Chapter 12 Canine Infectious Tracheobronchitis (Kennel Cough)
Canine infectious tracheobronchitis (ITB), also known as kennel cough, is a collection of highly contagious infectious diseases of the canine respiratory tract that cause acute tracheobronchitis and sudden onset of a paroxysmal cough lasting several days.
ETIOLOGY
• The two most important causes of canine ITB are canine parainfluenza virus (CPIV) and Bordetella bronchiseptica, a gram-negative, aerobic coccobacillus.
• Other infectious agents occasionally isolated from coughing dogs include canine adenoviruses (especially CAV-2), canine herpesvirus, reoviruses (types 1, 2, and 3), and mycoplasmas; however, these are considered to be of minor importance.
• Clinical outbreaks of disease often involve concurrent infection with more than one of these agents. Clinical disease is more severe in animals co-infected with more than one agent.
• Cats can also occasionally develop clinical respiratory disease associated with B. bronchiseptica (see Chapter 11).
Transmission
• These agents also can be transmitted by fomites (e.g., personnel, cages, and food and water bowls).
• Dogs infected with CPIV or CAV-2 shed the virus for only 1 week following recovery; however, dogs infected with B. bronchiseptica or mycoplasmas can become chronic carriers with persistent shedding.
Pathogenesis
• Individually, these infectious agents cause mild self-limiting disease or are harbored in the airways of asymptomatic carriers. Mixed infections are common and have a synergistic effect in producing more severe clinical disease.
• The primary target of these agents is the upper airway epithelium. The result is epithelial injury, acute inflammation, and dysfunction of the airway cilia.
CLINICAL SIGNS
• Acute onset of a loud, paroxysmal, hacking cough is due to tracheobronchitis. Even though the cough is sometimes described as dry-sounding, ITB is characterized by increased production of mucus.
• Cough may be more frequent during exercise, excitement, or changes in temperature and humidity of inspired air.
• Typically, affected dogs continue to eat, remain active and alert, and are nonfebrile. In severe cases, anorexia, depression, and fever may be present.
• Complicating bacterial pneumonia and even rare fatalities can occur with severe disease, especially in mixed infections in young or unvaccinated puppies from crowded environments such as pet shops and animal shelters.
