Age, Season and Vaccination Status as Key Determinants of Respiratory Viral Infection in Dogs of North-East India

Abstract

The occurrence of respiratory viral infection in dogs is governed not only by the causative viral agent but also by several host and environmental factors, and identifying these risk factors is essential for designing effective, targeted control and vaccination strategies. However, risk-factor data on canine respiratory viral infection specific to North-East India remain scarce. This study was therefore undertaken to assess the incidence of virus-associated respiratory infection in relation to age, sex, breed, season and vaccination status in dogs presented with respiratory signs at the Veterinary Clinical Complex, College of Veterinary Science, AAU, Khanapara, Guwahati, Assam, over a period of one and a half years. A total of 280 dogs were examined and screened by PCR/RT-PCR, and the association between each risk factor and infection was tested using the chi-square test, with 97 dogs (34.64%) testing positive for one or more respiratory viruses. Incidence was significantly higher in puppies aged 0–6 months (16.79%) compared with older age groups (χ² = 19.56, P < 0.01), during the winter season (21.43%) compared with the pre-monsoon, monsoon and post-monsoon periods (χ² = 51.84, P < 0.01), and in unvaccinated dogs (22.14%) compared with vaccinated and irregularly vaccinated dogs (χ² = 47.64, P < 0.01). Among breeds, mongrels recorded the highest incidence (7.50%), followed by crossbred dogs (6.79%) and German Shepherds (5.36%), although the difference among breeds was not statistically significant (χ² = 6.95). A numerically higher, though statistically non-significant, incidence was also recorded in male dogs (21.07%) relative to females (13.57%). These findings identify young age, absence of regular vaccination and the winter season as the principal determinants of infection risk in this population, and underscore the importance of timely, complete vaccination schedules, targeted care for young and unvaccinated dogs, and season-specific owner awareness programmes in reducing the burden of respiratory viral disease among dogs of North-East India. Keywords: Canine respiratory viral infection; Risk factors; Age; Vaccination status; Seasonality