Co-infections with Respiratory Viruses in Dogs with Bacterial Pneumonia

Viitanen, S.J.; Lappalainen, A.; Rajamäki, M.M.

Bacterial pneumonia is a serious lower respiratory tract infection in dogs with substantial morbidity and risk of mortality. Although BP was described in Dogs decades ago, information on the mechanisms leading to the development of the disease still is limited. Factors such as diseases predisposing to aspiration, immunodeficiency, or ciliary dysfunction that lead to impairment of pulmonary defense mechanisms and thereby predispose to the development of BP have been described. 3 However, the role of preceding or concurrent infections with CIRD viruses has not been fully evaluated in dogs with BP, although it has been suspected to play a role in the etiology, as reported in humans with CAP. [34] [35] [36] [37] [38] [39] Previously, respiratory viral-bacterial co-infections mostly have been reported in dogs housed in dense populations, such as kennels and rescue shelters, and bacteria accompanying viruses have been primary CIRD bacteria (B. bronchiseptica, S. equi sp. zooepidemicus, and Mycoplasma spp.). 6, 7, 19, 44 Our study indicates that respiratory viruses, primarily CPIV, frequently are also found in dogs with BP, which is caused by opportunistic bacteria. Therefore, it is likely that CIRD viruses can predispose dogs to opportunistic bacterial lung infections by increasing bacterial adhesion, as has been reported in humans. 35 In this study, CPIV was the most common viral pathogen detected, which is in accordance with previous reports describing viruses responsible for CIRD in different countries. 6, 13, 19 Novel CRCoV was detected in 1 dog with BP, further demonstrating that CRCoV has a worldwide distribution and also may be detected in Northern Europe.