic leptospirosis in horses. ANIMALS: Eleven client-owned horses presented to an equine hospital because of acute onset of disease between 2015 and 2023. METHODS: Retrospective case series. Horses diagnosed with leptospirosis by 1 or more of urine PCR, serologic microscopic agglutination test (MAT), and histopathology. RESULTS: Common clinical signs included lethargy (10), anorexia (10), fever (9), tachypnea (9), abnormal lung sounds (9), and epistaxis (6). Acute kidney injury was present in all cases. Evidence of pulmonary hemorrhage and liver disease was found in 8 (73%) and 6 (55%) horses, respectively. In 6 (55%) horses, kidneys, lungs, and liver were affected. Urine quantitative polymerase chain reaction for detection of pathogenic Leptospira spp. was positive in 6 (55%) cases. On serology Leptospira interrogans serovar Australis, Autumnalis, and Bratislava accounted for 86% of all titers ≥1 : 800. Overall case fatality rate was 4/11 (36%). Main findings on necropsy were tubular necrosis, interstitial nephritis, hemorrhage in the alveoli, pulmonary edema, periportal hepatitis and necrosis, cholestasis, and cholangitis. CONCLUSIONS AND CLINICAL IMPORTANCE: Leptospirosis should be considered as a differential diagnosis in horses with evidence of acute systemic inflammation and acute renal injury, epistaxis, or hepatic disease. For increased likelihood of identifying positive cases, both MAT serology and urine PCR should be performed.

Aspergillus Fumigatus Spore Proteases Alter the Respiratory Mucosa Architecture and Facilitate Equine Herpesvirus 1 Infection.

Numerous Aspergillus fumigatus (Af) airborne spores are inhaled daily by humans and animals due to their ubiquitous presence. The interaction between the spores and the respiratory epithelium, as well as its impact on the epithelial barrier function, remains largely unknown. The epithelial barrier protects the respiratory epithelium against viral infections. However, it can be compromised by environmental contaminants such as pollen, thereby increasing susceptibility to respiratory viral infections, including alphaherpesvirus equine herpesvirus type 1 (EHV-1). To determine whether Af spores disrupt the epithelial integrity and enhance susceptibility to viral infections, equine respiratory mucosal ex vivo explants were pretreated with Af spore diffusate, followed by EHV-1 inoculation. Spore proteases were characterized by zymography and identified using mass spectrometry-based proteomics. Proteases of the serine protease, metalloprotease, and aspartic protease groups were identified. Morphological analysis of hematoxylin-eosin (HE)-stained sections of the explants revealed that Af spores induced the desquamation of epithelial cells and a significant increase in intercellular space at high and low concentrations, respectively. The increase in intercellular space in the epithelium caused by Af spore proteases correlated with an increase in EHV-1 infection. Together, our findings demonstrate that Af spore proteases disrupt epithelial integrity, potentially leading to increased viral infection of the respiratory epithelium.

Spatial and seasonal distribution of Leptospira spp. seropositive horses in the Northeast region of Brazil.

Leptospirosis is an anthropozoonosis of economic and public health importance, caused by bacteria of the genus Leptospira. Horses are deemed important in its transmission chain due to their proximity to humans, and because the species is often asymptomatic, making these animals potential silent reservoirs. In this context, the objectives of this study were to determine the prevalence of seropositive horses for Leptospira spp., and to identify the presence of Leptospira spp. serogroups and antibody titers, the occurrence of areas with higher density of infection cases and demographic characteristics associated with seropositivity in the states of Paraíba (PB), Pernambuco (PE), Rio Grande do Norte (RN) and Ceará (CE), in the Northeast region of Brazil, during rainy (May and June) and dry (October and November) seasons from 2017 to 2019. Using the microscopic agglutination test (MAT), 1152 equine serum samples from 225 municipalities were analyzed. Anti-Leptospira antibodies were detected in 23.9 % (95 % CI= 21.4 - 26.3 %) of the samples in the three-year period, with a frequency of 30.4 % (95 % CI= 26.7 - 34.2 %) during the rainy period (with greater emphasis on the Ballum serogroup) and 17.4 % (95 % CI= 14.3 - 20.5 %) in the dry period (with greater emphasis on the Sejroe serogroup). Age of horses ≥ 6 years (6-10 years, 11-15 years and ≥ 16 years), rainy season, and animal belonging to Pernambuco state were factors with higher seropositivities. Regarding spatial distribution, a higher percentage of seropositive animals was observed in Pernambuco (P < 0.05), in interstate border areas, and large urban centers, with a spatial cluster detected in the dry season of 2018 with relative risk of 2.8 (P = 0.049) times higher in municipalities within the cluster. It is suggested that measures for controlling rodents and contact with wild animals in equine farming, both in rainy and dry periods, combined with care regarding the use of pastures shared with cattle and the adoption of immunoprophylaxis are important in preventing and controlling leptospirosis in horses in the Northeast region of Brazil.

