The Many Causes of Kennel Cough
Kennel cough is the equivalent of the dog’s common cold. Each case of kennel cough typically has more than one cause, including bacteria, viruses or even non-infectious factors such as stress, particles in the air or the extremes of humidity. Kennel cough is usually highly contagious and is found most often in places where dogs congregate, such as dog parks, boarding and grooming facilities and doggie day care.
The main bacterial organisms that contribute to kennel cough are Bordetella bronchiseptica, which is considered to be the most important cause of kennel cough, Mycoplasma spp and Streptococcus. Viruses known to cause kennel cough include canine parainfluenza virushighly contagious respiratory virus, canine adenovirus 2, canine respiratory coronavirus distemper virus, canine herpesvirusvirus of the family Herpesviridae which most importantly causes a fatal hemorrhagic disease in puppies less than two to three weeks old, canine pneumovirus and canine influenza virus. Canine influenza virus is also known as canine flu or dog flu and is an especially contagious form of kennel cough but fortunately is a much less common cause of kennel cough.
Signs of kennel cough range from a mild, self-limiting cough for just a few days to pneumonia. Pneumonia is more likely to develop in puppies or adult dogs whose immune systems are suppressed by stress, disease, poor nutrition or advanced age. A dog with kennel cough may gag at the end of the cough and then cough up a white, foamy fluid, have red eyes and discharge from the eyes and nose, sneeze and/or snort. If the dog with kennel cough has a fever, it may be lethargic (sluggish and apathetic) and have little appetite. Some dogs with milder forms of kennel cough may appear completely normal except for coughing and sneezing. The cough is fairly often, repetitive and usually a hacking cough.
Kennel cough is transmitted by direct dog-to-dog contact through aerosols and droplets coughed into the air by infected dogs, as well objects like toys, bowls, bedding, collars, leashes and kennels. People also can transmit kennel cough to other dogs by not washing their hands after touching a sick dog. However, people cannot get kennel cough from dogs.
Various diagnostic tests can be run on blood and samples taken from the respiratory tract of affected dogs. A recent vaccination can make test results difficult to interpret in some cases by causing false-positive test results.
Your veterinarian will check for pneumonia by using the tests for kennel cough described above, as well as chest X-rays. Most of the time, X-rays can be completed in your veterinarian’s office as well as some bloodwork such as a CBC (complete blood count). Other tests may have to be submitted to an outside laboratory.
Mild cases of kennel cough usually respond to exercise restriction and treatment with cough suppressants and antibioticsa type of antimicrobial drug used in the treatment and prevention of bacterial infections. Though antibiotics may be unnecessary for mild cases that resolve on their own, there is no way to predict which cases will progress to chronic bacterial infection or pneumonia, so they are routinely prescribed for kennel cough. In prolonged and/or severe cases, a culture of the respiratory tract may be performed to determine which antibiotics are most likely to be effective. Vaccines are not thought to be helpful in treating dogs already infected with kennel cough.
Kennel cough and CIV vaccines do not typically prevent infection, but they decrease severity of clinical signs. All kennel cough vaccines seem to have similar effectiveness. While there are more than a dozen bacteria and viruses that can contribute to kennel cough, most kennel cough vaccines contain only one to three of these pathogens (bordetella, adenovirus and parainfluenza). Currently, no vaccines are available for Mycoplasma, Strep zo and the many other bacteria that can contribute to kennel cough.
Vaccines for the viral causes of kennel cough are available and are given as part of the puppy vaccine series, and then every one to three years depending on your veterinarian’s recommendations.
Texas veterinarians routinely recommend kennel cough vaccines for dogs that frequent boarding/breeding kennels, groomers, shelters, dog parks/shows, pet shops/stores and even frequent visits to veterinary clinics. Most boarding facilities may require the CIV vaccine as well as bordetella vaccines prior to agreeing to board the pet.
Wendy Blount, DVM, is a graduate of Texas A&M College of Veterinary Medicine who lives in Nacogdoches, Texas. Dr. Blount practices at Eastex Veterinary Clinic. She is the medical director for O’Mally PET low cost spay-neuter clinic and also gives continuing education seminars.