Which organism is part of the normal respiratory flora of laboratory animals and can cause kennel cough in dogs?

• A. Bordetella bronchiseptica
• B. Brucella abortus
• C. Campylobacter fetus
• D. Escherichia coli

Answer: (A)

Bordetella bronchiseptica is a small gram-negative coccobacillus that commonly colonizes the upper respiratory tract of many mammals, including laboratory animals, where it can exist as part of the normal respiratory flora. In dogs, this organism is the classic cause of kennel cough (infectious tracheobronchitis), a highly contagious respiratory infection characterized by a harsh, dry cough. Transmission occurs through aerosols or direct contact with infected animals, and vaccines for kennel cough often include a Bordetella component to reduce disease severity and shedding. The other organisms listed are linked to different disease patterns—Brucella abortus with brucellosis in cattle, Campylobacter fetus with enteric infections, and Escherichia coli primarily with gut flora and infections—not kennel cough.