Abstract
Feline parvovirus (FPV) and canine parvovirus (CPV) are highly contagious pathogens that cause severe enteritis in companion animals, leading to considerable morbidity and mortality, particularly in young and unvaccinated animals. The continuous evolution of CPV variants and increasing evidence of cross-species transmission present major challenges for disease diagnosis, surveillance, and control. This study aimed to determine the prevalence of FPV and CPV infections among cats and dogs in Gujarat, India, compare the diagnostic performance of rapid antigen testing (RAT), conventional polymerase chain reaction (PCR), and quantitative PCR (qPCR), characterize circulating viral variants through VP2 gene sequencing and phylogenetic analysis, and investigate evidence of cross-species circulation. A cross-sectional study was conducted between September 2024 and September 2025 using 200 fecal samples collected from 100 cats and 100 dogs presented to veterinary clinics, shelters, and rescue organizations in Gujarat, India. Samples were examined using RAT, conventional PCR targeting the VP2 gene, and duplex probe-based qPCR to differentially detect FPV and CPV. Representative positive samples were subjected to VP2 gene sequencing, phylogenetic analysis, and virus isolation in Crandell-Rees feline kidney cell cultures to evaluate viral replication. Epidemiological characteristics, including species, age, breed, vaccination status, and clinical presentation, were also assessed. RAT detected FPV and CPV in 10 (5.0%) and 80 (40.0%) samples, respectively, whereas conventional PCR identified 39 (19.5%) parvovirus-positive samples. Duplex qPCR demonstrated markedly superior sensitivity, detecting 124 (62.0%) positive samples, comprising 27 FPV and 97 CPV infections. Cross-species circulation was demonstrated by detection of CPV in 12% of cats and FPV in 1% of dogs. Sequencing of the VP2 gene revealed genetically conserved FPV isolates and predominance of CPV-2c among canine isolates, including a novel CPV-2c variant carrying unique amino acid substitutions suggestive of ongoing viral evolution. Virus isolation successfully confirmed replication in four of nine inoculated samples, producing characteristic cytopathic effects in Crandell-Rees feline kidney cells. FPV and CPV co-circulate among companion animals in Gujarat, with molecular evidence of cross-species transmission and predominance of CPV-2c variants. Duplex qPCR substantially outperformed RAT and conventional PCR, supporting its routine application for accurate diagnosis, epidemiological surveillance, and early detection of emerging parvovirus variants. Continuous molecular surveillance combined with sustained vaccination programs is essential to limit viral dissemination and improve control of parvoviral infections.