Whole-genome sequencing and pathogenicity analysis of Rhodococcus equi isolated in horses.

BACKGROUND: 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 1 prophage gene. Pathogenic system analysis predicted the presence of 418 virulence factors and 225 drug resistance genes. Secretion system analysis revealed the prediction of 297 secreted proteins and 1,106 transmembrane proteins. BJ13 exhibits genomic features, virulence-associated genes, potential drug resistance, and a virulence plasmid structure that may contribute to the evolution of its pathogenicity. Lastly, the pathogenicity of the isolated strain was assessed through animal experiments, which resulted in inflammatory reactions or damage in the lungs, liver, and spleen of mice. Moreover, by the 7th day post-infection, the mortality rate of the mice reached 50.0%, indicating complex immune regulatory mechanisms, including overexpression of IL-10 and increased production of pro-inflammatory cytokines like TNF-α. These findings validate the strong pathogenicity of the isolated strain and provide insights for studying the pathogenic mechanisms of Rhodococcus equi infection. CONCLUSIONS: The complete genome sequence of R. equi strain BJ13 provides valuable insights into its genomic characteristics, virulence potential, drug resistance, and secretion systems. The strong pathogenicity observed in animal experiments underscores the need for further investigation into the pathogenic mechanisms of R. equi infection.

Early-life gut bacterial community structure predicts disease risk and athletic performance in horses bred for racing.

Gut bacterial communities have a profound influence on the health of humans and animals. Early-life gut microbial community structure influences the development of immunological competence and susceptibility to disease. For the Thoroughbred racehorse, the significance of early-life microbial colonisation events on subsequent health and athletic performance is unknown. Here we present data from a three-year cohort study of horses bred for racing designed to explore interactions between early-life gut bacterial community structure, health events in later life and athletic performance on the racetrack. Our data show that gut bacterial community structure in the first months of life predicts the risk of specific diseases and athletic performance up to three years old. Foals with lower faecal bacterial diversity at one month old had a significantly increased risk of respiratory disease in later life which was also associated with higher relative abundance of faecal Pseudomonadaceae. Surprisingly, athletic performance up to three years old, measured by three different metrics, was positively associated with higher faecal bacterial diversity at one month old and with the relative abundance of specific bacterial families. We also present data on the impact of antibiotic exposure of foals during the first month of life. This resulted in significantly lower faecal bacterial diversity at 28 days old, a significantly increased risk of respiratory disease in later life and a significant reduction in average prize money earnings, a proxy for athletic performance. Our study reveals associations between early-life bacterial community profiles and health events in later life and it provides evidence of the detrimental impact of antimicrobial treatment in the first month of life on health and performance outcomes in later life. For the first time, this study demonstrates a relationship between early-life gut bacterial communities and subsequent athletic performance that has implications for athletes of all species including humans.

Molecular characterisation of Histoplasma capsulatum sensu lato from Ethiopian horses reveals two distinct phylogenetic clades.

Epizootic lymphangitis (EL) is a highly prevalent and contagious infectious disease affecting horses in many parts of Ethiopia caused by Histoplasma capsulatum sensu lato ('var. farciminosum'). In this study, 12 suspected isolates of H. capsulatum sensu lato or yeasts unidentified by conventional biochemical tests isolated from Ethiopian horses with EL were characterised by internal transcribed spacer sequencing. Six of the 12 isolates were identified to be members of H. capsulatum sensu lato and the other six were Pichia kudriavzevii (synonym: Candida krusei) (n = 3), Trichosporon asahii (n = 1), Geotrichum silvicola (n = 1) and Moesziomyces aphidis (n = 1), respectively. The six H. capsulatum sensu lato isolates were further characterised by multilocus sequence analysis. Four distinct gene loci (arf [462 bases], H-anti [410 bases], ole1 [338 bases] and tub1 [272 bases]) of these six isolates as well as those of two H. capsulatum sensu lato ('var. farciminosum') reference strains (ATCC 58332 and ATCC 28798) were polymerase chain reaction (PCR)-amplified and sequenced. Phylogenetic analyses of their concatenated nucleotide sequences showed that three of the isolates and the reference strain ATCC 58332 were identical and belonged to the Eurasia clade within Latin American (LAm) A (H. suramericanum), and those of the other three isolates and the reference strain ATCC 28798 were identical and belonged to the Africa clade. At least two distinct phylogenetic clades of H. capsulatum sensu lato were circulating in Ethiopian horses with EL. Advanced molecular technologies and bioinformatics tools are crucial for the accurate identification and typing of pathogens as well as the discovery of novel microorganisms in veterinary microbiology.

