Search Results (193)

Rhodococcus equi is an opportunistic intracellular pathogen responsible for severe pneumonia in foals and has emerged as an important cause of infection in immunocompromised humans. The treatment of R. equi infections in foals relies mainly on the combination of macrolides and rifampin. However, the increasing incidence of multidrug-resistant (MDR) isolates has raised significant therapeutic challenges. The mechanisms underlying this resistance include mutations in target genes, activation of efflux pumps, and biofilm formation, which collectively compromise the efficacy of conventional antibiotics. Recently, growing concern over antibiotic failure has accelerated research into alternative and synergistic strategies to enhance antibacterial efficacy and reduce the development of resistance. Natural and synthetic compounds, as well as optimized antibiotic combinations, have shown promising synergistic effects by enhancing intracellular accumulation, disrupting redox homeostasis, or inhibiting efflux systems. Experimental models employing checkerboard and time-kill assays, as well as redox-sensitive biosensors, have demonstrated that certain antibiotic combinations can influence bacterial susceptibility to antibiotic exposure. Furthermore, integrating molecular tools provides valuable insight into bacterial responses to oxidative and antibiotic stress, paving the way for novel therapeutic designs. This review summarizes the current understanding of the molecular factors contributing to antimicrobial resistance in R. equi and assesses new therapeutic approaches aimed at overcoming these challenges. It highlights recent findings on strategies to improve treatment outcomes and manage antimicrobial resistance. Full article

This study evaluated the effects of dietary protein levels during late gestation on nutrient digestibility, plasma amino acid profiles in jennies, and donkey foal growth performance. Twenty-four pregnant jennies were randomly assigned to one of three diets with different crude protein (CP) contents during late gestation: 12.48% (HP), 11.52% (MP), and 10.54% (LP) on a dry matter basis. All animals received the same diet immediately after parturition for a duration of 30 days. During the trial, two digestion experiments were conducted, blood samples were collected at 28 and 7 days prepartum, and weekly weight measurements of jennies and foals were recorded. The results indicated that the dietary protein level did not significantly affect feed intake in late gestation. However, apparent nutrient digestibility of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and ether extract (EE), and calcium (Ca) and phosphorus (P) was generally higher in the MP and LP groups than in the HP group, with MP showing the most consistent improvements across nutrients and timepoints (p < 0.05). Although the HP diet increased plasma concentrations of certain amino acids, including glutamic acid (Glu), valine (Val), methionine (Met), leucine (Leu), essential amino acids (EAAs), functional amino acids (FAAs), and branched chain amino acids (BCAAs), and elevated serum levels of glucose (GLU), blood urea nitrogen (BUN), and creatinine (CRE), it failed to improve postpartum weight recovery in jennies, highlighting that weight dynamics during this period are governed by factors beyond dietary protein content alone. Specifically, the LP group exhibited significantly higher cumulative postpartum weight loss over weeks 1–4 than the HP group (p = 0.004). Regarding offspring performance, both HP and MP diets improved foal birth weight, weekly body weight up to 4 weeks, average daily gain, and body height compared to the LP group (p < 0.05), with no significant differences observed between the HP and MP groups. In conclusion, for jennies under the current confined feeding system, a late-gestation diet containing 11.52% CP was adequate to support higher nutrient digestibility in the jennies and better growth performance in their foals, compared to a lower protein level (10.54% CP). However, increasing the dietary CP to 12.48% provided no additional benefits in nutrient utilization or overall productivity. Full article

