Beyond the surface: Exploring the blood microbiomes of Namibian dogs and cats

Research on blood microbiomes in dogs and cats remains limited, particularly in southern Africa. This study characterised blood-associated bacterial deoxyribonucleic acid in domestic dogs and cats from eight Namibian regions using near-full-length 16S ribosomal ribonucleic acid gene sequencing and an amplicon sequence variant (ASV) approach. Archived whole blood samples from 57 dogs and five cats, selected based on previous molecular screening results, were analysed using Pacific Biosciences long-read sequencing. Following quality control and contaminant filtering, 141 ASVs were retained across 61 samples. Proteobacteria predominated among the detected bacterial sequences, alongside Tenericutes, Bacteroidetes, Actinobacteria, and Firmicutes. Alpha diversity did not differ significantly between regions, whereas beta diversity revealed significant regional differences in microbial community composition ( P PERMANOVA = 0.002). Phylogenetic analysis identified ASVs closely related to Ehrlichia canis , Anaplasma platys , several haemotropic Mycoplasma species, and an uncultured Bartonella species. Notably, an E. canis -associated ASV was identified in feline samples, while additional ASVs associated with haemotropic Mycoplasma species and Bartonella expanded the molecular characterisation of these bacterial taxa in Namibian companion animals. This study represents the first ASV-based investigation of blood-associated bacterial communities in Namibian dogs and cats, providing insight into bacterial diversity and phylogenetic relationships. The findings expand our understanding of bacterial taxa of veterinary importance in Namibian companion animals and provide a foundation for further molecular surveillance and investigation of potentially pathogenic and zoonotic bacteria.