Canine coronavirus (CCoV) generally causes an infection with high morbidity and low mortality in dogs. In recent years, studies on coronaviruses have gained a momentum due to coronavirus outbreaks. Mutations in coronaviruses can result in deadly diseases in new hosts (such as SARS-CoV-2) or cause changes in organ-tissue affinity, as occurred with feline infectious peritonitis virus, exacerbating their pathogenesis. In recent studies on different types of CCoV, the pantropic strains characterized by hypervirulent and multi-systemic infections are believed to be emerging, in contrast to classical enteric coronavirus infections. In this study, we investigated emerging hypervirulent and multi-systemic CCoV strains using molecular and bioinformatic analysis, and examined differences between enteric and pantropic CCoV strains at the phylogenetic level. RT-PCR was performed with specific primers to identify the coronavirus M (membrane) and S (spike) genes, and samples were then subjected to DNA sequencing. In phylogenetic analysis, four out of 26 samples were classified as CCoV-1. The remaining 22 samples were all classified as CCoV-2a. In the CCoV-2a group, six samples were in branches close to enteric strains, and 16 samples were in the branches close to pantropic strains. Enteric and pantropic strains were compared by molecular genotyping of CCoV in dogs. Phylogenetic analysis of hypervirulent pantropic strains was carried out at the amino acid and nucleotide sequence levels. CCoV was found to be divergent from the original strain. This implies that some CCoV strains have become pantropic strains that cause multisystemic infections, and they should not be ruled out as the cause of severe diarrhea and multisystemic infections.

犬冠状病毒（CCoV）通常在犬中引起高发病率和低死亡率的感染。近年来，由于冠状病毒的爆发，对冠状病毒的研究得到了发展。冠状病毒中的突变可导致新宿主（如SARS-CoV-2）中的致命疾病，或引起猫科传染性腹膜炎病毒发生的器官组织亲和力变化，从而加剧其发病机理。在针对不同类型的CCoV的最新研究中，与经典的肠道冠状病毒感染相反，以高毒力和多系统感染为特征的全向性菌株被认为正在出现。在这项研究中，我们使用分子和生物信息学分析调查了新兴的高毒力和多系统CCoV菌株，并在系统发育水平上研究了肠型和全肠型CCoV菌株之间的差异。用特异性引物进行RT-PCR以鉴定冠状病毒M（膜）和S（穗）基因，然后对样品进行DNA测序。在系统发育分析中，26个样本中有四个被分类为CCoV-1。其余的22个样品均被分类为CCoV-2a。在CCoV-2a组中，有六个样品位于接近肠道菌株的分支中，有16个样品位于靠近全肠菌株的分支中。通过对犬的CCoV进行分子基因分型，比较了肠道和全肠菌株。在氨基酸和核苷酸序列水平上进行了高毒全能菌株的系统发育分析。发现CCoV与原始菌株不同。这意味着某些CCoV菌株已成为引起多系统感染的全系菌株，