Umbilical remnant disorders are common in neonatal foals and may require surgical intervention when complicated by infection or urinary involvement. Abdominal surgery in this population is often considered high risk, particularly due to postoperative complications and adhesion formation. The aim of this retrospective observational study was to evaluate the short- and long-term outcomes of foals undergoing omphalectomy with peritonealization of the umbilical arterial stumps. Medical records of foals younger than 30 days treated surgically between 2005 and 2025 were reviewed. Data regarding signalment, diagnosis, comorbidities, postoperative complications, and short-term survival were collected. Long-term follow-up was obtained by owner interview to assess post-discharge colic episodes and if they started their intended athletic activity. Seventy-one foals met the inclusion criteria. Overall, 83.1% survived to hospital discharge. Mortality was significantly associated with the presence of concurrent comorbidities and postoperative complications, but not with age or sex. Long-term follow-up was available for a subset of foals; post-discharge colic was reported in 6.4% of cases, with only one foal developing colic considered compatible with postoperative adhesions. Most foals with available follow-up successfully started their expected athletic activity. These findings suggest that omphalectomy with peritonealization of the umbilical arterial stumps is associated with favorable short- and long-term outcomes and may represent a safe surgical option in neonatal foals. Full article

Skin development undergoes significant molecular changes during early life stages in mammals. This study investigated transcriptomic differences in skin tissues between newborn (Y0) and one-year-old (Y1) Dezhou donkey foals using RNA-sequencing technology. Skin samples were collected from 13 Dezhou donkeys (7 newborns and 6 one-year-olds) and subjected to transcriptome analysis using the Illumina NovaSeq 6000 platform. A total of 133.66 Gb of clean data was obtained, yielding 252,342 transcripts and 204,683 unigenes. Differential expression analysis revealed 9878 significantly differentially expressed genes (DEGs) between age groups, with 4252 up-regulated and 5626 down-regulated genes in Y1 compared to Y0. Functional enrichment analysis identified key pathways, including ECM–receptor interaction, PI3K-Akt signaling, WNT signaling, and TGF-β signaling pathways. Notable findings included up-regulation of keratin genes (KRT1) and WNT family genes (WNT3, WNT4, WNT5, WNT6, WNT7, WNT10) in one-year-old foals, while collagen genes (COL1A, COL4A, COL5AS) and TGF-β signaling components (TGFB2, TGFB3, BMP5) were down-regulated. These results suggest that skin maturation involves enhanced barrier function, hair follicle development, and reduced collagen synthesis rates, providing insights into mammalian skin development mechanisms and potential applications in veterinary medicine and comparative biology. Full article

Pneumonia caused by the facultative intracellular pathogen Rhodococcus equi stands out as one of the most significant infections associated with a notably high mortality rate in foals worldwide. Limited therapeutic options and inadequate control and prevention measures result in substantial economic losses, underscoring the need for enhanced interventions. A cross-sectional, multi-province study was conducted on racehorse-breeding farms in Türkiye to estimate prevalence and index virulence, assess relatedness, and summarize antimicrobial susceptibility within a farm management context. Nasal and fecal swabs and environmental samples (soil and water) were cultured and confirmed; virulence was assessed with vapA-specific PCR, genetic relationship determined with PFGE, and antimicrobial susceptibility using disk diffusion. R. equi was detected in 10% of nasal swabs, 22.9% of fecal swabs, 29.4% of soil samples, and 5.9% of water samples; 46.2% of confirmed isolates were vapA-positive. Susceptibility patterns were favorable overall, with frequent ampicillin resistance, infrequent resistance to macrolides and rifampin, rare multidrug resistance, and no vancomycin resistance was detected. PFGE demonstrated substantial genotypic diversity, with 12 clusters and 29 distinct pulsotypes. Farm-level observations were exploratory. More frequent mechanical paddock cleaning coincided with the absence of foal deaths, and vapA-positive isolates were observed on farms with prior infection. Taken together, these findings support routine paddock hygiene, prompt isolation of clinically affected foals, culture-guided therapy, and continued surveillance, and they indicate a need for longitudinal and genomic studies to evaluate the impact. Full article

