27 - Canine Respiratory Coronavirus Infection

Abstract

•Causes: CRCoV belongs to the genus Betacoronavirus of the Coronaviridae family. It was thought to arise from bovine coronavirus (BoCoV) through a cross-species transmission event, as suspected for the closely related human coronavirus OC43 (HCoV-OC43). Viruses of the Betacoronavirus genus are typically responsible for either respiratory or enteric disease. Enteric CCoV is a different coronavirus that belongs to the genus Alphacoronavirus.•First Described: CRCoV was first reported in 2003 in a group of dogs newly introduced in a rehoming facility in the United Kingdom where enzootic respiratory disease was reported despite regular vaccination. The earliest report has been ascribed to an old sample collected in Canada in 1996 based on a retrospective study, but earlier circulation cannot be ruled out.•Affected Hosts: Natural infection with CRCoV has been reported only in dogs, supported by Koch’s postulates by experimental infection. Similarly, CCoV only causes disease in canids, although in 2021 a recombinant CCoV was identified in humans with respiratory illness in Malaysia.•Geographic Distribution: Both CRCoV and CCoV have been found worldwide. Serologic studies and molecular surveys have detected CRCoV in Europe, the United States and Canada, Japan, Korea, China and New Zealand, demonstrating a global distribution of CRCoV with various prevalence rates.•Route of Transmission: CRCoV is a highly infectious pathogen with respiratory tropism. Oronasal transmission due to shedding of viral particles through respiratory secretions is considered preferential. In addition, CRCoV has been detected in the feces from naturally infected dogs, thus suggesting a possible fecal-oral transmission, although this was not confirmed experimentally.•Major Clinical Signs: Like CCoV, CRCoV often causes subclinical infections. When disease occurs, CRCoV infection is associated with mild respiratory signs including nasal discharge, sneezing, and cough, which have been documented in natural and experimental infections. CRCoV is a significant contributor to the CIRD complex, predisposing dogs to secondary infections and more severe clinical signs. Occasionally, CRCoV has been detected in dogs with nonrespiratory disease, although whether this virus was responsible for the observed signs was unclear since other pathogens were also detected. A hypervirulent strain of CCoV, known as pantropic CoV, can also infect the respiratory tract, but most affected dogs have shown GI and neurologic signs, in association with leukopenia.•Differential Diagnoses: Differential diagnosis for CRCoV infection includes infection by other CIRD-associated pathogens, such as CAdV-2, CPIV, CHV-1, Bordetella bronchiseptica, Mycoplasma cynos, and Streptococcus equi subsp. zooepidemicus, together with influenza viruses, canine pneumovirus (CPnV), pantropic CCoV, and mammalian reovirus (MRV).•Treatment and Prevention: For CRCoV, no specific treatment has been tested yet and, to date, vaccines are not available. Vaccines available for prevention of CCoV infection do not protect against CRCoV infection.•Human Health Significance: There are no reports of disease caused by CRCoV in humans or animals other than dogs. Nonetheless, animal CoVs are regarded as a potential threat by the scientific community, chiefly after the emergence of SARS CoVs and Middle East Respiratory Syndrome (MERS), since potential cross-species transmission may occur from animals to humans.