Using multilocus sequence analysis with four concatenated housekeeping gene loci, at least two distinct phylogenetic clades, namely Eurasia clade and Africa clade, of Histoplasma capsulatum sensu lato were confirmed to be circulating in Ethiopian horses with epizootic lymphangitis.

Streptococcus equi subspecies equi from strangles suspected equines: molecular detection, antibiogram profiles and risk factors.

Strangles, caused by Streptococcus equi subspecies equi, is a highly infectious disease of equines causing major health issues and financial losses. The aim of the study was to detect the presence of the SeM gene in Streptococcus equi isolated from equine suspected of having strangles. A cross-sectional study design was conducted from July to December 2022 in five districts of the central Gondar zone, Ethiopia. One-hundred sixty swab samples were taken from animals that had been clinically suspected. The SeM gene was detected using polymerase chain reaction, and the antimicrobial susceptibility test was performed using the Kirby-Bauer disc diffusion method. The binary logistic regression model was employed to test for statistical significance. In 31.87% (51/160) of the samples, Streptococcus equi species were isolated, and 31.37% (16/51) of these species carried the SeM gene. There was a significant amount of tetracycline (81.5%), erythromycin (81.5%), and vancomycin (75.5%) resistance among the 16 isolates. Strangles were more likely to be present in animals who shared feed containers (AOR = 7.59; 95% CI = 1.44-39.93), drank from the same water troughs (AOR = 7.74; 95% CI = 1.44-41.01), and spent the night together (AOR = 5.97; 95% CI 1.41-25.37). The findings of this study showed that the research areas harboured Streptococcus equi subspecies equi. Sharing feed containers and water troughs were potential sources of strangles infection; thus, these containers need to be cleaned regularly.

Equidae pythiosis in Brazil and the world: a systematic review of the last 63 years (1960-2023).

This systematic review compiles reports of clinical pythiosis in horses, mules and donkeys from 1960 to 2023 worldwide, focusing on Brazil. We searched databases and included 71 articles detailing clinical characteristics, geographic distribution, epidemiology, diagnostic methods, therapies, and outcomes. The results showed that publications on equine pythiosis have significantly increased since 2010. Brazil reported the highest incidence, comprising 55% of cases, predominantly in the southern, northeastern, and central-western regions during summer and autumn. Cutaneous pythiosis was the most prevalent form, generally presenting as single lesions in the appendicular region, and affected females more than males. Diagnosis typically involved histopathology, used alone or with other methods. Various treatments have been employed, with surgery, often combined with chemotherapy and immunotherapy, being the most common. Notably, 80.84% of treated animals recovered, highlighting the effectiveness of these therapies in enhancing survival rates. The limitations of the study included the lack of data in published case reports, which made it difficult to collect and calculate epidemiological data. Additionally, we recognize that pythiosis in Brazil is underreported, since this disease does not have mandatory notification and several cases are not registered and/or reported in the literature. Lastly, it is hypothesized that equid pythiosis may be more widespread than currently known, and its real occurrence in Brazil remains uncertain.

An updated description of bacterial pneumonia in adult horses and factors associated with death.

BACKGROUND: Available descriptive studies on equine pneumonia are outdated or focus on specific horse or bacterial populations. OBJECTIVES: To describe the clinical presentation and bacterial isolates of adult horses with bacterial pneumonia and identify factors associated with death. ANIMALS: One hundred sixteen horses >2 years old with bacterial pneumonia. METHODS: Retrospective case series. Data regarding history, physical examination, clinicopathologic features, treatment, bacterial culture and sensitivity, and outcome were collected and analyzed retrospectively. RESULTS: Historical risk factors were present for 60% of cases, whereas abnormal vital signs on intake were present for <50%. Most horses (58%) underwent at least 1 change of antimicrobial treatment, and 67% received the highest-priority critically important antimicrobials. Streptococcus zooepidemicus was the most isolated bacteria (44%), followed by Escherichia coli (19%), Klebsiella spp. (18%), other Streptococcus species (17%), and Bacillus spp. (13%). Fusobacterium spp. were the most common anaerobic isolates (11%). Antimicrobial susceptibility varied widely. Survival to discharge was 73%. Heart rate at presentation (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.008-1.17, P = .03) and higher creatinine (OR 14.1, 95% CI 1.56-127.6, P = .02) increased the risk of death. Higher lymphocyte count (OR 0.27, 95% CI 0.08-0.94, P = .04) reduced risk. CONCLUSIONS AND CLINICAL IMPORTANCE: Contrasting older literature, Fusobacterium spp. were the most common anaerobes. Streptococcus zooepidemicus remained the most common isolate and was predictably susceptible to penicillin. Antimicrobial susceptibility was otherwise variable and broad applicability is limited as this was a single-center study. Increased risk of death associated with tachycardia and abnormally high serum creatinine concentration is consistent with previous studies.

