Kennel cough (also known as canine infectious tracheobronchitis) is an upper respiratory infection affecting dogs. There are multiple causative agents, the most common being the bacteria Bordetella bronchiseptica (found in 78.7% of cases in Southern Germany), followed by canine parainfluenza virus (37.7% of cases) and to a lesser extent canine coronavirus (9.8% of cases) It is highly contagious; however adult dogs may display immunity to reinfection even under constant exposure. Kennel cough is so named because the infection can spread quickly among dogs in the close quarters of a kennel or animal shelter.
Viral and bacterial causes of canine cough are spread through airborne droplets produced by sneezing and coughing. These agents also spread through contact with contaminated surfaces. Symptoms begin after a several day incubation period post-exposure, and in most cases will clear up on their own. However in young puppies or immunocompromised animals, mixed or secondary infections can progress to lower respiratory infections such as pneumonia. This disease is not a zoonose, i.e. it cannot be transmitted to humans.
The Incubation period is 5–7 days (with a range of 3–10). Symptoms can include a harsh, dry cough, retching, sneezing, snorting, gagging or vomiting in response to light pressing of the trachea or after excitement or exercise. The presence of a fever varies from case to case.
Viral infections such as canine parainfluenza or canine coronavirus are only shed for roughly 1 week following recovery; however respiratory infections involving Bordetella bronchiseptica can be transmissible for several weeks longer. While there was early evidence to suggest that B. bronchiseptica could be shed for many months post-infection, a more recent report places detectable nasal and pharyngeal levels of B. bronchiseptica in 45.6% of all clinically healthy dogs. This has potentially expanded the vector from currently-infected or recently-infected dogs to half the dog population as carriers. To put the relative levels of shedding bacteria into perspective, a study analyzing the shedding kinetics of B. bronchiseptica presents the highest levels of bacterial shedding one week post-exposure, with an order of magnitude decrease in shedding observed every week. This projection places negligible levels of shedding to be expected 6 weeks post-exposure (or ~5 weeks post-onset of symptoms). Dogs which had been administered intranasal vaccine 4 weeks prior to virulent B. bronchiseptica challenge displayed little to no bacterial shedding within 3 weeks of exposure to the virulent strain.
Treatment and prevention
Antibiotics are given to treat any bacterial infection present. Cough suppressants are used if the cough is not productive. Prevention is by vaccinating for canine adenovirus, distemper, parainfluenza, and Bordetella. In kennels, the best prevention is to keep all the cages disinfected. In some cases, such as "doggie daycares" or nontraditional playcare-type boarding environments, it is usually not a cleaning or disinfecting issue, but rather an airborne issue, as the dogs are in contact with each other's saliva and breath. Although most kennels require proof of vaccination, the vaccination is not a fail-safe preventative. Just like human influenza, even after receiving the vaccination, a dog can still contract mutated strains or less severe cases.
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