Canine mammary tumor (CMT) is the most common tumor in dogs, with 50% of malignant cases, and lacks an effective therapeutic schedule, hence its early diagnosis is of great importance to achieve a good prognosis. Microbiota is believed to play important roles in systemic diseases, including cancers. In this study, 91 tumors, 21 oral and fecal samples in total were collected from dogs with CMTs, and 31 oral and 21 fecal samples from healthy dogs were collected as control. The intratumoral, oral and gut bacterial community of dogs with CMTs and healthy dogs was profiled by 16S rRNA high-throughput sequencing and bioinformatic methods. The predominant intratumoral microbes were Ralstonia, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Pseudomonas, unidentified_Chloroplast and Bacteroides at the genus level. In addition, our findings demonstrated striking changes in the composition of the oral and gut bacterium community in the dogs suffered from CMTs compared to the healthy dogs, with a significant increase of Bacteroides which also was the significant microbial biomarker in the oral and gut bacterium community. It showed that the Bacteroides was shared in the intratumoral, oral and intestinal bacterial microbiomes, confirming that microbiota might travel from the mouth to the intestine and finally to the distant mammary tumor tissue. This study provides a new microbiological idea for the treatment of canine mammary tumors, and also provides a theoretical basis for the study of human breast cancer.

Canine pyometra frequently occurs in middle-aged to older intact bitches, which seriously affects the life of dogs and brings an economic loss to their owners. Hence, finding a key metabolite is very important for the diagnosis and development of a new safe and effective therapy for the disease. In this study, dogs with pyometra were identified by blood examinations, laboratory analyses and diagnostic imaging, and fifteen endometrium tissues of sick dogs with pyometra and fifteen controls were collected and their metabolites were identified utilizing a UHPLC-qTOF-MS-based untargeted metabolomics approach. The results indicated that the elevated inflammatory cells were observed in dogs with pyometra, suggesting that sick dogs suffered systemic inflammation. In the untargeted metabolic profile, 705 ion features in the positive polarity mode and 414 ion features in the negative polarity mode were obtained in endometrium tissues of sick dogs with pyometra, with a total of 275 differential metabolites (173 in positive and 102 in negative polarity modes). Moreover, the multivariate statistical analyses such as PCA and PLS-DA also showed that the metabolites were significantly different between the two groups. Then, these differential metabolites were subjected to pathway analysis using Metaboanalyst 4.0, and Galactose metabolism, cAMP signaling pathway and Glycerophospholipid metabolism were enriched, proving some insights into the metabolic changes during pyometra. Moreover, the receiver operating characteristic curves further confirmed kynurenic acid was expected to be a candidate biomarker of canine pyometra. In conclusion, this study provided a new idea for exploring early diagnosis methods and a safe and effective therapy for canine pyometra.

Gut microbes thrive by utilising host energy and, in return, provide valuable benefits, akin to a symbiotic relationship. Here, metagenomic sequencing was performed to characterise and compare the community composition, diversity and antibiotic resistance of the gut microbiota of Relict gull (Larus relictus) and Anatidae species. Alpha diversity analysis revealed that the intestinal microbial richness of L. relictus was significantly lower than that of Anatidae, with distinct differences observed in microbial composition. Notably, the intestines of L. relictus harboured more pathogenic bacteria such as clostridium, which may contribute to the decline in their population and endangered status. A total of 117 strains of Escherichia coli were isolated, with 90.60% exhibiting full susceptibility to 21 antibiotics, while 25.3% exhibited significant biofilm formation. Comprehensive Antibiotic Resistance Database data indicated that glycopeptide resistance genes were the most prevalent type carried by migratory birds, alongside quinolone, tetracycline and lincosamide resistance genes. The abundance of resistance genes carried by migratory birds decreased over time. This metagenomic analysis provides valuable insights into the intestinal microbial composition of these wild bird species, offering important guidance for their conservation efforts, particularly for L. relictus, and contributing to our understanding of pathogen spread and antibiotic-resistant bacteria.

The widespread application of carbapenems and other broad-spectrum antibiotics has significantly escalated the threat posed by highly drug-resistant Klebsiella pneumoniae to human public health. In this research, we isolated a carbapenem-resistant K. pneumoniae strain from the feces of pet dogs at a veterinary hospital in Changchun, Jilin Province, China. To gain insights into its genetic makeup and resistance mechanisms, we conducted comprehensive whole-genome sequencing and antimicrobial susceptibility testing on the isolated strain. Our findings revealed the presence of three distinct plasmids within the strain, classified as IncFIB&IncFII, IncR, and IncX3. Notably, the bla_NDM-5 gene, conferring resistance to carbapenems, was uniquely harbored on the IncX3 plasmid, which was devoid of any other resistance genes beyond bla_NDM-5. In contrast, the remaining two plasmids, IncFIB&IncFII and IncR, were found to encode an array of additional drug resistance genes, contributing to the strain’s broad-spectrum resistance phenotype. The IncX3 plasmid, specifically, measures 45,829 bp in length and harbors the IS5D-bla_NDM-5-Ble-MBL-PRAI cassette, which has been closely linked to the dissemination of bla_NDM-5 genes in K. pneumoniae strains. We reported the bla_NDM-5-carrying IncX3 in K. pneumoniae isolates recovered from the pet dog and revealed the molecular characterization. Emphasis should be placed on, and continuous monitoring carried out for, the dissemination of K. pneumoniae harboring the bla_NDM-5 gene among humans, companion animals, and their related environments.