The emergence of colistin-resistant Escherichia coli (E. coli) in livestock poses a major public health concern due to its zoonotic potential and multidrug resistance (MDR). The study aimed to detect mobilized colistin resistance genes (mcr-1 to mcr-9) in E. coli isolates, along with characterizing their antimicrobial susceptibility, resistance genes, virulence genes, and whole genome sequencing. We investigated E. coli contamination in a swine slaughterhouse in Nakhon Si Thammarat Province, Thailand. A total of 200 fecal samples were collected and screened for E. coli using selective media supplemented with colistin. A total of 200 fecal samples were collected from a swine slaughterhouse and screened for E. coli using selective media supplemented with colistin. Presumptive E. coli isolates were confirmed by PCR, followed by molecular detection of mcr-1 to mcr-9 genes. Antimicrobial susceptibility testing was performed using the disk diffusion method. Selected isolates were further analyzed for additional antimicrobial resistance genes and virulence associated genes by PCR. Whole genome sequencing was conducted on representative isolates exhibiting high levels of antimicrobial resistance. Our results showed that out of 200 fecal samples, 124 presumptive E. coli isolates were recovered from a swine slaughterhouse using selective media containing colistin. PCR confirmation identified 112 isolates (90.32%) as E. coli. Molecular detection of mobilized colistin resistance (mcr) genes (82 isolates, 73.21%) demonstrated that mcr-1 (50.89%) was the most prevalent, followed by mcr-9 (25.89%) and mcr-3 (24.11%). Overall, the 82 mcr E. coli isolates showed the highest level of resistance to ampicillin (97.56%), followed by tetracycline (95.12%), piperacillin (73.17%), and chloramphenicol (65.85%). For non-mcr E. coli isolates, the highest resistance percentage was observed for ampicillin (96.67%), followed by piperacillin (80%) and tetracycline (73.33%). Among the isolates, 75% exhibited MDR phenotypes, showing 22 distinct resistance profiles. The most common MDR pattern was AMP-PIP-TE-C-S (12.5%). Additional antimicrobial resistance genes, including aadA, ampC, and bla_TEM, were detected in over 60% of a subset of 30 tested isolates. The virulence gene analysis revealed that eae (74.10%), associated with enteropathogenic E. coli (EPEC), was the predominant pathotype. Whole genome sequencing of five selected isolates confirmed the presence of multiple antimicrobial resistance and virulence determinants. In conclusion, this study reveals a high prevalence of MDR E. coli harboring colistin resistance genes (mcr-1 to mcr-9) in a swine slaughterhouse in southern Thailand. The findings highlight the potential risk of zoonotic transmission of antimicrobial resistant E. coli through the food production chain and emphasize the importance of continuous genomic surveillance and prudent antimicrobial use in livestock production systems.

Antimicrobial resistance (AMR) in Escherichia coli (E. coli) from companion dogs is an emerging One Health concern because dogs may serve as asymptomatic reservoirs of multidrug-resistant (MDR) and potentially pathogenic bacteria that can be transmitted to humans. This study aimed to determine antimicrobial susceptibility profiles, characterize antimicrobial resistance and virulence associated genes, and identify nucleotide substitutions in resistance determinants of E. coli isolated from healthy dogs in Thailand. Fecal samples (n = 200; 100 samples per province) were collected from healthy dogs attending a total of 50 small animal clinics located in Nakhon Si Thammarat and Chiang Mai provinces between January and March 2026. E. coli isolates were identified by culture and polymerase chain reaction (PCR) confirmation. Antimicrobial susceptibility was evaluated against 12 antimicrobial agents using the disk diffusion method according to CLSI guidelines. Thirty randomly selected isolates were further screened for resistance and virulence-associated genes by PCR, and the tetA gene was sequenced to identify nucleotide substitutions. Differences in gene distributions between provinces were assessed using Fisher’s exact test. A total of 66 E. coli isolates were recovered. High resistance rates were observed for ampicillin (100%), piperacillin (84.85%), ceftriaxone (60.61%), tetracycline (56.06%), and aztreonam (46.97%). Multidrug resistance was identified in 47% of the isolates. The 30 isolates exhibiting the highest levels of antimicrobial resistance were selected for molecular characterization. Among these, the β-lactam resistance gene bla_TEM was significantly more prevalent in Nakhon Si Thammarat than in Chiang Mai (60% vs. 0%; p = 0.022). The virulence gene stx2 was also detected significantly more frequently in isolates from Nakhon Si Thammarat (93.33% vs. 26.67%; p < 0.001). Sequence analysis of tetA revealed multiple nucleotide substitutions in two isolates, suggesting ongoing genetic variation within tetracycline resistance determinants that may contribute to the evolution and persistence of antimicrobial resistance. These findings demonstrate that healthy dogs in Thailand can act as reservoirs of MDR and potentially virulent E. coli. The observed geographic variation in resistance and virulence gene distributions highlights the importance of antimicrobial stewardship and continuous molecular surveillance in companion animals within a One Health framework.