Background: Despite the availability of a killed whole-virus (KV) vaccine, diarrhea caused by equine rotavirus group A (ERVA) remains a significant health concern for foals in the United States. The vaccine is administered to pregnant mares, with foals protected by passive transfer of colostral antibodies. However, KV-induced immunity is only partially protective and maternal antibody levels in foals are often low and wane rapidly. To address these limitations, we developed a mRNA-based ERVA vaccine encoding the highly conserved VP8* protein to evaluate whether it can provide improved immune protection. Methods: Pregnant mares (n = 12 per group) were immunized either at months 8 and 10 of gestation with the VP8* mRNA or at months 8, 9, and 10 of gestation with the KV. Serum samples were collected from mares before and after immunization and from their foals at ages 1, 35, and 49 days. Serum samples were tested by indirect ELISA for VP8*-specific relative antibody concentrations and relative concentrations were compared for effects of study group and sample-time using linear mixed-effects regression. To detect functional antibodies against ERVA, a virus neutralization titer assay was performed to compare titers between mares vaccinated with the mRNA vaccine (and their foals) and unvaccinated control mares (and their foals). Results: Mares vaccinated with VP8* mRNA had significantly (p < 0.05) higher antibody concentrations after foaling than mares in the KV group, and foals of VP8* mRNA-vaccinated mares had significantly (p < 0.05) higher concentrations through age 49 days than foals in the KV group. In addition, the VP8* mRNA vaccine elicited higher titers of ERVA-neutralizing antibodies against both G3 and G14 strains. Conclusions: Longer-lasting, higher concentrations of virus-neutralizing antibodies might provide superior duration of immunity to ERVA in foals from mares vaccinated with VP8* mRNA. Full article

It is known that a mare’s body temperature drops before parturition, but no research has yet applied this thermal change to the prediction of foaling. In this study, the ventral tail base surface temperature (VTB-ST) was recorded by a tail-attached device equipped with a thermistor in pregnant mares kept in an outdoor paddock all day. The objective of the present study was to make an algorithm for predicting nocturnal foaling (18:00 to 6:00) and to verify the accuracy of the algorithm. Prediction of nocturnal foaling was performed at 15:00 every day. The foaling prediction model was validated using 147 days of data recorded from 22 mares. The sensitivity of the foaling prediction model proposed in this study was 68.2 to 81.8% and the precision was 51.4 to 62.5%. To our knowledge, the present study is the first one to establish an algorithm for predicting nocturnal foaling at a specific time interval using VTB-ST. Further study will be necessary to improve the foaling prediction model, as the accuracy of the algorithm proposed in this study was considered to be insufficient for practical use in stud farms. Full article

Assisted reproductive techniques are often extrapolated from horses to donkeys, despite poorer fertility outcomes in jennies. This issue has been attributed to unknown uterine species-specific differences. This study compared, through histomorphometry, the endometrium of jennies and mares. Endometrial biopsies (N = 12) were taken from reproductively sound jennies (n = 6) and mares (n = 6) in estrus. Histomorphometric analysis evaluated luminal (LE, µm) and glandular epithelium height (GE, µm), glandular lumen diameter (LD, µm), glandular area (GA, µm²), the number of glands (#G), and glandular tissue percentage (GT, %), measured in the stratum compactum (SC) and spongiosum (SS). A total of 30 measurements of glandular size parameters and 10 fields of glandular density parameters per sample were recorded. Results were statistically compared between species (jennies vs. mares), parity status (maiden vs. foaling), and stratum (SC vs. SS). Jennies exhibited higher (p < 0.05) values than mares for LE, LD-SC, GA-SC, and GT-SC. These findings suggest that the histomorphometric features observed in reproductively sound jennies reflect anatomical differences that might partly explain previously observed species differences in post-breeding uterine response. In conclusion, histomorphometry revealed significant endometrial differences between species, with jennies displaying taller luminal epithelium, greater glandular size, and higher glandular tissue percentage in the SC than mares. Full article

Horses are social animals, with early life experiences playing a crucial role in their physiological and behavioral development. This study explored the influence of herd dynamics and foundational training on behavioral and hormonal changes in weaned foals. We examined 13 six-month-old Quarter Horse foals over a three-month training period, performing behavioral observations, temperament assessments, and hormone analyses at the start, midpoint, and end of the training. The results indicated that affiliative behaviors decreased significantly, while agonistic behaviors first increased and then decreased. Cortisol levels consistently declined throughout this study, whereas oxytocin levels remained stable. Linear regression analysis showed that cortisol was positively associated with affiliative behaviors and influenced by fearfulness and stubbornness. Conversely, oxytocin was positively associated with friendliness. The handlers’ proficiency significantly affected the foals’ outcomes; those managed by more skilled handlers exhibited significant improvements in confidence, friendliness, and reductions in cortisol, fearfulness, and stubbornness. These findings suggest the importance of handler skill in influencing equine behavior and hormonal balance. In conclusion, this study demonstrated the significant impacts of socialization and training on the behavioral, temperamental, and hormonal profiles of weaned foals, confirming the importance of handler expertise in fostering desirable traits in young horses. Full article

