Background and Aim: Feline bocavirus (FBoV), a member of the Parvoviridae family, has been implicated in gastrointestinal and respiratory conditions in domestic cats. Despite increasing global recognition, the molecular epidemiology of FBoV in Vietnamese animal populations remains largely unexplored. This study aimed to detect and genetically characterize FBoV strains circulating among domestic cats in Northern Vietnam to better understand their genotypic diversity and potential clinical relevance. Materials and Methods: A total of 166 fecal samples were collected from domestic cats of varying age, sex, and clinical status across four provinces in Northern Vietnam between 2022 and 2023. DNA was extracted and screened for FBoV using conventional polymerase chain reaction targeting the non-structural (NS)-1 gene. Positive samples were subjected to Sanger sequencing, and partial NS1 sequences were analyzed using MEGA X for phylogenetic inference. Recombination analysis was performed using RDP 4.0, and statistical significance was assessed using Fisher’s exact test. Results: FBoV DNA was detected in 4 of 166 samples (2.41%), including one from a diarrheic cat and three from healthy cats. Phylogenetic analysis of the partial NS1 gene revealed that three strains belonged to genotype I and one to genotype II, all showing close genetic similarity to Chinese strains. Nucleotide identities among Vietnamese strains ranged from 64.68% to 99.57%. No recombination events were observed among the detected strains. FBoV was detected across age groups and both sexes, without significant associations. Co-infections with other enteric viruses (feline coronavirus, feline panleukopenia virus, feline astrovirus, and feline kobuvirus) were not observed in the FBoV-positive samples. Conclusion: This study provides the first molecular evidence of co-circulating FBoV genotypes I and II in domestic cats in Vietnam, indicating viral genetic diversity and suggesting possible regional transmission routes linked to neighboring countries. While FBoV was present in both symptomatic and asymptomatic cats, its clinical significance remains inconclusive. The findings underscore the need for expanded surveillance, complete genome analyses, and investigation into FBoV’s pathogenic potential and co-infection dynamics in the feline population. These data will be instrumental in shaping future diagnostic and control strategies for feline viral enteritis in Vietnam. Keywords: domestic cats, feline bocavirus, genotype, molecular epidemiology, NS1 gene, Vietnam.

Background and Aim: Feline parvovirus (FPV) remains one of the most important viral pathogens affecting domestic cats worldwide and continues to cause substantial morbidity and mortality despite the availability of effective vaccines. Information regarding the molecular epidemiology, full-length VP2 and NS1 gene characteristics, evolutionary dynamics, and circulation of canine parvovirus (CPV) variants in cats remains limited in Vietnam. Therefore, this study investigated the epidemiological, molecular, and evolutionary characteristics of feline parvoviruses circulating in domestic cats in Northern Vietnam between 2022 and 2025. Materials and Methods: A cross-sectional molecular epidemiological study was conducted using 244 rectal swab samples collected from healthy and clinically affected domestic cats in Hanoi, Bac Ninh, Hung Yen, and Ninh Binh provinces during 2022–2025. Viral DNA was detected by conventional polymerase chain reaction targeting the VP2 gene. Nine representative positive samples were subjected to sequencing of the full-length VP2 and NS1 genes. Phylogenetic relationships, nucleotide identity, amino acid substitutions, recombination events, and natural selection profiles were analyzed using established bioinformatics tools. Associations between epidemiological variables and FPV positivity were evaluated using Fisher’s exact test. Results: Eleven of 244 samples (4.51%) were positive for parvovirus DNA. Cats younger than 12 months exhibited significantly higher infection rates than older cats (p < 0.05), whereas breed, sex, and health status were not significantly associated with viral detection. The VP2 and NS1 genes exhibited high nucleotide conservation, with identities ranging from 97.72%–100% and 98.20%–99.90%, respectively. Phylogenetic analyses demonstrated that seven isolates clustered with Asian FPV lineages, whereas two isolates grouped within the CPV-2c lineage, providing molecular evidence of CPV-2c infection in domestic cats. No recombination events were detected in either gene. Evolutionary analyses identified two positively selected sites within the NS1 protein together with numerous negatively selected sites, indicating predominantly purifying selection with localized adaptive evolution. Conclusion: FPV remains actively circulating among domestic cats in Northern Vietnam, with highly conserved VP2 and NS1 genes. The detection of CPV-2c in cats provides evidence of interspecies viral circulation and highlights the importance of integrated molecular surveillance. The observed adaptive evolution within the NS1 protein improves current understanding of parvovirus evolution and provides valuable baseline information for future epidemiological investigations, vaccine monitoring, and disease control strategies. Keywords: adaptive evolution, canine parvovirus-2c, feline panleukopenia virus, molecular epidemiology, NS1 gene, phylogenetic analysis, polymerase chain reaction, Vietnam.