Streptococcus suis is an important cause of disease in pigs and an emerging source of severe human infection, with increasing concerns regarding antimicrobial resistance. This study assessed the occurrence and seroprevalence of S. suis in healthy pigs and characterized the antimicrobial susceptibility, serotypes, virulence associated genes, and genomic features of colonizing isolates. A total of 58 pigs (13 farm pigs and 45 abattoir pigs) were sampled. Among 176 presumptive isolates recovered by culture, 60 were confirmed as S. suis by polymerase chain reaction (PCR) and were subsequently analyzed. Antimicrobial susceptibility was determined by the disc diffusion method, selected resistance and virulence genes were detected by conventional PCR, and two representative isolates were subjected to whole-genome sequencing (WGS) and comparative genomic analyses. Seroprevalence was determined using an indirect ELISA detecting IgG antibodies against S. suis serotype 2 antigen. S. suis was confirmed in 60/176 presumptive isolates (34.1%), most frequently from nasal swabs and tonsils, whereas no blood isolates were detected. The seropositivity rate was 65.5%. High resistance rates were observed for ceftriaxone, ampicillin, cefepime, clindamycin, and tetracycline, and multidrug resistance was common. Tetracycline- and macrolide-associated resistance genes were frequently detected. Serotypes 2/1⁄2 predominated, whereas major classical invasive virulence genes were not detected, consistent with predominantly colonizing strains. Whole genome sequencing of two representative isolates confirmed species identity and revealed substantial genomic diversity, including a markedly larger genome in a tonsillar isolate, suggesting acquisition of accessory genetic elements. These findings demonstrate that healthy pigs can harbor genetically diverse and antimicrobial resistant S. suis, highlighting the importance of continued surveillance to support antimicrobial stewardship and reduce zoonotic risk.

Although internal fixation and surgical approaches promote fracture healing, some outcomes remain unsatisfactory. Advanced platelet-rich fibrin (A-PRF) has been shown to provide more growth factors, and in vitro cell proliferation has not been evaluated for treating bone fractures in veterinary medicine. The purpose of this study was to evaluate the bone-healing activity of A-PRF in traumatic canine fractures. Twelve dogs with single radius–ulna or tibia–fibula fractures were randomly assigned to two groups: a control group and an A-PRF group. Both groups were treated with a locking compression plate and screws and received pain control. Post-operatively, dogs were evaluated for serum C-reactive protein (CRP) levels and post-operative pain scores on days 1, 3, and 7. Lameness and weight-bearing scores were evaluated on days 1, 3, 7, 14, 30, and 60. Bone healing was assessed at 2 weeks, 1 month, and 2 months using calculated relative bone density (%). Compared with the control, the A-PRF group showed higher bone density at 2 months and lower lameness at 14 days post-operatively. Although the CRP level, an inflammation response marker, was higher in the A-PRF group within one day. No significant difference in pain score was observed. In conclusion, A-PRF serves as an effective adjunctive therapy for promoting bone healing when treating canine appendicular fractures with surgical internal fixation.

Early detection of canine cognitive dysfunction syndrome (CDS) is challenged by the limitations of single diagnostic tools, including owner-reported subjectivity and impractical behavioral testing protocols. This study examined a multidomain strategy integrating questionnaires, behavioral testing, and a circulating biomarker to identify measures associated with mild cognitive impairment in aged dogs. A total of 21 aged dogs were classified as cognitively normal (n = 9) or mildly cognitively impaired (n = 12) using the Canine Dementia Scale (CADES), and they were further assessed based on the Canine Cognitive Dysfunction Rating Scale (CCDR), a battery of behavioral tests across six cognitive domains, and serum brain-derived neurotrophic factor (BDNF) concentrations. The CADES scores differed significantly between the mildly cognitively impaired and cognitively normal groups (median 12.5 vs. 0, p < 0.01), whereas the CCDR scores did not (p = 0.114). Among the behavioral measures, the delayed match-to-sample task with a 20-s delay and the recognition index derived from novel object recognition testing were significantly associated with cognitive group classification; the other domains showed no significant associations. Serum BDNF concentrations did not differ between the groups or predict group membership. The results of this exploratory study show that targeted behavioral measures may be more strongly associated with mild cognitive impairment than circulating BDNF, thus supporting their potential utility for early cognitive screening in clinical settings. However, these findings should be interpreted with caution, and their diagnostic accuracy should be confirmed in larger cohorts with further validation.