Canine Kennel Cough         Infectious CanineTracheobronchitis, Bordetella

Kennel Cough in Dogs

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...also called Canine Cough, Bordetellosis and Infectious Canine Tracheobronchitis

Kennel Cough in dogs will stimulate a coarse, dry, hacking cough about three to seven days after the dog is initially infected.  It sounds as if the dog needs to "clear it's throat" and the cough will be triggered by any extra activity or exercise.  Many dogs that acquire Kennel Cough will cough every few minutes, all day long.  Their general state of health and alertness will be unaffected, they usually have no rise in temperature, and do not lose their appetite.  The signs of Canine Cough usually will last from 7 to 21 days and can be very annoying for the dog and the dog's owners.  Life threatening cases of Kennel Cough are extremely rare and a vast majority of dogs that acquire the infection will recover on their own with no medication.  Cough suppressants and occasionally antibiotics are the usual treatment selections.

WHAT IS KENNEL COUGH?
Actually, clinical cases of Kennel Cough are usually caused by several infectious agents working together to damage and irritate the lining of the dog's trachea and upper bronchii.  The damage to the tracheal lining is fairly superficial, but exposes nerve endings that become irritated simply by the passage of air over the damaged tracheal lining.  Once the organisms are eliminated the tracheal lining will heal rapidly. The most common organisms associated with Canine Cough are the bacteria called Bordetella bronchiseptica and two viruses called Parainfluenza virus and Adenovirus and even an organism called Mycoplasma. 

HOW IS IT TRANSMITTED?
The causative organisms can be present in the expired air of an infected dog, much the same way that human "colds" are transmitted.  The airborne organisms will be carried in the air in microscopically tiny water vapor or dust particles.  The airborne organisms, if inhaled by a susceptible dog, can attach to the lining of the trachea and upper airway passages, find a warm, moist surface on which to reside and replicate, and eventually damage the cells they infect. 

The reason this disease seems so common, and is even named "Kennel" cough, is that wherever there are numbers of dogs confined together in an enclosed environment such as a kennel, animal shelter, or indoor dog show, the disease is much more likely to be spread.  The same is true with the "colds" spread from human to human... they are much more likely to occur in a populated, enclosed environment such as an airplane, elevator, or  office.  All it takes for contagion to occur is a single source (infected dog), an enclosed environment, and susceptible individuals in close proximity to the source of the infection.  Infected dogs can spread the organisms for days to weeks even after seeming to have fully recovered!

NOTE:   Even in the most hygienic, well ventilated, spacious kennels the possibility of a dog acquiring Kennel Cough exists. Kennel Cough can be acquired from your neighbor's dog, from a Champion show dog at a dog show, from the animal hospital where your dog just came in for treatment of a cut paw...  Try not to blame the kennel operator if your dog develops Kennel Cough shortly after that weekend stay at the kennel!  There may have been an infected dog, unknown to anyone, that acted as a source for other dogs in the kennel.

Many dogs will have protective levels of immunity to Kennel Cough via minor exposures to the infective organisms and simply will not acquire the disease even if exposed.  Other dogs that may never have had immunizing subtle exposures will be susceptible to the Bordetella bacteria and associated viruses and develop the signs of coughing and hacking.

HOW IS IT TREATED?
Many dogs that contract Kennel Cough will display only minor signs of coughing that may last seven to ten days and will not require any medication at all.  The majority of dogs with the disease continue to eat, sleep, play and act normally... except for that annoying, dry, non-productive coughing that seems so persistent.  It is always a good idea, though, to have any dog examined if coughing is noticed because some very serious respiratory diseases such as Blastomycosis, Valley Fever, Heartworms and even cardiac disease might display similar sounding coughing.  Your veterinarian, through a careful physical exam and questioning regarding the dog's recent environment, will be able to establish if the dog's respiratory signs are from kennel Cough or some other respiratory insult.

Treatment is generally limited to symptomatic relief of the coughing with non-prescription, and occasionally prescription, cough suppressants.  If the dog is running a fever or there seems to be a persistent and severe cough, antibiotics are occasionally utilized to assist the dog in recovering from Kennel Cough.  It can happen that secondary bacterial invaders will complicate a case of Kennel Cough and prolong the recovery and severely affect the upper airway.  Therefore the use of antibiotics is determined on an individual basis.

HOW IS IT PREVENTED?
Many dogs, exposed to all sorts and numbers of other dogs, will never experience the effects of Canine Cough.  Some dog owners, though, prefer to take advantage of the current vaccines available that are quite effective in preventing the disease.  Usually these dog owners will have to board, show, field trial, or otherwise expose their dog to populations of other canines.  Since the chances of exposure and subsequent infection rise as the dog comes in close proximity with other dogs, the decision to vaccinate or not to vaccinate varies with each individual circumstance.  Generally, if your dog is not boarded or going to field trials or dog shows, you may not have a high level of need for vaccinating your dog against Kennel Cough.  If your dog happens to acquire Kennel Cough, it will then have some immunity to subsequent exposures.  The length of time these natural exposures and the vaccinations will produce protective immunity will vary greatly.  How often to vaccinate seems to have a subjective and elusive answer.

