ToThe Irish Leonberger Club
From AntonellaPuggioni DVM, CertVDI, DipECVDI
European Veterinary Specialist in Diagnostic Imaging
Lecturer In Veterinary Diagnostic Imaging
UniversityVeterinaryHospital
SubjectKennel Cough
DateNovember 2007
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Kennel cough
Definition:“Kennel cough” is the “familiar” term referring to a relatively common pathology of the respiratory tract (the trachea and bronchi) that is also and more appropriately called Infectious tracheobronchitis. The term kennel cough originated by the fact that this is a pathology, as often happens with highly contagious respiratory diseases, that spreads more easily and extremely quickly when there are several dogs confined together in a populated, enclosed environment such as that of a kennel.
In reality dogs can become infected without having been in a kennel, but just for having been in contact with an infected dog.
Etiology:Kennel cough has to be considered a complex infection as there are several micro-organisms that “work” together to cause the pathology, as opposed to having only one etiologic agent as the cause.
The main component of this group of pathogens is BordetellaBronchiseptica, a bacterium that accounts for 80-90% of the cases of kennel cough. However, most times there are concurrent viral infections and the two most common viruses involved are Adenovirus and parainfluenza virus and in fact Bordetella infection is considered a complication of the viral infection.
The pathology is highly contagious due to the fact that the pathogens are airborne with dust and small particles and when dogs are closed together are easily spread amongst them by inhalation.
Pathogenesis:The whole respiratory tract is lined by a thin layer of microvilli, that with with the aid of the mucous normally present in healthy animals, keep the tract free of pathogens and other particles that could cause a reaction. When the microvilli are not working properly due to arrival of aggressive pathogens, changes in temperature or even congenital deficiencies in the villi structure, the delicate balance of the environment of the respiratory tract is altered and the microvillous lining becomes an ideal environment for replication of inhaled organisms, thereby leading to the onset of the clinical signs of the infections.
Clinical signs:The clinical signs of uncomplicated infectious tracheobronchitis are usually mild. The typical clinical sign is a dry, non-productive, harsh cough, that almost sounds like retching or like the dog has something stuck in its throat; the cough may be elicited by exercise. The animal is otherwise in good form in the initial and mild stages, eating and exercising normally. Complications may include the development of fever, and in more rare cases, pneumonia.
The incubation period varies depending on the agent, from 3 up to 10days.The clinical signs last about 7 to 21 days.
An affected dog can keep spreading the infection for up to 14 weeks even after it becomes asymptomatic.
Treatment:The common treatment for kennel cough is a symptomatic therapy to suppress the cough, but is it essential that anti-tussive (anti-cough) agents are not used if the cough is productive. Antibiotics are often added whenBordetella infection is suspected, or signs consistent with secondary bacterial complications are present (e.g. fever or a purulent nasal discharge). Either way, the owner should not discard the condition as an insignificant one and try to treat the animal without seeking the expertise of a veterinarian.
Prevention:Kennel cough can be prevented up to a certain point with the use of vaccines.
Two main types are available: intranasal and intramuscular formulations. The intranasal one assures a quicker immune response (within 4-5days). Although the intramuscular injection requires more time to be effective, it has been suggested that the immunity may last longer. The downside is that the commonly used vaccines are only active against Bordetellabronchiseptica and Parainfluenza 3 virus, and not all the other components of the syndrome.
Animals that have been infected have some immunity; however, the duration of such immunity is hard to establish.