Kennel cough, or tracheobronchitis, describes a group of infections affecting the trachea and bronchial tubes that cause a harsh, spasmodic cough. The cough associated with kennel cough leads some owners to believe that their dogs have something stuck in their throats.
Roughly analogous to a human chest cold, most cases of tracheobronchitis resolve on their own without causing permanent harm to the dog. Severe cases of kennel cough, however, can result in pneumonia or other dangerous viral diseases, such as distemper.
The Mucociliary Escalator and Kennel Cough
Kennel cough is more likely to develop in dogs with damaged mucociliary escalators. The term “mucociliary escalator” refers to the mucus and cilia that trap foreign particles and move them out of the respiratory tract and is part of the respiratory system’s defenses.
Cilia “beat” in unison, creating a wave effect in the mucus layer that carries debris up and out of the respiratory tract, so it can be either coughed up or swallowed.
If the mucociliary escalator is damaged or compromised, infectious agents can enter the lungs and cause infections. Possible sources of mucociliary escalator damage include:
- cigarette smoke exposure
- cold temperatures
- exposure to excessive dust
- inadequate ventilation
- shipping stress
- stress due to crowded conditions.
Certain infections, such as parainfluenza, canine distemper, adenovirus and reovirus, can also damage the mucociliary escalator.
Bordetella and Kennel Cough
Rather than being caused by a single infection, kennel cough is a complicated virus that can be caused by a wide range of infectious agents. The list includes bacterial agents, viral agents (including canine distemper) and mycoplasma (organisms that combine features of viral and bacterial agents).
The most common cause of kennel cough is Bordetella brochiseptica, a type of bacteria that accounts for up to ninety percent of all cases of tracheobronchitis. While kennel cough is typically caused by more than one infectious agent, Bordetella is most often one of the main components.
Bordetella can directly affect the mucociliary escalator: within three hours of the infection the bacteria attach to the cilia, preventing the cilia from moving.
Kennel Cough Transmission
Kennel cough has always been associated with dog kennels, where large numbers of dogs are housed together. Oftentimes, kennels have poor air ventilation, promoting the spread of viruses and bacteria. In fact, a dog may be exposed to the bacteria that cause tracheobronchitis anywhere that is crowded, has poor ventilation and has warm air. Such locations may include:
- animal shelters
- boarding kennels
- dog parks
- grooming parlors
- obedience classes
- vaccine clinics
- veterinary clinics.
The most noticeable symptom of kennel cough is a dry, barking cough that sounds like something is stuck in the dog’s throat. Indeed, most veterinarians, on hearing worried owners say something is lodged in their pet’s throat, immediately suspect kennel cough.
The cough results from inflammation of the trachea and bronchial tubes. At the end of a coughing spasm, the dog often coughs up a white, foamy discharge.
Other than the cough, most dogs appear in good health, remaining active with normal appetites. Some may develop conjunctivitis (inflammation of the eye membranes), rhinitis (nasal membrane inflammation) or nasal discharge.
While tracheobronchitis is usually not a long-term health risk, problematic symptoms include:
- thick yellow or green nasal discharge
- unusual lung sounds.
These symptoms may indicate further infection, such as pneumonia or canine distemper. Blood work and chest x-rays may be required to determine if other conditions are present.
Treating Kennel Cough
Most cases of kennel cough clear up without the need for treatment and resolve on their own within one to two weeks.
While some veterinarians will prescribe antibiotics to speed recovery, others prefer not to use antibiotics unless tracheobronchitis is severe or persistent. In either case, veterinarians may also recommend cough suppressants to alleviate coughing symptoms as the disease runs its course.
Having had kennel cough once does not make dogs immune to further bouts of tracheobronchitis, as kennel cough can be caused by many different infectious agents. A bout of Bordetella, the agent most often responsible for kennel cough, only grants short term immunity to the bacterium. Consequently, the dog may be re-infected with Bordetella in the future.
Vaccinations and Kennel Cough
Kennel cough vaccinations come in two forms, intranasal and injectable. The intranasal vaccine may be given when pups are as young as two weeks old and provides immunity for up to a year. Following this initial dose, booster shots are required to maintain immunity. Intranasal vaccinations provide a quick immune response, along with local immunity against kennel cough.
Injectable vaccinations require two initial doses and an annual booster. Injectable kennel cough vaccinations may not provide complete immunity but will make a bout of kennel cough less severe.