Be aware that vaccinating with just the commercial Kennel Cough vaccine alone (contains only the Bordetella agent) may not be fully protective because of the other infectious agents that are involved with producing the disease.  Some of the other agents such as Parainfluenza and Adenovirus are part of the routine multivalent vaccinations generally given yearly to dogs.  The intra-nasal Bordetella vaccine may produce immunity slightly faster than the injectable vaccine if the dog has never been previously vaccinated for kennel Cough. It is generally assumed that the intranasal route of inoculation works the fastest in getting protective levels of immunity established.  However, studies have indicated that in dogs that have been previously immunized by either the intranasal or injectable route and that have some level of immunity already present, vaccination by the injectable route actually boosts immunity faster than the intranasal route.  When the injectable vaccine is given as an annual booster (to boost any immune levels already present) the maximum effects of the vaccine will be achieved by 5 days after the vaccination.  So when should the intranasal route be utilized?  Some veterinarians suggest that it be used only in unvaccinated dogs and in young pups receiving their first vaccination.  In these unvaccinated animals the first immunization would be via the intranasal route and then two additional inoculations by the injectable route are given.  Then yearly injectable inoculations are given to enhance the protective levels of immunity.

NOTE:  If you plan to board your dog, or protect it from exposure, remember to vaccinate a few weeks prior to potential exposure to allow full protective immunity to build up.

One of my most memorable emergency calls occurred late one cold December night.

It involved a dog that was affected by what is misleadingly called kennel cough.  The owner demanded that I look at her dog immediately (it was near midnight) because she was certain that the dog had something caught in his throat.  “He’s been gagging and makes this dry, hacking coughing sound nearly every five minutes” was the report.  The Golden Retriever was still active, alert and was eating normally and so I tried to use that evidence to support my claim that there surely would not be anything actually caught in the dog’s throat.  The owner said they noticed the cough three days ago when they picked the dog up from a two-week stay in a local boarding facility.  Unconvinced that her dog really didn’t fit the category of an “emergency patient”, the owner nevertheless held her ground and we met at the animal hospital.

Dogs with kennel cough, just like the Golden Retriever I evaluated that night, seldom go off feed, seldom become lethargic or withdrawn, and rarely need hospitalization.  They do need evaluation, though; the persistent, hacking, hoarse cough they experience is terribly annoying to them and anyone around them.  The usual course of the cough will persist for two to three weeks and in a great majority of cases will be self-limiting… the dog will recover nicely without medical intervention.  There are exceptions, though, and complications can arise such as pneumonia.  Most veterinarians will utilize antibiotics and cough suppressants to assist the dog’s recovery if a fever is present or if there are signs that a complicating bacterial pneumonia is present.

Kennel cough really has a better name, one that is more descriptive of what is truly happening in the dog.  Henceforth in this column it will be referred to as ITB… infectious tracheobronchitis.  The cause of this disorder of the lining of the trachea and bronchi is usually due to bacteria called Bordetella.  Damage and irritation to the mucous and epithelial cells lining the upper respiratory tract occurs when Bordetella and other organisms set up residence in those cells.  In many cases parainfluenza virus and Adenoviruses will invade the cells along with the bacteria.  That may be precisely why sometimes antibiotics (which rarely have any effect on viruses) seem to be of little help and the dog continues to cough and hack for days.  The veterinarian may well prescribe cough suppressant medication to make the patient more comfortable during the recovery period.

One of the reasons ITB seems more likely to occur in kennels is that the causative organisms are often transported in an airborne fashion without direct contact between an affected dog and a healthy dog.  Airborne moisture, dust, molds, and other solids can transport the organisms long distances.  Even the cleanest kennel environment with good sanitation and ventilation could have a resident dog that has ITB that will act as a source for other unprotected dogs.

I recently spoke to veterinarian Malcolm Kram, associate director, Veterinary Operations at Pfizer Animal Health, a major manufacturer of animal vaccines and drugs, about the environmental aspects of this infection.  “I’m concerned that many dog owners have the concept that ‘kennel cough’ is a disorder that only occurs when an animal is housed in a kennel environment such as a boarding kennel.  We really should be referring to this infection as Infectious Tracheobronchitis, because the truth is that this infection can be acquired from any dog that is harboring the organisms that cause the disease.  Especially in environments such as dog parks, grooming establishments, obedience classes, field trials or other areas where a number of dogs congregate, there can be carriers who potentially could transmit ITB.”  Kram mentioned that even after an affected dog ceases to cough and seems to be fully recovered, some could continue to be carriers and act as a source of exposure for unprotected dogs for as long as fourteen weeks!

Can ITB cause serious trouble?  Kram informs us “Dogs most at risk for serious complications are older dogs with pre-existing health problems such as heart disease, respiratory problems or immune deficiency.  And the short-faced breeds of dogs, dogs with tracheal stenosis and dogs with elongated soft palates can have a very difficult time with a bout of ITB.”  Should house pets that are seldom boarded or visit dog parks be vaccinated?  For the answer to that question Kram stresses the importance for each dog owner to take up the ITB vaccination question with his or her veterinarian.