This study investigated the bacterial community composition and diversity in air and exercise yard bedding samples from large-scale donkey farms in Liaocheng, China, during summer using 16S rRNA high-throughput sequencing. Air samples were collected from five functional areas of donkey barns, while bedding samples were obtained from eight farms housing Dezhou donkeys. Sequencing analysis revealed 894 operational taxonomic units (OTUs) in air samples and 3127 OTUs in bedding samples. Alpha diversity indices indicated that the mare barn exhibited the highest microbial diversity in air, while the foal barn showed the lowest. Actinobacteriota, Proteobacteria, and Firmicutes were the dominant phyla across different functional areas. Rhodococcus was identified as the predominant airborne genus, representing a potential pneumonia risk in foals. In bedding materials, Firmicutes, Actinobacteriota, and Proteobacteria predominated, with Corynebacterium, Salinicoccus, and Solibacillus as dominant genera. Several potentially pathogenic bacteria were detected, including Rhodococcus, Corynebacterium, Clostridium, Streptococcus, and Escherichia-Shigella. These findings provide critical insights into the microbial ecology of intensive donkey farming environments and offer scientific evidence for developing targeted biosecurity strategies to safeguard animal health and promote sustainable livestock production. Full article

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 months were enrolled and divided into a colt and a filly group, and after weaning, were kept as such. Blood samples were collected before and up to 7 days after weaning. Serum cortisol and cytokines (IL-2, IL-6, IL-10, TNF-α, IFN-γ) were quantified using equine-specific ELISA kits. Routine descriptive statistics were used to present the data, and inferences were drawn using a two-way repeated measures ANOVA. The level of significance was set at p < 0.05. Results showed significant differences in the concentrations of IL-10 (p < 0.001), IFN-γ (p < 0.01), and TNF-α (p < 0.01) on various days post-weaning. An apparent significant sex effect was not shown, but IL-10 peaked on day 3 in fillies. IFN-γ decreased significantly by day 5 in both sexes. Conversely, TNF-α levels increased significantly by day 5. No significant changes were observed for cortisol. Full article

Background: Pain after giving birth is commonly observed in horses, yet there has not been a specific tool developed for assessing this pain in postpartum mares. The goal was to adapt existing equine pain scales and to preliminarily validate a practical pain scale for use by veterinarians and caregivers after foaling. Methods: The pain scale was developed by adapting items from other pain scales, including established orthopedic and colic equine pain scales, and incorporating caregiver feedback. The final scale includes eight areas for assessing pain: behavior, facial expressions, vital signs, udder examination, gastrointestinal function, hoof temperature, response to food, and movement. Observations were conducted on ten heavy draft mares that experienced dystocia, with pain scores recorded twice daily for 1 to 4 days postpartum. Simultaneous saliva samples were collected to measure cortisol levels. Results: The pain scale proved feasible for use at the stall and allowed for partial scoring when certain assessments were deemed risky. Pain scores were highest on the first day after foaling and decreased as the mares recovered. In a case of clinical deterioration, a substantial increase in pain score was noted. Increased pain scores were associated with elevated cortisol levels, supporting the biological relevance of the scale. In clinical practice, if a pain score exceeded 40% of the maximum score, the mare was identified as a patient requiring analgesic treatment. Conclusions: This postpartum-specific pain scale provides a standardized method for assessing pain in mares after foaling and may assist in guiding appropriate pain management. Although the proposed pain scale shows promise as a clinical tool, the present results are preliminary and require confirmation in larger studies. Full article