Aspergillus fumigatus binding IgA and IgG1 are increased in bronchoalveolar lavage fluid of horses with neutrophilic asthma.

Introduction: Equine asthma (EA) is a common lower airway disease in horses, but whether its pathogenesis is allergic is ambiguous. Extrinsic stimuli like hay dust induce acute exacerbation of clinical signs and sustained local neutrophilic inflammation in susceptible horses. Aspergillus fumigatus is an EA stimulus, but it is unclear if it merely acts as an IgE-provoking allergen. We aimed to comprehensively analyze immunoglobulin (Ig) isotypes in EA, elucidating their binding to different A. fumigatus antigens, and their quantities systemically in serum and locally in bronchoalveolar lavage fluid (BALF). Methods: Serum and BALF from healthy horses (HE, n = 18) and horses with mild-moderate asthma (MEA, n = 20) or severe asthma (SEA, n = 24) were compared. Ig isotype (IgG1, IgG3/5, IgG4/7, IgG6, IgA, and IgE) binding to nine antigens (A. fumigatus lysate, and recombinant Asp f 1, Asp f 7, Asp f 8, dipeptidyl-peptidase 5, class II aldolase/adducin domain protein, glucoamylase, beta-hexosaminidase, and peptide hydrolase) was compared by enzyme-linked immunosorbent assays. Total Ig isotype contents were determined by bead-based assays. Results: MEA and SEA differed from HE but hardly from each other. Compared to HE, asthmatic horses showed increased anti-A. fumigatus binding of IgG (BALF and serum) and IgA (BALF). Serum and BALF IgE binding and total IgE contents were similar between HE and EA. Single antigens, as well as A. fumigatus lysate, yielded similar Ig binding patterns. Serum and BALF IgG1 binding to all antigens was increased in SEA and to several antigens in MEA. Serum IgG4/7 binding to two antigens was increased in SEA. BALF IgA binding to all antigens was increased in SEA and MEA. Total BALF IgG1 and IgG4/7 contents were increased in SEA, and serum IgG4/7 content was increased in MEA compared to HE. Yet, total isotype contents differentiated EA and HE less clearly than antigen-binding Ig. Discussion: A. fumigatus immunogenicity was confirmed without identification of single dominant antigens here. A. fumigatus provoked elevated BALF IgG1 and IgA binding, and these isotypes appear relevant for neutrophilic EA, which does not support allergy. BALF Ig isotype differentiation beyond IgE is crucial for a comprehensive analysis of immune responses to fungi in EA pathogenesis.

The effect of anthelmintic treatment and efficacy on the faecal microbiota of healthy adult horses.

Changes to the faecal microbiota of horses associated with administration of anthelmintic drugs is poorly defined. This study included horses with cyathostomin infection where susceptibility and resistance to oxfendazole and abamectin was known. This study assessed the changes to the faecal microbiota associated with administration of two different anthelmintics in this population. Twenty-four adult horses were included. Faecal egg counts were performed on all horses prior to random allocation into abamectin (n=8), oxfendazole (n=8) or Control groups (n=8) and at Day 14 post treatment. Faecal samples were collected for microbiota analysis prior to anthelmintic administration and on Day 3 and Day 14. From each faecal sample, DNA was extracted prior to PCR amplification, next generation sequencing and analysis using QIIME2. Anthelmintic treatment was associated with changes in alpha diversity (p <0.05), with increased evenness and diversity at Day 14 and increased richness at Day 3 within the abamectin group. Differences in relative abundance of bacteria at the phyla, family and genus taxonomic levels occurred after treatment; indicating that the microbiota was altered with anthelmintic administration. The results support that anthelmintic administration and removal of cyathostomins from the large intestine of horses is associated with changes in the faecal microbiota. The results suggest that removal of cyathostomins is associated with greater differences in microbiota, compared to anthelmintic drug administration that is ineffective in reducing cyathostomin infection. Cyathostomin removal was supported by adequate reduction of faecal egg counts, determined by faecal egg count reduction testing.