Abstract: [Objective] In August 2023,an outbreak of infectious disease characterized by respiratory symptoms was reported on one cattle farm in Tianjin. To determine the cause of the disease,we conducted etiological diagnosis of the relevant pathogens in the affected calves. [Method] Lung specimens were collected from dead calves. We used the PCR method to detect seven bovine respiratory pathogens,including Bovine parainfluenza virus type 3,Bovine respiratory syncytial virus,Bovine herpesvirus type 1,Bovine adenovirus type 3,Mycobacterium bovis, Bovine Klebsiella bovis and Mycoplasma bovis. [Result] The results showed that two pathogens,BHV-1 and BAdV-3,were detected in the samples,and there was mixed infection. No other pathogens were detected. [Conclusion] This study confirmed the existence and prevalence of BHV-1 and BAdV-3 in dairy cows in this cattle farm,which provided reference for the prevention and control of respiratory diseases.

Key words: Bovine herpesvirus type 1, Bovine adenovirus type 3, etiology