H3N2 Canine Influenza Virus Infection in a Dog.

In 2015, H3N2 canine influenza emerged in dogs in the greater Chicago area. During this time, a 10-year-old German Shepherd dog presented to the referring veterinarian with lethargy and coughing that quickly progressed to death. This report describes the macroscopic and microscopic lesions and the molecular testing performed to identify the novel North American H3N2 strain of canine influenza. The larynx, pharynx, and trachea were covered by a fibrinonecrotic membrane. Bilaterally, the lungs had multifocal subpleural necrosis of the caudal lung lobes with hemorrhage, congestion, and pulmonary edema. Staphylococcus pseudointermedius was isolated from the lung. Mycoplasma cynos was identified by real-time polymerase chain reaction from nasal passages, oropharynx, larynx, trachea, and cranial lung lobes. The neuraminidase gene sequence from the influenza virus isolated obtained from this dog had ≥98% homology to the strain circulating in the Chicago area.