Detection of respiratory viruses in shelter dogs maintained under varying environmental conditions

Monteiro, Francielle Liz; Cargnelutti, Juliana Felipetto; Martins, Mathias; Anziliero, Deniz; Erhardt, Magnólia Martins; Weiblen, Rudi; Flores, Eduardo Furtado

In this shelter, CDV, CPIV and CAdV-2 were detected in single or mixed infections, corresponding to 78% of the positive dogs. CPIV was detected in 71% of the samples, of which 30% were single infections and 41% were associated with CAdV-2 and/or CDV. CPIV is considered the primary virus involved in respiratory disease in dogs, 2,7,26-29 and has been most frequently reported in conditions of high animal density. 2 CPIV infection produces pathology in the tracheal epithelium 15 and favors secondary respiratory infections by other pathogens such as CAdV-2. 6 In shelter #1, CDV was detected only associated with CAdV-2 and/or CPIV, corresponding to 21% of the positive samples. CDV replication occurs in epithelial cells and macrophages of the upper respiratory system, pharynx and tonsils, followed by lymph node infection and systemic dissemination that can evolve to multisystem disease and immunosuppression. 30 For this reason, bacterial secondary infections are often detected in dogs with distemper in addition to coinfection by other viruses, such as CAdV-2 and CaHV-1. 5, 31, 32 CAdV-2 detection in 45% of the samples from shelter #1 may have been influenced by the high CPIV and CDV infections in the kennel because CPIV promotes primary lesions in the tracheal epithelium 15 and CDV induces immunosuppression. 30 Additionally, adenoviruses are highly resistant in environmental conditions and remain viable in the environment for an extended duration, thereby favoring dissemination among animals. 6 Notably, a high prevalence of CAdV in dog populations has been reported in shelters without a history of vaccination. 33, 34 An investigation of respiratory viruses in dogs in Germany analyzed 58 samples of shelter animals with and without respiratory signs and detected 22.4% (13/58) to be positive for CPIV and one positive for CAdV-2 and CPIV. 29 A similar study performed in Germany examined 68 nasal swabs of domestic dogs 28 ; in this study, 7.4% (5/68) of the samples were positive for CPIV, 2.9% (2/68) for CAdV-2 and 1.5% (1/68) for CDV. Despite varying frequencies, these studies reported CPIV to be the most frequent respiratory virus in dogs, followed by CAdV-2 and CDV.