Mammalian orthoreoviruses (MRVs) and Rotavirus A (RVA) are double-stranded RNA viruses with zoonotic potential that can infect a wide range of mammalian hosts, including companion animals. Data on their circulation in dogs and cats remain limited worldwide. Building on a previous study conducted on shelter-housed dogs and cats (RC IZSVE 12/19), this study investigated the presence of MRV and RVA in owned dogs and cats primarily from Northeastern Italy. Between 2023 and 2025, a total of 648 fecal samples from 278 dogs to 370 cats were collected within a research project (RF MRV 21) and analyzed by multiplex rRT-PCR targeting conserved regions of the MRV L1 and RVA NSP3 genes. MRV-positive samples were subjected to viral isolation in Vero cells. Samples were also examined for Canine and Feline Coronavirus (CCoV and FCoV), Canine parvovirus type 2 and Feline panleukopenia virus (CPV-2 and FPV) and intestinal parasites using standard copromicroscopic methods as part of differential diagnosis for gastroenteric disorders. MRV RNA was detected in 2 dogs (0.7%) and 3 cats (0.8%). RVA was identified in 4 dogs (1.4%) and 7 cats (1.9%). MRV isolation was attempted from all positive samples (dogs: 2/278, 0.72%; cats: 3/370, 0.81%), as well as from MRV-positive samples identified in the previous study (dogs: 1/257, 0.39%; cats: 11/388, 2.83%), and was successfully achieved for seven feline (7/14, 50.00%) and one canine samples (1/3, 33.33%). For animals positive for MRV and/or RVA, if symptomatic, the more common differential diagnoses were considered. This study provides comprehensive molecular evidence of MRV and RVA circulation in dogs and cats in Italy. The detection and successful isolation of MRVs from both species highlight their potential role in viral ecology and the importance of continued surveillance to assess zoonotic risks at the human-animal interface.
Campalto et al. (Wed,) studied this question.