| Kennel cough is a disease affecting the trachea and
bronchi caused by two infectious agents; a virus, parainfluenza and a
bacteria, Bordetella Bronchiseptica. Kennel cough is characterized by a
deep, harsh, hacking cough which most people describe as sounding like
“something stuck in my dog’s throat.”
How Does Infection Occur?
The normal respiratory tract has substantial safeguards against invading
infectious agents.
The most important of these is probably what is called the mucociliary
escalator. This safeguard consists of tiny hairlike structures called
cilia, which protrude from the cells lining the respiratory tract, and a
coat of mucus over them. The cilia beat in a coordinated fashion.
Debris, including infectious agents, get trapped in the sticky mucus and
the cilia move the mucus upward towards the throat where the collection
of debris and mucus may be coughed up and/or swallowed.
The mucociliary escalator is damaged by the following:
- Shipping stress
- Crowding stress
- Heavy dust exposure
- Cigarette smoke exposure
- Infectious agents (viruses such as reovirus, adenovirus, parainfluenza
virus, and even the distemper virus can be initiating infections)
- Cold temperature
- Poor ventilation
Without this protective mechanism, invading bacteria, especially
Bordetella bronchiseptica may simply march down the airways unimpeded.
Bordetella bronchiseptica has some tricks of its own as well:
- It is able to bind directly to cilia, rendering them unable to move
within 3 hours of contact.
- It secretes substances that disable the immune cells normally
responsible for consuming and destroying bacteria.
Because it is common for Bordetella to be accompanied by at least one
other infections agent (such as one of the viruses listed above), kennel
cough is actually a complex of infections rather than infection by one
agent.
Classically, dogs get infected when they are kept in a crowded situation
with poor air circulation but lots of warm air (i.e., a boarding kennel,
vaccination clinic, obedience class, local park, animal shelter, animal
hospital waiting room, or grooming parlor).
How do we diagnose Kennel Cough?
Kennel cough must be differentiated from many of the other diseases that
can cause coughing, including:
- Pneumonia
- Heart Failure
- Tumors in the Lungs
- Foreign Bodies in the respiratory tree
- Allergic Bronchitis
Diagnosis is based on clinical history, vaccination history, x-rays of
the chest and blood tests.
How Contagious Is it? Bordetella infection is highly contagious to other dogs, and can be
picked up by rabbits, guinea pigs, pigs, cats (if they are very young
and housed in groups). It is not contagious to humans though it is
closely related to Bordetella pertussis, the agent of whooping cough.
The incubation period (time from exposure to showing clinical symptoms)
ranges from 2 to 14 days.
How is it Treated? Kennel cough is treated antibiotics which kill the Bordetella organism.
In addition, cough suppressants are utilized to provide comfort during
recovery. The viral portion of the infection can not be treated directly
and must run its course.
When Is it a Serious Condition?
In very young puppies and debilitated pets, especially those with a
recent shipping history (i.e., pet store puppies) are especially prone
to severe cases of infectious tracheobronchitis which may develop into
pneumonia (infection of the lungs). In dogs where the distemper virus is
involved (usually shelter or pet store puppies), there is tremendous
potential for serious consequences. In these circumstances more
aggressive diagnostic testing (including tracheal washes and culture of
sputum) and treatment measures (such as nebulization with antibiotics
directly into the lungs) may be required.
Prevention:
Vaccinations are available to help prevent kennel cough infection. We
recommend that all dogs be vaccinated as puppies against kennel cough
and be boosted annually (sometimes every 6 months for pets that are
traveling or boarding a lot). Intranasal vaccination may be given as
early as 2 weeks of age and immunity generally lasts 10 to 12 months.
(Usually this vaccine is boosted annually.) The advantage of intranasal
vaccination is that the local immunity is stimulated, right at the site
where the natural infection would be trying to take hold.
It takes 4 days to generate a solid immune response after intranasal
vaccination so it is best if vaccination is given at least 4 days prior
to the exposure. Some dogs will have some sneezing or nasal discharge in
the week following intranasal vaccination.
The viruses Parainfluenza, Adenovirus type 2, and canine distemper, all
members of the Kennel Cough complex, are all covered by the standard
DHLPP vaccine, the basic vaccine for dogs.
VACCINATION IS NOT USEFUL IN A DOG ALREADY INCUBATING KENNEL COUGH
Conclusion:
Kennel cough complex is a common infectious disease that generally
responds to treatment. Regular vaccination can help prevent the disease.
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