This study investigated the effects of varying proline supplementation doses in weaned foals. Twenty-eight weaned foals (approximately 5 months of age; body weight: 54.45 ± 11.33 kg; with an equal number of males and females) were randomly assigned to one of four groups—a control group, a low-dose group (20 mg/kg·d), a medium-dose group (40 mg/kg·d), and a high-dose group (60 mg/kg·d)— receiving continuous supplementation for 60 days. Blood samples were collected periodically for the analysis of hormones, antioxidants, immune parameters, and plasma amino acids. Concurrently, fecal 16S rRNA sequencing was performed to assess the microbial community composition. We observed a significant time-dependent interaction between medium-to-high proline supplementation and time. Proline supplementation resulted in dose-dependent increases in foal body weight (p = 0.002), hormone levels (p < 7.49 × 10⁻⁶), antioxidant capacity (p < 1.56 × 10⁻³), immune function (p < 0.005), and key blood biochemical parameters (p < 0.019). Concurrently, supplementation with medium and high doses of proline significantly reduced the plasma concentrations of amino acids such as proline and arginine (p < 0.05). The medium dose achieved the optimal balance between promoting growth and maintaining high nitrogen utilization efficiency. At the microbial level, medium-dose proline significantly enhanced fecal microbial diversity, particularly enriching characteristic taxa like g_Christensenellaceae_R-7_group. Furthermore, functional inference from PICRUSt2 revealed that medium-dose proline supplementation was associated with a higher microbial potential for amino acid degradation and metabolism, in line with the decreasing plasma concentrations of the corresponding amino acids. This research enhances our understanding of the “host–microbiota interaction” mechanism in weaned foals and provides important theoretical support for mitigating weaning stress and optimizing nutritional strategies. Full article

The logistic modeling of diauxic growth and biphasic antibacterial activity (AA) production was enhanced for four lactic acid bacteria (Lactococcus lactis CECT 539, Pediococcus acidilactici NRRL B-5627, Lactobacillus casei CECT 4043, and Enterococcus faecium CECT 410) during realkalized fed-batch fermentations. The improved growth model, also validated for describing the diauxic growth of Mos breed roosters and foals, overcomes a key limitation of the bi-logistic model, which assumes the existence of two distinct populations growing from the start of the culture, each following a different growth profile. In contrast, the improved logistic growth model developed in this study accounts for a single population growing at two rates, offering a fit to the experimental data comparable to that of the commonly used bi-logistic model. The enhanced model for product synthesis accurately describes biphasic AA production, assuming that antibacterial products are synthesized as growth-associated metabolites, depending on the final pH reached in the cultures at each sampling time. Additionally, it is easier to apply than the unmodified or modified differential forms of the Luedeking–Piret model. This study demonstrated, for the first time, the applicability of these two models in describing the diauxic growth and biphasic AA synthesis of LAB. Full article

This study investigated the effects of dietary mannan oligosaccharide (MOS) supplementation on growth performance, serum biochemistry, metabolomic profiles, and fecal microbiota in lactating Dezhou donkeys. Sixteen healthy jennies and their foals were randomly allocated to a control group (MCON), a group receiving no MOS, or an MOS-supplemented group (MMO; 0.5 g/kg diet) for 60 days. Compared with the MCON group, the MMO group showed a mitigation of lactational weight reduction, improved serum protein profiles, and favorable modulation of lipid metabolism. Furthermore, serum metabolomic analysis revealed 102 differentially abundant metabolites, which were enriched in 17 KEGG pathways involved in energy metabolism, bile secretion, and anti-inflammatory signaling. Key metabolites such as L-4-Chlorotryptophan, Gly-Trp, and cholylthreonine indicated enhanced nutrient metabolism and gut barrier function. Moreover, MOS supplementation significantly increased alpha diversity of the gut microbiota, altered community composition, and promoted the abundance of beneficial genera, including Clostridium and Bacteroides. Collectively, these results demonstrate that MOS supplementation improves metabolic health, modulates immune and antioxidant responses, and fosters a beneficial gut microbial ecosystem in lactating donkeys, suggesting its potential as an effective prebiotic in equine nutrition. Full article