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

Canine infectious respiratory disease (CIRD) may be associated with single virus infections or with a multifactorial etiology and are assigned to infectious agents that replicate sequentially or in synergy. 1 The main viral agents involved in CIRD include Canine distemper virus (CDV), Canine parainfluenza virus (CPIV), Canine adenovirus type 2 (CAdV-2) and Canid herpesvirus 1 (CaHV-1). 2 In Brazil, CDV infection is endemic in dog populations, is associated with respiratory and/or multisystemic disease, and causes thousands of deaths each year. 3, 4 Due to its impact on animal health, CDV is one of the most important infectious diseases in dogs. 2, 5 Similarly to CDV, CAdV-2 has a worldwide distribution and is a major agent of canine infectious tracheobronchitis (CIT) or "kennel cough", a disease characterized by restricted infection of the respiratory system. 6 CPIV has a wide distribution in canine populations with an estimated seroprevalence ranging from 30 to 70%. 7 CPIV infection is related to high population density; the virus is highly transmissible and presents with rapid dissemination between animals. 2 CaHV-1 has a worldwide distribution and is associated with respiratory and reproductive disease. 8 Like other Alphaherpesviruses, CaHV-1 establishes latent infections in nerve ganglia and can periodically reactivate the infection. 9 An estimated 30-100% of domestic dogs have antibodies to CaHV-1. 10 The transmission of respiratory viruses occurs through direct or indirect contact between animals, primarily through contaminated nasal secretions and aerosols. 1 CIRD may affect dogs of both genders and ages; puppies under 90 days old are more susceptible, as well as immunosuppressed dogs, animals without a history of vaccination; vaccination failures or maternal immunity may also contribute. 11 The disease presents a seasonal pattern with a higher incidence in cold months. 12 The diagnosis of CIRD is largely based on the epidemiology, clinical signs and response to therapy. However, an etiologic diagnosis requires the identification of the agent or its products (proteins or nucleic acids). 4 Vaccination is largely used to prevent or control respiratory infections in dogs and helps minimize clinical disease; however, current vaccines are not always effective. 11 In Brazil, despite the wide distribution of these infections and informal reports by veterinarians, very few reports describe viral respiratory disease in dogs. [13] [14] [15] [16] [17] [18] Additionally, there is little information regarding these infections in local environments with high densities and constant animal movement such as dog shelters. The identification of the more common respiratory viruses in dogs in various epidemiological conditions is essential for developing efficient control and prevention measures.