Human–animal interactions are a cornerstone of the One Health approach, especially in Pakistan, where dogs occupy diverse ecological niches from households to streets, markets, veterinary clinics, and rural communities. These close and frequent contacts, coupled with increasing urbanization, animal movement, and climate variability, create opportunities for cross-species transmission of infectious agents, including influenza A viruses (IAV). Given their broad host range and high genetic plasticity, IAVs pose significant veterinary and public health concerns.
Dogs are susceptible to IAV from multiple origins, including avian (H3N2 and H5N1), equine (H3N8), and human (pandemic H1N1 and seasonal H3N2) sources. Among these, H3N8 and H3N2 have established themselves as the predominant canine influenza virus (CIV) subtypes globally. The avian-origin H3N2 CIV was first identified in South Korea (2004) and later in China (2006) and has since become endemic in Asia and North America. However, no data on CIV circulation, genetic diversity, or evolution have yet been reported from Pakistan, highlighting a critical gap in molecular surveillance.
In February 2026, a 7-year-old intact male Labrador (~25?kg) from Lahore, Pakistan, presented with acute respiratory signs, anorexia, persistent cough, thick nasal discharge, fever (104°F), lethargy, and ocular discharge. The dog had a history of frequent domestic travel and was annually vaccinated with Nobivac DHPPi, a multivalent parenteral vaccine intended to provide protection against canine distemper virus (CDV), canine adenovirus type 1 (CAV-1; infectious canine hepatitis), canine parvovirus (CPV), canine parainfluenza virus (CPi), and respiratory disease associated with canine adenovirus type 2 (CAV-2). Nasal swabs were collected in normal saline and tested for Canine Infectious Respiratory Disease Complex (CIRDC) pathogens using standard molecular assays. All major CIRDC agents tested negative except IAV, which was confirmed via PCR targeting the M and HA gene segments. The dog recovered within 2?weeks following supportive therapy.