Kennel cough

This weekend, I was hoping to be racing my first ever dry land sled race, with Frankie, at an NVSDC event near Bendigo. After their very successful Bootcamp two weeks ago, the NVSDC had organised another training day to run on Saturday, followed by the first races of their season tonight and Sunday morning. But instead, J, the dogs and I have had a quiet weekend in Melbourne. We, along with everyone else who attended the Bootcamp, have been asked by the NVSDC to observe a quarantine period this weekend, in an attempt to stop an outbreak of kennel cough.

Firstly, let me say that, fortunately, all our dogs are still, two weeks after the suspected exposure, symptom free and well.

Secondly, we believe that the quarantine was a very sensible precaution and we have been happy to give up a weekend away, believing that this will give us an added sense of safety for the well being of our dogs for the racing season to come.

Kennel cough, or infectious tracheobronchitis, has never been something I've personally experienced, so I immediately hit the internet to find out more about it. And the short version is that kennel cough is a generic description used to describe any cough that dogs can pass around, when they live in a group or visit a boarding kennel.

The long version, is that kennel cough is not a single pathogen, but can be caused by at least five different pathogens that I've found so far - one bacteria and four viruses. That means that, unless a vet actually runs tests to identify the pathogen, its guesswork to figure out the incubation period, contagious period and best treatment. 

From Left: Bordetella bronchiseptica, Adenovirus, parainfluenza, a lung sample with canine coronavirus and Influenza A type H3N8. 

Please note that only one of the pathogens shown above has a binomial species name - B. bronchiseptica  - because only one is a living organism - a bacteria. That's the only one that our magic antibiotics can treat. (BTW cool name - septic lung ??? - wow!) Its actually a very close relative of B. pertussis which causes whooping cough, but unlike B. pertussis, it is resistant to several big groups of antibiotics. Being a gram-negative bacteria, it resistant to penicillin - its outer coating is too tough for the antibiotic to get through.

The other pathogens are all viruses. That means non-living, and therefore hard to treat. If humans get a cold and a cough, how often do the doctors say "fluids and rest"? Because there's nothing else we can do.

The last one there IS an influenza virus - its actually the one that caused the Equine Influenza that shut down a lot of the horse events on the Australian east coast a little while back when it was first introduced to Australia. It has not yet made the jump to humans.  These days we have a choice of influenza anti-virals - Australian Relenza and American Tamiflu - which inhibit the action of the neuraminidase protein (that's the N in the name H3N8) to prevent the virus particles escaping from the upper respiratory cells that they have high-jacked and spreading. These drugs are not available for veterinary use.

So, according to my in-house expert, J, the most common response to kennel cough is to treat the symptoms - the cough. Without a thorough series of tests to determine which pathogen has caused the illness, it is too difficult to deal with the cause. Most owners will dose with cough syrup or other cold and flu remedies, as recommended by their vet, and rest their dogs.

 Moisture droplets from a cough or sneeze can hang in the air, unseen, for up to 20 minutes.

Moisture droplets from a cough or sneeze can hang in the air, unseen, for up to 20 minutes.

Because the cough offers an excellent method to spread any pathogen molecules and toxins from the infected upper respiratory tract, kennel cough is highly contagious. Particles of most viruses can survive on surfaces like door knobs and footpaths. Even when human hands, dog equipment and housing are all disinfected, the airborne particles can still spread around a kennel, doggy day care or, in our case, a camp site. Like all infections, the dogs will usually start being contagious before they show symptoms, but because of the range of causes, the infectious period varies widely.

When a dog  (or horse) with a healthy immune system or current vaccination starts to improve without treatment, this is due to their bodies successfully producing sufficient antibodies to destroy the pathogens within the respiratory tract. This process involves antibodies matching the antigens on the pathogen surfaces forming an antibody-antigen clump which is then destroyed by a macrophage (nature's own Pac Man cells). 

At the same time, the B cells that are producing the antibodies are also producing B memory cells that will remain in the dog's immune system arsenal, ready to repel the next invasion by this particular pathogen. Unfortunately, many dogs seem to suffer from recurrences of kennel cough, especially when a kennel "passes" the pathogen back and forth. Possibly this is due to stress related issues that compromise the B memory cells, or to the mutations of the pathogen requiring new antibodies and new B memory cells, or to secondary infections by other pathogens that can cause the same symptoms. 

Meanwhile, the danger of infection to other dogs is not over once the dogs stop coughing. In many cases, the macrophages will breakdown the pathogen and then expel the particles. This viral "shedding" mimics the natural budding of the virus from its host cells, and can contribute to the viral load found on surfaces. Any virus particles that are still able to burrow into a host cell, may restart the infection.

Of course, like human versions of whooping cough and influenza, dogs can be vaccinated against kennel cough and its many pathogens. In Australia, the C5 vaccination is used to prevent a range of kennel cough and other pathogens, including Bordetella , parainfluenza and distemper. The vaccination is not always a 100% protection, but generally prevents a very severe infection. In most adult, healthy, immunised dogs, kennel cough is not very serious. However, in many very young, elderly or otherwise unwell dogs, it can be dangerous and even fatal.

We're not sure if our dogs were exposed to kennel cough at the NVSDC Bootcamp, as the details of the infected dog have not been released. Its not even clear whether that dog had been exposed before the bootcamp or possibly caught the infection afterwards. However, the NVSDC Committee took the precaution of asking ALL Bootcamp attendees to quarantine their dogs until absolutely certain that they had not caught the cough. If even one infected dog had attended this weekend's planned races, they could have spread the disease to any neighbouring dogs, or dogs with whom borrowed harnesses or other gear were shared. Once the race season is in full swing, there will be race events happening regularly enough that a dog could attend a race and spread the infection before it is even showing symptoms, creating a chain of infections that would eventually put all our dogs at risk.

The NVSDC Committee took action to inform all Bootcamp attendees of the risks, and decided to cancel the event rather than create a situation that could lead to infections spreading amongst the sledding community of Victoria, Canberra, South Australia and New South Wales. Obviously, they and those of us who were preparing to attend were sorry to miss the event, but it was generally felt that it was worth it to avoid the risk. 

Tonight, instead of sleeping in the trailer, I'll be tucked up warm in my bed. And instead of listening to dogs cough, I'm hoping the only sounds I'll hear will be the muted barks they sometimes make as they chase possums in their dreams. 

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